,,by ,,! ,,same ,,au?or4 ,,fun ,,) ,,magnetism4 ,a book & complete outfit = ,sixty-,"o ,exp]im5ts4 ,,fun ,,) ,,electricity4 ,a book & complete outfit = ,sixty ,exp]im5ts4 ,,fun ,,) ,,puzzles4 ,a book & complete outfit = ,f\r ,hundr$ ,puzzles4 ,,fun ,,) ,,soap-,,bubbles4 ,a book & complete outfit = ,fancy ,bubbles & ,films4 ,,hu/le-,,ball4 ,an ,am]ican game4 ,play$ by means ( magic w&s & poli%$ balls ( /eel4 ,,j+o4 ,! great w> game1 includ+ ,,j+o ,,junior4 ,,h[ ,,two ,,boys ,,made ,,_! ,,own ,,electrical ,,app>atus4 ,a book conta9+ complete directions = mak+ all k9ds ( simple app>atus = ! /udy ( elem5t>y electricity4 ,,! ,,/udy ,,( ,,elem5t>y ,,electricity ,,& ,,magnetism ,,by ,,exp]im5t4 ,?is book is design$ z a text-book = amateurs1 /ud5ts1 & o!rs :o wi% to take up a sy/ematic c\rse ( simple exp]im5ts at home or 9 s*ool4 ,,9 ,,prep>ation4 ,,?+s ,a ,,boy ,,%\ld ,,"k ,,ab\t ,,electricity4 ,?is book expla9s1 9 simple1 /raight=w>d language1 _m ?+s ab\t electricity2 ?+s 9 :i* ! ,am]ican boy is int5sely int]e/$2 ?+s he wants to "k2 ?+s he %\ld "k4 ,ask ,y\r ,toy ,deal]1 ,/ation]1 or ,booksell] = our ,books1 ,games1 ,puzzles1 ,educational ,amusem5ts1 ,etc4 ,?omas ,m4 ,/4 ,john1 #djg ,we/ #ea/ ,/41 ,new ,york4 ,! ,/udy ( ,elem5t>y ,electricity & ,magnetism by ,exp]im5t ,conta9+ ,,two ,,hundr$ ,,exp]im5ts ,,p]=m$ ,,) ,,simple1 ,,home-,,made ,,app>atus ,,by ,,?omas ,m4 ,,/4 ,,john1 ,met4 ,e4 ,au?or ( ,fun ,) ,magnetism1 ,fun ,) ,electricity1 ,h[ ,two ,boys ,made ,_! ,own ,electrical ,app>atus1 ,etc4 ,illu/ration3 ,logo ,,new ,,york ,,?omas ,m4 ,,/4 ,,john #djg ,we/ #ea/ ,/reet #aijj ,copyright1 #aijj1 ,by ,,?omas ,m4 ,,/4 ,,john4 ,to ! ,/ud5t4 ,?is book is design$ z a text-book = amateurs1 /ud5ts1 & o!rs :o wi% to take up a sy/ematic c\rse ( elem5t>y electrical exp]im5ts at home or 9 s*ool4 ,! /ud5t is advis$ to beg9 at ! beg9n+1 to p]=m ! exp]im5ts 9 ! ord] giv51 & to und]/& ea* /ep be=e proce$+4 ,c]ta9 pr9ciples & explanations necess>ily prec$e ! practical & p]haps m int]e/+ applications ( ^? pr9ciples4 ,9 select+ ! app>atus = ! exp]im5ts 9 ?is book1 ! au?or has kept con/antly 9 m9d ! fact t ! av]age /ud5t w n buy ! exp5sive pieces usually describ$ 9 text-books4 ,! two hundr$ exp]im5ts giv5 c be p]=m$ ) simple1 inexp5sive app>atus2 9 fact1 ! /ud5t %\ld make at lea/ a "p ( 8 own app>atus4 ,= ! b5efit ( ^? :o wi% to make _! own app>atus1 ! au?or has giv51 ?r\gh\t ! "w1 explanations t w aid 9 ! con/ruction ( c]ta9 pieces especially adapt$ to ^! exp]im5ts4 ,= ^? :o h ! au?or's ,h[ ,two ,boys ,made ,_! ,own ,electrical ,app>atus1 con/ant ref]5ces h be5 made to x z ! ,app>atus ,book1 z ?is conta9s full details = mak+ almo/ all k9ds ( simple app>atus ne$$ 9 ,! ,/udy ( ,elem5t>y ,electricity & ,magnetism by ,exp]im5t4 ,,?omas ,m4 ,,/4 ,,john4 ,new ,york1 ,april1 #aijj4 ,! ,/udy ( ,elem5t>y ,electricity & ,magnetism by ,exp]im5t ,,"p ,i--,,magnetism ,,"p ,,ii--,,/atic ,,electricity ,,"p ,,iii--,,curr5t ,,electricity ,! ,/udy ( ,elem5t>y ,electricity & ,magnetism by ,exp]im5t4 ,,table ,,( ,,cont5ts4 ,,"p ,i4--,,magnetism4 ,,page4 ,,*apt] ,i4 ,iron & ,/eel #c ,introduction4--,k9ds ( iron & /eel4--,exp4 #a1 ,to /udy /eel4--,discussion4--,exp4 #b1 ,to f9d :e!r a piece ( h>d /eel c be made s(t]4--,anneal+4--,exp4 #c1 ,to f9d :e!r a piece ( anneal$ /eel c be h>d5$4--,h>d5+2 ,temp]+4--,exp4 #d1 ,to te/ ! h>d5+ prop]ties ( s(t iron4--,discussion4 ,,*apt] ,,ii4 ,magnets #g ,k9ds ( magnets4--,exp4 #e1 ,to /udy ! horse%oe magnet4--,poles2 ,equator4--,exp4 #f1 ,to asc]ta9 ! nature ( sub/ances attract$ by a magnet4--,magnetic ,bodies2 ,diamagnetic ,bodies4--,practical ,uses ( ,magnets4--,exp4 #g1 ,to /udy ! action ( magnetism ?r\gh v>i\s sub/ances4--,magnetic ,transp>5cy2 ,magnetic ,scre5s4--,exp4 #h1 ,to f9d :e!r a magnet c give magnetism to a piece ( /eel4--,discussion2 ,b> ,magnets4--,exp4 #i1 ,to make small magnets4--,exp4 #aj1 ,to f9d :e!r a freely-sw++ b> magnet t5ds to po9t 9 any p>ticul> direction4--,nor?-seek+ ,poles2 ,s\?-seek+ ,poles2 ,po9t+ ,p[]4--,! ,magnetic ,ne$le2 ,! ,compass4--,exp4 #aa1 ,to /udy ! action ( magnets ^u ea* o!r4--,exp4 #ab1 ,to /udy ! action ( a magnet ^u s(t iron4--,laws ( ,attraction & ,repulsion4--,exp4 #ac1 ,to le>n h[ to produce a desir$ pole at a giv5 end ( a piece ( /eel4--,rule = ,poles4--,our ,compass4--,review2 ,magnetic ,problems4--,exp4 #ad1 ,to f9d :e!r ! poles ( a magnet c be rev]s$4--,discussion2 ,rev]sal ( ,poles4--,exp4 #ae1 ,to f9d :e!r we c make a magnet ) two ,n poles4--,exp4 #af1 ,to /udy ! b> magnet ) two ,n poles4--,discussion2 ,consequ5t ,poles4--,exp4 #ag1 ,to /udy consequ5t poles4 ,exp4 #ah1 ,to /udy ! !ory ( magnetism4--,!ory ( ,magnetism2 ,magnetic ,saturation4--,exp4 #ai1 ,to f9d :e!r s(t iron w p]man5tly reta9 magnetism4--,ret5tivity or ,co]cive ,=ce2 ,residual ,magnetism4--,exp4 #bj1 ,to te/ ! ret5tivity ( s(t /eel4--,discussion4--,exp4 #ba1 ,to te/ ! ret5tivity ( h>d /eel4--,exp4 #bb1 ,to te/ ! effect ( heat ^u a magnet4--,discussion4--,exp4 #bc1 ,to te/ ! effect ( break+ a magnet4--,discussion4 ,,*apt] ,,iii4 ,induc$ ,magnetism #bj ,exp4 #bd1 ,to f9d :e!r we c magnetize a piece ( iron )\t t\*+ x ) a magnet4--,tempor>y ,magnetism2 ,induc$ ,magnetism4--,exp4 #be1 ,to f9d :e!r a piece ( /eel c be p]man5tly magnetiz$ by induction4--,exp4 #bf1 ,to /udy ! inductive action ( a magnet ^u a piece ( s(t iron4--,pol>ization2 ,pole ,pieces4--,exps4 #bg-cj1 ,to /udy pole pieces4 ,,*apt] ,,iv4 ,! ,magnetic ,field #bc ,exp4 #ca1 ,to /udy ! space ar\nd ! magnet1 9 :i* pieces ( iron become tempor>y magnets by induction4--,discussion2 ,! ,magnetic ,field4--,exp4 #cb1 ,to /udy ! magnetic field ( a b> magnet4--,magnetic ,figures2 ,l9es ( ,magnetic ,=ce4--,exps4 #cc-cg1 ,to /udy ! magnetic fields ( v>i\s comb9ations ( b> magnets4--,exps4 #ch-ci1 ,to /udy ! lift+ p[] ( comb9ations ( b> magnets4--,discussion2 ,comp\nd ,magnets4--,exps4 #dj-db1 ,to /udy ! magnetic field ( ! horse%oe magnet4--,discussion2 ,resi/ance to ,l9es ( ,=ce4--,exp4 #dc1 ,to %[ t l9es ( =ce are on all sides ( a magnet4--,discussion4--,exp4 #dd1 ,to /udy a horse%oe magnet ) movable poles4--,discussion2 ,advantages ( ,horse%oe ,magnets4 ,,*apt] ,v4 ,t]re/rial ,magnetism #ca ,! ,magnetism ( ! ,e>?4--,decl9ation4--,exp4 #de1 ,to /udy ! l9es ( =ce above & bel[ a b> magnet plac$ horizontally4--,! ,dip or ,incl9ation ( ! ,magnetic ,ne$le4--,exp4 #df1 ,to /udy ! dip or incl9ation ( ! magnetic ne$le due to ! action ( ! e>?4--,discussion2 ,balanc+ ,magnetic ,ne$les4--,exps4 #dg-dh1 ,to /udy ! inductive influ5ce ( ! e>?4--,discussion4--,natural ,magnets4--,exp4 #di1 ,to te/ ! effect ( twi/+ a wire held nor? & s\? 9 ! e>?'s magnetic field4--,exp4 #ej1 ,to te/ = magnetism 9 b>s ( iron1 tools1 etc4 ,,"p ,,ii4--,,/atic ,,electricity4 ,,*apt] ,,vi4 ,electrification #ci ,"s ,v>ieties ( ,electricity4--,exp4 #ea-eb1 ,to /udy electrification by friction4--,discussion4--,electrifi$ & ,neutral bodies4--,=ce2 ,resi/ance2 ,"w2 ,pot5tial ,en]gy2 ,electrification4--,heat & ,electrification4--,exps4 #ec-ed1 ,to /udy electrical attraction4--,discussion4--,exp4 #ee1 ,to /udy mutual attractions4--,mutual ,attractions4--,exps4 #ef-eh1 ,to /udy electrical repulsions4--,! ,c>bon ,electroscope4--,discussion ( ,exp]im5ts #ef1 #eg1 #eh4--;,exp4 #ei1 ,to /udy ! electrification ( glass4--,que/ions4--,exp4 #fj1 ,to comp>e ! electrification produc$ by ebonite & flannel ) t produc$ by glass & silk4--,discussion4--,laws4 ,,*apt] ,,vii4 ,insulators & ,conductors #dg ,exps4 #fa-fc1 ,to /udy insulators4--,conductors4--,exp4 #fd1 ,to /udy conduction4--,discussion4--,exp4 #fe1 ,to /udy conduction4--,telegraph l9e us+ /atic electricity4--,discussion4--,relation betwe5 conductors & insulators4--,electrics & ,non-electrics4--,exp4 #ff1 ,to /udy ! effect ( moi/ure ^u an insulator4--,discussion4--,exp4 #fg1 ,to te/ ! effects ( moi/ure ^u bodies to be electrifi$4 ,,*apt] ,,viii4 ,*>g+ & ,dis*>g+ ,conductors #eb ,! ,electrophorus4--,exp4 #fh1 ,to le>n h[ to use ! electrophorus4--,exp4 #fi1 ,to /udy *>g+ by conduction4--,exp4 #gj1 ,to /udy pot5tial2 ,electromotive =ce4--,pressure2 ,pot5tial2 ,electromotive =ce2 ,curr5t1 ,sp>k4--,!ories ab\t ,electrifications4--,exp4 #ga1 ,to /udy "s me?ods ( dis*>g+ an electrifi$ body4--,disruptive1 ,conductive & ,convective ,dis*>ges4--,exp4 #gb1 ,to /udy int]mitt5t or /ep-by-/ep dis*>ges4--,discussion4--,exp4 #gc1 ,to asc]ta9 ! location ( ! *>ge ^u an electrifi$ conductor4--,discussion4--,holl[ & ,solid ,conductors4--,exp4 #gd1 ,to /udy ! effect ( po9ts ^u a *>g$ conductor4--,electric ,d5sity4--,electric ,w9d4 ,,*apt] ,,ix4 ,induc$ ,electrification #fj ,electric ,fields2 ,l9es ( ,=ce4--,exp4 #ge1 ,to /udy electric induction4--,electric ,pol>ization2 ,!ory ( ,induction4--,exp4 #gf1 ,to le>n h[ to *>ge a body by induction4--,free & ,b\nd ,electrifications4--,exp4 #gg1 ,to %[ t a neutral body is pol>iz$ be=e x is attract$ by a *>g$ "o4--,pol>ization ,prec$es ,attraction4--,exp4 #gh1 ,to f9d :e!r electric induction w act ?r\gh an insulator4--,dielectrics4--,exp4 #gi1 ,to f9d :e!r a pol>iz$ conductor c act inductively ^u ano!r conductor4--,successive ,induction4--,inductive ,capacity4--,exp4 #hj1 ,to /udy ! action ( ! electrophorus4--,discussion4--,details ( action4--,exp4 #ha1 ,to see1 he>1 & feel ! results ( inductive influ5ce & pol>ization4--,discussion4 ,,*apt] ,x4 ,cond5sation ( ,electrification #fh ,exp4 #hb1 ,to f9d :e!r a l>ge surface w hold m electrification ?an a small "o4--,electrical ,capacity4--,exp4 #hc1 ,to f9d :e!r ! capacity ( a giv5 conductor c be increas$ )\t increas+ its size4--,cond5sation2 ,cond5s]s4--,! ,leyd5 ,j>4--,fulm9at+ ,panes4--,induction ,coil ,cond5s]s4--,subm>9e ,cables4--,exp4 #hd1 ,to /udy ! cond5sation ( electrification4--,discussion4--,exp4 #he1 ,to /udy ! action ( ! cond5s]4--,discussion4--,exp4 #hf1 ,to /udy ! effect ( electrical dis*>ges ^u ! human body4--,%ocks2 ,dis*>g]s4--,exps4 #hg-hh1 ,to %[ ! /rong attraction betwe5 opposite electrifications 9 ! cond5s]4--,discussion4--,exp4 #hi1 ,to %[ h[ ! cond5s] may be sl[ly dis*>g$4--,! ,electric ,*ime4--,exp4 #ij1 ,to asc]ta9 ! location ( a *>ge 9 a cond5s]4--,discussion4--,exp4 #ia1 ,to f9d :e!r any electrification rema9s 9 ! cond5s] aft] x has once be5 dis*>g$4--,residual ,*>ge4--,exp4 #ib1 ,to /udy successive cond5sation2 ! *ime cascade4--,discussion4 ,,*apt] ,,xi4 ,electroscopes #gg ,electroscopes4--,our leaf electroscope4--,exp4 #ic1 ,to /udy ! leaf electroscope2 *>g+ by conduction4--,discussion4--,exp4 #ie1 ,to le>n "s uses ( ! electroscope4--,discussion4--,! ,pro(-plane4 ,,*apt] ,,xii4 ,miscellane\s ,exp]im5ts #ha ,exp4 #if1 ,to %[ t friction always produces two k9ds ( electrification4--,discussion4--,exp4 #ig1 ,to %[ successive sp>ks4--,exp4 #ih1 ,to %[ to ! eye ! /rong attraction betwe5 a *>g$ & a neutral body4--,exp4 #ii1 ,to feel ! /rong attraction betwe5 a *>g$ & a neutral body4--,exp4 #ajj1 ,! human body a frictional electric ma*9e4--,/atic ,electric ,ma*9es4 ,,*apt] ,,xiii4 ,atmosph]ic ,electricity #hd ,atmosph]ic ,electricity4--,lightn+4--,?und]4--,ligh tn+ ,rods4--,causes ( ,atmosph]ic ,electricity4--,/4 ,elmo's ,fire4--,aurora ,borealis4 ,,"p ,,iii4--,,curr5t ,,electricity4 ,,*apt] ,,xiv4 ,,con/ruction ,,& ,,use ,,( ,,app>atus #hi ,exp4 #aja1 ,to /udy ! effect ( ! electric curr5t ^u ! magnetic ne$le4--,electrical ,connections4--,curr5t ,detectors4--,exp4 #ajb1 ,to /udy ! con/ruction & use ( a simple key4--,exp4 #ajc1 ,to /udy ! con/ruction & use ( a simple curr5t rev]s]4--,exp4 #ajd1 ,to /udy ! simple curr5t detector4--,exp4 #aje1 ,to /udy ! con/ruction & use ( ! simple galvanoscope4--,discussion2 ,true ,read+s4--,exp4 #ajf1 ,to /udy ! con/ruction & use ( a simple a/atic ne$le4--,a/atic ,ne$les4--,exp4 #ajg1 ,to /udy ! con/ruction & use ( a simple a/atic galvanoscope4--,a/atic ,galvanoscopes4 ,,*apt] ,,xv4 ,,galvanic ,,cells ,,& ,,batt]ies #ajb ,exp4 #ajh1 ,to /udy ! effect ( dilute sulphuric acid ^u c>bon & v>i\s metals4--,to amalgamate4--,dilute sulphuric acid4--,discussion4--,exp4 #aji1 ,to /udy ! effect ( dilute sulphuric acid ^u v>i\s comb9ations ( metals4--,discussion4--,exp4 #aaj1 ,to /udy ! con/ruction ( a simple ,voltaic or ,galvanic cell4--,! ,electric ,curr5t4--,s\rce ( ! ,electrification4--,! ,electric ,circuit2 ,op5 & ,clos$ ,circuits4--,plates or ,elem5ts4--,direction ( ,curr5t4--,poles or ,electrodes4--,*emical ,action 9 ! ,simple ,galvanic ,cell4--,action 9 ,cell ,us+ ,impure ,z9c2 ,action ,us+ ,pure ,z9c4--,exp4 #aaa1 ,to see :at is meant by local curr5ts 9 ! cell4--,local ,action2 ,local ,curr5ts4--,reasons = ,amalgamat+ ,z9c ,plates4--,exp4 #aab1 ,to /udy ! s+le-fluid ,galvanic ,cell4--,! ,simple ,cell4--,pol>ization ( ,cells4--,effects ( ,pol>ization4--,rem$ies = ,pol>ization2 ,depol>iz]s4--,exp4 #aac1 ,to /udy ! two-fluid ,galvanic ,cell4--,sett+ ,up ! ,two-,fluid ,cell4--,c>e ( ,two-,fluid ,cell4--,copp] ,sulphate ,solution4--,*emical ,action 9 ! ,two-,fluid ,cell4--,v>i\s ,galvanic ,cells2 ,op5 & ,clos$ ,circuit ,cells4--,! ,leclan* ,cell--,dry ,cells4--,! ,bi*romate ( ,pota% ,cell4--,! ,daniell ,cell4--,! ,gravity ,cell4 ,,*apt] ,,xvi4 ,,! ,,electric ,,circuit #aae ,exp4 #aad1 ,to see :at is meant by divid$ circuits & %unts4--,divid$ ,circuits2 ,%unts4--,exp4 #aae1 ,to see :at is meant by %ort circuits4 ,,*apt] ,,xvii4 ,,electromotive ,,=ce #aag ,electromotive ,=ce4--,unit ( ,e4 ,m4 ,f42 ,! ,volt4--,exp4 #aaf1 ,to see :e!r ! ,e4 ,m4 ,f4 ( a cell dep5ds ^u ! mat]ials us$ 9 its con/ruction4--,discussion4--,electromoti ve ,s]ies4--,exp4 #aag1 ,to see :e!r ! ,e4 ,m4 ,f4 ( a cell dep5ds ^u its size4--,discussion4 ,,*apt] ,,xviii4 ,,electrical ,,resi/ance #abj ,resi/ance4--,exp4 #aah1 ,to /udy ! g5]al effect ( resi/ance ^u a curr5t4--,ext]nal ,resi/ance2 ,int]nal ,resi/ance2 ,unit ( ,resi/ance2 ,! ,ohm4--,resi/ance ,coils2 ,resi/ance ,boxes4--,simple ,resi/ance ,coil4--,exp4 #aai1 ,to te/ ! p[] ( v>i\s sub/ances to conduct galvanic electricity4--,conductors & ,nonconductors4--,exp4 #abj1 ,to f9d ! effect ( sulphuric acid ^u ! conductivity ( wat]4--,int]nal ,resi/ance4--,exp4 #aba1 ,to f9d :at effect ! l5g? ( a wire has ^u its electrical resi/ance4--,discussion4--,exp4 #abb1 ,to f9d :at effect ! size 7area ( cross-section7 ( a wire has ^u its electrical resi/ance4--,discussion4--,exp4 #abc1 ,to comp>e ! resi/ance ( a divid$ circuit ) ! resi/ance ( "o ( its bran*es4 ,discussion4--,exp4 #abd1 ,to /udy ! effect ( decreas+ ! resi/ance 9 "o bran* ( a divid$ circuit4--,curr5t 9 ,divid$ ,circuits4 ,,*apt] ,,xix4 ,,measurem5t ,,( ,,resi/ance #acj ,exp4 #abe1 ,to /udy ! con/ruction & use ( a simple ,:eat/one's ,bridge4--,! ,simple ,bridge4--,equipot5tial ,po9ts4--,example4--,exp4 #abf1 ,to measure ! resi/ance ( a wire by means ( ,:eat/one's ,bridge2 ! bridge me?od4--,all[ances = ,connections4--,exps4 #abg-acg1 ,to measure ! resi/ances ( v>i\s wires1 coils1 etc41 by ! bridge me?od4--,table4--,exp4 #ach1 ,to /udy ! effect ( heat ^u ! resi/ance ( metals4--,effect ( ,heat ^u ,resi/ance4--,exp4 #aci1 ,to measure ! resi/ance ( a wire by ! me?od ( sub/itution4--,simple ,rheo/at4--,exp4 #adj1 ,to measure ! ,e4 ,m4 ,f4 ( a cell by comp>ison ) ! two-fluid cell4--,exp4 #ada1 ,to measure ! int]nal resi/ance ( a cell by ! me?od ( opposition4 ,,*apt] ,,xx4 ,,curr5t ,,/r5g? #adb ,/r5g? ( ,curr5t4--,unit ( ,curr5t ,/r5g?2 ,! ,amp]e4--,measurem5t ( ,curr5t ,/r5g?4--,! ,tang5t ,galvanomet]4--,! ,ammet]4--,! ,voltamet]4--,unit ( ,quantity2 ,! ,c\lomb4--,electrical ,horse-p[]2 ,! ,watt4--,ohm's ,law4--,int]nal ,resi/ance & ,curr5t ,/r5g?4--,exp4 #adb1 ,hav+ a cell ) l>ge plates1 to f9d h[ ! /r5g? ( ! curr5t is affect$ by *anges 9 ! position ( ! plates1 ! ext]nal resi/ance be+ small4--,exp4 #adc1 ,same z ,exp4 #adb1 b ) small plates4--,exp4 #add1 ,to f9d :e!r ! *anges 9 curr5t /r5g?1 due to *anges 9 int]nal resi/ance1 are z great :5 ! ext]nal resi/ance is l>ge1 z !y are :5 ! ext]nal resi/ance is small4--,discussion1 ) examples4--,arrangem5t ( ,cells & ,curr5t ,/r5g?4--,cells 9 ,s]ies4--,cells ,abrea/4--,exp4 #ade1 ,to f9d ! be/ way to jo9 two simil> cells :5 ! ext]nal resi/ance is small4--,exp4 #adf1 ,to f9d ! be/ way to jo9 two simil> cells :5 ! ext]nal resi/ance is l>ge4--,be/ ,arrangem5t ( ,cells4 ,,*apt] ,,xxi4 ,,*emical ,,effects ,,( ,,! ,,electric ,,curr5t #aea ,*emical ,action & ,electricity4--,electrolysis4--,exp4 #adg1 ,to /udy ! electrolysis ( wat]4--,composition ( ,wat]4--,electromotive ,=ce ( ,pol>ization4--,exp4 #adh1 ,to coat iron ) copp]4--,exp4 #adi1 ,to /udy ! electrolysis ( a solution ( copp] sulphate4--,electroplat+4--,exp4 #aej1 ,to /udy ! *emi/ry ( electroplat+4--,discussion4--,electrotyp +4--,voltamet]s4--,exp4 #aea1 ,to /udy ! con/ruction & action ( a simple /orage cell4--,second>y or ,/orage ,cells4 ,,*apt] ,,xxii4 ,,electromagnetism #aeh ,electromagnetism4--,exp4 #aeb1 ,to /udy ! l9es ( =ce ab\t a /raight wire c>ry+ a curr5t4--,amp]e's ,rule4--,l9es ( ,=ce ,ab\t ,p>allel ,wires4--,exp4 #aec1 ,to /udy ! l9es ( =ce ab\t a coil ( wire l t ^u ! galvanoscope4--,exp4 #aed1 ,to /udy ! magnetic field ab\t a small coil ( wire4--,coils4--,pol>ity ( ,coils4--,exp4 #aee1 ,to te/ ! attract+ & suck+ p[] ( a magnetiz$ coil or helix4--,exp4 #aef1 ,to f9d :e!r a piece ( /eel c be p]man5tly magnetiz$ by an electric curr5t4--,exp4 #aeg1 ,to /udy ! effect ( a piece ( iron plac$ inside ( a magnetiz$ coil ( wire4 ,,*apt] ,,xxiii4 ,,electromagnets #afe ,electromagnets4--,cores ( ,electromagnets4--,exps4 #aeh-afc1 ,to /udy /raight electromagnets2 ,lift+ p[]2 ,residual magnetism ( core2 ,magnetic tick2 ,magnetic figures2 ,magnetic field4--,horse%oe ,electromagnets4--,use ( ,yoke4--,exp]im5tal ,magnets4--,me?od ( ,jo9+ ,coils4--,exps4 #afd-agc1 ,to /udy horse%oe electromagnets2 ,to te/ ! poles2 ,to /udy ! inductive action ( "o core ^u ! o!r2 ,magnetic figures2 ,p]man5t ,magnetic ,figures2 ,lift+ p[]2 ,residual magnetism :5 magnetic circuit is clos$4--,clos$ ,magnetic ,circuits4 ,,*apt] ,,xxiv4 ,,!rmoelectricity #age ,exp4 #agd1 ,to f9d :e!r electricity c be produc$ by heat4--,home-made ,!rmopile4--,!rmoelectricity4--,pelti] ,effect4--,!rmopiles4 ,,*apt] ,,xxv4 ,,induc$ ,,curr5ts #agh ,electromagnetic ,induction4--,exp4 #age1 ,to f9d :e!r a curr5t c be g5]at$ ) a b> magnet & a holl[ coil ( wire4--,discussion4--,induc$ ,curr5ts & ,"w4--,exp4 #agf1 ,to f9d :e!r a curr5t c be g5]at$ ) a b> magnet & a coil ( wire hav+ an iron core4--,exp4 #agg1 ,to f9d :e!r a curr5t c be g5]at$ ) a horse%oe magnet & a coil ( wire hav+ an iron core4--,induc$ ,curr5ts & ,l9es ( ,=ce4--,exp4 #agh1 ,to f9d :e!r a curr5t c be g5]at$ ) an electromagnet & a holl[ coil ( wire4--,exp4 #agi1 ,to f9d :e!r a curr5t c be g5]at$ ) an electromagnet & a coil ( wire hav+ an iron core4--,discussion ( ,exps4 #agh-agi4--;,exp4 #ahj1 ,to /udy ! effect ( />t+ or /opp+ a curr5t ne> a coil ( wire or o!r clos$ circuit4--,exp4 #aha1 ,to /udy ! effect ( />t+ or /opp+ a curr5t 9 a coil plac$ inside ( ano!r coil4--,discussion ( ,exps4 #ahj-aha4--;,direction ( ,induc$ ,curr5t4--,laws ( ,induction4--,prim>y & ,second>y ,curr5ts4--,exp4 #ahb1 ,to see :at is meant by alt]nat+ curr5ts4--,direct & ,alt]nat+ ,curr5ts4--,self-induction2 ,extra ,curr5ts4 ,,*apt] ,,xxvi4 ,,! ,,production ,,( ,,motion ,,by ,,curr5ts #ahg ,curr5ts & ,motion4--,exp4 #ahc1 ,motion produc$ ) a holl[ coil & a piece ( iron4--,exp4 #ahd1 ,motion ) holl[ coil & b> magnet4--,exp4 #ahe1 ,motion ) electromagnet & piece ( iron4--,exp4 #ahf1 ,motion ) electromagnet & b> magnet4--,exp4 #ahg1 ,motion ) electromagnet & horse%oe magnet4--,exp4 #ahh1 ,motion ) two electromagnets4--,discussion ( ,exps4 #ahc-ahh4--;,exp4 #ahi1 ,rot>y motion ) a holl[ coil ( wire & a p]man5t magnet4--,exp4 #aij1 ,rot>y motion ) an electromagnet & a p]man5t magnet4--,discussion ( ,exps4 #ahi-aij4 ,,*apt] ,,xxvii4 ,,applications ,,( ,,electricity #aib ,?+s ,electricity ,c ,d4--,exp4 #aia1 ,to /udy ! action ( a simple telegraph s\nd]4--,discussion4--,telegraph ,l9e2 ,connections4--,op]ation ( ,l9e4--,exp4 #aib1 ,to /udy ! action ( ! relay on telegraph l9es4--,! ,relay4--,exp4 #aic1 ,to /udy ! action ( a two-pole telegraph in/rum5t4--,exp4 #aid1 ,to /udy ! action ( a simple s+le ne$le telegraph in/rum5t4--,exp4 #aie1 ,to /udy ! action ( a simple automatic contact break]1 or curr5t int]rupt]4--,automatic ,curr5t ,int]rupt]s4--,exp4 #aif1 ,to /udy ! action ( a simple electric bell1 or a buzz]4--,electric ,bells & ,buzz]s4--,exp4 #aig1 ,to /udy ! action ( a simple telegraph record]4--,exp4 #aih1 ,to /udy ! action ( a simple annunciator4--,discussion4--,exp4 #aii1 ,to /udy ! %ock+ effects ( ! extra curr5t4 ,induction ,coils4--,action ( ,induction ,coils4--,trans=m]s4--,! ,dynamo4--,! ,electric ,motor4--,exp4 #bjj1 ,to /udy ! action ( ! telephone4--,! ,telephone4--,! ,bell1 or ,magneto-transmitt]4--,! ,receiv]4--,! ,c>bon ,transmitt]4--,induction ,coils 9 ,telephone ,"w4--,electric ,light+ & ,heat+4--,arc ,lamps4--,! ,inc&esc5t ,lamp4 ,,*apt] ,,xxviii4 ,,wire ,,tables #bjh ,,app>atus ,,li/ #baj ,,index #bae ,,magnetism ,a ,few ,dont's = ,"y ,/ud5ts4 ,don't fail to make at lea/ a "p ( y\r own app>atus2 !re is a great deal ( satisfaction & pleasure 9 home-made app>atus4 ,don't exp]im5t 9 all p>ts ( ! h\se1 if work+ at home4 ,fit up a small room = y\r d51 & c>ry ! key4 ,don't beg9 an exp]im5t be=e y really "k :at y are try+ to d4 ,read ! directions c>efully1 !n beg94 ,don't ru% ?r\gh an exp]im5t to see :at happ5s at ! end ( x4 ,see :at happ5s at ea* /ep1 & notice e little ?+ t seems unusual4 ,don't try to d all p>ts ( an exp]im5t at ! same "t4 ,und]/& "o "p1 !n proce$4 ,don't fail to ask y\rself que/ions1 & =m an op9ion ab\t ! results ( an exp]im5t be=e y read :at ! au?or has to say ab\t x4 ,don't fail to keep a note-book4 ,keep all ! data & ari?metical "w = future ref]5ce4 ,don't leave ! app>atus ar\nd aft] y h f9i%$ ! day's "w4 ,,"p ,i4--,,magnetism4 ,,*apt] ,i4 ,,iron ,,& ,,/eel4 #a4 ,introduction4 ,we %\ld "k some?+ ab\t iron & /eel at ! />t1 because we are to use !m 9 ne>ly e exp]im5t4 ,! success ) "s ( ! exp]im5ts w dep5d l>gely ^u ! quality ( ! iron & /eel us$4 ,:5 we buy a piece ( iron f ! blacksmi?1 we get m ?an iron = our money4 ,hidd5 9 ?is iron are o!r sub/ances 7c>bon1 phosphorus1 silicon1 etc471 :i* are call$ impurities by ! *emi/4 ,if all ! impurities 7 tak5 out ( ! iron1 h[ev]1 we %\ld h no?+ b a p[d] left2 ?is ! *emi/ w\ld call *emically pure iron1 b x w\ld be ( no value :atev] to ! blacksmi? or me*anic4 ,! impurities 9 iron & /eel are j :at are ne$$ to hold ! p>ticles ( iron toge!r1 & to make !m valuable4 ,by regulat+ ! am\nt ( c>bon1 phosphorus1 etc41 manufactur]s c make diff]5t grades & qualities ( iron or /eel4 ,:5 c>bon is unit$ ) ! pure iron1 we get :at is commonly call$ iron4 #b4 ,k9ds ( ,iron & ,/eel4 ,ca/ iron is ! mo/ impure =m ( iron4 ,/oves1 l>ge kettles1 flatirons1 etc41 are made ( ca/ iron4 ,wr\ght iron is ! pure/ =m ( comm]cial iron4 ,x usually comes 9 b>s or rods4 ,blacksmi?s hamm] ^! into %apes to use on wagons1 ma*9]y1 etc4 ,/eel conta9s m c>bon ?an wr\ght iron1 & less ?an ca/ iron4 ,s(t /eel is v mu* l wr\ght iron 9 appe>ance1 & x is us$ l wr\ght iron4 ,h>d /eel has m c>bon 9 x ?an s(t /eel4 ,tools1 ne$les1 etc41 are made ( ?is4 ,,exp]im5t #a4 ,to /udy /eel4 ,app>atus4 ,a /eel sew+-ne$le 7,no4 #a74;,a ,footnote ,a3 ,,note4 ,ea* piece ( app>atus us$ 9 ! foll[+ exp]im5ts has a numb]4 ,see ,app>atus li/ at ! back ( ?is book = details4 ,! numb]s giv5 "u ,app>atus1 9 ea* exp]im5t1 ref] to ?is li/4 #c4 ,directions4 7,a7 ,b5d a sew+-ne$le until x breaks4 ,is ! /eel brittle8 7,b7 ,if y h a file1 te/ ! h>dness ( ! ne$le4 #d4 ,discussion4 ,ne$le /eel is usually ( good quality4 ,x w be v useful 9 _m exp]im5ts4 ,d y "k h[ to make ! ne$le s(t]8 ,,exp]im5t #b4 ,to f9d :e!r a piece ( h>d /eel c be made s(t]4 ,illu/ration3 ,fig4 #a4 ,app>atus4 ,fig4 #a4 ,a ne$le2 a cork1 ,ck 7,no4 #b72 light$ c&le 7,no4 #c74 ,! bottom ( ! c&le %\ld be w>m$ & /uck to a pa/ebo>d base4 #e4 ,directions4 7,a7 ,/ick ! po9t ( ! ne$le into ,ck1 ,fig4 #a1 !n hold ! ne$le 9 ! flame until x is r$-hot4 7,! upp] "p ( ! flame is ! hotte/47 7,b7 ,all[ ! ne$le to cool 9 ! air4 7,c7 ,te/ ! brittl5ess ( ! /eel by b5d+ x4 ,te/ its h>dness ) a file 7,exp4 #a74 #f4 ,anneal+4 ,?is process ( s(t5+ /eel by fir/ heat+ x & !n all[+ x to cool sl[ly1 is call$ anneal+4 ,all pieces ( iron & /eel are1 ( c\rse1 h>d2 b y h le>n$ t "s pieces are mu* h>d] ?an o!rs4 ,,exp]im5t #c4 ,to f9d :e!r a piece ( anneal$ /eel c be h>d5$4 ,app>atus4 ,! ne$le j anneal$ & b5t2 cork1 etc41 ( ,exp4 #b2 a glass ( cold wat]4 #g4 ,directions4 7,a7 ,heat ! b5t portion ( ! ne$le 9 ! c&le flame 7,exp4 #b7 until x is r$-hot1 !n imm$iately plunge ! ne$le into ! wat]4 7,b7 ,te/ its brittl5ess & h>dness1 z 9 ,exp4 #b4 #h4 ,h>d5+2 ,temp]+4 ,good /eel is a v valuable mat]ial2 ! same piece may be made h>d or s(t at w4 ,by sudd5 cool+1 ! /eel becomes v h>d4 ,?is process is call$ h>d5+1 b x makes ! /eel too brittle = _m purposes4 ,by temp]+ is meant ! lett+ d[n ( ! /eel f ! v h>d /ate to any desir$ degree ( h>dness4 ,?is may be done by sudd5ly cool+ ! /eel :5 at ! "r temp]ature1 x n be+ hot en\gh to produce extreme h>dness4 7,! approximate temp]ature ( hot /eel c be told by ! colors :i* =m on a clean surface4 ,^! are due to oxides :i* =m z ! /eel gradually rises 9 temp]ature47 ,,exp]im5t #d4 ,to te/ ! h>d5+ prop]ties ( s(t iron4 ,app>atus4 ,a piece ( s(t iron wire ab\t #c 94 7#g4e cm47 long 7,no4 #d72 ! c&le1 wat]1 etc41 ( ,exp4 #c4 #i4 ,directions4 7,a7 ,te/ ! wire by b5d+ & fil+4 7,b7 ,heat ! wire 9 ! c&le flame z y did ! ne$le 7,fig4 #a71 !n cool x sudd5ly ) ! wat]4 ,/udy ! results4 #aj4 ,discussion4 ,s(t iron conta9s mu* less c>bon ?an /eel4 ,! h>d5+ quality :i* /eel has is due to ! prop] am\nt ( c>bon 9 x4 ,if y h p]=m$ ! exp]im5ts s f>1 y w be mu* m able to und]/& lat] ones1 & y w see :y we are oblig$ to use s(t iron = "s p>ts ( electrical app>atus1 & h>d /eel = o!r p>ts4 ,,*apt] ,,ii4 ,,magnets4 #aa4 ,k9ds ( ,magnets4 ,among ! v>ieties ( magnets :i* we %all discuss1 are ! natural1 artificial1 tempor>y1 p]man5t1 b>1 horse%oe1 comp\nd1 & electro-magnet4 ,illu/ration3 ,fig4 #b4 ,! ,horse%oe ,magnet1 ,h ,m 7,fig4 #b71 is ! mo/ popul> =m ( small magnets4 ,! r$ pa9t has no?+ to d ) ! magnetism4 ,! piece1 ,a1 is call$ its armature1 & is made ( s(t iron1 :ile ! magnet itself %\ld be made ( ! be/ /eel1 prop]ly h>d5$4 ,! armature %\ld always be 9 place :5 ! magnet is n 9 use1 & c>e %\ld be tak5 to ?or\ghly clean ! ends ( ! magnet be=e replac+ ! armature4 ,! horse%oe magnet is artificial1 & x is call$ a p]man5t magnet1 because x reta9s its /r5g? = a long "t1 if prop]ly c>$ =4 ,,exp]im5t #e4 ,to /udy ! horse%oe magnet4 ,app>atus4 ,fig4 #b4 ,! horse%oe magnet1 ,h ,m 7,no4 #af74 #ab4 ,directions4 7,a7 ,remove ! armature1 ,a1 f ! magnet1 !n move ,a ab\t ^u ,h ,m to see 7#a7 if ! curv$ "p ( ,h ,m has any attraction = ,a1 & 7#b7 to see if !re is any attraction = ,a at po9ts betwe5 ! curve & ! extreme ends ( ,h ,m4 #ac4 ,poles2 ,equator4 ,! ends ( a magnet are call$ its poles4 ,! end m>k$ ) a l9e1 or an ,n1 %\ld be ! nor? pole4 ,! unm>k$ end is ! s\? pole4 ,n & ,s are abbreviations = nor? & s\?4 ,! c5tral "p1 at :i* !re seems to be no magnetism1 is call$ ! neutral po9t or equator4 ,,exp]im5t #f4 ,to asc]ta9 ! nature ( sub/ances attract$ by a magnet4 ,app>atus4 ,! horse%oe magnet1 ,h ,m 7,fig4 #b72 silv]1 copp]1 & nickel co9s2 iron fil+s 7,no4 #ag71 nails1 tacks1 p9s1 ne$les2 pieces ( brass1 lead1 copp]1 t91 etc4 7,ord9>y t9 is really %eet iron cov]$ ) t947 ,use ! v>i\s batt]y plates = ! diff]5t metals4 #ad4 ,directions4 7,a7 ,try ! effect ( ,h ,m ^u ! above sub/ances1 & ^u any o!r sub/ances ?\ght (4 #ae4 ,magnetic ,bodies2 ,diamagnetic ,bodies4 ,sub/ances :i* are attract$ by a magnet are said to be magnetic4 ,a piece ( s(t iron wire is magnetic1 al?\gh n a magnet4 ,v /rong magnets %[ t nickel1 oxyg51 & a few o!r sub/ances n conta9+ iron1 are also magnetic4 ,"s elem5ts are actually repell$ by a p[]ful magnet2 ^! are call$ diamagnetic bodies4 ,x is ?\ght t all bodies are m or less affect$ by a magnet4 #af4 ,practical ,uses ( ,magnets4 ,_m practical uses are made ( magnets1 su* z ! automatic pick+ out ( small pieces ( iron f gra9 be=e x is gr\nd into fl\r1 & ! sep>ation ( iron f o!r metals1 etc4 ,! mo/ important uses ( magnets are 9 ! compass & 9 connection ) ! electric curr5t1 z 9 ma*9es l dynamos & motors4 7,see exp]im5ts ) electro-magnets47 ,,exp]im5t #g4 ,to /udy ! action ( magnetism ?r\gh v>i\s sub/ances4 ,app>atus4 ,horse%oe magnet1 ,h ,m2 a %eet ( /iff pap]2 pieces ( %eet glass1 iron1 z9c1 copp]1 lead1 ?9 wood1 etc42 sew+-ne$le4 7,a t9 box may be us$ = ! iron1 & batt]y plates = ! o!r metals47 #ag4 ,directions4 7,a7 ,place ! ne$le ^u ! pap] & move ,h ,m ab\t imm$iately "u x4 7,b7 ,9 place ( ! pap]1 try wood1 glass1 etc4 7,c7 ,inv5t an exp]im5t to %[ t magnetism w act ?r\gh y\r h&4 7,d7 ,inv5t an exp]im5t to %[ t magnetism w act ?r\gh wat]4 #ah4 ,magnetic ,transp>5cy2 ,magnetic ,scre5s4 ,sub/ances1 l pap]1 are said to be transp>5t to magnetism4 ,iron does n all[ magnetism to pass ?r\gh x z readily z pap] & glass2 9 fact1 ?ick iron may act z a magnetic scre54 ,,exp]im5t #h4 ,to f9d :e!r a magnet c give magnetism to a piece ( /eel4 #ai4 ,note4 ,y h se5 t ! horse%oe magnet c lift nails1 iron fil+s1 etc42 y h us$ ?is lift+ p[] to %[ t ! magnet 0 really a magnet1 & n m]ely an ord9>y piece ( iron pa9t$ r$4 ,c we give "s ( its magnetism to ano!r piece ( /eel8 ,c we pass ! magnetism along f "o piece ( /eel to ano!r8 ,app>atus4 ,! horse%oe magnet1 ,h ,m2 two sew+-ne$les t h nev] be5 ne> a magnet2 iron fil+s4 #bj4 ,directions4 7,a7 ,te/ ! ne$les = magnetism ) ! iron fil+s1 & be sure t !y are n magnetiz$4 7,b7 ,remove ! armature1 ,a1 f ,h ,m1 !n t\* ! po9t ( "o ( ! ne$les to "o pole ( ,h ,m4 7,c7 ,lay ,h ,m aside1 & te/ ! po9t ( ! ne$le = magnetism4 7,d7 ,if y f9d t ! ne$le is magnetiz$1 rub its po9t ^u ! po9t ( ! o!r ne$le2 !n te/ ! po9t ( ! second ne$le = magnetism4 #ba4 ,discussion2 ,b> ,magnets4 ,a piece ( good /eel w attract iron aft] m]ely t\*+ a magnet4 ,to ?or\ghly magnetize x1 h[ev]1 a m]e t\* is n suffici5t4 ,!re are sev]al ways ( mak+ magnets1 dep5d+ ^u ! size1 %ape1 & /r5g? desir$4 ,= ^! exp]im5ts1 ! /ud5t ne$s only a good horse%oe magnet1 or1 bett] /ill1 ! electro-magnets describ$ lat]2 ) ^! any numb] ( small magnets may be made4 ,/raight magnets are call$ b> magnets4 ,,exp]im5t #i4 ,to make small magnets4 ,app>atus4 ,fig4 #c4 ,! horse%oe magnet1 ,h ,m2 sew+-ne$les2 iron fil+s4 7,see ,app>atus ,book1 ,pg4 #adj1 = v>i\s k9ds ( /eel suitable = small magnets47 #bb4 ,directions4 7,a7 ,hold ,h ,m 7,fig4 #c7 9 ! left h&1 its poles be+ upp]mo/4 ,grasp ! po9t ( ! ne$le ) ! "r h&1 & place its po9t ^u ! ,n or m>k$ pole ( ,h ,m4 7,b7 ,pull ! ne$le along 9 ! direction ( its l5g? 7see ! arr[71 cont9u+ ! motion until its head is at lea/ an in* f ! pole4 7,c7 ,raise ! ne$le at lea/ an in* above ,h ,m1 l[] x to its =m] position 7,fig4 #c71 & repeat ! op]ation #c or #d times4 ,d n slide ! ne$le back & =? ^u ! pole1 & be c>eful n to let x accid5tally t\* ! ,s pole ( ,h ,m4 7,d7 ,te/ ! ne$le = magnetism ) iron fil+s1 & save x = ! next exp]im5t4 ,illu/ration3 ,fig4 #c4 ,illu/ration3 ,fig4 #d4 ,,exp]im5t #aj4 ,to f9d :e!r a freely-sw++ b> magnet t5ds to po9t 9 any p>ticul> direction4 ,app>atus4 ,fig4 #d4 ,a magnetiz$ sew+-ne$le 7,exp4 #i72 ! flat cork1 ,ck 7,no4 #b72 a di% ( wat]4 7,y c use a tumbl]1 b a l>g] di% is bett]47 #bc4 ,note4 ,an oily sew+-ne$le may be float$ )\t ! cork by c>efully l[]+ x to ! surface ( ! wat]4 ,all magnets1 pieces ( iron & /eel1 knives1 etc41 %\ld be remov$ f ! table :5 try+ su* exp]im5ts4 ,:y8 #bd4 ,directions4 7,a7 ,place ! little b> magnet 7! ne$le7 ^u ! float+ cork1 turn x 9 v>i\s positions1 & note ! result4 #be4 ,nor?-seek+ ,poles2 ,s\?-seek+ ,poles2 ,po9t+ ,p[]4 ,x %\ld be not$ t ! po9t sw+s to ! nor?1 provid$ ! ne$le is magnetiz$ z direct$ 9 ,exp4 #i4 ,?is is call$ ! nor?1 or nor?-seek+ pole4 ,! ,n-seek+ pole is sometimes call$ ! m>k$ pole4 ,= conv5i5ce1 we %all h]eaft] speak ( ! ,n-seek+ pole z ! ,n pole1 & ( ! ,s-seek+ pole z ! ,s pole4 ,we %all h]eaft] speak ( ! t5d5cy :i* a b> magnet has to po9t ,n & ,s1 z its po9t+ p[]4 ,an unmagnetiz$ ne$le has no po9t+ p[]4 #bf4 ,! ,magnetic ,ne$le2 ,! ,compass4 ,a small b> magnet1 support$ ^u a pivot1 or susp5d$ s t x may freely turn1 is call$ a magnetic ne$le4 ,:5 balanc$ ^u a pivot hav+ "u x a graduat$ circle m>k$ ,n1 ,e1 ,s1 ,w1 etc41 x is call$ a compass4 ,^! h be5 us$ = c5turies4 7,see ,app>atus ,book = ,home-made ,magnetic ,ne$les47 ,,exp]im5t #aa4 ,to /udy ! action ( magnets ^u ea* o!r4 ,app>atus4 ,two magnetiz$ sew+-ne$les 7magnetiz$ z 9 ,exp4 #i72 ! cork1 etc41 ( ,exp4 #aj4 #bg4 ,directions4 7,a7 ,float ea* little b> magnet 7ne$les7 sep>ately to locate ! ,n poles4 7,b7 ,leave "o magnet ^u ! cork1 & ) ! h& br+ ! ,n pole ( ! o!r magnet imm$iately ov] ! ,n pole ( ! float+ "o4 ,note ! result4 7,c7 ,try ! effect ( two ,s poles ^u ea* o!r4 7,d7 ,:at is ! result :5 a ,n pole ( "o is br\ght ne> a ,s pole ( ! o!r8 ,,exp]im5t #ab4 ,to /udy ! action ( a magnet ^u s(t iron4 ,app>atus4 ,a magnetiz$ sew+-ne$le2 cork1 etc41 ( ,exp4 #aj2 a piece ( s(t iron wire1 #c 94 long2 iron fil+s4 #bh4 ,directions4 7,a7 ,te/ ! wire = magnetism ) fil+s4 ,be sure t x is n magnetiz$4 ,if x %[s any magnetism1 twi/ x ?or\ghly be=e us+4 7,exp4 #ai47 7,b7 ,float ! magnetiz$ ne$le 7,exp4 #aj71 !n br+ ! end ( ! wire ne> "o pole ( ! ne$le & !n ne> ! o!r pole4 7,c7 ,place ! wire ^u ! cork1 hold ! ne$le 9 ! h& & exp]im5t4 #bi4 ,laws ( ,attraction & ,repulsion4 ,f exp]im5ts #aa & #ab are d]iv$ ^! laws3 7#a7 ,l poles repel ea* o!r2 7#b7 ,unlike poles attract ea* o!r2 7#c7 ,ei!r pole attracts & is attract$ by unmagnetiz$ iron or /eel4 ,! attraction betwe5 a magnet & a piece ( iron or /eel is mutual4 ,attraction1 alone1 simply indicates t at lea/ "o ( ! bodies is magnetiz$2 repulsion proves t bo? are magnetiz$4 ,,exp]im5t #ac4 ,to le>n h[ to produce a desir$ pole at a giv5 end ( a piece ( /eel4 ,app>atus4 ,same z 9 ,exp4 #i4 #cj4 ,directions4 7,a7 ,magnetize a sew+-ne$le 7,exp4 #i7 by rubb+ x ^u ! ,n pole ( ,h ,m f po9t to head4 ,float x & locate its ,n pole4 7,b7 ,take ano!r ne$le t has n be5 magnetiz$1 & rub x on ! same pole 7,n7 f head to po9t4 ,locate its ,n pole4 7,c7 ,magnetize ano!r ne$le by rubb+ x f po9t to head ^u ! ,s pole ( ,h ,m2 locate its ,n pole4 ,c y n[ det]m9e1 be=eh&1 h[ ! poles ( ! ne$le magnet w be arrang$8 #ca4 ,rule = ,poles4 ,! end ( a piece ( /eel :i* la/ t\*es a ,n pole ( a magnet1 = example1 becomes a ,s pole4 #cb4 ,our ,compass 7,no4 #ah74 ,:ile ! float+ magnetic ne$le describ$ 9 ,exp4 #aj1 & %[n 9 ,fig4 #d1 does v well1 x w be f\nd m conv5i5t to use a compass :5ev] poles ( pieces ( /eel are to be te/$4 ,fig4 #e %[s m]ely ! cov] ( ! box :i* s]ves z a base = ! magnetic ne$le furni%$4 ,we %all h]eaft] speak ( ?is app>atus z our compass1 ,o ,c4 7,see ,app>atus ,book1 ,*ap4 ,,vii1 = v>i\s =ms ( home-made magnetic ne$les & compasses47 #cc4 ,review2 ,magnetic ,problems4 ,to be sure t y und]/& & rememb] :at 0 le>n$ 9 ,exp4 #aa1 d ^! problems3 #a4 ,us+ ! ,s pole ( ! horse%oe magnet1 magnetize a ne$le s t its head w become a ,n pole4 ,te/ ) float+ cork1 z 9 ,exp4 #aa4 #b4 ,us+ ! ,n pole ( ! horse%oe magnet1 magnetize a ne$le s t its head %all be a ,s pole4 ,te/4 #c4 ,magnetize two ne$les1 "o on ! ,n & "o on ! ,s pole ( ! horse%oe magnet1 9 su* a way t ! two po9ts w repel ea* o!r4 ,te/4 ,if ! /ud5t _c d ^! little problems at once1 & te/ ! results satisfactorily to himself1 he %\ld /udy ! previ\s exp]im5ts aga9 be=e proce$+4 ,illu/ration3 ,fig4 #e4 ,illu/ration3 ,fig4 #f4 ,,exp]im5t #ad4 ,to f9d :e!r ! poles ( a magnet c be rev]s$4 ,app>atus4 ,fig4 #f4 ,! horse%oe magnet1 ,h ,m2 a ?9 wire nail1 ,w ,n1 #b 94 7#e cm47 long2 a piece ( /iff pap]1 cut z %[n1 to hold ,w ,n2 ?read ) :i* to susp5d ! pap]2 compass1 ,o ,c 7,no4 #ah74 #cd4 ,directions4 7,a7 ,magnetize ,w ,n s t its po9t %all be a ,s pole4 ,te/ ) ,o ,c to make sure t y are "r4 7,b7 ,sw+ ,w ,n 9 ! pap] 7,fig4 #f71 !n sl[ly br+ ! ,s pole ( ,h ,m ne> its po9t4 ,note result4 7,c7 ,quickly br+ ! ,s pole ( ,h ,m ne> ! po9t4 ,is ,w ,n /ill repell$8 ,has its ,s pole be5 rev]s$8 #ce4 ,discussion2 ,rev]sal ( ,poles4 ,! poles ( weak magnets may be easily rev]s$4 ,?is (t5 occurs :5 ! app>atus is mix$ toge!r4 ,x is always be/1 be=e beg9n+ an exp]im5t1 to remagnetize ! pieces ( /eel :i* h already s]v$ z magnets4 ,! same may be %[n by magnetiz+ a ne$le1 rubb+ x fir/ 9 "o direction1 & !n 9 ano!r ^u ! magnet1 te/+1 9 ea* case1 ! poles produc$4 ,,exp]im5t #ae4 ,to f9d :e!r we c make a magnet ) two ,n poles4 ,app>atus4 ,! horse%oe magnet1 ,h ,m2 an unmagnetiz$ sew+-ne$le2 compass1 ,o ,c 7,no4 #ah74 #cf4 ,note4 ,y h already le>n$ t ! pol>ity ( a weak magnet c be *ang$ 7,exp4 #ad74 ,c y ?9k ( any me?od by :i* two ,n poles c be made 9 "o piece ( /eel8 #cg4 ,directions4 7,a7 ,place ! ne$le ^u ,h ,m1 z 9 ,fig4 #g4 7,b7 ,keep+ ! "p1 ,c1 9 contact ) ! ,n pole ( ,h ,m1 & us+ ! ,n pole ( ,h ,m z a pivot1 turn ! ne$le end = end s t its head w be 9 contact ) ! ,s pole ( ,h ,m4 7,c7 ,pull ! ne$le /raight f ,h ,m1 be+ c>eful n to slide x 9 ei!r direction4 7,d7 ,te/ ! pol>ity ( ! ends ) ,o ,c 7,fig4 #e71 & save x = ! next exp]im5t4 ,illu/ration3 ,fig4 #g4 ,illu/ration3 ,fig4 #h4 ,,exp]im5t #af4 ,to /udy ! b> magnet ) two ,n poles4 ,app>atus4 ,! /range magnet j made 7,exp4 #ae72 iron fil+s2 compass1 ,o ,c 7,no4 #ah74 #ch4 ,directions4 7,a7 ,spr9kle fil+s ov] ! :ole l5g? ( ! ne$le & !n raise x 7,fig4 #h74 7,b7 ,break ! ne$le at its c5t]1 & te/1 ) ,o ,c1 ! two new ends produc$ at t po9t4 ,rememb] t repulsion is ! te/ = pol>ity4 #ci4 ,discussion2 ,consequ5t ,poles4 ,iron fil+s cl+ to a magnet :]e poles are locat$4 ,9 ?is case1 two small magnets 7 made 9 "o piece ( /eel2 !y _h a common ,s pole at ! c5t]4 ,! po9t+ p[] 7 #be7 ( su* a magnet is v slight2 w\ld x h any po9t+ p[] if we c\ld make ! end poles ( equal /r5g?8 ,int]m$iate poles1 l ^? 9 ! ne$le j discuss$1 are call$ consequ5t poles4 ,practical uses are made ( consequ5t poles 9 ! con/ruction ( motors & dynamos4 ,,exp]im5t #ag4 ,to /udy consequ5t poles4 ,app>atus4 ,an unmagnetiz$ sew+-ne$le2 horse%oe magnet1 ,h ,m 7,no4 #af72 iron fil+s 7,no4 #ag72 compass 7,no4 #ah74 #dj4 ,directions4 7,a7 ,let w1 x1 y1 & z /& = f\r places along ! body ( ! ne$le1 w be+ at its po9t & z at its head4 7,b7 ,t\* w ) ! ,n pole ( ,h ,m1 x ) ! ,s pole1 y ) ! ,n pole1 & z ) ! ,s pole4 ,d n slide ,h ,m along on ! ne$le1 j t\* ! ne$le z direct$4 7,c7 ,cov] ! ne$le ) fil+s1 !n lift x4 ,,exp]im5t #ah4 ,to /udy ! !ory ( magnetism4 ,app>atus4 ,a ?9 b> magnet1 ,b ,m 7,no4 #ba72 iron fil+s2 a %eet ( pap]4 ,fig4 #i %[s simply ! edge ( ,b ,m & ! pap]4 ,b ,m %\ld be magnetiz$ z direct$ 9 ,exp4 #i4 ,illu/ration3 ,fig4 #i4 #da4 ,directions4 7,a7 ,spr9kle "s iron fil+s ^u a %eet ( pap]4 7,b7 ,br+ "o pole ( ,b ,m 9 contact ) ! fil+s 7,fig4 #i71 & lightly sweep x ?r\gh !m sev]al times1 always 9 ! same direction4 ,are ! fil+s simply pu%$ ab\t8 7,c7 ,d ! same ) a /ick1 & comp>e ! result ) t produc$ ) ,b ,m4 #db4 ,!ory ( ,magnetism2 ,magnetic ,saturation4 ,?is br++ into l9e ! p>ticles ( iron indicates t ea* p>ticle became a magnet4 ,?is exp]im5t %\ld aid 9 und]/&+ :at is ?\ght to take place :5 /eel is magnetiz$4 ,! pile ( fil+s repres5ts ! body to be magnetiz$1 & ea* little fil+ /&s = a p>ticle ( t body4 ,a b> ( /eel is compos$ ( extremely small p>ticles1 call$ molecules4 ,!y are v close toge!r & d n move f place to place z easily z ! pieces ( fil+s4 ,a magnet1 h[ev]1 :5 prop]ly rubb$ ^u ! /eel1 seems to h p[] to make ! molecules po9t 9 ! same direction4 ,?is produces an effect ^u ! :ole b>4 ,ea* molecule ( ! /eel is suppos$ to be a magnet4 ,:5 ^! little magnets pull toge!r1 ! :ole b> becomes a /rong magnet4 ,:5 a magnet is j>r$1 & ! little magnetiz$ molecules are mix$ aga91 !y pull 9 all sorts ( directions ^u ea* o!r4 ,?is less5s ! attraction = outside bodies4 ,/eel is said to be saturat$1 :5 x conta9s z mu* magnetism z possible4 ,a piece ( /eel becomes slightly long] :5 magnetiz$4 ,x is ?\ght1 by _m1 t !re is a curr5t ( electricity ar\nd ea* molecule1 mak+ a little magnet ( x4 7,see electro-magnets47 ,,exp]im5t #ai4 ,to f9d :e!r s(t iron w p]man5tly reta9 magnetism4 ,app>atus4 ,a piece ( s(t iron wire1 #c or #d 94 7#g4e to #aj cm47 long 7,no4 #d72 ! horse%oe magnet1 ,h ,m2 iron fil+s2 flat cork1 ,f ,c 7,no4 #b71 & ! di% ( wat] us$ 9 ,exp4 #aj 7,fig4 #d74 #dc4 ,directions4 7,a7 ,magnetize ! wire 7,exp4 #i74 ,notice t ! wire cl+s /rongly to ,h ,m4 7,b7 ,te/ ! lift+ p[] ( ! little wire magnet by see+ ab\t h[ _m iron fil+s its poles w raise4 7,c7 ,te/ ! po9t+ p[] 7 #be7 ( ! wire by float+ x on ,f ,c 7,fig4 #d74 7,d7 ,hold+ "o end ( ! wire 9 ! h&1 ?or\ghly j> x by /rik+ ! o!r end sev]al times aga9/ a h>d surface4 7,e7 ,te/ ! lift+ & po9t+ p[]s1 z 9 ,b & ,c4 #dd4 ,ret5tivity or ,co]cive ,=ce2 ,residual ,magnetism4 ,s(t iron loses mo/ ( its magnetism :5 simply remov$ beyond ! action ( a magnet4 ,we say t x does n reta9 magnetism2 t is1 x has v little ret5tivity or co]cive =ce4 ,?is is an important fact1 ! action ( _m electric ma*9es & in/rum5ts dep5d+ ^u x4 ,a slight am\nt ( magnetism rema9s1 h[ev]1 9 ! s(te/ iron1 aft] remov+ x f a magnet4 ,?is is call$ residual magnetism4 ,a piece ( iron may %[ poles1 :5 te/$ ) ! compass1 al?\gh x may h almo/ no po9t+ p[]4 ,,exp]im5t #bj4 ,to te/ ! ret5tivity ( s(t /eel4 ,app>atus4 ,a wire nail1 ,w ,n 7,no4 #ai72 horse%oe magnet1 ,h ,m2 iron fil+s2 flat cork1 ,f ,c2 ! di% ( wat] 7,exp4 #aj1 ,fig4 #d74 #de4 ,directions4 7,a7 ,) ,h ,m magnetize ! nail2 ?is is made ( s(t /eel4 7,b7 ,te/ ! lift+ & po9t+ p[]s ( ,w ,n 7,exp4 #ai74 7,c7 ,/rike ,w ,n sev]al times ) a hamm] to j> x4 7,d7 ,aga9 te/ its lift+ & po9t+ p[]s4 #df4 ,discussion4 ,s(t /eel has a great] ret5tivity ?an s(t iron4 ,x conta9s less c>bon ?an ca/ or tool /eel1 & is call$ mild /eel or ma*9]y /eel4 ,y d n want s(t /eel = p]man5t magnets4 ,,exp]im5t #ba4 ,to te/ ! ret5tivity ( h>d /eel4 ,app>atus4 ,a h>d /eel sew+-ne$le 7,no4 #a72 o!r articles us$ 9 ,exp4 #bj4 #dg4 ,directions4 7,a7 ,magnetize ! ne$le ) ,h ,m4 7,b7 ,te/ its lift+ & po9t+ p[]s 7,exp4 #ai74 7,c7 ,hamm] ! ne$le & te/ aga9 z 9 7,b74 ,,exp]im5t #bb4 ,to te/ ! effect ( heat ^u a magnet4 ,app>atus4 ,a magnetiz$ sew+-ne$le2 ! c&le1 cork1 etc41 ( ,exp4 #b4 7,see ,fig4 #a47 #dh4 ,directions4 7,a7 ,te/ ! ne$le = magnetism4 7,b7 ,/ick ! ne$le into ! cork 7,fig4 #a71 & heat x until x is r$-hot4 7,c7 ,te/ ! ne$le aga9 = magnetism4 7,d7 ,see if y c aga9 magnetize ! ne$le4 #di4 ,discussion4 ,heat+ a body is suppos$ to ?or\ghly /ir up its molecules4 ,j>r+ or twi/+ a magnet t5ds to weak5 x4 7,see ,exp4 #ai47 ,! molecules ( /eel d n move ab\t or *ange _! relative positions z readily z ^? ( s(t iron4 ,:5 ! molecules ( h>d /eel are once arrang$1 by magnetiz+ !m1 = example1 !y /rongly resi/ any outside influ5ces :i* t5d to mix !m up aga94 ,a magnet does n attract a piece ( r$-hot iron4 ,! p>ticles ( ! hot iron are suppos$ to vibrate too rapidly to be br\ght into l9e2 t is1 ! iron _c become pol>iz$ by induction4 7,see ,exp4 #bd47 ,,exp]im5t #bc4 ,to te/ ! effect ( break+ a magnet4 ,app>atus4 ,a magnetiz$ sew+-ne$le2 iron fil+s2 compass1 ,o ,c 7,no4 #ah74 ,illu/ration3 ,fig4 #aj4 #ej4 ,directions4 7,a7 ,break ! little b> magnet 7ne$le71 & te/ ! two new ends produc$ = magnetism1 ) ! iron fil+s4 7,fig4 #aj74 7,b7 ,t\* ! two new poles toge!r to see :e!r !y are l or unlike4 7,c7 ,te/ ! nature ( ! poles ) ,o ,c 7,fig4 #e7 7,d7 ,break "o ( ! halves & te/ its p>ts4 #ea4 ,discussion4 ,! above results agree ) ! !ory t ea* molecule is a magnet 7,exp4 #ah74 ,no matt] into h[ _m pieces a magnet is brok51 ea* "p becomes a magnet4 7,fig4 #aj74 ,?is %[s t ^? molecules ne> ! equator ( ! magnet really h magnetism4 ,_! en]gy1 h[ev]1 is all us$ ^u ! adjo9+ molecules2 h5ce no ext]nal bodies are attract$ at t po9t4 ,,*apt] ,,iii4 ,,induc$ ,,magnetism4 ,illu/ration3 ,fig4 #aa4 ,,exp]im5t #bd4 ,to f9d :e!r we c magnetize a piece ( iron )\t t\*+ x ) a magnet4 ,app>atus4 ,horse%oe magnet1 ,h ,m2 iron fil+s1 ,i ,f 7,fig4 #aa74 #eb4 ,directions4 7,a7 ,hold ! armature ( ! magnet 9 a v]tical position 7,fig4 #aa71 its l[] end be+ directly 9 a little pile ( iron fil+s4 7,b7 ,br+ ! ,n pole ( ,h ,m ne> ! upp] end ( ,a1 b d n let !m t\* ea* o!r4 7,c7 ,keep+ ,a & ! pole ( ,h ,m ! same di/ance ap>t1 lift !m4 ,d any fil+s cl+ to ,a8 7,d7 ,)\t mov+ or j>r+ ,a1 take ,h ,m away f x & note result ^u ! fil+s4 #ec4 ,tempor>y ,magnetism2 ,induc$ ,magnetism4 ,! armature1 ,a1 0 induc$ to become a magnet )\t ev5 t\*+ ,h ,m4 ,its magnetism 0 tempor>y1 h[ev]1 z ! fil+s dropp$ z soon z ! inductive action ( ,h ,m 0 remov$4 ,a small am\nt ( residual magnetism 7#dd7 rema9$ 9 ,a4 ,s(t iron is exce$+ly valuable1 because x has v little ret5tivity 7#dd71 & because x c be easily magnetiz$ by induction4 ,! armature 0 made ( s(t iron4 ,x _h induc$ magnetism4 ,x 0 a tempor>y magnet4 ,,exp]im5t #be4 ,to f9d :e!r a piece ( /eel c be p]man5tly magnetiz$ by induction4 ,app>atus4 ,an unmagnetiz$ sew+-ne$le2 horse%oe magnet1 ,h ,m2 iron fil+s2 %eet ( /iff pap]4 #ed4 ,directions4 7,a7 ,te/ ! ne$le = magnetism4 7,b7 ,place ! unmagnetiz$ ne$le ^u ! pap]1 !n move ,h ,m ab\t imm$iately "u x1 s t ! ne$le w be attract$4 7,c7 ,te/ ! ne$le aga9 = p]man5t magnetism4 ,illu/ration3 ,fig4 #ab4 ,,exp]im5t #bf4 ,to /udy ! inductive action ( a magnet ^u a piece ( s(t iron4 ,app>atus4 ,horse%oe magnet1 ,h ,m2 iron fil+s1 ,i ,f2 a piece ( s(t iron wire ab\t an in* long1 ,i ,w 7,fig4 #ab71 plac$ ^u ! ,n pole ( ,h ,m2 compass1 ,o ,c 7,no4 #ah71 7 #cb74 #ee ,directions4 7,a7 ,te/ ! l[] end ( ,i ,w = magnetism ) ,i ,f4 7,b7 ,leav+ ,i ,w ^u ! ,n pole ( ,h ,m1 te/ ! pole at ! l[] end ( ,i ,w ) ,o ,c1 to det]m9e :e!r x is ,n or ,s4 7,c7 ,j> ,i ,w 7,exp4 #ai71 !n place x ^u ! ,s pole ( ,h ,m1 & aga9 te/ ! pol>ity ( ! l[] end4 #ef4 ,pol>ization2 ,pole ,pieces4 ,! wire1 ,i ,w 7,fig4 #ab71 0 act$ ^u by induction 7,exp4 #bd7 & behav$ l a magnet4 ,poles 7 produc$ 9 x1 s we say t ! wire 0 pol>iz$4 ,pieces ( iron1 plac$ ^u ! poles ( a magnet1 are call$ pole pieces4 ,x %\ld be not$ t ! l[] end ( ! wire has a pole l ! pole ( ,h ,m1 to :i* x is atta*$4 ,,exp]im5ts #bg-cj4 ,to /udy pole pieces4 ,app>atus = ,exp]im5ts #bg-cj4 ,horse%oe magnet1 ,h ,m2 s(t iron wires2 iron fil+s1 ,i ,f4 #eg4 ,directions4 7,a7 ,susp5d two wires1 ea* ab\t an in* long 7,fig4 #ac7 f "o pole ( ,h ,m4 ,d _! l[] ends attract or repel ea* o!r8 ,illu/ration3 ,fig4 #ac4 ,illu/ration3 ,fig4 #ad4 ,,exp]im5t #bh4 #eh4 ,directions4 7,a7 ,place ! two wires j us$ s t "o %all cl+ to ! ,n pole ( ,h ,m1 & ! o!r to ! ,s pole ( ,h ,m 7,fig4 #ad74 7,b7 ,br+ ! l[] ends ( ! wires ne> ea* o!r4 ,d !y attract or repel ea* o!r8 ,,exp]im5t #bi4 #ei4 ,directions4 7,a7 ,b5d a #b-;in* iron wire1 z 9 ,fig4 #ae1 & place x ^u ! poles ( ,h ,m4 7,b7 ,see if its c5tral "p1 m>k$ ,x1 w /rongly attract fil+s4 ,illu/ration3 ,fig4 #ae4 ,illu/ration3 ,fig4 #af4 ,,exp]im5t #cj4 #fj4 ,directions4 7,a7 ,b5d ! wire j us$ a little m1 & place its ends ^u "o pole ( ,h ,m 7,fig4 #af74 7,b7 ,see if ! iron fil+s & small wires w cl+ to its c5tral "p4 ,,*apt] ,,iv4 ,,! ,,magnetic ,,field4 ,,exp]im5t #ca4 ,to /udy ! space ar\nd a magnet1 9 :i* pieces ( iron become tempor>y magnets by induction4 ,app>atus4 ,a b> magnet1 ,b ,m 7,no4 #ba72 a compass 7,no4 #ah72 a %eet ( /iff pap] ab\t #a ft4 7#cj cm47 squ>e1 ) a c5t] l9e1 ,c ,l1 drawn p>allel to "o ( its sides 7,fig4 #af-a_/b71 & ) ano!r l9e1 ,e ,w1 drawn p]p5dicul> to ,c ,l4 7,see ,app>atus ,book1 ,*ap4 ,,vi41 = v>i\s ways ( mak+ home-made p]man5t magnets47 #fa4 ,directions4 7,a7 ,lay ! pap] ^u ! table1 & place ! compass ov] ! c5t] ( ! l9e1 ,c ,l1 previ\sly drawn4 7,b7 ,place ! eye directly ov] ! compass-ne$le1 !n turn ! pap] until ! l9e is ,n & ,s2 t is1 until ! l9e is p>allel to ! l5g? ( ! ne$le4 ,p9 ! pap] to ! table to hold its c5t] l9e ,n & ,s4 7,c7 ,place ,b ,m ^u ! pap]1 z %[n 7,fig4 #af-a_/b71 its ,n pole to ! nor?1 & its c5t] at ! cross l9e1 ,e ,w4 ,illu/ration3 ,fig4 #af-a_/b4 7,d7 ,sl[ly move ! compass entirely ar\nd & ne> ,b ,m1 & note ! v>i\s positions tak5 by ! ne$le4 ,note especially ! way 9 :i* its ,n pole po9ts4 ,?is is to get a g5]al idea ( ! action ( ! ne$le4 7,e7 ,place ! compass 9 ! position m>k$ #a1 :i* is on ,e ,w1 ab\t #a 94 f ! l9e1 ,c ,l4 ,press ! wood5 support d[n firmly ^u ! pap] to %[1 by ! d5t made 9 ! pap] by ! p9-head1 ! exact place on ! pap] t is "u ! c5t] ( ! compass-ne$le4 ,be=e remov+ ! compass f ?is position1 look d[n ^u x aga91 & make a dot on ! pap] ) a p5cil directly "u ea* end ( ! ne$le4 ,remove ! compass1 & draw a l9e ?r\gh ! d5t & ! two dots j made4 ,?is w %[ a plan ( ! exact position ( ! ne$le4 7,f7 ,repeat ?is = ! v>i\s po9ts m>k$ #b1 #d1 #f 94 f ,c ,l1 always m>k+ on ! plan ! position ( ! ,n pole ( ! ne$le4 ,d ! same ) ! o!r po9ts m>k$ on ,fig4 #af-a_/b by dots1 & /udy ! result+ diagram4 #fb4 ,discussion2 ,! ,magnetic ,field4 ,! compass-ne$le 0 decid$ly affect$ all ar\nd ,b ,m 7,fig4 #ag71 %[+ t induction c take place 9 a consid]able space ar\nd a magnet2 ?is space is call$ ! magnetic field ( ! magnet4 ,let u consid] "o position tak5 by ! compass-ne$le 9 ! field ( ,b ,m 7,fig4 #ag71 z1 = example1 ! "o 9 :i* ! ne$le has be5 made black4 ,! ,s pole ( ! black ne$le is attract$ by ! ,n pole ( ,b ,m1 & is repell$ by ! ,s pole ( ,b ,m4 ,! ,n pole ( ! compass-ne$le is attract$ by ! ,s pole ( ,b ,m1 & is repell$ by ,b ,m's ,n pole4 ,! position :i* x takes1 !re=e1 is due to ! action ( ^! #d =ces1 toge!r ) its t5d5cy to po9t ,n & ,s4 ,illu/ration3 ,fig4 #ag4 ,e magnet has a c]ta9 magnetic field1 ) its l9es ( =ce pass+ ?r\gh ! surr\nd+ air 9 c]ta9 def9ite positions4 ,z soon1 h[ev]1 z a piece ( iron or ano!r magnet is br\ght )9 ! field1 ! orig9al position ( ! l9es ( =ce is *ang$4 ,?is has to be consid]$ 9 ! con/ruction ( electrical ma*9]y4 ,,exp]im5t #cb4 ,to /udy ! magnetic field ( a b> magnet4 ,app>atus4 ,a %eet ( /iff pap]2 iron fil+s1 ,i ,f2 b> magnet1 ,b ,m 7,no4 #ba72 a sift] = ! fil+s 7,no4 #bd72 7,see ,app>atus ,book1 #dh1 #di1 #ej1 = home-made sift]s47 #fc4 ,directions4 7,a7 ,place ,b ,m ^u ! table1 & lay ! pap] ov] x4 7,b7 ,) ! sift] spr9kle "s fil+s ^u ! pap] directly ov] ,b ,m1 !n tap ! pap] g5tly1 to assi/ ! p>ticles to take f9al positions4 ,/udy ! results4 #fd4 ,magnetic ,figures2 ,l9es ( ,magnetic ,=ce4 ,! fil+s cle>ly indicat$ ! ext5t & nature ( ! magnetic field ( ,b ,m4 ,y %\ld notice h[ ! fil+s radiate f ! poles1 & h[ !y =m curves f "o pole to ! o!r4 ,!y make ^u ! pap] a magnetic figure4 ,ea* p>ticle ( ! fil+s becomes a little magnet1 by induction 7,exp4 #bd71 & takes a position :i* dep5ds ^u attractions & repulsions1 z discuss$ 9 ,exp4 #ca4 ,magnetism seems to rea* out 9 l9es f ! poles ( a magnet4 ,! position & direction ( "s ( ! l9es are %[n by ! l9es ( fil+s4 ,!y are v di/9ct ne> ! poles1 & are consid]$1 = conv5i5ce1 to />t f ! ,n pole ( a magnet1 :]e !y sep>ate4 ,!y !n pass ?r\gh ! air on all sides ( ! magnet1 & f9ally ent] x aga9 at ! ,s pole4 ,^! l9es are call$ l9es ( =ce or l9es ( magnetic induction4 ,! poles mu/ n be consid]$ m]e po9ts at ! ends ( a magnet4 ,z %[n by magnetic figures1 ! l9es ( magnetic induction fl[ f a consid]able portion ( ! magnet's ends4 ,,exp]im5ts #cc-cg4 ,to /udy ! magnetic fields ( v>i\s comb9ations ( b> magnets4 ,app>atus = ,exps4 #cc-cg4 ,two b> magnets1 ,b ,m 7,nos4 #ba1 #bb72 an iron r+1 ,i ,r 7,no4 #bc72 iron fil+s1 ,i ,f2 a %eet ( /iff pap]2 ! sift] 7,no4 #bd74 #fe4 ,note4 ,! /ud5t w f9d x v helpful to make ! magnetic figures ( ! comb9ations giv54 ,?or\ghly magnetize ! b> magnets ^u an electro-magnet1 or ^u a /rong horse%oe magnet1 & m>k _! ,n poles 9 "s way4 ,! ,n poles may be m>k$ by /ick+ a small piece ( pap] to !m4 #ff4 ,directions4 7,a7 ,arrange ! two magnets1 ,b ,m1 z 9 ,fig4 #ah1 ) _! unlike poles ab\t an in* ap>t4 7,! dott$ circle indicates ! iron r+ to be us$ 9 ! next exp]im5t4 ,ab\t a qu>t]1 only1 ( ! magnets are %[n47 7,b7 ,place ! pap] ov] ! magnets1 & sift fil+s ^u x imm$iately ov] ! unlike poles4 ,note p>ticul>ly ! l9es ( fil+s betwe5 ,n & ,s4 7,c7 ,make a sket* ( ! result4 7,see exp]im5ts ) electromagnets1 & ! illu/rations ( magnetic figures ) !m47 ,,exp]im5t #cd4 #fg4 ,directions4 7,a7 ,leav+ ! opposite poles an in* ap>t1 z 9 ,exp4 #cc1 place ! iron r+1 ,i ,r 7,no4 #bc71 betwe5 !m 7,fig4 #ah1 dott$ circles74 7,b7 ,place ! pap] ov] x all1 & spr9kle fil+s ^u x to get ! magnetic figure4 7,c7 ,make a sket* ( ! result+ figure1 & comp>e x ) ! figure made 9 ,exp4 #cc4 ,:y d ! l9es ( =ce appe> indi/9ct 9 ! c5t] ( ! r+ & ar\nd x8 7,see #gd47 ,illu/ration3 ,fig4 #ah4 ,illu/ration3 ,fig4 #ai4 ,,exp]im5t #ce4 #fh4 ,directions4 7,a7 ,arrange ! two b> magnets1 z 9 ,exp4 #cc1 b ) _! two ,n poles an in* ap>t4 7,b7 ,make ! magnetic figure ( ! comb9ation4 ,d ! l9es ( =ce fl[ f "o ,n pole directly to ! ,n pole ( ! o!r8 ,d ! p>ticles ( fil+s rea*+ out f "o ,b ,m attract or repel ^? f ! o!r ,b ,m8 ,,exp]im5t #cf4 #fi4 ,directions4 7,a7 ,place ! two b> magnets side by side1 s t _! unlike poles %all be arrang$ z 9 ,fig4 #ai4 7,b7 ,make ! magnetic figure4 ,,exp]im5t #cg4 #gj4 ,directions4 7,a7 ,turn "o ,b ,m end = end1 s t _! l poles %all be ne> ea* o!r1 b o!rwise arrang$ z 9 ,fig4 #ai4 7,b7 ,make & /udy ! magnetic figure4 ,,exp]im5ts #ch-ci4 ,to /udy ! lift+ p[] ( comb9ations ( b> magnets4 ,app>atus = ,exps4 #ch-ci4 ,two b> magnets1 ,b ,m 7,no4 #ba1 #bb71 ( ab\t equal /r5g?2 iron fil+s1 ,i ,f4 #ga4 ,directions4 7,a7 ,f9d out ab\t h[ _m fil+s y c lift ) ! ,n pole ( "o magnet4 7,b7 ,place ! two magnets toge!r 7,fig4 #bj71 _! l poles be+ 9 contact2 !n see :e!r ! two ,n poles w lift m or less fil+s ?an "o pole4 ,illu/ration3 ,fig4 #bj4 ,,exp]im5t #ci4 #gb4 ,directions4 7,a7 ,remove all fil+s f ! two magnets j us$1 & hold !m tightly toge!r 7,fig4 #bj71 ) _! unlike poles 9 contact4 7,b7 ,comp>e ! am\nt ( fil+s y c lift at "o end ( ?is comb9ation ) t lift$ 9 ,exp4 #ch 7,a7 & 7,b74 #gc4 ,discussion2 ,comp\nd ,magnets4 ,_m l9es ( =ce pass into ! air f two l poles4 ,su* a comb9ation is call$ a comp\nd magnet4 ,a piece ( ?9 /eel c be magnetiz$ m /rongly 9 proportion to its weight ?an a ?ick piece1 because ! magnetism does n seem to p5etrate beyond a c]ta9 di/ance into ! /eel4 ,?9 /eel may be magnetiz$ practically ?r\gh & ?r\gh4 ,a ?ick magnet has b a cru/ ( magnetiz$ molecules2 9 fact1 a ?ick magnet may be greatly weak5$ by eat+ ! outside cru/ away ) acid4 ,by rivet+ sev]al ?9 b> or horse%oe magnets toge!r1 ?ick p]man5t magnets ( consid]able /r5g? are made4 #gd4 ,l9es ( =ce1 9 pass+ f ! ,n to ! ,s pole ( a magnet1 meet a resi/ance 9 ! air1 :i* does n c>ry or conduct !m z easily z iron or /eel4 ,9 ! arrangem5t ( ,exp4 #ci ! l9es ( =ce are n oblig$ to pu% _! way ?r\gh ! air1 z ea* magnet s]ves z a return conductor = ! l9es ( =ce ( ! o!r4 ,ei!r magnet may be consid]$ an armature = ! o!r4 ,to %[ 9 ano!r way t few l9es ( =ce pass into ! air1 ! /ud5t may lay ! above comb9ation ^u ! table & make a magnetic figure4 7,see ,app>atus ,book1 p4 #ch1 = me?od ( mak+ home-made comp\nd magnets47 ,9 ! case :]e a r+ 0 plac$ betwe5 ! poles ( two b> magnets 7,exp4 #cd71 ! l9es ( =ce f ! ,n pole jump$ across ! fir/ air-space4 ,!y !n disappe>$ 9 ! body ( ! r+1 until !y 7 oblig$ to jump across ! second air-space1 to get to ! ,s pole4 ,! weakness ( ! field 9 ! c5tral space 0 cle>ly %[n by ! fil+s4 ,!re 7 no /ray l9es ( =ce pass+ ?r\gh ! air1 because x 0 easi] = !m to g ?r\gh ! iron r+4 ,?is w be discuss$ aga9 "u ,dynamos & ,motors4 7,see also #gh47 ,,exp]im5ts #dj-db4 ,to /udy ! magnetic field ( ! horse%oe magnet4 ,app>atus = ,exps4 #dj-db4 ,horse%oe magnet1 ,h ,m2 iron fil+s1 ,i ,f2 %eet ( /iff pap]4 #ge4 ,directions4 7,a7 ,place ,h ,m1 ) its armature remov$1 flat ^u ! table1 & cov] x ) ! pap]2 !n make ! magnetic figure4 7,exp4 #cb47 7,b7 ,comp>e ! numb] ( well-def9$ curves at ! poles ) ! numb] at ! equator4 ,,exp]im5t #da4 #gf4 ,directions4 7,a7 ,make ! magnetic figure ( ,h ,m ) its armature 9 place4 7,b7 ,is ! attraction = outside bodies increas$ or decreas$ by plac+ ! armature on ,h ,m8 ,,exp]im5t #db4 #gg4 ,directions4 7,a7 ,lay ,h ,m flat ^u ! table1 & place "o or two mat*es betwe5 its poles & ! armature2 cov] ) pap] z be=e1 & make ! magnetic figure4 ,d l9es ( =ce /ill pass ?r\gh ! armature8 #gh4 ,discussion2 ,resi/ance to l9es ( ,=ce4 ,x is evid5t1 f ! la/ #c exp]im5ts1 t l9es ( =ce w pass ?r\gh iron :5ev] possible1 on _! way f ! ,n to ! ,s pole ( a magnet4 ,:5 ! armature ( a horse%oe magnet is 9 place1 mo/ ( ! l9es ( magnetic induction cr[d toge!r & pass ?r\gh x r ?an pu% _! way ?r\gh ! air4 ,air is n a good conductor ( l9es ( =ce2 & ! magnet has to d "w to ov]come ! resi/ance ( ! air1 :5 ! armature is remov$1 9 ord] to complete ! magnetic circuit4 ,?is "w causes a magnet to become gradually weak]4 ,! s(t iron armature is an excell5t conductor ( l9es ( =ce2 x completes ! magnetic circuit s p]fectly t v little "w is left = ! magnet to d4 ,,exp]im5t #dc4 ,to %[ t l9es ( =ce are on all sides ( a magnet4 ,app>atus4 ,our compass1 ,o ,c 7,no4 #ah72 horse%oe magnet1 ,h ,m2 glass tumbl]1 ,g ,t2 %eet ( /iff pap]2 iron fil+s1 ,i ,f4 ,arrange z 9 ,fig4 #ba4 ,h ,m may be support$ 9 a v]tical position by plac+ pap]1 or a h&k]*ief1 "u x4 ,! poles %\ld j t\* ! /iff pap] plac$ ov] ! tumbl]4 ,illu/ration3 ,fig4 #ba4 #gi4 ,directions4 7,a7 ,spr9kle iron fil+s ^u ! pap]1 & /udy ! result+ magnetic figure4 7,b7 ,place ,o ,c ^u ! pap] 9 diff]5t positions4 ,does ! magnetic ne$le always come to re/ ab\t p>allel to ! l9es ( fil+s8 #hj4 ,discussion4 ,! /ud5t %\ld keep 9 m9d ! fact t ! fil+s 9 ! magnetic figure %[ ! approximate ext5t & =m ( ! magnetic field simply 9 "o plane4 ,if ! pap] 7 held 9 "s o!r position ne> ! magnet 79 a tilt$ position1 = example17 ! l9es ( fil+s w\ld n be ! same z ^? produc$ 9 ,exp4 #dj-db4 ,! l9es ( =ce come out ( e side ( ! ,n pole4 ,:5 a magnetic ne$le is plac$ 9 any magnetic field1 its ,n pole po9ts 9 ! direction 9 :i* ! l9es ( =ce are pass+2 t is1 x po9ts t[>ds ! ,s pole ( ! magnet produc+ ! field4 ,,exp]im5t #dd4 ,to /udy a horse%oe magnet ) movable poles4 ,app>atus4 ,a n>r[ /rip ( spr+ /eel1 ,s ,s 7,no4 #be72 iron fil+s1 ,i ,f4 #ha4 ,directions4 7,a7 ,magnetize ! spr+ /eel1 ,s ,s4 7,b7 ,b5d ,s ,s until its poles are ab\t #a_/d 94 ap>t1 !n us+ x z a horse%oe magnet1 & keep+ its poles ! same di/ance ap>t1 see ab\t h[ _m fil+s y c lift4 7,c7 ,clean ! poles ( ,s ,s1 press !m tightly toge!r1 !n aga9 te/ its lift+ p[] ) fil+s4 ,illu/ration3 ,fig4 #bb4 #hb4 ,discussion2 ,advantages ( ,horse%oe ,magnets4 ,:5 ! opposite poles ( ! flexible magnet are press$ toge!r1 ! l9es ( =ce d n h to pass ?r\gh ! air2 !re is v little attraction = outside bodies4 ,! same effect is produc$ ) ! armature 7,exp4 #da74 ,a horse%oe magnet has a /rong attraction = its armature1 because x has a d\ble p[] to induce & to attract4 ,suppose ! ,n pole ( a b> magnet1 ,b ,m 7,fig4 #bb71 be plac$ ne> "o end ( a piece ( iron1 z1 = example1 ! armature1 ,a4 ,a w become a tempor>y magnet by induction 7,exp4 #bd74 ,! ,s pole ( ,a1 pol>iz$ by induction1 w be attract$ by ,b ,m1 :ile its ,n pole w be repell$ by ,b ,m2 s1 y see1 t a b> magnet does n pull to advantage4 ,,*apt] ,v4 ,,t]re/rial ,,magnetism4 #hc4 ,! ,magnetism ( ! ,e>?4 ,! /ud5t mu/ h guess$1 be=e ?is1 t ! e>? acts l a magnet4 ,x causes ! magnetic ne$le to take a c]ta9 position at e place ^u its surface1 & ?is position dep5ds ^u ! e>?'s attractions & repulsions = x4 ,! e>? has l9es ( =ce :i* fl[ f its ,n magnetic pole1 & ^! l9es1 be=e !y c get to ! e>?'s ,s magnetic pole1 mu/ spread out ?r\gh ! air on all sides ( ! e>?4 ,z ! magnetic ne$le po9ts to ! e>?'s ,n magnetic pole 7:i* is m ?an #a1jjj miles f its real ,n pole71 x is evid5t t ! compass-ne$le does n %[ ! true nor? = all places ^u ! e>?'s surface4 ,9 fact1 ! ,n pole ( ! ne$le may po9t ,e1 ,w1 or ev5 ,s4 ,?is effect w\ld be se5 by c>ry+ a compass ar\nd ! e>?'s ,n magnetic pole4 ,illu/ration3 ,fig4 #bc4 #hd4 ,decl9ation4 ,= conv5i5ce1 we %all repres5t ! true ,n & ,s1 at ! place :]e y are exp]im5t+1 by ! full l9e1 ,n ,s1 9 ,fig4 #bc4 ,! dott$ l9e %[s ! direction tak5 by ! compass-ne$le4 ,! angle1 ,a1 betwe5 !m1 is call$ ! angle ( v>iation or ! decl9ation4 ,?is angle is n ! same = all places2 &1 9 fact1 x *anges sl[ly at any giv5 place2 s x becomes necess>y to con/ruct magnetic maps = ! use ( m>9]s & o!rs4 ,,exp]im5t #de4 ,to /udy ! l9es ( =ce above & bel[ a b> magnet plac$ horizontally4 ,app>atus4 ,a b> magnet1 ,b ,m 7,no4 #ba72 compass1 ,o ,c 7,no4 #ah74 #he4 ,directions4 7,a7 ,lay ,b ,m ^u ! table & place ,o ,c ^u its c5t]4 ,note ! position ( ! compass-ne$le4 7,b7 ,slide ,o ,c along f "o end ( ,b ,m to ! o!r1 & /udy ! effect ^u its ne$le4 ,d l9es ( =ce curve ov] ,b ,m z well z ar\nd its sides1 z %[n 9 ,exp4 #ca8 7,c7 ,place ,o ,c ^u ! table4 ,hold ,b ,m horizontally above ,o ,c1 & move ,o ,c back & =? "u ,b ,m4 ,does ! ne$le rema9 horizontal1 or does x %[ t l9es ( =ce pass "u ,b ,m on _! way f its ,n to its ,s pole8 ,illu/ration3 ,fig4 #bd4 #hf4 ,! ,dip or ,incl9ation ( ! ,magnetic ,ne$le4 ,! ne$le is said to dip :5 x takes positions l ^? 9 ,fig4 #bd4 ,compass-ne$les %\ld be horizontal1 :5 prop]ly balanc$1 & entirely free f all effects o!r ?an ^? ( ! e>?4 ,! excessive dip %[n 7,fig4 #bd7 is due1 ( c\rse1 to ! ef=ts ( ! magnetic ne$le to place itself 9 ! direction 9 :i* ! l9es ( =ce ( ,b ,m pass4 ,,exp]im5t #df4 ,to /udy ! dip or incl9ation ( ! magnetic ne$le1 due to ! action ( ! e>?4 ,app>atus4 ,fig4 #be4 ,our compass1 ,o ,c 7,no4 #ah72 horse%oe magnet1 ,h ,m 7,no4 #af72 piece ( pap]4 #hg4 ,directions4 7,a7 ,place ,o ,c ^u ! table1 & m>k ^u a piece ( pap] ! height ( ! ,n pole ( its ne$le above ! table4 7,fig4 #be47 ,! pap] %\ld be held 9 a v]tical position1 & ne> ! pole4 ,illu/ration3 ,fig4 #be4 7,b7 ,) ,h ,m rev]se ! poles ( ! compass-ne$le 7,exp4 #ac71 s t its =m] ,n pole %all become a ,s pole4 7,c7 ,place ! ne$le ^u its pivot aga91 & m>k ^u ! pap]1 z be=e1 ! height ( its new ,n pole above ! table4 ,does ! ne$le rema9 horizontal8 7,d7 ,remagnetize ! ne$le1 & rev]se its poles s t x w aga9 balance4 ,illu/ration3 ,fig4 #bf4 #hh4 ,discussion2 ,balanc+ ,magnetic ,ne$les4 ,if a piece ( unmagnetiz$ /eel be balanc$ & !n magnetiz$1 x w no long] rema9 horizontal2 x w dip4 ,try ?is4 ,compass-ne$les are balanc$ aft] !y are magnetiz$4 ,c y n[ see :y ! ne$le did n rema9 horizontal aft] its poles 7 *ang$8 ,a piece ( /eel fir/ balanc$ & !n magnetiz$1 has to h its ,s pole slightly weight$1 z sugge/$ by ! l9e at ,s 7,fig4 #bf x71 to make x horizontal4 ,! magnetic ne$le does n t5d to dip at ! e>?'s equator1 because ! l9es ( =ce ( ! e>? are ne>ly horizontal at ! equator4 ,z we pass t[>d ! nor? or s\? on ! e>?1 ! l9es ( =ce slant m & m z !y come f or ent] ! e>?'s magnetic poles4 ,:at position w\ld ! ne$le take if we %\ld hold x directly ov] ! e>?'s ,n magnetic pole8 ,fig4 #bd %[s :at ! ne$le does :5 held ne> ! poles ( a b> magnet4 ,,exp]im5ts #dg-dh4 ,to /udy ! inductive influ5ce ( ! e>?4 ,app>atus = ,exps4 #dg-dh4 ,compass1 ,o ,c1 7,no4 #ah72 an iron /ove pok]1 or o!r rod ( iron2 a hamm]4 7,! iron & hamm] are n furni%$47 #hi4 ,note4 ,y h se5 7,exp4 #bd71 t iron becomes magnetiz$ by induction :5 plac$ ne> a magnet4 ,z ! e>? acts l a huge magnet1 hav+ poles1 l9es ( =ce1 etc41 w x magnetize pieces ( iron :i* are 9 ! air or ^u its surface8 #ij4 ,directions4 7,a7 ,te/ ! pok] = poles ) ,o ,c1 rememb]+ t repulsion is necess>y to prove t x is pol>iz$4 ,if ! pok] has v weak poles1 proce$2 b if x %[s "s /r5g?1 hold x 9 an ea/ & we/ direction1 & hit x sev]al %>p bl[s on ! end ) ! hamm]4 ,te/ = pol>ity aga94 7,b7 ,) "o h& hold ! pok] 9 ! ,n & ,s l9e1 give x a dip t[>d ! nor?1 & /rike x sev]al times ) ! hamm] to ?or\ghly /ir up its molecules4 7,c7 ,te/ aga9 = poles ) ,o ,c1 & note especially :e!r ! l[] end 7( ! pok]7 became a ,n or a ,s pole4 ,,exp]im5t #dh4 #ia4 ,directions4 7,a7 ,turn ! pok] end = end 7,see ,exp4 #dg72 repeat ! /rik+1 & te/ aga9 ! pole produc$ at ! l[] & nor? end ( x4 7,b7 ,n[ hold ! pok] horizontally 9 ! ea/ & we/ l9e1 & p\nd x4 7,c7 ,te/ = poles4 ,has ?is /r5g!n$ or weak5$ ! pok] magnet8 #ib4 ,discussion4 ,dipp+ ! pok] places x ne>ly 9 ! same direction z t tak5 by ! e>?'s l9es ( =ce4 ,! magnetic influ5ce ( ! e>? acts to advantage ^u ! pok]1 by induction1 only :5 ! pok] is prop]ly held4 ,x no d\bt occurs to ! /ud5t t ! end ( a magnetic ne$le :i* po9ts to ! nor? is really opposite 9 nature to ! nor? magnetic pole ( ! e>?4 ,! ,n pole ( a ne$le1 !n1 mu/ be 9 reality a ,s pole to be attract$ by ! e>?'s ,n pole4 ,x has be5 agre$1 = conv5i5ce1 to call ! ,n-seek+ pole ( a magnet its ,n pole4 #ic4 ,natural ,magnets4 ,ne>ly all pieces ( iron become m or less magnetiz$ by ! inductive action ( ! e>?'s magnetism4 ,y\r pok] 0 slightly magnetiz$ at ! />t1 p]haps1 f /&+ 9 a dipp+ position4 ,induction takes place along l9es ( =ce4 ,9 nor!rn latitudes ! e>?'s l9es ( =ce h a dip to ! nor?4 ,y %\ld n[ see :y ! greate/ effect 0 produc$ ^u ! pok] :5 x1 also1 0 made to dip4 ,p>ts ( ma*9]y1 /eel frames ( bridges & build+s1 tools 9 ! %op1 & ev5 c]ta9 iron ores1 become pol>iz$ by ?is inductive action4 ,^! might all be call$ natural magnets4 ,magnetic iron ore1 call$ lode/one1 is ref]r$ to1 h[ev]1 :5 speak+ ( natural magnets4 ,lode/one 0 us$ ?\s&s ( ye>s ago to indicate ,n & ,s1 & x 0 discov]$1 lat]1 t x c\ld imp>t its p[] to pieces ( /eel :5 ! two 7 rubb$ toge!r4 ,,exp]im5t #di4 ,to te/ ! effect ( twi/+ a wire held nor? & s\? 9 ! e>?'s magnetic field4 ,app>atus4 ,compass1 ,o ,c 7,no4 #ah72 a piece ( s(t iron wire1 #f 94 7#ae cm47 long 7,no4 #ae74 ,b5d up ab\t an in* ( ! wire at ea* end s t x may be firmly held :5 twi/+ x4 ,note4 ,y h se5 t we c p\nd magnetism into or out ( a piece ( iron at w4 ,c we twi/ x into a wire & out aga9 )\t ! use ( magnets8 #id4 ,directions4 7,a7 ,te/ ! wire = poles ) ,o ,c4 7,b7 ,hold ! wire 9 a ,n & ,s direction1 dipp+ x at ! same "t1 z direct$ 9 ,exp4 #dg = ! pok]1 & twi/ x back & =?4 7,c7 ,te/ aga9 = poles ) ,o ,c4 ,z ! poles ( ! wire may be v weak1 br+ !m sl[ly t[>d ! compass-ne$le 7see ,exp4 #ad71 & note ! fir/ motions produc$ ^u ! ne$le4 7,d7 ,hold ! wire horizontally ea/ & we/1 twi/ & te/ aga94 ,has its magnetism become weak] or /rong] ?an be=e8 ,,exp]im5t #ej4 ,to te/ = magnetism 9 b>s ( iron1 tools1 etc4 ,app>atus4 ,/eel drills2 files2 *isels2 b>s or rods ( iron t h be5 /&+ 9 an upright position2 /ove-lid lift]s2 /ove pok]s1 etc41 etc42 a compass4 #ie4 ,directions4 7,a7 ,) ! compass te/ ! ends ( ! above = magnetism1 & note :i* ends are ,s4 ,notes4 ,,/atic ,,electricity ,,"p ,,ii4--,,/atic ,,electricity ,,*apt] ,,vi4 ,,electrification4 #ajj4 ,"s ,v>ieties ( ,electricity4 ,/atic electricity does n seem to fl[ 9 curr5ts z readily z "s o!r v>ieties2 its t5d5cy is to /& /ill1 h5ce ! "n1 /atic4 ,! simple/ way to produce x is by friction4 ,!rmo electricity is produc$ by *anges 9 temp]ature4 ,:5 c]ta9 comb9ations ( metals become hott] or cold]1 a curr5t is produc$4 ,voltaic or ,galvanic electricity is produc$ by *emical action4 ,batt]ies give ?is v>iety4 ,induc$ electricity is produc$ by o!r curr5ts1 & by comb9ations ( magnets & mov+ coils ( wire1 z 9 ! dynamo4 ,?is is1 by f>1 ! mo/ important v>iety ( electricity1 & ! dynamo is ! mo/ important produc] ( x4 ,ea* ( ! above v>ieties ( electricity w be /udi$ exp]im5tally ) simple app>atus4 ,,exp]im5ts #ea-eb4 ,to /udy electrification by friction4 ,app>atus4 ,ebonite %eet1 ,e ,s 7,no4 #bf72 flannel clo?1 ,f ,c 7,no4 #cj74 ,see :at is said 9 preface ab\t /atic electricity4 #aja4 ,directions4 7,a7 ,exam9e ,e ,s4 ,note t its surface is n smoo?1 l t ( ord9>y h>d-rubb] combs4 ,c y ?9k ( any reason = ?is8 7,b7 ,hold its flat surface ne> y\r face1 !n ne> ! back ( y\r h&4 ,d y feel any?+ unusual8 7,c7 ,lay ,e ,s ^u a flat bo>d1 or uncov]$ wood5 table1 & slide x ab\t4 ,c y easily pick x up8 7,d7 ,place ,e ,s flat ^u ! table aga92 keep x f slid+ ab\t ) y\r left h&1 & rub x vigor\sly = a m9ute ) ,f ,c4 ,does ,e ,s act exactly z x did be=e 9 7,b7 & 7,c78 7,e7 ,repeat ! exp]im5t 9 a d>k room4 7,f7 ,?or\ghly electrify ,e ,s1 & see if x w cl+ to ! wall /rongly en\gh to support its own weight4 #ajb4 ,discussion2 ,electrifi$ & ,neutral ,bodies4 ,! ebonite %eet became electrifi$ or *>g$2 & z ! electrification 0 produc$ by friction1 we may say t ! action ( ! ebonite indicat$ ! pres5ce ( frictional electricity4 ,no "o c tell j :y ! ebonite act$ s que]ly1 b we c le>n a great deal by exp]im5t+4 ,bodies :i* are n *>g$ are said to be neutral4 ,! table1 *airs1 e>?1 etc41 are neutral4 ,we may consid] t a neutral body has be5 dis*>g$4 #ajc4 ,=ce2 ,resi/ance2 ,"w2 ,pot5tial ,en]gy2 ,electrification4 ,x takes =ce to raise wat] into a tank plac$ on ! ro(4 ,9 rais+ ! wat]1 "w has to be done1 & we h to d ! "w2 b :5 we once h ! wat] 9 ! tank we h accompli%$ some?+4 ,! wat] has pot5tial en]gy2 t is1 on acc\nt ( its high position1 we c make x d "s "w by simply turn+ a /op-cock s t ! wat] c run out & turn a wat]-:eel1 = example4 ,x takes =ce to vigor\sly rub a piece ( ebonite ) a flannel clo?1 = resi/ance has to be ov]come2 t is1 "w has to be done4 ,sev]al ?+s are accompli%$ by ?is "w2 heat is produc$1 = we c feel t ! ebonite gets w>m2 we c he> s\nds & see sp>ks4 ,! simple muscul> ex]tion on our "p has be5 *ang$ to heat1 light1 & s\nd4 ,! mo/ wond]ful "p ( x all1 h[ev]1 is t we h electrifi$ or *>g$ ! ebonite4 ,we did ! "w at fir/1 & n[ ! ebonite has ! p[] to d some?+1 z y w soon see4 ,electrification is1 !n1 a sort ( pot5tial en]gy4 #ajd4 ,heat & ,electrification4 ,we say t heat passes to or f a body to make x hot or cold4 ,heat produces ! s5sation ( w>m?1 b heat isn't w>m?4 ,we c =ce a cold body to become hot2 9 o!r words1 we c get x into a hot condition 9 v>i\s ways1 su* z rubb+ x1 hamm]+ x1 or by plac+ x ne> or 9 contact ) ano!r hot body4 ,electrification is1 also1 a condition or /ate into :i* we c =ce a body2 b electrification isn't electricity4 ,we "k :e!r a body is hot or cold by its effects ^u u1 ^u !rmomet]s1 & ^u o!r bodies4 ,we c tell1 also1 :e!r a body is electrifi$ or n by ! way x acts1 &1 9 c]ta9 cases1 by ! s\nd1 heat1 & light :i* accompany ! electrification4 ,d n get ! idea t an electrifi$ body is cov]$ ) a lay] ( electricity j z a bo>d is cov]$ ) a lay] ( pa9t4 ,illu/ration3 ,fig4 #bh4 ,,exp]im5t #eb4 #aje4 ,directions4 ,repeat ,exp4 #ea1 b 9 place ( ! ebonite1 use hot tissue-pap]1 hot br[n pap]1 hot newspap]1 or a hot silk h&k]*ief4 ,rub y\r h& vigor\sly ov] !m4 ,d ^! become *>g$8 ,,exp]im5ts #ec-ed4 ,to /udy electrical attractions4 ,app>atus4 ,! ebonite %eet1 ,e ,s 7,no4 #bf72 flannel clo?1 ,f ,c 7,no4 #cj72 small pieces ( dry tissue-pap]1 ,t ,p 7,no4 #ca72 ?read 7,no4 #cb74 #ajf4 ,directions4 7,a7 ,?or\ghly electrify ,e ,s z be=e1 !n lift & hold x 9 ! air4 7,fig4 #bh47 7,b7 ,see :at ! pap] & ?read w d :5 held loosely ne> ,e ,s4 #ajg4 ,discussion4 ,exp4 #ec %[s t an electrifi$ body attracts neutral ones4 ,?is mu* 0 kn[n ab\t electricity ov] #b1jjj ye>s ago4 ,!y didn't h ebonite !n1 b "s ( ! educat$ m5 ( ,greece knew t amb] w\ld attract light bodies aft] be+ rubb$4 ,! ,greek ^w = amb] is elektron1 & f ?is has be5 made ! ^w electricity4 ,,exp]im5t #ed4 #ajh4 ,directions4 ,*>ge a %eet ( hot pap] by friction2 lift x1 by its opposite ends1 & l[] x ov] small pieces ( tissue-pap] plac$ on ! table4 ,:at happ5s to ! little pieces8 ,,exp]im5t #ee4 ,to /udy mutual attractions4 ,app>atus4 ,! support & its atta*m5ts 7,see #aji72 support wire1 ,s ,w 7,no4 #cf72 silk ?read1 ,s ,t 7,no4 #cc71 or a rubb] b&1 ,r ,b 7,no4 #de72 ebonite rod1 ,e ,r 7,no4 #bh72 flannel clo?1 ,f ,c 7,no4 #cj72 wire sw+1 ,w ,s 7,no4 #cg74 ,tie "o end ( ,s ,t to ,w ,s1 ,fig4 #bi2 tie ! o!r end ( ,s ,t to ,s ,w2 adju/ ,w ,s by b5d+1 if necess>y1 s t x w securely hold ,e ,r4 ,x w be f\nd conv5i5t to use a rubb] b& in/ead ( ,s ,t2 if y d1 let ,w ,s /raddle "o end ( ,r ,b 7,fig4 #cc71 & hang ! o!r end ( ,r ,b ^u ,s ,w4 #aji4 ,! support consi/s ( a support base 7,s ,b1 ,fig4 #ef71 a support rod 7,s ,r1 ,fig4 #ef71 & a support wire 7,s ,w1 ,fig4 #bi74 ,!re is a small hole 9 "o end ( ,s ,r to receive ! wire1 ,s ,w1 & a l>ge hole 9 ! o!r end to take ! %ort ebonite :i* holds ! insulat+ table 7,fig4 #cb74 ,a little pap] %\ld be w\nd ar\nd ! l[] end ( ,s ,r1 s t x w /& solidly 9 ! spool :i* =ms a "p ( ! base4 #aaj4 ,directions4 7,a7 ,electrify ,e ,r ) ,f ,c1 & place ,e ,r 9 ! sw+1 ,w ,s 7,fig4 #bi74 ,illu/ration3 ,fig4 #bi4 7,b7 ,br+ y\r f+] ne> "o side ( ! rubb$ end ( ,e ,r1 !n ne> ! unrubb$ end1 & comp>e ! results4 #aaa4 ,mutual ,attractions4 ,a neutral body1 l ! h&1 = example1 attracts electrifi$ ones4 ,f ,exp4 #ec1 #ed1 #ee1 x is se5 t ! attraction betwe5 a neutral & an electrifi$ body is mutual2 ea* attracts ! o!r4 ,,exp]im5t #ef4 ,to /udy electrical repulsions4 ,app>atus4 ,same z = ,exp4 #ee2 ebonite %eet1 ,e ,s 7,no4 #bf74 #aab4 ,directions4 7,a7 ,*>ge ,e ,r1 & place x 9 ,w ,s1 ,fig4 #bi4 7,b7 ,*>ge ,e ,s1 & br+ x sl[ly ne> "o side ( ! *>g$ end ( ,e ,r4 ,,exp]im5t #eg4 ,to /udy electrical repulsions4 ,app>atus4 ,a %eet ( tissue-pap]1 ,t ,p 7,no4 #ca72 %e>s or a knife4 ,cut ,t ,p1 z 9 ,fig4 #cj4 ,ea* leg %\ld be ab\t #a_/d 94 wide & #c or #d 94 long4 #aac4 ,directions4 7,a7 ,heat ! pap]1 !n place x flat ^u ! table & electrify x by rubb+ x ) y\r h&4 ,y mu/ rub away f ! uncut "p1 or y w break ! legs4 7,b7 ,raise ,t ,p1 hold+ x by ! uncut "p4 ,note ! action ( legs1 & make a sket* ( !m4 ,illu/ration3 ,fig4 #cj4 ,illu/ration3 ,fig4 #ca4 ,,exp]im5t #eh4 ,to /udy electrical repulsions4 ,app>atus4 ,ebonite rod1 ,e ,r 7,no4 #bh72 a c>bon electroscope1 ,c ,e1 ,fig4 #ca 7see #aad72 ! support complete 7see #aji72 small piece ( damp tissue-pap]4 #aad4 ,! ,c>bon ,electroscope4 ,light an ord9>y mat*1 & let x burn until x is *>r$ ?r\gh & ?r\gh4 ,! black sub/ance rema9+ is c>bon4 ,?is is v light2 x has1 also1 ano!r important prop]ty :i* y w soon und]/&4 ,tie a small piece ( ! c>bon to "o end ( a dry silk ?read1 & fa/5 ! o!r end ( ! ?read to ! support wire1 ,s ,w1 :i* is fa/5$ to ! support 7,fig4 #ca74 ,we %all call ?is piece ( app>atus ! c>bon e-lec-tro-scope4 7,see ,electroscopes1 ,*apt] ,,xviii41 ,app>atus ,book47 #aae4 ,directions4 7,a7 ,electrify ,e ,r1 !n hold x ne> ! c>bon ( ! electroscope4 7,b7 ,br+ ! *>g$ rod ne> little pieces ( damp tissue-pap]4 #aaf4 ,discussion ( ,exp]im5ts #ef1 #eg1 #eh4 ,9 #ef ! two pieces ( ebonite 7 made ( ! same mat]ial1 & bo? 7 rubb$ ) flannel4 ,!y mu/ h be5 simil>ly electrifi$4 ,9 #eg1 diff]5t p>ts ( ! same piece ( pap] 7 simil>ly electrifi$4 ,9 #eh1 ! little piece ( c>bon took "s ( ! electrification f ! *>g$ rod1 j z x w\ld take molasses f y\r f+] %\ld y\r /icky f+] t\* x4 ,! electrification on ! c>bon mu/ h be5 ( ! same k9d z t on ! rod4 ,! c>bon 0 *>g$ by contact4 ,we le>n1 !n1 t two bodies repel ea* o!r :5 !y h ! same k9d ( electrification4 ,d two *>g$ bodies always repel ea* o!r8 ,is x possible t !re are diff]5t k9ds ( electrifications8 ,,exp]im5t #ei4 ,to /udy ! electrification ( glass4 ,app>atus4 ,! %eet ( glass1 ,g 7,no4 #ch71 heat$ 7a hot bottle or lamp *imney w d72 a piece ( silk l>ge en\gh to rub ,g4 7,a silk h&k]*ief is j ! ?+1 b 9 case y h no silk1 use ! flannel clo?1 ,f ,c1 ,no4 #cj47 #aag4 ,directions4 7,a7 ,vigor\sly rub ! hot glass ) ! silk 7or flannel71 also heat$4 7,b7 ,te/ ,g = electrification by means ( little pieces ( tissue-pap] & ! c>bon electroscope1 ,exp4 #eh4 #aah4 ,que/ions4 ,w two pieces ( electrifi$ glass repel ea* o!r8 ,arrange an exp]im5t to %[ :e!r y are "r or n4 ,is ! *>ge on ! glass exactly l t on ! ebonite8 ,d y "k h[ to f9d out8 ,,exp]im5t #fj4 ,to comp>e ! electrification produc$ by ebonite & flannel ) t produc$ by glass & silk4 ,app>atus4 ,! support 7see #aji72 wire sw+1 ,w ,s 7,no4 #cg72 ebonite rod1 etc41 ( ,exp4 #ee 7,fig4 #bi72 ! glass1 ,g1 & silk ( ,exp4 #ei4 #aai4 ,directions4 7,a7 ,electrify ,e ,r1 & place x 9 ,w ,s1 ,fig4 #bi4 7,b7 ,br+ ! un*>g$ glass ne> ,e ,r1 not+ ! action ( ,e ,r4 7,c7 ,heat & electrify ,g2 br+ x ne> ,e ,r1 & c>efully note :e!r ! attraction betwe5 !m is /rong] or weak] ?an be=e1 or :e!r !y repel ea* o!r4 #abj4 ,discussion4 ,we "k t ! glass 0 electrifi$1 because x lift$ tissue-pap]2 h5ce1 its *>ge 0 n ( ! same k9d z t on ! ebonite4 ,_h ! electrifications be5 exactly alike1 we %\ld h _h a repulsion 7,exps4 #ef1 #eg1 #eh74 ,! exact diff]5ce betwe5 ^! two k9ds ( electrifications is n kn[n4 ,x has be5 agre$1 = conv5i5ce1 to call t produc$ by glass & silk a positive electrification4 ,) ebonite & flannel a negative electrification is produc$4 ,! sign is g5]ally writt5 = ! ^w positive1 & - = negative4 ,^! signs indicate k9d1 & n m or less1 z 9 ari?metic4 #aba4 ,laws4 ,we h le>n$ f ! exp]im5ts ^! facts1 :i* are call$ laws3 7#a7 ,*>ges ( ! same k9d repel ea* o!r2 7#b7 *>ges ( unlike k9ds attract ea* o!r2 7#c7 ei!r k9d ( a *>ge attracts1 & is attract$ by a neutral body4 ,,*apt] ,,vii4 ,,insulators ,,& ,,conductors4 ,,exp]im5t #fa4 ,to /udy insulators4 ,app>atus4 ,ebonite rod1 ,e ,r 7,no4 #bh72 flannel clo?1 ,f ,c 7,no4 #cj72 tissue-pap]1 ,t ,p 7,no4 #ca74 #abb4 ,directions4 7,a7 ,hold+ "o end ( ,e ,r 9 ! h&1 *>ge ! o!r end by rubb+ x ) ,f ,c4 7,b7 ,) bits ( ! ,t ,p te/ ea* end ( ,e ,r = a *>ge1 & comp>e ! results4 ,,exp]im5t #fb4 ,to /udy insulators4 ,app>atus4 ,! ebonite %eet1 ,e ,s 7,no4 #bf72 flannel clo?1 ,f ,c 7,no4 #cj74 #abc4 ,directions4 7,a7 ,?or\ghly electrify ,e ,s 7,exp4 #ea1 ,d71 !n lift & hold x 9 ! air1 z 9 ,fig4 #bh4 7,b7 ,by mov+ y\r r\nd$ knuckle ab\t ne> ! surface ( ,e ,s1 see if y c get m ?an "o sp>k f x4 ,,exp]im5t #fc4 ,to /udy insulators4 ,app>atus4 ,a h>d-rubb] comb 7n furni%$72 flannel clo?1 ,f ,c 7,no4 #cj72 dull po9t$ nail 7,no4 #ai74 #abd4 ,directions4 7,a7 ,electrify ! comb ) ,f ,c4 7,b7 ,move ! nail along ne> ! tee? ( ! comb1 & li/5 c>efully4 #abe4 ,discussion ( ,exp]im5ts #fa1 #fb1 #fc2 ,insulators4 ,9 #fa ! electrification rema9$ at "o end ( ! rod4 ,9 #fb & #fc ! sp>ks %[$ t all p>ts ( ! ebonite 7 n dis*>g$ at ! same "t4 ,a sub/ance1 l ebonite1 :i* w n all[ electrification to pass f "o "p ( x to ano!r1 is call$ an insulator4 ,silk & glass are also insulators4 ,d y n[ see :y a silk ?read 0 us$ to make ! c>bon electroscope8 ,:y d !y fa/5 telegraph wires to glass insulators8 #abf4 ,conductors4 ,x has already be5 /at$ t wat] 9 an elevat$ tank has pot5tial en]gy4 ,we c all[ ! wat] to fl[ ?r\gh a conduct+ pipe to ano!r tank a little l[] ?an ! fir/1 & x w /ill reta9 mu* ( ! pot5tial en]gy1 b n all4 ,c we conduct f "o place to ano!r ?is peculi> /ate ( ?+s1 ?is que] =m ( pot5tial en]gy :i* we call electrification8 ,x is cle>1 f ! la/ exp]im5ts1 t 9 ord] to d x we ne$ some?+ besides ebonite1 :i* really acts l a clos$ /op-cock to ! fl[ ( electrification4 ,to keep electrification 9 "o place we ne$ an insulator2 to get x f "o place to ano!r we ne$ a conductor4 ,insulators are z important z conductors4 ,y saw t sp>ks w5t to ! f+] f ! ebonite1 s we call ! f+] a conductor4 ,y h le>n$ t attractions & repulsions %[ ! pres5ce ( electrification4 ,c we h our *>g$ body 9 "o place & get attractions or repulsions at "s o!r place8 ,illu/ration3 ,fig4 #cb4 ,,exp]im5t #fd4 ,to /udy conduction4 ,app>atus4 ,fig4 #cb2 ! support 7see #aji72 a b5t hairp91 ,h ,p 7,no4 #ci72 ebonite %eet1 ,e ,s2 flannel clo?1 ,f ,c2 t9 disk1 ,b ,f ,b 7,no4 #dj71 :i* is ! bottom ( ! flat-box1 ,f ,b2 ! insulat+ table1 ,i ,t 7see #abg74 #abg4 ,! ,insulat+ ,table consi/s ( a t9 box 7exactly l t us$ = ! electrophorus cov]71 & an ebonite rod ab\t #a-c_/d 94 long4 ,see #aci = full details ab\t fitt+ ! rod into ! box1 etc4 ,! l[] end ( ! %ort rod fits into ! l>ge hole 9 "o end ( ! support rod1 ,s ,r4 ,arrange z 9 ,fig4 #cb4 ,b ,f ,b %\ld sw+ ab\t v easily4 #abh4 ,directions4 7,a7 ,*>ge ,e ,s1 !n rub x ^u ,i ,t1 z %[n1 not+ ! action ( ,b ,f ,b4 #abi4 ,discussion4 ,ebonite be+ an insulator 7 #abe71 we say t ,i ,t1 ,h ,p & ,b ,f ,b 7 insulat$4 ,y c see t ! electrification mu/ h pass$ ?r\gh ,i ,t & ,h ,p to get to ! disk1 ,b ,f ,b4 ,h ,p 0 ! conductor1 all[+ ! disk1 also1 to become *>g$4 ,! wood1 ,s ,r1 is a conductor1 &1 z x 0 n insulat$ f ! e>?1 ,s ,r 0 neutral4 ,acc\nt = ! attraction4 7,see #aba47 ,illu/ration3 ,fig4 #cc4 ,,exp]im5t #fe4 ,to /udy conduction4 ,app>atus4 ,a copp] wire1 ,c ,w 7,no4 #dd72 insulat+ rubb] b&1 ,r ,b 7,no4 #de1 ,fig4 #cc72 wire sw+1 ,w ,s 7,no4 #cg72 ! o!r half ( ! flat box1 ,t ,f ,b 7,no4 #da72 app>atus ( ,exp4 #fi4 #acj4 ,telegraph ,l9e4 ,to h our telegraph l9e us+ frictional electricity complete1 we mu/ h3 7#a7 ,"s way ( g5]at+ or mak+ ! electricity2 7#b7 ,"s means ( gett+ x or its effects to ! o!r end ( ! l9e2 7#c7 ,"s way ( %[+ t x has be5 tak5 !re4 ,! *>g$ ,e ,s w be ! s\rce ( ! electrification4 ,new ,york w repres5t ! end at :i* we s5d ! message1 s at ,n4 ,y4 we mu/ h a s5d+ in/rum5t4 ,see ,fig4 #cc1 :i* expla9s itself4 ,r ,b or a silk ?read mu/ be us$ to insulate ! s5d]4 ,ar\nd "o leg ( ,w ,s is twi/$ "o b>e end ( ! conductor1 ,c ,w4 ,bo/on w repres5t ! end ( ! l9e at :i* ! message is receiv$1 & !re we ne$ a receiv+ in/rum5t4 ,?is is simil> to ! app>atus describ$ 9 ,exp4 #fi1 ,fig4 #cg4 ,9 addition to ?is1 tie ! middle ( a moi/ cotton ?read t is #f 94 long1 to ,b ,c 7,fig4 #cg71 & let its two free ends lie ov] ! top & rea* d[n aga9/ ! bottom ( ! t92 t is1 on ! left-h& side4 ,fig4 #db w give y an idea 9 reg>d to ! looks ( ! ?read2 at fir/1 h[ev]1 x %\ld be close to ! bottom ( ! t94 ,twi/ ! o!r b>e end ( ! copp] wire ar\nd ,b ,c4 ,:5 ! l9e is prop]ly con/ruct$ & ready = use1 bo? in/rum5ts & ,c ,w are entirely insulat$4 ,d n let any "p ( ,c ,w t\* ! table or y\r clo?+4 #aca4 ,directions4 7,a7 ,t\* ! insulat$ s5d+ in/rum5t ) ! *>g$ ebonite %eet1 & wat* = any motion 9 ! receiv+ in/rum5t4 ,note4 ,bett] results w be obta9$ by us+ ! *>g$ electrophorus cov] z ! s\rce ( electrification1 in/ead ( ,e ,s4 7,exp4 #fh47 #acb4 ,discussion4 ,! action "h 0 l t 9 ! previ\s exp]im5t1 ! diff]5ce be+ t a long] conductor 0 us$4 ,electrification is always look+ = "s place to get to ! e>?1 j z wat] w run f a ro( to ! gr\nd4 ,y w und]/& m ab\t x a little lat]4 ,9 our app>atus j describ$1 ! only way t ! e>? c\ld be rea*$ 0 ?r\gh ! wood5 rod ,s ,r4 ,d n get ! idea t real messages are s5t 9 any su* way1 or t electricity fl[s ?r\gh a wire z wat] fl[s ?r\gh a pipe4 #acc4 ,relation betwe5 ,conductors & ,insulators4 ,! above t]ms are m]ely relative4 ,/atic electricity is easily conduct$ by dry wood1 :ile ,galvanic electricity is practically insulat$ by x4 ,a sub/ance may be an insulator = curr5ts ( l[ pot5tial1 :ile at ! same "t x w conduct high pot5tial curr5ts4 7,see ,pot5tial #add47 #acd4 ,electrics & ,non-electrics4 ,bodies l glass1 seal+-wax1 amb]1 etc41 7 call$ electrics by ! fir/ /ud5ts ( electricity1 because x 0 ^u ^! sub/ances t !y c\ld easily produce electrification4 ,!y call$ iron & o!r metals non-electrics1 because !y c\ld detect no electrification aft] rubb+ !m4 ,c y expla9 :y !y did n detect any electrification on metals8 ,c y devise an exp]im5t to prove t metals may be *>g$8 ,d y see any relation betwe5 a non-electric & a conductor8 ,,exp]im5t #ff4 ,to /udy ! effect ( moi/ure ^u an insulator4 ,app>atus4 ,same z = ,exp4 #fe1 ) ! exception ( ! copp] wire2 ?is is to be replac$ by a dry silk ?read ab\t #b feet 7#fj cm47 long 7,no4 #cc74 #ace4 ,directions4 7,a7 ,see if a *>ge c be s5t ?r\gh ! ?read1 9 ! same mann] z x 0 ?r\gh ! copp]4 ,is dry silk a conductor8 7,b7 ,?or\ghly wet ! ?read1 be+ c>eful n to wet ! rubb] b& insulator 7,fig4 #cc72 see if wet silk is a conductor4 #acf4 ,discussion4 ,dry silk is an insulator1 :ile wet silk is a good conductor ( /atic electricity4 ,x is ! wat]1 h[ev]1 :i* really does ! conduct+4 ,ev5 small am\nts ( moi/ure on glass1 or o!r insulators1 w all[ ! *>ge to escape4 ,glass collects mu* moi/ure f ! air4 ,d y n[ see :y x is necess>y1 to get good results1 to h ! pap]1 glass1 etc41 hot be=e electrify+ !m8 ,,exp]im5t #fg4 ,to te/ ! effects ( moi/ure ^u bodies to be electrifi$4 ,app>atus4 ,two pieces ( newspap]1 ea* ab\t #d 94 7#aj cm47 squ>e4 #acg4 ,directions4 7,a7 ,heat "o piece to make x ?or\ghly dry1 & leave ! o!r cold4 7,b7 ,/roke ea*1 say #aj times1 ) y\r h&1 press+ !m ^u ! table2 !n place !m ^u ! wall at ! same "t1 be+ c>eful n to let !m t\* y\r clo?+4 ,see :i* w cl+ to ! wall ! long]4 ,,*apt] ,,viii4 ,,*>g+ ,,& ,,dis*>g+ ,,conductors4 #ach4 ,! ,electrophorus4 ,:ile ! ebonite %eet alone1 or a good h>d-rubb] comb1 may be us$ = _m exp]im5ts 9 frictional electricity1 ! sp>ks produc$ are small1 & ! ebonite has to be electrifi$ z (t5 z x is dis*>g$4 ,to obta9 real good sp>ks1 & to avoid ?is cont9ual rubb+1 ! /ud5t %\ld be provid$ ) an e-lec-troph'-o-rus4 ,?is is1 really1 a simple1 *eap1 & effici5t frictional electric ma*9e4 ,an electrophorus consi/s ( #b insulators & #a conductor--t is1 ( #c p>ts3 7#a7 insulat+ h&le1 7#b7 cov]1 & 7#c7 a plate or base ( insulat+ mat]ial4 ,illu/ration3 ,fig4 #cd4 #aci4 ,our ,electrophorus is %[n 9 ,fig4 #cd4 ,= ! insulat+ h&le use ! ebonite rod1 ,e ,r 7,no4 #bh72 = ! plate1 use ! ebonite %eet1 ,e ,s 7,no4 #bf74 ,! electrophorus cov]1 ,e ,c 7,no4 #db71 furni%$1 is a t9 box ) a fancy top4 ,a hole has be5 pun*$ 9 ! c5t] ( its top1 & into ! hole has be5 rivet$ a %ort tube1 s t ! h&le1 ,e ,r1 c be firmly held4 ,! hole has be5 made a little l>g] ?an ,e ,r = conv5i5ce4 ,to make ,e ,r fit tightly 9 ! hole1 s t y c lift ,e ,c1 wrap a small piece ( pap] ar\nd ! end ( ,e ,r be=e pu%+ x into ! hole4 ,y c easily f9d out h[ mu* pap] to use to make a good fit4 ,) a knife cut away all loose po9ts ( pap] t /ick out ( ! hole ar\nd ,e ,r2 ?is is important4 ,! top & bottom ( ,e ,c %\ld be press$ firmly toge!r4 ,fir/ le>n h[ to use ! electrophorus4 ,) ! l>ge am\nt ( electrification produc$ we c !n f9d out h[ x works4 ,,exp]im5t #fh4 ,to le>n h[ to use ! electrophorus4 ,app>atus4 ,%[n 9 ,figs4 #cd1 #ce4 ,d n fail to read #aci4 #adj4 ,directions4 7,a7 ,place ,e ,s ^u a flat1 uncov]$1 wood5 table1 & rub x vigor\sly = a m9ute ) ! w>m flannel1 ,f ,c1 to ?or\ghly *>ge x4 ,d n let ,e ,s slide ab\t1 & d n lift x f ! table4 7,b7 ,) ! "r h& grasp ,e ,r at its extreme end1 & place ,e ,c ^u ,e ,s4 7,c7 ,t\* ,e ,c = an in/ant ) a f+] ( y\r left h& 7,fig4 #ce74 7,d7 ,remove y\r f+] entirely f ,e ,c1 !n lift ,e ,c by its insulat+ h&le1 ,e ,r1 at ! same "t hold+ ,e ,s d[n to ! table1 if x tries to foll[ ,e ,c4 ,illu/ration3 ,fig4 #ce4 ,illu/ration3 ,fig4 #cf4 7,e7 ,br+ y\r left h& ne> ,e ,c 7,fig4 #cf74 ,y %\ld get a good sp>k f ,e ,c4 7,f7 ,x is n necess>y to imm$iately rub ,e ,s aga94 ,y h dis*>g$ ,e ,c by tak+ a sp>k f x4 ,to re*>ge x1 simply place x ^u ,e ,s aga92 let x rema9 !re :ile y c\nt #e2 t\* x z be=e1 & !n lift by ,e ,r4 #ada4 ,extra ,notes4 ,y may repeat ! above op]ation _m times4 ,z soon z ! sp>ks beg9 to get small1 electrify ,e ,s aga94 ,! *>ge on ,e ,c is 1 al?\gh t on ,e ,s is -4 ,y w und]/&1 lat]1 :y ?is is s4 ,if y d n get a good sp>k f ! electrophorus1 read ! directions aga94 ,! ebonite mu/ be well electrifi$2 ! cov] mu/ be lift$ by ! end ( its h&le2 y mu/ t\* ! cov] & )draw y\r f+] f x be=e lift+4 ,y mu/ all[ ! cov] to rema9 ^u ! ebonite #c or #d seconds ea* "t4 ,! bo>d1 or table1 ^u :i* ,e ,s re/s1 mu/ be flat1 & n w>p$1 s t ,e ,c w fit d[n p]fectly ^u ,e ,s4 ,,exp]im5t #fi4 ,to /udy *>g+ by conduction4 ,app>atus4 ,fig4 #cg4 ,to "o end ( a silk ?read1 ,s ,t1 is ti$ a little b5t clamp1 ,b ,c 7,no4 #df72 ! o!r end ( ,s ,t is ti$ to ! support wire1 ,s ,w 7,no4 #cf72 ! bottom ( ! flat box1 ,b ,f ,b 7,no4 #dj71 is support$ by ,b ,c1 & ?us insulat$ f ! table & e>?2 ! electrophorus 7,exp4 #fh7 is also necess>y4 #adb4 ,directions4 7,a7 ,*>ge ,e ,c 7,exp4 #fh71 & br+ x ne> ,b ,f ,b 7,fig4 #cg74 ,note ! sp>k4 7,b7 ,repeat 7,a7 twice1 not+ ! relative sizes ( ! sp>ks4 ,does ,b ,f ,b cont9ue to be attract$ by ,e ,c8 7,c7 ,br+ y\r knuckle sl[ly t[>ds ! *>g$ disk1 ,b ,f ,b4 ,illu/ration3 ,fig4 #cg4 ,illu/ration3 ,fig4 #ch4 ,,exp]im5t #gj4 ,to /udy pot5tial2 electro-motive =ce4 ,app>atus4 ,! insulat+ table1 ,i ,t1 ,fig4 #ch4 7,= details see ,exp4 #fd2 ! electrophorus ,exp4 #fh74 #adc4 ,directions4 7,a7 ,pass a sp>k f ! ?or\ghly *>g$ ,e ,c 7,exp4 #fh7 to ,i ,t4 7,b7 ,re*>ge ,e ,c1 & see h[ _m times ,i ,t w take good sp>ks f x1 & note ! relative sizes ( ! sp>ks4 7,c7 ,z soon z ,i ,t refuses to take m sp>ks f ,e ,c1 t\* ,e ,c to see if x is completely dis*>g$4 7,d7 ,t\* ,i ,t4 #add4 ,pressure2 ,pot5tial2 ,electro-motive ,=ce4 ,wat] runs d[n hill4 ,x always tries to run f a high place to a l[] "o4 ,electrification acts v mu* l wat] 9 ?is respect4 ,we say t wat] has a pressure1 or a head ( s _m feet4 ,9 speak+ ( a *>ge1 we say t x has a pot5tial1 or an electro-motive =ce4 ,wat] may h a high or l[ pressure1 & a *>ge may h a high or l[ pot5tial4 ,! great] ! pressure ( wat]1 ! h>d] x tries to break away & get some:]e2 ! great] ! pot5tial ( a *>ge1 ! f>!r x w jump to y\r h&4 #add;a4 ,curr5t2 ,sp>k4 ,electrification w easily pass f a place ( high pot5tial to "o ( l[ pot5tial ?r\gh a conductor1 & :5 x passes we say we h an electric curr5t1 or a curr5t ( electricity4 ,wat] has no desire to fl[ on a dead level1 & ! electric curr5t does n c>e to fl[ betwe5 two places ( equal pot5tial4 ,! pot5tial ( ! e>? & ( all neutral bodies is z]o2 t is1 !y h no *>ge1 no pot5tial2 s x is v easy = a *>ge to escape into ! e>?4 ,dry air is a pretty good insulator1 b :5 ! attraction betwe5 a *>g$ & a neutral body gets great en\gh1 ! sp>k rips "r ?r\gh ! air4 ,b5jam9 ,frankl9 prov$ by exp]im5t t lightn+ is caus$ by ! electrification 9 ! cl\ds & air4 7,see ,atmosph]ic ,electricity47 #ade4 ,!ories ab\t ,electrifications4 ,! ,"o-,fluid ,!ory sugge/s t neutral bodies h a c]ta9 am\nt ( electrification1 & t !y h a c]ta9 pot5tial call$ z]o pot5tial4 ,if ! pot5tial ( a body becomes great] ?an t ( ! e>?1 ! body is said to be positively electrifi$2 if ! pot5tial ( ! body is less ?an t ( ! e>?1 x is said to be negatively electrifi$4 ,if we fill a bottle ) sea wat]1 we h a great deal ( wat] :5 we comp>e x ) ! bottle1 b a v little wat] :5 we comp>e x ) ! sea4 ,! e>? is s l>ge t small am\nts ( electrification tak5 f x or add$ to x d n affect its pot5tial to any ext5t4 #adf4 ,! ,two-,fluid ,!ory sugge/s t !re are two absolutely diff]5t k9ds ( electrification1 "o call$ positive 771 & ! o!r negative 7-74 ,:5 ^! two are equal 9 quantity1 ! body is said to be neutral4 ,if ! body conta9s m ?an -1 ! body is said to be *>g$ positively4 ,x is evid5t !n1 if ! two-fluid !ory be accept$1 t no matt] h[ /rongly a body is *>g$ positively !re mu/ be 9 x "s negative electrification2 t is1 we may *>ge a neutral body by add+ electrification to x1 or by tak+ - electrification f x4 ,!re mu/ always be1 !n1 "s & - electrifications 9 a body4 ,^! !ories d n require mu* consid]ation by ! /ud5t ( elem5t>y electricity4 ,! be/ ?+ he c d is to le>n :at electricity c d1 & h[ x c be us$4 ,illu/ration3 ,fig4 #ci4 ,,exp]im5t #ga4 ,to /udy "s me?ods ( dis*>g+ an electrifi$ body4 ,app>atus4 ,! electrophorus 7,exp4 #fh72 an ord9>y p9 7,fig4 #ci74 #adg4 ,note4 ,y h se5 sp>ks pass f ,e ,c to y\r r\nd$ knuckle1 & to o!r conductors4 ,9 all ( ^! cases ! dis*>ge 0 sudd51 "o sp>k do+ ! "w4 ,c we sl[ly dis*>ge ,e ,c1 or dis*>ge x )\t s\nds8 #adh4 ,directions4 7,a7 ,?or\ghly *>ge ,e ,c1 & te/ x ) y\r knuckle to be sure t x is work+ prop]ly4 7,b7 ,*>ge ,e ,c aga92 hold ! p9 9 y\r left h& 7,fig4 #ci71 & sl[ly br+ its head t[>d ,e ,c2 li/5 = sp>ks4 7,c7 ,re*>ge ,e ,c1 & br+ ! po9t ( ! p9 sl[ly t[>d x4 ,t\* ,e ,c to see :e!r x has be5 dis*>g$ or n4 #adi4 ,disruptive1 ,conductive1 & ,convective ,dis*>ges4 ,sudd5 dis*>ges1 accompani$ by bright sp>ks1 are said to be disruptive4 ,:5 ! electrification is cont9u\sly c>ri$ away by a conductor1 !re is a conductive dis*>ge4 ,!re is a convective dis*>ge :5 ! electrification escapes f po9ts into ! air4 7,see #aee47 ,! nature ( ! dis*>ge dep5ds ^u ! pot5tial ( ! *>ge1 ^u ! nature ( ! *>g$ conductor1 & ^u ! nature ( ! surr\nd+ air & objects4 ,convective dis*>ges are (t5 sil5t1 z 9 ,exp4 #ga 7,c74 ,9 ?is case1 electrification pass$ f ! e>? ?r\gh ! p9-po9t to ! cov] to neutralize x4 7,see ,induc$ ,electricity47 ,illu/ration3 ,fig4 #dj4 ,,exp]im5t #gb4 ,to /udy int]mitt5t or /ep-by-/ep dis*>ges4 ,app>atus4 ,electrophorus 7,exp4 #fh72 c>bon electroscope 7 #aad71 7,exp4 #eh74 #aej4 ,directions4 7,a7 ,*>ge ,e ,c1 !n hold y\r h& on "o side ( ! c>bon 7,fig4 #dj71 & hold ,e ,c ^u ! opposite side4 ,:at %\ld ! c>bon d8 #aea4 ,discussion4 ,! c>bon & ,e ,c 7 insulat$1 :ile ! h& 0 gr\nd$--t is1 x 0 connect$ ) ! e>?4 ,c>bon is a good conductor2 x may be quickly *>g$ & dis*>g$4 ,,exp]im5t #gc4 ,to asc]ta9 ! location ( ! *>ge ^u an electrifi$ conductor4 ,app>atus4 ,! electrophorus 7,exp4 #fh72 ! insulat+ table1 ,i ,t 7,exp4 #fd72 ! t9 box1 ,t ,b 7,no4 #dg71 ,fig4 #da2 a piece ( moi/ cotton ?read1 ,c ,t1 #e or #f 94 long1 b5t d\ble1 & hung ov] ! edge ( ! op5 box1 ,t ,b4 ,"o-half ( ,c ,t %\ld be inside ( ,t ,b1 :i*1 9 turn1 %\ld /& on ,i ,t4 ,illu/ration3 ,fig4 #da4 #aeb4 ,directions4 7,a7 ,*>ge ,e ,c2 pass a sp>k to ,t ,b1 & note ! action ( bo? p>ts ( ,c ,t4 #aec4 ,holl[ & ,solid ,conductors4 ,! moi/ ?read1 be+ a conductor1 became *>g$ z well z ! box4 ,! electrification seem$ to be entirely on ! outside ( ,t ,b4 ,a holl[ conductor w hold z l>ge a *>ge z a solid "o hav+ ! same am\nt ( surface4 ,?is ref]s to *>ges ( /atic electricity1 n to curr5ts4 ,an electric curr5t passes ?r\gh ! :ole sub/ance ( a conductor4 ,,exp]im5t #gd4 ,to /udy ! effect ( po9ts ^u a *>g$ conductor4 ,app>atus4 ,! electrophorus 7,fig4 #cd72 a p91 b5t slightly to keep x f roll+4 #aed4 ,directions4 7,a7 ,*>ge ,e ,c2 te/ its *>ge ) y\r knuckle4 ,be sure t y get a good sp>k4 7,b7 ,*>ge ,e ,c aga91 & hold x by its insulat+ h&le1 ,e ,r1 long en\gh to c\nt #aj be=e dis*>g+ x ) y\r knuckle4 ,be sure t x holds its *>ge dur+ ?is "t4 7,c7 ,:ile ,e ,c is ^u ,e ,s 7,fig4 #cd71 lay ! b5t p9 ^u ,e ,c1 s t its po9t w project into ! air4 ,! po9t %\ld /ick out ab\t #a_/d 94 f ! edge ( ,e ,c4 7,d7 ,t\* ,e ,c2 raise x by ,e ,r2 c\nt #aj z be=e2 !n te/ ) y\r knuckle to see if ,e ,c is /ill *>g$4 #aee4 ,electric ,d5sity2 ,electric ,w9d4 ,a *>ge resides ^u ! outside ( a conductor 7,exp4 #gc71 & x cont9ually tries to escape4 ,x seems to pile up at po9ts & corn]s1 & we say t x is d5s] at su* places ?an at well-r\nd$ p>ts ( a *>g$ conductor4 ,all po9ts & %>p places %\ld be remov$ f a conductor1 if x is desir$ to keep a *>ge = any l5g? ( "t4 ,electrification may escape f a po9t s rapidly t curr5ts are produc$ 9 ! surr\nd+ air4 ,z ! p>ticles ( air become *>g$1 !y repel ea* o!r4 ,! movem5t ( ! air p>ticles may be s great t a light$ c&le w be affect$ :5 plac$ ne> ! po9t4 ,?is curr5t ( air is call$ electric w9d4 ,electrification easily passes f po9ts1 & ! electrophorus may be easily & sil5tly dis*>g$ by hold+ a po9t$ p9 ne> x 7,exp4 #ga1 ,c74 ,?orns1 leaves ) %>p edges1 etc41 h a great effect ^u atmosph]ic electricity4 ,!y all[ a sil5t escape ( electrification f ! e>? to neutralize t 9 ! cl\ds :i* is opposite 9 nature4 7,see ,atmosph]ic ,electricity47 ,,*apt] ,,ix4 ,,induc$ ,,electrification4 #aef4 ,electric ,field2 ,l9es ( ,=ce4 ,9 our /udy ( magnetism y le>n$ t a magnet c act ?r\gh ! air1 & induce a piece ( iron to become a magnet4 ,y saw h[ ! iron fil+s arrang$ !mselves ar\nd ! magnet1 %[+ t ! l9es ( =ce rea*$ out f ! poles 9 a v peculi> mann]4 ,!re is an electric field all ar\nd a *>g$ conductor1 j z !re is a magnetic field ab\t a magnet4 ,! l9es ( =ce 9 ! electric field pass f ! positively *>g$ body to ! negatively *>g$ "o1 or to "s neutral "o1 :i*1 y w soon see1 is practically ! same ?+4 ,:5 ! positively *>g$ electrophorus cov] is held above ! negatively *>g$ ebonite %eet1 a v /rong electric field exi/s betwe5 !m4 #aeg4 ,note4 ,y h se5 t we c *>ge an insulat$ conductor by t\*+ x ) ! *>g$ cov]1 or by all[+ a sp>k to pass to ! conductor4 ,:at effect1 if any1 has a *>g$ body ^u an insulat$ conductor be=e !y t\* ea* o!r1 & be=e any sp>k passes to ! conductor8 ,illu/ration3 ,fig4 #db4 ,,exp]im5t #ge4 ,to /udy electric induction4 ,app>atus4 ,fig4 #db4 ,! insulat+ table1 ,i ,t 7= details see ,exp4 #fd72 t9 box1 ,t ,b 7,no4 #dg1 ,fig4 #db72 moi/ cotton ?read1 ,c ,t2 ! electrophorus 7,exp4 #fh72 tie ,c ,t ar\nd "o end ( ! clos$ ,t ,b1 & leave ! ends ( ,c ,t long en\gh to hang d[n ov] ! end4 ,place a mat* on ea* side ( ,t ,b to keep x f roll+4 #aeh4 ,directions4 ,"p #a4--7;,a7 ,pass a sp>k f ! *>g$ ,e ,c to ,t ,b1 & note ! action ( ! ?read1 :i* w be our electroscope4 ,remove ,e ,c4 7,b7 ,t\* ! *>g$ ,t ,b ) ! f+]1 wat*+ ,c ,t4 ,"p #b4 7,c7 ,br+ ! re-*>g$ ,e ,c ne> ! neutral ,t ,b1 & p>allel to its end surface2 b keep !m at lea/ an in* ap>t1 s t a sp>k _c pass4 ,wat* ,c ,t4 7,d7 ,)draw ,e ,c1 & try to expla9 ! action ( ,c ,t4 #aei4 ,electric ,pol>ization2 ,!ory ( ,induction4 ,?is exp]im5t %\ld rem9d ! /ud5t ( ,exp4 #bd1 9 magnetism1 9 :i* a piece ( s(t iron 0 magnetiz$ by ! inductive action ( a magnet4 ,! s(t iron 0 9 a magnetic field2 x became pol>iz$4 ,is x possible t ! box1 ,t ,b1 0 pol>iz$1 be+ 9 ! electric field ( ,e ,c8 ,we "k1 by ! action ( ,c ,t 7,fig4 #db71 t ! top end ( ,t ,b 0 *>g$ :ile ,e ,c 0 9 place4 ,! *>ge 0 n conduct$4 ,y "k1 f previ\s exp]im5ts1 t & - electrifications ru% toge!r :5ev] possible4 ,:y c we n suppose t a neutral body1 l ! box at ! />t1 conta9s an equal am\nt ( bo? k9ds1 & t ^! diff]5t electrifications h already ru%$ toge!r8 ,if y imag9e a small army ( positive soldi]s /ruggl+1 man to man1 ) ! same numb] ( equally /rong negative soldi]s1 y c readily see t "o-half ( !m c hold ! o!r half f runn+ away4 ,a body rema9s neutral1 !n1 accord+ to ?is idea1 z long z x has an equal quantity ( ! two opposite k9ds ( electrification4 7,see ,!ories1 #ade1 #adf47 ,z soon z ! positively *>g$ ,e ,c 0 br\ght ne> ,t ,b1 x de/roy$ ! neutrality ( ,t ,b1 by pull+ at its - electrification1 & by pu%+ back its electrification to ! top end & into ,c ,t4 ,we say t ! *>g$ ,e ,c produc$ a sep>ation ( ! comb9$ electrifications ( ,t ,b by induction1 & n by contact4 ,z soon z ! inductive action ( ,e ,c 0 remov$1 ,t ,b became neutral aga94 ,illu/ration3 ,figs4 #dc-dd4 #afj4 ,note4 ,figs4 #dc & #dd may aid ! /ud5t4 ,9 ,fig4 #dc1 ,t ,b is suppos$ to be neutral4 ,! d\ble sign means t ! & - electrifications are unit$2 &1 z !re are an equal numb] ( bo? k9ds1 none are left free to tell ! tale4 ,fig4 #dd %[s :at happ5s :5 ! ,e ,c is ne>4 ,:at w\ld happ5 if we c\ld cut into ,t ,b at ! middle ) an insulat$ knife :ile x is pol>iz$ by ,e ,c8 ,,exp]im5t #gf4 ,to le>n h[ to *>ge a body by induction4 ,app>atus4 ,fig4 #db1 same z 9 ,exp4 #ge4 #afa4 ,directions4 7,a7 ,br+ ! *>g$ ,e ,c )9 an in* ( ! bottom ( ,t ,b1 & z soon z ,c ,t is repell$1 %[+ t ,t ,b is pol>iz$ 7,exp4 #ge71 t\* ,t ,b ) y\r f+]2 !n remove y\r f+] :ile y /ill hold ,e ,c 9 place4 7,b7 ,)draw ,e ,c & its inductive action4 ,expla9 ! motions ( ,c ,t dur+ ! exp]im5t4 ,is x /ill repell$ by ,t ,b aft] ,e ,c is remov$8 #afb4 ,free & ,b\nd ,electrifications4 ,z expla9$ 9 ,exp4 #ge1 & z %[n 9 ,fig4 #dd1 ,t ,b became pol>iz$4 ,! - electrification 0 drawn t[>ds ,e ,c2 x 0 held or b\nd !re z long z ,e ,c 0 ne>4 ,! 0 actually repell$ by ,e ,c1 & x 0 free to escape ?r\gh y\r arm z soon z ,t ,b 0 t\*$1 leav+ ! top end ( ,t ,b neutral4 ,z soon z ,e ,c 0 remov$1 ! - electrification1 no long] held by ,e ,c1 spread all ov] ,t ,b & on to ,c ,t4 ,t ,b 0 *>g$ by induction4 ,x 0 *>g$ negatively by driv+ out electrification4 ,,exp]im5t #gg4 ,to %[ t a neutral body is pol>iz$ be=e x is attract$ by a *>g$ "o4 ,app>atus4 ,! electrophorus 7,exp4 #fh72 dry tissue-pap]1 ,t ,p4 ,cut out #b pieces ( ,t ,p1 ea* ab\t #a_/d in* squ>e4 #afc4 ,directions4 7,a7 ,place ! bits ( dry ,t ,p ^u a bo>d or table1 & conv9ce y\rself t !y are attract$ equally by ! *>g$ ,e ,c4 7,b7 ,slightly moi/5 "o piece ( ,t ,p only4 ,see if "o is attract$ by ,e ,c m readily ?an ! o!r4 #afd4 ,pol>ization ,prec$es ,attraction4 ,dry tissue-pap] is n a good conductor2 y h se5 7,exp4 #eb7 t x c be electrifi$1 :i* indicates t x is at lea/ a p>tial insulator4 ,insulators are n easily pol>iz$4 7,:y87 ,ev5 if ! pieces ( ,t ,p 7 pol>iz$1 ! opposite electrifications 7 s ne> ea* o!r t ! attraction ( ,e ,c = ! - 0 ne>ly ov]come by ! repulsion = ! 2 ! result be+ t ,t ,p 0 n /rongly attract$ by ,e ,c until ! _h a *ance to escape4 ,! moi/ tissue-pap] all[$ its to escape m quickly ?an ! dry piece4 ,a conductor is attract$ by a *>g$ body m /rongly ?an an insulator1 because ! latt] is n easily pol>iz$4 ,a neutral body1 !n1 is really no long] neutral :5 x is 9 ! electric field4 ,pol>ization prec$es attraction4 ,,exp]im5t #gh4 ,to f9d :e!r electric induction w act ?r\gh an insulator4 ,app>atus4 ,small bits ( c>bon 7,exp4 #eh72 bits ( moi/ tissue-pap]1 ,t ,p2 "o-half ( ! flat box1 ,t ,f ,b 7,no4 #da72 %eet ( glass1 ,g 7,no4 #ch72 electrophorus 7,exp4 #fh74 ,place ! c>bon & ,t ,p into ,t ,f ,b 7,fig4 #de71 & cov] ) ! glass4 #afe4 ,directions4 7,a7 ,*>ge ! electrophorus cov]1 ,e ,c 7,exp4 #fh71 move x ab\t a little above ! glass1 & see if ! c>bon1 etc41 are attract$4 #aff4 ,dielectrics4 ,! c>bon mu/ h be5 pol>iz$ & attract$ ?r\gh ! glass4 ,y saw1 ,exp4 #g1 t ! l9es ( magnetic =ce c\ld p5etrate & act ?r\gh pap]1 glass1 etc42 x is n[ evid5t t ! electric field is n easily f5c$ 91 ev5 by an insulator4 ,sub/ances1 l ! glass1 :i* all[ ?is inductive influ5ce to act ?r\gh !m1 are call$ dielectrics4 ,illu/ration3 ,fig4 #de4 ,illu/ration3 ,fig4 #df4 ,,exp]im5t #gi4 ,to f9d :e!r a pol>iz$ conductor c act inductively ^u ano!r conductor4 ,app>atus4 ,fig4 #df4 ,insulat+ table1 ,i ,t 7= details see ,exp4 #fd72 ebonite %eet1 ,e ,s 7,no4 #bg72 flat box complete ,f ,b 7,nos4 #dj1 #da72 %eet ( glass1 ,g 7,no4 #ch72 small piece ( slightly moi/ tissue-pap]1 ,t ,p2 *>g$ electrophorus cov]1 ,e ,c4 ,arrange z %[n4 #afg4 ,directions4 7,a7 ,hold ,e ,c1 *>g$1 ne> & "u ,i ,t1 !n br+ y\r f+]1 ,f1 ne> ,t ,p4 ,expla9 ! action ( ,t ,p4 #afh4 ,successive ,induction4 ,! inductive influ5ce ( ,e ,c fir/ pol>iz$ ,i ,t2 ?is act$ ?r\gh ! dielectric1 ,e ,s1 & pol>iz$ ,f ,b1 :i*1 9 turn1 pol>iz$ ,t ,p ?r\gh ! second dielectric1 ,g4 ,?is induction aft] induction is call$ successive induction4 #afi4 ,inductive ,capacity4 ,dielectrics are insulators4 ,two sub/ances may be equally good insulators1 t is1 !y may equally well resi/ ! spread ( electrification ov] _! surfaces1 or ! fl[ ( ! electric curr5t ?r\gh !m1 :ile "o may be1 nev]!less1 a bett] dielectric ?an ! o!r4 ,! bett] ! dielectric1 ! easi] x is = ! electric field to pol>ize a conductor plac$ beyond ! dielectric4 ,a good dielectric is said to h a high inductive p[] or capacity4 ,glass is ab\t #c times z good a dielectric z dry air2 & z ! latt] 7"u c]ta9 conditions7 is tak5 z ! /&>d1 or z unity1 we may say t ! specific inductive capacity ( glass is ab\t #c4 ,,exp]im5t #hj4 ,to /udy ! action ( ! electrophorus4 ,app>atus4 ,! electrophorus 7,exp4 #fh72 small bits ( moi/ tissue-pap]1 ,t ,p4 #agj4 ,directions4 7,a7 ,?or\ghly electrify ,e ,s1 ,fig4 #cd1 & place ,e ,c ^u x by its h&le1 ,e ,r4 7,b7 ,t\* ,e ,c1 z direct$ 9 ,exp4 #fh1 & li/5 = a small sp>k :i* %\ld pass f ,e ,c to y\r f+]4 7,c7 ,aga91 place a little piece ( ,t ,p ^u ,e ,c be=e l[]+ x ^u ,e ,s4 ,d n t\* ,e ,c1 b br+ y\r f+] ne> ,t ,p4 ,:at does ,t ,p d8 ,n[1 t\* ,e ,c & see1 :5 y br+ y\r f+] ne> x1 if ,t ,p acts z x did be=e4 7,d7 ,aga91 place sev]al pieces ( ,t ,p ^u ,e ,c 7,e ,s be+ ?or\ghly *>g$72 t\* ,e ,c1 !n lift x by its h&le4 ,note action ( ,t ,p1 :i* %\ld be slightly moi/4 #aga4 ,discussion4 ,! electrification ^u ! ebonite is negative 7,exp4 #fj74 ,al?\gh ,e ,s & ,e ,c 7,fig4 #cd7 seem q smoo?1 !re are _m little hills1 valleys1 & air-spaces betwe5 !m1 :i* keep !m f t\*+ ea* o!r p]fectly4 ,! ebonite has ! electric field at ! />t1 & x really acts across ^! m9ute air-spaces by induction 7,exp4 #ge71 & pol>izes ,e ,c4 ,! air-spaces =m ! dielectric 7,exp4 #gh74 ,! - electrification ( ,e ,c be+ repell$ by ! - ( ,e ,s1 x is driv5 to ! top ( ,e ,c1 :ile ! is drawn to ! bottom4 ,?is is kept f ru%+ to ! - ( ,e ,s by ! air dielectric1 & because ,e ,s is a non-conductor4 ,by t\*+ ,e ,c ! free - escapes to ! e>?1 leav+ ,e ,c positively *>g$ :5 x is lift$4 ,illu/ration3 ,fig4 #dg4 ,illu/ration3 ,fig4 #dh4 ,illu/ration3 ,fig4 #di4 ,illu/ration3 ,fig4 #ej4 ,illu/ration3 ,fig4 #ea4 #agb4 ,details ( ,action4 ,! diff]5t /eps 9 ! action ( ! electrophorus are %[n graphically 9 ,figs4 #dg to #ea4 ,fig4 #dg %[s ,e ,s negatively *>g$4 ,e ,c is neutral at fir/1 ,fig4 #dh2 t is1 x is suppos$ to conta9 bo? & -1 z %[n by ! d\ble sign 7 #afj74 ,fig4 #di %[s t ,e ,c has be5 pol>iz$ by ! inductive action ( ,e ,s4 ,! repell$ - escapes to ! f+] 7?is escap+ is :at gave ! small sp>k to ! f+] & *>g$ ! ,t ,p 9 ! la/ exp]im5t71 leav+ ! top un*>g$1 :ile ! is b\nd 7,fig4 #ej74 ,z soon z ,e ,c is lift$ 7,fig4 #ea7 ! spreads all ov] ,e ,c1 :i* is !n *>g$4 ,! 1 ^u go+ to ! top1 *>g$ ! pieces ( ,t ,p 7,exp4 #hj1 ,d71 caus+ !m to be repell$4 ,! *>ge ( - ^u ,e ,s has n be5 remov$1 s ! op]ation may be repeat$ _m times be=e ,e ,s mu/ be aga9 electrifi$4 ,! - electrification on ! ebonite acts inductively ?r\gh ,e ,s1 draw+ up electrification f ! e>?4 ,to make ?is action easi] a sole1 or metal conductor1 is (t5 plac$ "u ! ebonite4 ,,exp]im5t #ha4 ,to see1 he>1 & feel ! results ( inductive influ5ce & pol>ization4 ,app>atus4 ,ebonite %eet1 ,e ,s 7,no4 #bf72 insulat+ table1 ,i ,t2 flannel clo?1 ,f ,c4 #agc4 ,directions4 7,a7 ,?or\ghly *>ge ,e ,s ) ,f ,c4 ,) ! "r h& br+ ,e ,s ne> & p>allel to ! top surface ( ,i ,t1 b d n let !m t\* ea* o!r4 7,b7 ,remove ,e ,s1 !n t\* ,i ,t to see if x is *>g$4 7,c7 ,repeat 7,a71 & :ile y hold ,e ,s ab\t #a_/b in* f ,i ,t1 _! flat surfaces be+ p>allel1 t\* ,i ,t4 ,wat* = any sp>ks1 & note any peculi> actions ( ,e ,s4 7,d7 ,remove y\r f+] f ,i ,t1 !n )draw ,e ,s2 f9ally t\* ,i ,t ) y\r knuckle4 #agd4 ,discussion4 ,?is app>atus is really ! electrophorus upside d[n4 ,x %[s v cle>ly 7#a7 ! escape ( ! - electrification f ,i ,t1 by ! sp>k2 7#b7 t ! attraction betwe5 ,i ,t & ,e ,s is mu* great] ?an be=e1 :5 ?is - is remov$2 & 7#c7 x %[s ! diff]5t /eps ( ! induc+ & *>g+ process1 z describ$ 9 ,exp4 #ge1 & z %[n 9 ,figs4 #dc & #dd4 ,,*apt] ,x4 ,,cond5sation ,,( ,,electrification4 ,,exp]im5t #hb4 ,to f9d :e!r a l>ge surface w hold m electrification ?an a small "o4 ,app>atus4 ,! insulat+ table 7= details1 see ,exp4 #fd72 a l>ge t9 bas9 or pan 7n furni%$72 ! electrophorus 7,exp4 #fh74 #age4 ,directions4 7,a7 ,te/ ! electrophorus & be sure t x is work+ prop]ly4 7,b7 ,z 9 ,exp4 #gj1 see h[ _m good sp>ks ,i ,t w take f ,e ,c 7:i* %\ld be re*>g$ at ea* trial7 be=e ! pot5tial ( ,i ,t is rais$ s t x equals ! pot5tial ( ,e ,c4 7,c7 ,c>efully set ! bas9 or pan ^u ,i ,t1 !n c\nt ! numb] ( good sp>ks y c pass to x f ,e ,c 7re*>g$ at ea* trial74 ,comp>e ! numb] ( sp>ks necess>y to raise ! pot5tial ( ! l>ge surface until x equals t ( ,e ,c1 ) ! numb] f\nd 9 "p 7,b74 #agf4 ,electrical ,capacity4 ,x takes m heat to raise ! temp]ature ( a gallon ( ice-wat] to ! boil+ po9t1 ?an x takes = a qu>t ( ice-wat]4 ,y h j se5 t a l>ge insulat$ surface w take m sp>ks f a *>g$ body ?an a small "o1 be=e its pot5tial is rais$ to t ( ! small "o1 & to t ( ! *>g+ body4 ,we say t a l>ge surface has a great] capacity ?an a small "o1 ! %ape & o!r conditions be+ ! same4 ,,exp]im5t #hc4 ,to f9d :e!r ! capacity ( a giv5 conductor c be increas$ )\t increas+ its size4 ,app>atus4 ,fig4 #eb4 ,insulat+ table4 ,i ,t 7,exp4 #fd72 ! extra ebonite %eet1 ,e ,s 7,no4 #bg72 ! complete flat box1 ,f ,b 7,no4 #dj1 #da72 ! *>g$ electrophorus cov]1 ,e ,c 7,exp4 #fh74 ,arrange1 z %[n1 ,i ,t be+ insulat$ f ! e>? by ,e ,s4 ,f ,b %\ld re/ ^u a wood5 table or o!r l>ge conductor4 #agg4 ,directions4 7,a7 ,see h[ _m good sp>ks ,i ,t w take f ,e ,c4 ,re-*>ge ,e ,c at ea* c\nt1 & note ! relative sizes ( ! sp>ks4 7,b7 ,dis*>ge ,i ,t by t\*+ x ) y\r knuckle4 ,illu/ration3 ,fig4 #eb4 #agh4 ,cond5sation2 ,cond5s]s4 ,z ,i ,t easily held m sp>ks ?an x w\ld take be=e 7,exp4 #gj71 we say t its capacity has be5 increas$4 ,its pot5tial didn't increase1 because t c\ld n get great] ?an ! pot5tial ( ,e ,c1 ! *>g+ body4 ,to describe ?is /ate ( affairs1 we say t ! electrification 0 d5s] ?an be=e1 & t x 0 cond5s$4 ,! capacity ( ,i ,t 0 greatly increas$ by ! pres5ce ( ano!r conductor1 ,f ,b1 insulat$ f ,i ,t1 b gr\nd$4 ,su* a comb9ation1 #b conductors1 ) a dielectric betwe5 !m1 is call$ a cond5s]4 ,a cond5s] c hold mu* m electrification at a c]ta9 pot5tial ?an an equal am\nt ( surface c hold :5 n prop]ly arrang$4 ,we might call a cond5s] a /orage batt]y = /atic electricity4 ,! capacity ( a cond5s] dep5ds1 among o!r ?+s1 ^u ! area ( ! conduct+ surfaces1 & ^u ! ?ickness & nature ( ! dielectric4 ,among ! v>i\s =ms ( cond5s]s may be m5tion$ ! ,leyd5 j>1 & ! fulm9at+ pane4 #agi4 ,! ,leyd5 ,j> consi/s ( a wide-m\!d glass j>1 ) t9-foil pa/$ ^u ! inside & outside to )9 #b or #c in*es ( ! top4 ,! inn] coat or conductor is connect$ to a knob or ball at ! top by means ( a *a94 ,to *>ge ! j>1 ! out] coat is connect$ ) ! e>? by hold+ x 9 ! h&1 or by re/+ x ^u a table :ile ! electrification is pass$ to ! knob4 ,a ,leyd5 ,batt]y consi/s ( #b or m connect$ j>s1 ! object be+ to increase ! area ( ! surface4 ,! j> is dis*>g$ by t\*+ "o end ( a dis*>g] 7 #ahh7 to ! out] coat1 & sw++ its o!r end ov] to ! knob1 :5 a bright sp>k w pass betwe5 ! knob & dis*>g]4 7,see ,exp4 #hf47 #ahj4 ,fulm9at+ ,panes1 or ,frankl9's ,plates1 are practically ! same z a ,leyd5 ,j>4 ,! t9-foil1 h[ev]1 is pa/$ ^u ! opposite sides ( a pane ( glass1 a m>g9 ( ab\t an in* be+ left all ar\nd4 ,"o side ( ! pane is *>g$1 & takes ! place ( ! inside coat ( ! j>4 ,! o!r side is gr\nd$4 ,! pane is dis*>g$ by connect+ ! two %eets ( foil4 #aha4 ,induction ,coil ,cond5s]s consi/ ( %eets ( t9-foil sep>at$ by %eets ( p>aff9$ pap]1 :i* act z ! dielectric4 7,see ,induction ,coils47 #ahb4 ,subm>9e ,cables1 ) ! surr\nd+ wat]1 act l cond5s]s1 ! result be+ t ! cond5s+ effect sl[s up ! electric curr5t & ret>ds ! signals4 ,^! make a cond5s] ( enorm\s capacity4 ,! wires inside =m "o conductor1 & ! wat] ! o!r1 :ile ! insulation ar\nd ! wires =ms ! dielectric4 ,,exp]im5t #hd4 ,to /udy ! cond5sation ( electrification4 ,app>atus4 ,same z 9 la/ exp]im5t1 b arrange s t ,f ,b & ,i ,t %all be ne> ea* o!r at "o side2 t is1 s t ! edge ( ,e ,s %all be ev5 ) ! edges ( ! two t9s4 #ahc4 ,directions4 7,a7 ,pass good sp>ks to ,i ,t f ! *>g$ ,e ,c until some?+ happ5s4 ,wat* ! side :]e ,i ,t & ,f ,b are ne> ea* o!r4 #ahd4 ,discussion4 ,we may say t ! electrification 0 cond5s$1 9 ?is exp]im5t1 until ! *>ge became s great t ! cond5s] sudd5ly dis*>g$ itself4 ,cond5s]s may be made 9 _m ways1 b !y all consi/ ( #b conductors1 ) a dielectric betwe5 !m4 ,"o conductor is insulat$1 & receives ! *>ge2 ! o!r conductor is gr\nd$4 ,illu/ration3 ,fig4 #ec4 ,,exp]im5t #he4 ,to /udy ! action ( ! cond5s]4 ,app>atus4 ,fig4 #ec4 ,! insulat+ table1 ,i ,t2 ebonite %eet1 ,e ,s 7,no4 #bg72 flat box1 ,f ,b1 complete 7,nos4 #dj1 #da72 ! electrophorus 7,exp4 #fh74 ,note t ?is is really ! same app>atus z t j us$2 bo? conductors ( ?is cond5s]1 h[ev]1 are insulat$ & rev]s$ 9 position4 #ahe4 ,directions4 7,a7 ,see t y\r electrophorus works prop]ly1 !n f9d out h[ _m good sp>ks y c pass f ,e ,c to ,f ,b1 re*>g+ ,e ,c ea* "t4 ,note ! relative sizes ( ! sp>ks1 & comp>e ! result ) ! numb] tak5 by ! cond5s] 9 ! la/ exp]im5t4 7,b7 ,:5 ,f ,b seems to be fully *>g$1 t\* ,i ,t ) y\r knuckle4 7,f y\r /udy ( induction :at %\ld be ! result87 7,c7 ,n[ see if ,f ,b w aga9 take good sp>ks f ! *>g$ ,e ,c4 ,pass sp>ks to ,f ,b until x seems fully *>g$4 7,d7 ,aga9 t\* ,i ,t1 !n repeat 7,a7 & 7,b7 sev]al times1 until a bright sp>k passes f ,f ,b ov] ! edge ( ,e ,s to ,i ,t4 #ahf4 ,discussion4 ,! action ( ! cond5s]1 z cle>ly %[n1 dep5ds ^u induction4 ,y %\ld n[ be able to expla9 & %[ by diagram ! diff]5t /eps4 ,e ,c 0 positively *>g$ 7,exp4 #hj74 ,?is also *>g$ ,f ,b positively by contact4 ,f ,b act$ inductively ?r\gh ! dielectric1 ,e ,s1 draw+ up "s ( ! - 9 ,i ,t1 & repell+ "s ( ! 4 ,z ,i ,t 0 insulat$1 ?is free electrification c\ld n escape4 ,be=e we t\*$ ,i ,t1 its & - electrifications1 al?\gh p>tially sep>at$1 7 /ruggl+ aga9/ ?is inductive action2 &1 on acc\nt ( _! /rong attraction = ea* o!r1 our ef=ts to *>ge ! cond5s] 7 ret>d$4 ,^u t\*+ ,i ,t ! free escap$ to ! e>?4 7,?is 0 ! cause ( ! sp>k47 ,?is left "s - electrification b\nd on ! und]side ( ,e ,s1 & "s b\nd on ! upp]side ( ,e ,s4 ,! capacity ( ,f ,b 0 increas$ by ?is process1 z ! already put into x 0 v mu* occupi$ by ! attractions ( ! induc$ - j "u ,e ,s4 ,z m 0 giv5 to ,f ,b1 m - 0 drawn up "u ,e ,s & m 0 pu%$ out ( ,i ,t4 ,?is action w5t on until ! two conductors 7 /rongly & oppositely *>g$4 ,?is action goes on cont9u\sly :5 ! l[] conductor is gr\nd$4 ,! sp>k betwe5 ! t9s 0 due to ! ru%+ toge!r ( ! & - electrifications2 x %[$ t !re 0 a mom5t>y curr5t ( electricity4 ,,exp]im5t #hf4 ,to /udy ! effect ( electrical dis*>ges ^u ! human body4 ,app>atus4 ,! cond5s] 7,fig4 #eb71 ) ,e ,s c5trally plac$ s t ! app>atus _c dis*>ge itself2 ! hairp9 dis*>g]1 ,h ,p ,d 7,no4 #dh72 ! electrophorus4 #ahg4 ,directions4 7,a7 ,*>ge ! cond5s] 7,exp4 #hc7 ) #aj good sp>ks f ,e ,c1 !n t\* ,i ,t 7,fig4 #eb74 7,b7 ,re*>ge ! cond5s] ) #aj sp>ks1 !n t\* ,f ,b4 ,dis*>ge x by aga9 t\*+ ,i ,t z 9 7,a74 7,c7 ,re*>ge ) #aj sp>ks2 !n place y\r ?umb aga9/ ,f ,b1 & quickly sw+ ! fir/ f+] ( ! same h& ov] to ,i ,t1 & get a slight %ock4 7,d7 ,re*>ge ) z _m sp>ks z y ?9k y c /&4 7,e7 ,in/ead ( us+ y\r h& to dis*>ge ! cond5s]1 try ! b5t hairp94 ,keep+ "o end aga9/ ,f ,b1 sw+ ! o!r end ov] ne> ,i ,t4 #ahh4 ,%ocks2 ,dis*>g]s4 ,! two conductors be+ oppositely *>g$ 9 ! cond5s] 7,exp4 #he71 x is only necess>y to place "s conductor betwe5 !m to all[ ! *>ges to ru% toge!r4 ,any conductor s us$ is call$ a dis*>g]4 ,! h& c>ri$ ! :ole curr5t :i* caus$ ! %ock4 ,:5 ,i ,t 0 t\*$ fir/1 ! curr5t 0 oblig$ to pass ?r\gh y\r body1 ?r\gh ! floor1 & up ! table-legs into ,f ,b4 ,always t\* ! gr\nd$ conductor fir/ ) ! dis*>g]1 s t y w get a good sp>k & n a %ock4 ,,exp]im5ts #hg-hh4 ,to %[ ! /rong attraction betwe5 ! opposite electrifications 9 ! cond5s]4 ,app>atus4 ,flat box1 ,f ,b 7,nos4 #dj1 #da72 %eet ( glass1 ,g 7,no4 #ch72 electrophorus 7,exp4 #fh74 ,! two p>ts ( ,f ,b are us$ = ! conductors ( ! cond5s] 7,fig4 #ed7 = ! sake ( lightness4 ,! bottoms %\ld be next to ! glass1 :i* is us$ = ! dielectric on acc\nt ( its /iffness4 ,! l[] t9 %\ld re/ ^u ! table4 ,! glass %\ld be p]fectly clean & dry 7hot74 #ahi4 ,directions4 7,a7 ,*>ge ! cond5s] ) #ae or #bj good sp>ks f ,e ,c4 7,b7 ,lift ! cond5s] by "o corn] ( ,g 7,fig4 #ed71 be+ c>eful n to dis*>ge x4 ,expla9 :y ! l[] conductor foll[s ! glass4 ,illu/ration3 ,fig4 #ed4 ,,exp]im5t #hh4 #aij4 ,directions4 7,a7 ,*>ge & lift ! cond5s] z j expla9$ 7,exp4 #hg74 ,fig4 #ed4 7,b7 ,) y\r "r h& t\* ! upp] t9 alone1 !n ! l[] t9 alone4 7,c7 ,t\* bo? t9s at ! same "t1 & note ! action ( ! l[] "o4 #aia4 ,discussion4 ,?is cle>ly %[s h[ /rongly ! two electrifications are b\nd 9 ! cond5s]4 ,ea* refuses to escape to ! e>?1 b !y in/antly ru% toge!r at ! fir/ opportunity4 ,! dielectric may be %att]$ 9 a v heavily-*>g$ cond5s] by ?is /rong attraction4 ,illu/ration3 ,fig4 #ee4 ,,exp]im5t #hi4 ,to %[ h[ ! cond5s] maybe sl[ly dis*>g$4 ,app>atus4 ,fig4 #ee4 ,! cond5s] 7,exp4 #hc72 ! c>bon electroscope ) support 7,exp4 #eh72 ! electrophorus 7,exp4 #fh74 #aib4 ,directions4 7,a7 ,*>ge ! cond5s] by means ( ! electrophorus2 !n hang ! c>bon s t x c sw+ betwe5 ! upp] conductor & ,e ,c plac$ z %[n4 #aic4 ,! ,electric ,*ime4 ,! *>g+ & dis*>g+ ( ! c>bon be+ rapid1 x acts l a *ime z x taps aga9/ ! t9s4 ,,exp]im5t #ij4 ,to asc]ta9 ! location ( ! *>ge 9 ! cond5s]4 ,app>atus4 ,! cond5s]1 consi/+ ( flat box1 ,f ,b 7,nos4 #dj1 #da72 ebonite %eet1 ,e ,s 7,no4 #bg72 insulat+ table1 ,i ,t 7,exp4 #fd72 7:5 *>g+1 arrange z 9 ,fig4 #eb472 ! electrophorus2 hairp9 dis*>g]1 ,h ,p ,d 7,no4 #dh74 #aid4 ,directions4 7,a7 ,*>ge ! cond5s] ) #ae or #bj good sp>ks f ,e ,c4 7,b7 ,lift ,i ,t away f ,e ,s by its insulat+ h&le1 & set x ^u ! table4 7,x may be necess>y to hold ,e ,s d[n47 7,c7 ,lift ,e ,s directly up & away f ,f ,b4 7,lift by #b corn]s2 d n scrape ,e ,s along on ,f ,b2 d n all[ ,e ,s to t\* y\r clo?+47 7,d7 ,replace ,e ,s & !n ,i ,t by its h&le quickly1 mak+ ! cond5s] complete aga94 7,e7 ,) ,h ,p ,d see if ! cond5s] /ill holds a *>ge4 ,t\* ,f ,b fir/ 7,exp4 #hf74 #aie4 ,discussion4 ,z ! conductors 7 completely dis*>g$1 be+ left = a few mom5ts ^u ! table1 x is evid5t t ! opposite electrifications mu/ reside 9 & ^u ! dielectric4 ,! conductors all[ an ev5 & rapid dis*>ge f all p>ts ( ! dielectric at ! same "t4 ,! dielectric is consid]ably /ra9$ :5 a cond5s] is heavily *>g$4 ,?is /ra91 caus$ by ! attraction ( ! opposite electrifications1 may be great en\gh to break or puncture ! dielectric4 ,,exp]im5t #ia4 ,to f9d :e!r any electrification rema9s 9 ! cond5s] aft] x has once be5 dis*>g$4 ,app>atus4 ,! cond5s] 7,fig4 #eb72 ! electrophorus 7,exp4 #fh72 hairp9 dis*>g]1 ,h ,p ,d4 #aif4 ,directions4 7,a7 ,?or\ghly *>ge ! cond5s]4 7,b7 ,dis*>ge x ) ,h ,p ,d1 be+ sure to t\* ,f ,b fir/1 & to t\* ,i ,t = an in/ant :ile ,h ,p ,d is aga9/ ,f ,b4 7,c7 ,aft] a few mom5ts use ,h ,p ,d aga91 & see if y get a slight sp>k4 #aig4 ,residual ,*>ge4 ,! two electrifications on ! opposite sides ( ! dielectric h su* an attraction = ea* o!r1 :5 ! cond5s] is *>g$1 t !y seem to p5etrate1 or soak into1 ! dielectric4 ,^! d n completely soak out aga9 at ! dis*>ge4 ,! small am\nt left is call$ a residual *>ge4 ,illu/ration3 ,fig4 #ef4 ,,exp]im5t #ib4 ,to /udy successive cond5sation2 ! *ime cascade4 ,app>atus4 ,fig4 #ef4 ,?is really consi/s ( two cond5s]s1 jo9$ by a wire4 ,! upp] cond5s] consi/s ( ,t ,f ,b 7,no4 #da71 ,e ,s 7,no4 #bg71 & ! insulat+ table1 ,i ,t4 7,see ,exp4 #fd47 ,! l[] cond5s] consi/s ( ! cov] ( ! t9 box1 ,c ,t ,b 7,no4 #dg71 ! %eet ( glass ,g 7,no4 #ch71 & ,b ,f ,b 7,no4 #dj74 ,! t9 box1 ,t ,b 7,no4 #dg71 is plac$ "u ?is to raise x1 simply4 ,a wire or hairp91 ,h ,p1 is hung ^u ! edge ( ,t ,f ,b1 its l[] end be+ inside ( ,c ,t ,b & n q t\*+ x4 ,?is acts l a p5dulum1 :i* is to sw+ to ,c ,t ,b at ! prop] "t4 ,! s\rce ( electrification is ,e ,c4 ,note4 ,y h le>n$ t 9 *>g+ ! cond5s] ) ! positively *>g$ ,e ,c1 electrification is driv5 f ,f ,b into ! e>?4 ,c we use ?is to *>ge a second cond5s]8 #aih4 ,directions4 7,a7 ,pass #ae or #bj good sp>ks f ,e ,c to ! "u side ( ,i ,t 7,fig4 #ef71 not+ ! action ( ,h ,p4 7,b7 ,hold ,e ,c 9 ! h&1 &1 ) its insulat+ h&le1 poke ,h ,p away f ! cond5s]s4 ,d n dis*>ge !m4 7,c7 ,) ,h ,p ,d te/ ! l[] cond5s] = a *>ge1 t\*+ ,t ,b fir/4 7,d7 ,) ,h ,p ,d t\* ,t ,f ,b fir/ 7:y871 & dis*>ge ! upp] cond5s]4 #aii4 ,discussion4 ,a long r[ ( cond5s]s may be *>g$ 9 ?is way4 ,!re is no advantage 9 x1 z ! electrification is m]ely divid$ betwe5 !m4 ,h[ c two cond5s]s be jo9$ to get ! advantages ( a l>ge surface8 ,,*apt] ,,xi4 ,,electroscopes4 #bjj4 ,electroscopes are in/rum5ts to %[ ! pres5ce1 relative am\nt1 or k9d ( electrification on a body4 7,see ,app>atus ,book1 ,*ap4 ,,xviii1 = ,home-,made ,electroscopes47 ,! c>bon electroscope has be5 describ$ 7,exp4 #eh74 ,! pi?-ball electroscope is made by us+ pi? f eld]1 corn-/alk1 or milk-we$1 9 place ( ! c>bon4 ,! gold-leaf electroscope is a v delicate in/rum5t4 ,! gold-leaf is support$1 z sugge/$ 9 ,fig4 #eg1 at ! l[] end ( a wire conductor :i* /icks ?r\gh & hangs f ! cork ( a glass j> or flask4 ,to ! top end ( ! wire is sold]$ a ball or disk4 ,! glass j> insulates ! gold-leaf1 & keeps x dry & free f du/4 ,illu/ration3 ,fig4 #eg4 #bja4 ,our ,leaf ,electroscope 7,fig4 #eg7 is made ) alum9um-leaf4 ,gold-leaf is too delicate = unskilful h&l+1 & alum9um w d = all ord9>y exp]im5ts4 ,to cut x into any desir$ %ape1 place x betwe5 two %eets ( pap]1 !n cut ?r\gh pap] & all4 #bjb4 ,con/ruction4 ,b5d "o leg ( a hairp91 ,h ,p1 z 9 ,fig4 #eg1 & slide x onto ,i ,t4 ,hang a wire1 ,w1 or ano!r hair p9 /raight5$1 !n b5t1 f ! horizontal leg ( ,h ,p4 ,?is is to support ! leaves1 ,l1 :i* are made f a /rip ( alum9um-leaf ab\t #d 94 long & #c_/d 94 wide4 ,moi/5 ! "u side ( ! horizontal "p ( ,w ) pa/e or mucilage2 press x ^u ! middle ( ! /rip laid flat ^u ! table1 & !n lift ,w4 ,! leaves %\ld cl+ to ,w4 ,ea* leaf %\ld be1 !n1 #b 94 long4 ,!y %\ld hang close toge!r :5 n 9 use4 ,a l>ge *imney1 or fruit-j>1 may be us$ to surr\nd ! leaves1 & to keep curr5ts ( air f !m4 ,! leaves %\ld n t\* ! side ( ! j> :5 spread4 ,,exp]im5t #ic4 ,to /udy ! leaf electroscope2 *>g+ by conduction4 ,app>atus4 ,! leaf electroscope 7,fig4 #eg1 #bja1 #bjb72 ebonite rod1 ,e ,r 7,no4 #bh72 flannel clo?1 ,f ,c 7,no4 #cj74 #bjc4 ,directions4 7,a7 ,?or\ghly *>ge ,e ,r1 !n scrape x along ^u ,i ,t1 not+ ! action ( ! leaves1 ,l4 7,b7 ,see if ! leaves w rema9 spread = "s "t4 7,c7 ,t\* ,i ,t to dis*>ge x1 & note ! action ( ,l4 #bjd4 ,discussion4 ,no explanation %\ld be necess>y = ?is4 ,are ! leaves *>g$ alike8 ,z !y 7 *>g$ by contact1 is ! electrification on !m or -8 ,,exp]im5t #id4 ,to *>ge ! leaf electroscope by induction4 ,app>atus4 ,our electroscope 7,fig4 #eg1 #bjb72 ebonite %eet1 ,e ,s 7,no4 #bg72 flannel clo?1 ,f ,c 7,no4 #cj74 #bje4 ,directions4 7,a7 ,*>ge ,e ,s ) ,f ,c1 !n hold ,e ,s above ,i ,t 7,fig4 #eg71 _! surfaces be+ kept p>allel & ab\t #b or #c in*es ap>t4 ,wat* ! leaves4 7,b7 ,)draw ,e ,s4 ,d ! leaves rema9 spread8 7,c7 ,repeat 7,a71 & be=e remov+ ,e ,s1 t\* ,i ,t4 7,d7 ,remove y\r f+] f ,i ,t1 !n )draw ,e ,s4 ,d ! leaves n[ rema9 spread8 #bjf4 ,discussion4 ,! p]man5t div]g5ce ( ,l 0 due to a *>ge giv5 by induction4 7,exp4 #gf47 ,z ,e ,s 0 -1 :at 0 ! k9d ( a *>ge 9 ,l8 ,did any electrification g to ! electroscope f ,e ,s8 ,9 7,c7 :at became ( ! *>ge 9 ,l8 ,expla9 :y ! leaves aga9 div]g$ 9 7,d74 ,! electroscope 0 *>g$ ) electrification by tak+ - out ( x4 ,,exp]im5t #ie4 ,to le>n "s uses ( ! electroscope4 ,app>atus4 ,our electroscope 7,fig4 #eg1 #bjb72 ebonite rod1 ,e ,r 7,no4 #bh72 ebonite %eet1 ,e ,s 7,no4 #bg72 glass1 ,g 7,no4 #ch72 flannel clo?1 ,f ,c 7,no4 #cj74 #bjg4 ,directions4 7,a7 ,) ! *>g$ ,e ,r *>ge ! electroscope negatively by conduction 7,exp4 #ic74 ,note ! am\nt ( p]man5t div]g5ce ( ! leaves4 7,b7 ,electrify ! glass1 :i* w be 1 7or use ! ,e ,c71 & sl[ly l[] x ov] ,i ,t1 not+ ! effect ^u ,l4 ,raise & l[] ,g or ,e ,c sev]al times4 ,does ,g1 :i* has an opposite *>ge to ! electroscope1 make ,l div]ge m or less8 7,c7 ,dis*>ge ! electroscope & re*>ge z 9 7,a74 7,d7 ,sl[ly l[] ! *>g$ ,e ,s ov] ,i ,t4 7,e7 ,sl[ly l[] ! palm ( y\r h& ov] ,i ,t4 ,note4 ,if ! ,g is br\ght too ne> ! -ly *>g$ electroscope1 ,l w fir/ collapse & !n in/antly div]ge aga9 ) a *>ge by contact4 ,! fir/ motions %\ld be obs]v$4 #bjh4 ,discussion4 ,z a neutral body causes a slight collapse ( ! leaves1 z well z a body *>g$ positively 7:5 ! *>ge 9 ! leaves is -71 an increase ( div]g5ce is really ! only sure te/ to tell h[ a body is *>g$4 ,! - leaves collapse :5 a body is br\ght ne> ,i ,t1 because ! - 9 !m is drawn up t[>ds ! body4 ,! leaves div]ge m :5 a - body is br\ght ne>1 because ! - 9 ,i ,t is repell$ into !m4 #bji4 ,! ,pro(-plane4 ,s9ce *>ges ( /atic electricity reside ^u ! outside ( conductors1 x is an easy matt] to take samples ( ! electrification4 ,?is may be done ) a little in/rum5t call$ a c>ri]1 or pro(-plane4 ,x consi/s ( a small conductor ) an insulat+ h&le4 ,a r+ or co9 may be us$ = ! conductor1 & a silk ?read = ! h&le4 ,by t\*+ ! c>ri] to any *>g$ body1 x1 also1 becomes *>g$2 & ! nature ( ! *>ge may be det]m9$ by ! use ( a previ\sly *>g$ leaf electroscope 7,exp4 #ie74 ,a delicate gold-leaf electroscope w\ld be ru9$ by com+ 9 contact ) a heavily *>g$ body4 ,! c>ri] all[s a small sample to be te/$4 ,,*apt] ,,xii4 ,,miscellane\s ,,exp]im5ts4 ,illu/ration3 ,fig4 #eh4 ,,exp]im5t #if4 ,to %[ t friction always produces two k9ds ( electrifications4 ,app>atus4 ,fig4 #eh4 ,! c>bon electroscope 7,exp4 #eh72 flannel clo?1 ,f ,c1 d\bl$ twice to make #d ?icknesses 7see ,fig4 #eh72 ebonite %eet1 ,e ,s 7,no4 #bf72 ebonite rod1 ,e ,r 7,no4 #bh72 *>g$ electrophorus cov]1 ,e ,c4 #baj4 ,directions4 7,a7 ,vigor\sly rub ,e ,s ) ,f ,c 7fold$ z 9 ,fig4 #eh74 ,see if y c discov] any attraction betwe5 !m4 7,b7 ,rub ,e ,s aga91 b d n lift ,f ,c f x ) ! h& alone4 ,slip ,e ,r "u ! top fold 9 ,f ,c 7,fig4 #eh71 & lift ,f ,c /raight up f ,e ,s4 ,d n let ,f ,c t\* ! table or y\r h&4 7,c7 ,see if ,f ,c is *>g$1 us+ #b or #c diff]5t te/s4 7,d7 ,*>ge ! electroscope ) ,f ,c until ! c>bon is /rongly repell$4 7,e7 ,br+ ! positively *>g$ ,e ,c sl[ly ne> ! c>bon1 & note ! result4 7,f7 ,sl[ly br+ ! negatively *>g$ ,e ,s ne> ! c>bon t has be5 *>g$ by contact ) ,f ,c4 #baa4 ,discussion4 ,?is exp]im5t %[$ t :ile ! ebonite 0 negatively *>g$1 ! flannel 0 positively *>g$4 ,"o k9d ( electrification is nev] produc$ )\t ! o!r4 ,x c also be %[n t ! two k9ds are equal 9 am\nt4 ,,exp]im5t #ig4 ,to %[ successive sp>ks4 ,app>atus4 ,fig4 #ei4 ,! electrophorus 7,exp4 #fh72 ! extra ebonite %eet1 ,e ,s 7,no4 #bg72 ?ree co9s 7m>k$ ,a1 ,b1 ,c1 9 ,fig4 #ei74 ,! co9s %\ld ne>ly t\* ea* o!r1 & re/ ^u ,e ,s4 ,a "p1 only1 ( ! electrophorus cov] is %[n4 #bab4 ,directions4 7,a7 ,?or\ghly *>ge ! electrophorus cov]4 7,b7 ,place y\r f+] ^u ! co9 m>k$ ,a1 to gr\nd x1 !n quickly t\* ! co9 ,c ) ! *>g$ cov]1 at ! same "t wat*+ = sp>ks betwe5 ! co9s4 ,if y _c see ! sp>ks1 d>k5 ! room a little1 & look at ! c5t] co91 ,b1 :ile do+ ! exp]im5t4 ,illu/ration3 ,fig4 #ei4 ,illu/ration3 ,fig4 #fj4 ,,exp]im5t #ih4 ,to %[ to ! eye ! /rong attraction betwe5 a *>g$ & a neutral body4 ,app>atus4 ,! flat box1 ,f ,b 7,nos4 #dj1 #da72 ! electrophorus 7see ,exp4 #fh74 #bac4 ,directions4 7,a7 ,/& ,f ,b ^u its edge ^u a level table1 !n br+ ! *>g$ electrophorus cov] ne> x4 7,b7 ,in/ead ( ! above1 use light hoops made ( pap]1 egg%ells1 fea!rs1 sawdu/1 etc4 ,,exp]im5t #ii4 ,to feel ! /rong attraction betwe5 a *>g$ & a neutral body4 ,app>atus4 ,fig4 #fj4 ,! flat box ,f ,b 7,nos4 #dj1 #da72 ! electrophorus 7,exp4 #fh74 #bad4 ,directions4 7,a7 ,hold ,f ,b 9 ! left h&1 z %[n1 !n sl[ly br+ ne> x ! *>g$ cov]1 at ! same "t look+ betwe5 !m s t y c keep !m ! same di/ance ap>t all ! way r\nd4 7,b7 ,br+ !m ne> en\gh to all[ a sp>k to pass f ,e ,c to ,f ,b4 ,,exp]im5t #ajj4 ,! human body a frictional electric ma*9e4 ,app>atus4 ,y\rself2 a c>pet2 a room ) dry air1 easily _h on a cold w9t]'s day4 #bae4 ,directions4 7,a7 ,scrape y\r feet along ^u ! c>pet1 !n quickly t\* y\r f+] to "s conductor1 z1 = example1 a fri5d's nose4 7,b7 ,x is possible to light ! gas by ! above process4 ,h a fri5d turn on ! gas j be=e y br+ y\r f+] to ! jet1 & be sure t ! sp>k f y\r f+] passes ?r\gh ! gas on its way to ! conductor1 ! jet4 7,c7 ,br+ y\r f+] quickly ne> a small piece ( tissue pap] aft] y h scrap$ y\r feet along to *>ge y\r body4 #baf4 ,/atic ,electric ,ma*9es are us$ to produce l>ge quantities ( /atic electricity4 ,9 ! e>ly =ms1 ! electrification 0 produc$ by friction4 ,mod]n ma*9es dep5d ^u ! pr9ciple ( induction4 ,! electrophorus 7,exp4 #fh7 is really a v simple =m ( induction ma*9e4 ,! pot5tial ( ^! ma*9es is v great1 z ! sp>k may jump _m in*es4 ,?\s&s ( ,galvanic cells w\ld be ne$$ to make a sp>k an in* long4 ,:5 ! sp>k passes ?r\gh ! air x meets ) an extremely high resi/ance1 z air practically insulates ord9>y electricity4 ,?is high resi/ance 9 ! circuit r$uces ! /r5g? ( ! curr5t4 ,:ile ! pot5tial is v high1 ! /r5g? ( ! curr5t is v l[4 7,see ,ohm's ,law47 ,,*apt] ,,xiii4 ,,atmosph]ic ,,electricity4 #bag4 ,atmosph]ic ,electricity4 ,! air is g5]ally electrifi$1 ev5 9 cle> wea!r4 ,its *>ge is usually 4 ,cl\ds are sometimes 1 & sometimes -4 ,! cause ( atmosph]ic electricity is n ?or\ghly und]/ood4 ,x is ?\ght1 by "s1 to be due to ! friction ( ! p>ticles ( vapor ^u ea* o!r4 ,x is also ?\ght t ! evaporation ( sea wat]1 & ! friction ( w9ds1 produce x4 #bah4 ,lightn+4 ,b5jam9 ,frankl91 9 #ageb1 prov$ by 8 fam\s kite exp]im5t t atmosph]ic & frictional electricities 7 ( ! same nature4 ,by means ( a kite1 ! /r+ be+ wet by ! ra91 he succe$$1 dur+ a ?und]-/orm1 9 draw+ sp>ks1 *>g+ cond5s]s1 etc4 ,lightn+ may be produc$ by ! passage ( electricity betwe5 cl\ds1 or betwe5 ! cl\d & ! e>?1 :i*1 ) ! int]v5+ air1 h ! effect ( a cond5s]4 ,if "o cl\d is *>g$1 x acts inductively ^u ano!r1 produc+ 9 x ! opposite k9d ( electrification4 ,:5 ! attraction betwe5 ! two electrifications becomes great en\gh1 x ov]comes ! resi/ance ( ! air1 & lightn+ is produc$4 ,! fla% is practically in/antane\s4 ,! direction tak5 seems to dep5d ^u ! conditions ( ! surr\nd+ air4 ,x has g5]ally a zigzag motion1 & is !n call$ *a9 lightn+4 ,! air 9 ! pa? ( ! electricity becomes int5sely heat$2 x is ?is effect1 & n ! electricity :i* we see4 ,9 hot wea!r fla%es are (t5 se5 :i* light up :ole cl\ds1 no ?und] be+ he>d4 ,?is is call$ heat lightn+1 & is g5]ally consid]$ to be due to di/ant dis*>ges1 ! light ( :i* is reflect$ by ! cl\ds4 ,! pot5tial ( ! lightn+ sp>k is beyond all calculation4 ,! sp>k jumps ?r\gh miles ( air1 :i* is1 really1 an insulator4 ,?is sp>k repres5ts billions & billions ( volts4 #bai4 ,?und] is caus$ by ! viol5t di/urbances produc$ 9 ! atmosph]e by lightn+4 ,! nature ( ! s\nd dep5ds1 among o!r ?+s1 ^u ! di/ance ( ! obs]v] f ! dis*>ge1 & ^u ! l5g? & %ape ( ! pa? tak54 ,cl\ds1 hills1 & o!r objects produce e*oes1 :i* also modify ! orig9al s\nd4 ,x takes ne>ly five seconds = ! s\nd to travel "o mile4 #bbj4 ,lightn+-,rods1 :5 well con/ruct$1 (t5 prev5t viol5t dis*>ges ( atmosph]ic electricity4 ,!y h po9t$ prongs at ! top1 :i* all[ ! negative ( ! e>? 7:i* is be+ attract$ by ! cl\d :5 x is positively *>g$7 to pass quietly into ! air above2 ?is neutralizes ! cl\d4 ,9 case ( a dis*>ge1 ! rods aid 9 conduct+ ! electricity to ! e>?4 #bba4 ,causes ( ,atmosph]ic ,electricity4 ,!re are sev]al !ories ab\t ?is4 ,"s ?9k t x is due to ! rotation ( ! e>?1 diff]5t p>ts be+ act$ ^u diff]5tly by ! heat ( ! sun4 ,"s claim t ! evaporation ( ! wat] 9 ! ocean produces x1 :ile o!rs say t ! electrification is produc$ 9 ! cl\ds by ! friction ( _! p>ticles ^u ea* o!r4 ,! matt] has n be5 settl$4 #bbb4 ,/4 ,elmo's ,fire ,electrification f ! e>? is (t5 drawn up ?r\gh ! ma/s ( %ips to neutralize t 9 ! cl\ds 7see #bbj71 &1 z x escapes f ! po9ts ( ! ma/s1 light is produc$4 ,?is may be cle>ly %[n by repeat+ ,exp4 #ga 9 ! d>k2 ! head ( ! p9 7,fig4 #ci7 w repres5t ! end ( a ma/1 & ! *>g$ electrophorus cov] w be ! *>g$ cl\d4 #bbc4 ,aurora ,borealis1 also call$ ,nor!rn ,lights1 are lum9\s effects (t5 se5 9 ! nor?4 ,!y (t5 occur at ! same "t ) magnetic /orms1 at :i* times telegraph & telephone "w may be di/urb$4 ,! exact cause ( ?is light is n kn[n1 b x is ?\ght by _m to be due to di/urbances 9 ! e>?'s magnetism1 caus$ by ! action ( ! sun4 ,,curr5t ,,electricity4 ,,"p ,,iii4--,,curr5t ,,electricity4 ,,*apt] ,,xiv4 ,,con/ruction ,,& ,,use ,,( ,,app>atus4 ,note4--,be=e tak+ up ! /udy ( cells & ! electric curr5t1 let u p]=m a few exp]im5ts 9 ord] to und]/& ! con/ruction & use ( "s ( ! app>atus ne$$ = su* /udy4 ,a dry cell w be us$ z ! s\rce ( ! electricity = ^! fir/ exp]im5ts1 because x is conv5i5t4 ,y w und]/& its action lat]4 ,use ?is cell only z direct$2 improp] use ( x might spoil x4 ,illu/ration3 ,fig4 #fa4 ,,exp]im5t #aja4 ,to /udy ! effect ( ! electric curr5t ^u ! magnetic ne$le4 ,app>atus4 ,a compass 7,no4 #ah72 a dry cell1 ,d ,c 7,no4 #ea72 wires ) spr+ connectors atta*$ 7 #bbf7 = mak+ connections4 ,fig4 #ff %[s a plan or top view ( ! arrangem5t4 ,any o!r =m ( cell w d 9 place ( ,d ,c4 #bbf4 ,electrical ,connections4 ,"o mu/ con/antly jo9 wires1 connect wires ) app>atus1 or connect "o piece ( app>atus to ano!r1 to make ! prop] electrical connections4 ,a v simple me?od ( connections has be5 us$ 9 all ! app>atus describ$ 9 ^! exp]im5ts4 ,a little arrangem5t :i* we %all call a spr+ connector1 ,s ,c1 7,fig4 #fa71 gives u a means ( quickly mak+ connections2 t is1 x does away ) exp5sive b9d+-po/s4 ,x is made ( brass1 nickel plat$1 & may be us$ any:]e )\t affect+ ! magnetic ne$le4 ,six or eight wires1 ab\t ,no4 #bd gauge1 ea* ab\t #a-a_/b ft4 long1 %\ld be prep>$ ) a connector at ea* end4 ,y may use wire furni%$ 7,no4 #ec74 ,scrape ! insulation f ! ends ( ! wires = ab\t #a-a_/b in*es1 !n twi/ ! b>e ends ar\nd ! connectors z %[n 9 ,fig4 #fa4 ,! wire %\ld pass ar\nd tightly at lea/ #d or #e times & !n be twi/$ a little1 z %[n1 to help tight5 x4 ,d n put x on s poorly or 9 su* quantity t ! "p1 ,b1 w spread4 #bbg4 ,fig4 #fb %[s h[ ! connector %\ld be slipp$ ^u a ?9 piece ( metal1 ,m1 l t on ! galvanoscope1 = example4 ,! wire1 ,w1 f ! app>atus itself is p]man5tly fa/5$ "u ! head ( ! screw1 ,s1 :ile ! wire f any o!r app>atus is "o ( ^? kept on h& z above m5tion$ & connect$ ) ,s ,c4 ,illu/ration3 ,fig4 #fb4 ,illu/ration3 ,fig4 #fc4 ,illu/ration3 ,fig4 #fd4 #bbh4 ,fig4 #fc %[s h[ sev]al wires may be quickly jo9$1 electrically1 by slipp+ ! connectors at _! ends ^u a ?9 metal plate1 ,m ,p1 :i* may be a piece ( t91 z9c1 copp]1 etc4 ,m ,p %\ld n be too ?ick4 ,9 case ! connectors become too mu* spread to p9* ! plate1 squeeze ! "p1 ,a1 a little m toge!r4 #bbi4 ,fig4 #fd %[s ! me?od ( connect+ ) ! special =m ( b9d+-po/ us$1 = example1 ^u ! resi/ance coil1 ,r ,c4 ,! end1 ,c1 ( ,s ,c1 is press$ d[n into ! tube1 ,t1 until y feel1 by mov+ x1 t x spr+s firmly aga9/ ! sides ( ! tube4 ,9 case y wi% ,s ,c to fit v tightly 9 ,t1 "o ( ! legs may be slightly b5t outw>ds4 ,illu/ration3 ,fig4 #fe4 #bcj4 ,! connector may be us$ 9 /ill ano!r way2 t is1 by pu%+ ! "p1 ,a1 into ! hole ( an ord9>y b9d+-po/1 7,fig4 #fe71 & us+ x j ! same z a ?ick wire4 #bca4 ,directions4 7,a7 ,/& ! compass & ,d ,c ne> ea* o!r 7,fig4 #ff74 ,atta* "o end ( an insulat$ copp] wire1 ,c ,w1 to ! b9d+-po/1 ,c1 :i* is on ! c>bon plate ( ! cell4 ,d n jo9 ! o!r end to ! o!r b9d+-po/1 ,zn1 ( ! z9c plate4 7,b7 ,) ! left h& hold ,c ,w above & ne> ! compass-ne$le1 & 9 ! ,n & ,s l9e1 s t x w ext5d ov] ! entire l5g? ( ! ne$le4 7,c7 ,take ! free end ( ,c ,w 9 ! "r h& & t\* b9d+-po/1 ,zn1 = an in/ant only1 wat*+ ! ne$le4 ,repeat4 #bcb4 ,curr5t ,detectors4 ,we "k t a magnet c act1 by induction1 ?r\gh ! air ^u a piece ( iron or ^u ano!r magnet4 ,! deflection ( ! ne$le 9 ?is exp]im5t %[s t !re mu/ be a magnetic field ar\nd a wire c>ry+ a curr5t4 ,?is fact is ( ! greate/ possible importance4 ,! simple magnetic ne$le1 :5 us$ z above1 becomes a detector ( electricity4 ,illu/ration3 ,fig4 #ff4 ,illu/ration3 ,fig4 #fg4 ,,exp]im5t #ajb4 ,to /udy ! con/ruction & use ( a simple key4 ,app>atus4 ,a key1 ,k 7,no4 #ee7 7 #bcc72 a dry cell1 ,d ,c1 7,no4 #ea72 a compass1 ,o ,c 7,no4 #ah74 ,arrange z %[n 9 ,fig4 #fg1 :i* is a top view or plan4 ,connect ! pieces ( app>atus ) wires & spr+ connectors 7 #bbf74 ,b9d+-po/1 ,c1 is jo9$ to ,i 797 ( ! key2 ,o 7out7 ( key is jo9$ to b9d+-po/1 ,zn1 ! wire1 ,c ,w1 pass+ directly ov] & ne> ,o ,c1 :i* is to be us$ z a detector4 ,! curr5t _c pass until ! lev]1 ,l1 is press$4 ,a metal plate1 ,m ,p1 is us$ to connect two %ort wires 7 #bbh7 9 case ,c ,w is n long en\gh4 ,illu/ration3 ,fig4 #fh4 #bcc4 ,a key is m]ely a piece ( app>atus by :i* ! circuit c be conv5i5tly & rapidly op5$ & clos$ at ! w ( ! op]ator2 t is1 by x ! electricity c be quickly turn$ on or (f4 ,fig4 #fh %[s a simple =m ( key4 ,to ! base1 ,b1 are fa/5$ two metal pieces or /raps1 ! upp] "o1 ,l1 be+ ! lev] or key prop]4 ,! front end ( ,l is rais$ above ,o1 s t ! two d n t\* ea* o!r unless ,l is firmly press$ d[n4 ,a screw1 ,s1 keeps ,l f spr++ too f> above ,o4 ,= conv5i5ce we %all suppose t ! wire lead+ to ! key jo9s x at ,i 7972 ! wire f ! key is jo9$ to ,o 7out71 by means ( connectors 7 #bbf74 ,! key may be put into any circuit by fir/ cutt+ a wire & !n jo9+ ! ends to ,i & ,o4 ,spr+ connectors make ! be/ connections ) ?is =m ( key4 7,= ,home-,made ,keys see ,app>atus ,book47 #bcd4 ,directions4 7,a7 ,! magnetic ne$le be+ directly "u ! wire1 press ,l d[n = an in/ant only & note ! action ( ! ne$le4 7,b7 ,press ,l aga91 hold x d[n = #c seconds1 n ov] t1 & wat* ! ne$le4 ,discussion4 ,! key all[s u to easily regulate ! l5g? ( "t dur+ :i* ! curr5t passes4 ,?is exp]im5t %[s1 also1 t ! magnetic field ab\t ! wire disappe>s z soon z ! curr5t ceases to pass4 ,illu/ration3 ,fig4 #fi4 ,,exp]im5t #ajc4 ,to /udy ! con/ruction & use ( a simple curr5t rev]s]4 ,app>atus4 ,a dry cell1 ,d ,c 7,no4 #ea72 a compass1 ,o ,c 7,no4 #ah72 a curr5t rev]s]1 ,c ,r 7,no4 #eg7 7,see #bce72 an insulat$ copp] wire1 ,c ,w1 #b or #c feet long1 ) spr+ connectors jo9$ to its ends 7 #bbf74 ,arrange z 9 ,fig4 #gj4 ,! wire1 ,c ,w1 lead+ f ,x %\ld be held by ! left h& s t x w be j above 7or bel[7 & p>allel to ! magnetic ne$le4 ,! curr5t _c pass ?r\gh ,c ,w until "o ( ! /raps or lev]s on ,c ,r is press$4 7,see ,app>atus ,book = ,home-,made ,rev]s]s47 #bce4 ,! ,curr5t ,rev]s]4 7,no4 #eg47 ,to ! wood5 base 7,fig4 #fi7 are fa/5$ f\r metal /raps1 ea* turn$ up at ! end s t spr+ connectors 7 #bbg7 c be slipp$ on to make electric connections ) o!r pieces ( app>atus4 ,suppose t at ,c & ,z connections are made ) ! c>bon & z9c ( ! cell1 by means ( wires & spr+ connectors 7 #bbf74 ,! curr5t comes f ! cell to ,c4 ,z ! two /raps1 #b & #c1 press firmly up aga9/ /rap #d1 & d n t\* #a1 x is evid5t t no curr5t c pass f #a to #b or to #c until !y are press$ d[n ^u #a4 ,two wires are jo9$ by spr+ connectors to #b & #c at _! turn$ up ends1 ,x & ,y1 & ^! wires lead to any desir$ in/rum5t4 ,illu/ration3 ,fig4 #gj4 #bcf4 ,directions4 7,a7 ,press d[n lev] #b 7,fig4 #gj71 = an in/ant only1 at ! same "t not+ c>efully 9 :i* direction ! ,n pole ( ! ne$le is deflect$4 7,b7 ,aft] all[+ lev] #b to spr+ up aga91 & aft] ! ne$le comes to re/1 press d[n lev] #c = an in/ant1 wat*+ ! ne$le4 ,is ! ,n pole ( ! ne$le deflect$ 9 ! same direction z x 0 9 7,a78 #bcg4 ,discussion4 ,! rev]s] gives u a quick & easy means ( rev]s+ ! curr5t :i* is to pass ?r\gh any desir$ in/rum5t1 fir/ 9 "o direction & !n 9 ! opposite direction4 ,suppose 7,fig4 #fi7 t ! curr5t ent]s ,c ,r at ,c1 z x does :5 ,c is jo9$ to ! c>bon ( ! cell2 ! curr5t c g no f>!r until "o lev] is l[]$4 ,if lev] #b 7,fig4 #fi7 be n[ press$ d[n1 z 9 "p 7,a71 ! curr5t w pass along #b1 :i* does n n[ t\* #d1 out ?r\gh ,x to a coil ( wire or any in/rum5t1 & back to ! rev]s] by ! wire jo9$ to ,y4 ,x w !n pass f #c onto #d1 to ,z1 & back to ! ,cell2 t is1 ! curr5t ent]s ,c ,w at ,x4 ,:5 lev] #c is press$1 ! curr5t /ill ent]+ ,c ,r at ,c1 ! electricity w pass onto #c & out at ,y1 & back ?r\gh ,x1 #d & ,z to ! cell4 ,! curr5t1 !n1 c be made to pass out ( ,x or ,y at w by press+ ! prop] lev]4 ,?is exp]im5t also tea*es some?+ ab\t curr5ts1 b ^! w be discuss$ lat]4 ,illu/ration3 ,fig4 #ga4 ,,exp]im5t #ajd4 ,to /udy ! simple curr5t detector4 ,app>atus4 ,! compass 7,no4 #ah72 dry cell1 ,d ,c 7,no4 #ea72 curr5t rev]s]1 ,c ,r 7,no4 #eg72 copp] wire1 ,c ,w1 a few feet long1 ) spr+ connectors on its ends4 7,see ,app>atus ,book1 ,*apt] ,,xiii1 = ,home-,made ,detectors47 #bch4 ,directions4 7,a7 ,jo9 ! ends ( ! wire to ,x & ,y ( ! rev]s]1 ,c ,r1 z 9 ! la/ exp]im5t4 ,coil up ,c ,w s t y c hold ! coil ) y\r left h&1 z %[n 9 ,fig4 #ga1 ! magnetic ne$le be+ inside ( x & p>allel to x4 7,b7 ,press lev] #b ( ! rev]s] = an in/ant only4 ,is ! ne$le deflect$ m or less ?an x 0 :5 ! wire simply pass$ ov] or "u x once8 7,c7 ,rev]se ! curr5t ?r\gh ,c ,w by press+ lev] #c1 & note ! result4 7,d7 ,get cle>ly 9 m9d :i* way ! ,n pole ( ! ne$le is deflect$ :5 ! curr5t ent]s ,c ,w at ,x1 also :5 x ent]s at ,y4 #bci4 ,discussion4 ,! curr5t pass$ ov] ! ne$le 9 "o direction1 & "u x 9 ! opposite direction2 t is1 ! "p ( ! wire above helps t bel[4 ,ea* turn ( ! wire increases ! /r5g? ( ! magnetic field ab\t ! coil1 & helps to deflect ! ne$le4 ,9 ?is way1 by increas+ ! numb] ( turns1 detectors may be made t w %[ ! pres5ce ( v weak curr5ts4 ,! magnetic fields ab\t wires & coils w be /udi$ 9 a lat] *apt]4 ,illu/ration3 ,fig4 #gb4 ,,exp]im5t #aje4 ,to /udy ! con/ruction & use ( ! simple galvanoscope4 ,app>atus4 ,! galvanoscope1 ,g ,v1 complete 7,no4 #eh71 describ$ 9 #bdj-bdf2 dry cell1 ,d ,c 7,no4 #ea72 curr5t rev]s]1 ,c ,r 7,no4 #eg7 7 #bce72 wires1 ) spr+ connectors1 to jo9 ! diff]5t pieces ( app>atus 7#bbf74 7,see ,app>atus ,book1 ,*apt] ,,xiii1 = ,home-,made ,galvanoscopes47 #bdj4 ,! ,galvanoscope 7,fig4 #gb7 is m ?an a m]e detector ( electricity4 ,) x we %all be able to /udy1 m fully1 cells1 curr5ts1 etc41 etc4 ,we mu/ fir/ und]/& its con/ruction4 #bda4 ,! ,coil-support1 ,c ,s1 is fa/5$ to ! cross-piece1 ,c ,p1 on :i* are ! #c b9d+-po/s or coil-ends1 ,l1 ,m & ,r 7left1 middle1 "r74 ,! legs1 ,g ,l1 are screw$ to ,c ,p 9 su* a way t ,c ,p is held a little above ! table3 ?is all[s ,c ,s to be tipp$ to ! front or re> to adju/ x v]tically4 ,on acc\nt ( ! peculi> arrangem5t ( ! legs1 ! galvanoscope c be made to /& firmly1 ev5 ^u unev5 surfaces4 ,! screws hold+ ,g ,l %\ld n be put 9 f> en\gh to te> ! ?reads 9 ! wood1 ,c ,p4 #bdb4 ,! ,galvanoscope ,coils1 ,g ,c1 are two 9 numb]1 bo? be+ fa/5$ to ! coil-support1 ,c ,s4 ,! fir/ coil has five turns ( wire1 its ends be+ fa/5$ to ,l & ,m2 ! o!r coil has t5 turns1 ) ends at ,m & ,r4 ,! curr5t c1 at w1 be made to pass ?r\gh #e1 #aj or #ae turns ( wire by mak+ ! prop] connections4 ,suppose t we h two wires direct f a cell1 or f ! curr5t rev]s]1 ) spr+ connectors on !m s t we c slip !m onto ,l1 ,m or ,r1 :i* /& = left1 middle or "r4 ,:5 ! wires are jo9$ to ,l & ,m ! curr5t c pass ?r\gh b #e turns2 :5 jo9$ to ,m & ,r x w g ?r\gh #aj turns2 & :5 to ,l & ,r x w pass ?r\gh ! entire #ae turns4 ,:5 ! curr5t ent]s ! galvanoscope at ,l & passes out at ,m or ,r1 x w pass ?r\gh ! turns ( wire f left to "r1 at ! top2 t is1 x w pass 9 a clockwise direction4 #bdc4 ,! ,compass-ne$le1 furni%$ ) ,o ,c 7,no4 #ah71 w d also = ?is galvanoscope4 ,x %\ld be plac$ ^u ! p9-po9t aft] fix+ on ! po9t]s 7 #bdf74 ,! l5g? ( ! ne$le %\ld be p>allel to ! plane ( ! coil :5 no curr5t passes2 t is1 ! coil & coil-support %\ld be 9 ! ,n & ,s l9e4 ,! ne$le c be c5t]$ 9 reg>d to "r & left1 & 9 reg>d to up & d[n1 by prop]ly adju/+ ! position ( ! p9-po9t support1 ,p ,p ,s2 ?is is held firmly to ,c ,s by two spr+-connectors4 ,by remov+ ,s ,c1 ! support1 ,p ,p ,s1 may be rais$ or l[]$4 #bdd4 ,to place ! coil 9 ! ,n & ,s l9e1 simply sw+ ! galvanoscope bodily ar\nd1 at ! same "t look+ d[n ^u ! ne$le1 until ! l5g? ( ! ne$le becomes p>allel to ! coil-support4 ,:5 once c>efully adju/$ ,n & ,s1 a l9e may be drawn ^u ! table z a guide = its position 9 future exp]im5ts4 ,! coil %\ld /& 9 a v]tical plane1 & ?is /raight up & d[n position c be easily adju/$4 ,to place ! coil 9 ! ,e & ,w l9e1 turn x until ! po9t]s are at ! #ij 7#ij degree7 m>ks1--! #j 7z]o degree7 m>ks rema9+1 ( c\rse1 z describ$ above4 #bde4 ,! ,degree-,c>d1 ,g ,d ,c 7,fig4 #gb7 has a dot at its c5t]1 to %[ :]e to make a p9-hole = ! p9 t supports ! compass-ne$le4 ,) ?is y c tell h[ _m degrees ! ne$le is deflect$ :5 ! curr5t passes4 ,?is c>d1 ,g ,d ,c1 %\ld be press$ d[n ov] ! p9-po9t4 ,! z]o po9ts ( ,g ,d ,c %\ld be ,n & ,s1 also1 :5 ! coil is 9 t position2 t is1 !y %\ld be 9 ! plane ( ! coil4 ,! po9t]s on ! ne$le 7 #bdf7 w !n be at ,o1 :5 ! ne$le is at re/1 no curr5t pass+ ?r\gh ! coils4 7,see ,app>atus ,book #bgb = ,home-,made ,degree-,c>d47 ,g ,d ,c may be held p]man5tly 9 position aft] x is adju/$1 by /ick+ a %ort p9 ?r\gh x into ,p ,p ,s4 ,d n let ?is p9 int]f]e1 h[ev]1 ) ! sw++ ( ! ne$le4 ,illu/ration3 ,fig4 #gc4 #bdf4 ,po9t]s 7,fig4 #gc7 %\ld be fa/5$ to ! ne$le1 9 ord] to make ! read+s ( degrees accurate4 ,fa/5 to ! compass-ne$le a piece ( ,no4 #cj insulat$ copp] wire1 z %[n4 ,x may be cut to ! prop] l5g? aft] x is w\nd ar\nd ! ne$le4 ,see t ! wire does n t\* ! p9 :5 ne$le is 9 place2 balance ne$le by cutt+ a little f ! heavi] end ( wire ) %e>s2 b5d ! ends ( wire s t !y are at opposite sides ( ! degree-c>d1 bo? po9t+ at ,o1 = example4 ,! ne$le mu/ sw+ freely1 be nicely balanc$1 & ! wire mu/ n t\* p9 or degree-c>d4 ,illu/ration3 ,fig4 #gd4 #bdg4 ,directions4 7,a7 ,arrange z 9 ,fig4 #gd1 ! coil be+ ,n & ,s 7 #bdd74 ,jo9 ! ends ( ! wires1 #b & #c1 ) ! #e-turn coil ( ,g ,v z %[n4 ,wire1 #b1 is connect$ to ,l 7,fig4 #gb74 ,press lev] #b ( ,c ,r 7,fig4 #fi7 = an in/ant1 wat*+ ! compass-ne$le & not+ h[ _m degrees x sw+s ! fir/ "t4 ,get ?or\ghly 9 m9d ! direction 9 :i* ! ,n pole ( ! ne$le is deflect$ :5 ! curr5t passes ar\nd ,g ,c 9 a clockwise direction4 ,!re mu/ be no magnets1 iron1 or pieces ( /eel )9 #c feet ( ,a ,g4 7,b7 ,press lev]1 #c1 = an in/ant1 wat*+ ! ne$le4 ,! curr5t w n[ pass 9 an anti-clockwise direction4 ,is ! ne$le deflect$ ab\t ! same numb] ( degrees z 9 7,a78 7,c7 ,*ange ! ends ( ! wires1 #b & #c1 to ! #aj-turn coil 7 #bdb7 & repeat 7,a7 & 7,b74 7,d7 ,*ange #b & #c to ,l & ,r 7,fig4 #gb71 ?us all[+ ! curr5t to pass ar\nd #ae turns2 !n repeat 7,a7 & 7,b74 #bdh4 ,discussion2 ,true ,read+s4 ,is n possible to get ! magnetic ne$le1 ,m1 exactly 9 ! c5t] ( ,g ,c2 ! po9t]s w n exactly be 9 ! axis ( ,m2 ! coils w n be exactly ,n & ,s3 h5ce1 if y pass a c]ta9 curr5t ?r\gh ! coil & ! po9t] reads #bj degrees1 y w f9d1 if y rev]se ! curr5t1 t ! po9t] may read #bd degrees on ! o!r side ( ! z]o m>k4 ,to get ! true read+1 av]age ! two1 9 ?is case ! av]age be+ #bb degrees4 ,! galvanoscope gives u an in/rum5t ) :i* we c /udy1 m fully1 cells1 curr5ts1 etc4 #bdi4 ,note ( ,caution4 ,x has already be5 /at$ t ! compass-ne$le %\ld be 9 ! c5t] ( ! coil 7 #bdc71 & t ! coil %\ld be 9 ! ,n & ,s l9e 7 #bdd74 ,9 addition to ! above1 see t !re are no magnets ne> ,g ,v1 :5 us+ x2 tap ,g ,v occasionally to be sure t ! ne$le sw+s freely1 hold ! eye directly ov] ! po9t]s :5 read+ degrees2 ! po9t]s %\ld be at z]o :5 no curr5t passes ?r\gh ,g ,v2 be sure t ! electrical connections are good4 ,!re are sev]al s\rces ( error 9 tak+ read+s1 & 9 all ! quantitative exp]im5ts giv54 ,! au?or takes x = grant$ t su* errors w be look$ out = by ! tea*]4 ,illu/ration3 ,fig4 #ge4 ,,exp]im5t #ajf4 ,to /udy ! con/ruction & use ( a simple a/atic ne$le4 ,app>atus4 ,two unmagnetiz$ sew+-ne$les 7,no4 #a72 horse%oe magnet1 ,h ,m 7,no4 #af72 piece ( /iff pap] d\bl$ & cut z 9 ,fig4 #ge2 a p9-po9t on :i* to support ! pap]4 ,! p9 may be /uck ?r\gh a cork1 or t ( ,o ,c 7,no4 #ah7 may be us$4 #bej4 ,directions4 7,a7 ,draw ea* ne$le across ! ,n pole ( ,h ,m five times f po9t to head 7,exp4 #i74 ,?is %\ld make !m ( ne>ly equal /r5g?1 bo? po9ts be+ ,n poles4 7,b7 ,/ick ! ne$les ?r\gh ! pap] z %[n1 ! ,n poles be+ at ! same end ( ! pap]4 ,balance ! pap] ^u ! p9-po9t4 ,has ?is comb9ation a /rong or weak po9t+-p[]8 7,c7 ,turn "o ( ! ne$les end = end4 ,aga9 te/ ! po9t+-p[]4 #bea4 ,discussion2 ,a/atic ,ne$les4 ,by arrang+ ! ne$les s t _! poles oppose ea* o!r1 ! po9t+-p[] becomes almo/ no?+4 ,?is sort ( a ne$le is ne$$ 9 "s exp]im5ts 9 electricity4 ,_! magnetic fields are /ill reta9$4 ,! comb9ation is call$ an a/atic ne$le2 x is us$ to detect v feeble curr5ts4 ,! m ne>ly equal ! magnets are 9 /r5g?1 ! bett]4 ,!y are usually arrang$ ) "o above ! o!r 7,fig4 #gf74 ,illu/ration3 ,fig4 #gf4 ,illu/ration3 ,fig4 #gg4 ,,exp]im5t #ajg4 ,to /udy ! con/ruction & use ( a simple a/atic galvanoscope4 ,app>atus4 ,an a/atic galvanoscope1 ,a ,g 7,no4 #ei7 7 #beb-bed72 dry cell1 ,d ,c 7,no4 #ea72 curr5t rev]s]1 ,c ,r 7,no4 #eg7 7 #bce72 wires = connections 7 #bbf74 ,arrange z %[n 9 ,fig4 #hj1 :i* is a top view4 ,! wires f ,c ,r are connect$ to ! b9d+-po/s ( ,a ,g at ! back1 ! spr+ connectors be+ slipp$ into !m 7 #bbi74 #beb4 ,con/ruction ( ! ,a/atic ,galvanoscope4 ,:5 n to be us$ = a long "t1 or = %ipp+1 ! legs1 ,a 7,fig4 #gg7 may be remov$1 & ! :ole pack$ inside ( ! box1 ,b4 ,! ,coil1 ,c1 has a resi/ance ( ab\t #e ohms1 & is fa/5$ to ! coil-support1 ,c ,s4 ,! ends ( ! coil are p]man5tly fa/5$ to ! b9d+-po/s1 ,l & ,r 7left & "r74 ,! ends are s arrang$ t :5 ! curr5t ent]s at ,l x w pass ar\nd ! coil 9 a clockwise direction4 #bec4 ,! ,a/atic ,ne$le 7,exp4 #ajf7 is support$ by a small ?read1 ,t1 :i* is ti$ to ! ?read-wire1 ,t ,w4 ,?is ,t ,w spr+s into an eyelet1 ,e1 :i*1 9 turn1 re/s 9 a hole made 9 ! end ( ,b4 ,e %\ld turn easily 9 ! hole1 b x %\ld n wabble4 ,fig4 #gh %[s a sectional view ( ! coil & ne$le4 ,! wire1 ,w1 %\ld be b5t1 z %[n1 s t ! magnets c be z ne> ! c5t]-l9e ( ,c z possible4 ,fig4 #gi %[s a front view ( ! ne$le4 ,z a matt] ( conv5i5ce x w be be/ to arrange ! poles ( ! ne$les1 z %[n1 to agree ) ! descriptions ( ! exp]im5ts4 ,to keep ! ne$le f be+ affect$ by air curr5ts1 ! glass plate 7,no4 #ch7 may be plac$ 9 front ( ! box1 ,b4 ,/& x ^u ! legs1 ,a1 & tie a /r+ ar\nd x1 & ,b1 to hold x 9 place4 ,illu/ration3 ,fig4 #gh4 ,illu/ration3 ,fig4 #gi4 #bed4 ,adju/+ ! ,ne$le4 ,z ,t is ti$ to ,t ,w1 ! ne$le may be swung completely ar\nd by turn+ ,t ,w4 ,?is %\ld be done until ! l5g? ( ! ne$le is p>allel to ! turns ( ,c4 ,! up & d[n position ( ! ne$le %\ld be fix$ z ne>ly z possible :5 fa/5+ ,t to ,t ,w1 ! exact place be+ f9ally fix$ by rais+ or l[]+ ,t ,w ?r\gh ,e4 ,! spr+ 9 ,t ,w %\ld hold x firmly 9 ,e aft] adju/m5t4 ,! wire1 ,w1 jo9+ ! ne$le-magnets %\ld n t\* ! coil4 ,x may be made to j sw+ free f ,c by tilt+ ! box =w>d or backw>d a little4 ,! con/ruction ( ! legs1 etc41 makes x possible to tilt ! box1 & to make x /& firmly ^u an irregul> surface4 ,illu/ration3 ,fig4 #hj4 #bee4 ,directions4 7,a7 ,see t !re are no magnets )9 #c feet ( ,a ,g4 ,te/ ! a/atic ne$le1 aft] y h x prop]ly susp5d$1 to conv9ce y\rself t x does n try to sw+ ar\nd 9 a ,n & ,s l9e4 ,9 case ! ne$le-magnets h be5 9 contact ) o!r magnets1 or are n equally magnetiz$1 remagnetize !m z direct$ 9 ,exp4 #ajf4 ,!y mu/ rema9 9 any position giv5 !m by turn+ ,t ,w4 ,f9ally1 br+ !m p>allel to ! turns ( ! coil4 7,see #bed47 ,arrange z 9 ,fig4 #hj4 7,b7 ,press lev] #b ( ,c ,r 7 #bce7 = an in/ant only4 ,?is all[s ! curr5t to ent] ,a ,g at ,l4 ,repeat sev]al times until y ?or\ghly fix 9 y\r m9d ! direction 9 :i* ! "r-h& end ( ! ne$le is deflect$4 ,does ! ne$le jump sudd5ly :5 ! curr5t passes8 7,c7 ,press lev] #c = an in/ant only4 ,/udy ! result4 #bef4 ,a/atic ,galvanoscopes4 ,x is evid5t t 9 ! ord9>y curr5t detector 7,exp4 #ajd71 ! po9t+ p[] ( ! ne$le has to be ov]come by ! magnetic field ab\t ! coil1 be=e ! ne$le c be =c$ f its ,n & ,s l9e4 ,v weak curr5ts w n visibly move ! ne$le 9 ord9>y detectors4 ,to make a s5sitive in/rum5t we mu/ h /rong fields ab\t bo? ! ne$le & coil1 & we mu/1 at ! same "t1 decrease ! po9t+ p[] ( ! ne$le4 ,bo? ( ^! ?+s are accompli%$ by us+ an a/atic ne$le 9 connection ) a coil conta9+ consid]able wire4 ,! uses ( ! a/atic galvanoscope w be /udi$ m fully 9 lat] exp]im5ts4 ,,*apt] ,,xv4 ,,galvanic ,,cells ,,& ,,batt]ies4 ,,exp]im5t #ajh4 ,to /udy ! effect ( dilute sulphuric acid ^u c>bon & v>i\s metals4 ,app>atus4 ,a piece ea* ( copp] & iron wire #d 941 7#aj cm47 long2 two n>r[ /rips ( %eet z9c 7,no4 #fj71 "o be+ amalgamat$ 7 #beg72 a c>bon rod 7,no4 #fd72 a tumbl] 7,no4 #fe71 p>tly fill$ ) dilute sulphuric acid1 7 #beh72 m]cury 7,no4 #eb74 #beg4 ,to amalgamate "o ( ! above z9c /rips is to coat x ) m]cury4 ,remove all jewelry f ! h&s be=e proce$+4 ,wa% ! z9c ) wat]1 & ) a clo? remove all dirt f its surface4 ,amalgamat$ z9c is v brittle1 s lay x flat ^u a piece ( bo>d or ^u a plate1 aft] dipp+ x = an in/ant 9 ! dilute acid4 ,place a small drop or two ( m]cury ^u ! /rip1 & rub ! m]cury ab\t ^u bo? sides ( ! z9c ) a clo? made wet ) ! dilute acid4 ,m]cury cl+s /rongly to z9c or t91 s y may use a n>r[ piece ( ei!r z a spoon to c>ry a small drop f ! supply to ! z9c4 ,tap x ^u ! z9c to dislodge ! drops4 ,d n get on too mu* m]cury1 j en\gh to coat x1 or1 at lea/1 t "p ( x t w be "u ! acid4 ,be c>eful n to break ! ?9 z9c :5 amalgamat+ x1 z x gets v brittle4 ,x %\ld look bright4 7,see ,app>atus ,book #cb1 #cc47 ,note4 ,%\ld any m]cury get ^u copp] plates x may be remov$ by heat+ !m 9 a flame4 #beh4 ,dilute sulphuric acid1 = ^! exp]im5ts1 %\ld be made by mix+ #a "p1 by volume1 ( conc5trat$ acid1 ) #bj p>ts ( wat]4 ,d n let ! acid get ^u clo!s or c>pets4 ,d n add wat] to acid4 ,mix by sl[ly add+ ! acid to ! wat] 9 a glass or e>!n di%1 /irr+ at ! same "t4 ,mix ov] a s9k or out ( doors4 7,= full] details see ,app4 ,book2 #ba1 #bb1 #bc1 #bd1 #be47 ,to save "t1 make at lea/ a qu>t ( ! mixture1 bottle1 & label x = use4 #bei4 ,directions4 7,a7 ,b5d ov] "o end ( ea* ( ! wires & metal /rips1 & hang !m ^u ! edge ( ! tumbl] 7,fig4 #ha71 s t _! l[] ends %all be 9 ! acid4 ,d n let !m t\* ea* o!r4 ,/& ! c>bon rod 9 ! acid4 ,if !re is no visible action ^u any ( ! above sub/ances1 add a few drops ( conc5trat$ acid to ! tumbl]4 ,note c>efully :at takes place 9 ! tumbl]1 & /ate :i* ( ! sub/ances are dissolv$1 :i* simply made bright]1 & :i* n act$ ^u at all4 #bfj4 ,discussion4 ,! bubbles ( gas t arise f ! z9c :5 x dissolves are hydrog51 & !y indicate t a vigor\s *emical action is go+ on 9 ! tumbl]1 & t ! z9c is be+ eat5 away4 ,illu/ration3 ,fig4 #ha4 ,illu/ration3 ,fig4 #hb4 ,,exp]im5t #aji4 ,to /udy ! effect ( dilute sulphuric acid ^u v>i\s comb9ations ( metals4 ,app>atus4 ,! same z 9 ! la/ exp]im5t4 ,a small piece ( amalgamat$ z9c1 h[ev]1 w be bett] ?an ! :ole /rip4 #bfa4 ,directions4 7,a7 ,twi/ "o end ( ! clean copp] wire ar\nd ! small piece ( amalgamat$ z9c 7,fig4 #hb74 ,hold "o end ( ! wire 9 ! h& & dip ! comb9ation into ! acid4 ,:at takes place8 ,wat* ! surface ( ! copp]1 rememb]+ t ea*1 alone1 0 n act$ ^u by ! acid 7,exp4 #ajh74 7,b7 ,use ! clean iron wire 9 place ( ! copp] wire1 & repeat 7,a74 ,wat* ! surface ( ! iron4 7,c7 ,) a /r+ or ?read tie a small piece ( well amalgamat$ z9c to ! c>bon rod 7,fig4 #hb71 !n dip ! comb9ation into ! acid4 ,wat* ! surface ( ! c>bon4 #bfb4 ,discussion4 ,:ile amalgamat$ z9c is n rapidly dissolv$ by dilute sulphuric acid1 a vigor\s action ( "s k9d takes place :5 x is 9 contact ) ano!r metal or ) c>bon 9 ! acid4 ,! bubbles ( hydrog5 t are lib]at$ d n seem to come f ! z9c2 !y appe> to gr[1 9 ! fluid1 directly at ! surface ( ! copp]1 iron1 or o!r metal us$ ) ! z9c4 ,?is %[s t some?+ besides ! m]e dissolv+ ( a metal takes place4 ,c we arrange our app>atus s t we c get "s useful results f ?is action8 ,,exp]im5t #aaj4 ,to /udy ! con/ruction ( a simple ,voltaic or ,galvanic cell4 ,app>atus4 ,a n>r[ /rip ( z9c 7,no4 #fj71 amalgamat$ z direct$ 9 #beg4 7,an amalgamat$ z9c rod 7,no4 #gd7 may be us$ 9 place ( ! /rip72 a n>r[ /rip ( %eet copp] 7,no4 #fg72 ! tumbl] ( dilute acid ( ,exp4 #ajh2 a flexible copp] wire ab\t #b feet long1 ) spr+ connectors 7,no4 #ed7 atta*$ to its ends4 7,see ,electrical ,connections1 #bbf47 ,illu/ration3 ,fig4 #hc4 #bfc4 ,directions4 7,a7 ,hold+ ! amalgamat$ z9c /rip 9 "o h& & ! copp] /rip 9 ! o!r 7,fig4 #hc71 dip !m into ! acid1 b d n let !m t\* ea* o!r4 ,note any *emical action4 7,b7 ,t\* ! copp] & z9c toge!r1 bel[ ! surface ( ! acid4 ,wat* ! copp]4 7,c7 ,sep>ate ! l[] ends ( ! /rips1 !n t\* !m toge!r above ! acid4 ,any?+ /ill happ5 to ! copp]8 7,d7 ,slip "o spr+ connector ) ! atta*$ wire ^u ! z9c /rip1 !n /& ! /rips 9 ! tumbl]1 s t !y c n t\* ea* o!r4 ,n[ t\* ! copp] /rip ) ! free end ( ! wire1 at ! same "t wat*+ ! copp]4 7,e7 ,raise ! wire f ,cu1 t\* x to ,cu aga91 & repeat sev]al times until y are sure t some?+ takes place e "t ! wire t\*es ,cu4 #bfd4 ,! ,electric ,curr5t4 ,some?+ mu/ happ5 9 or ?r\gh ! wire1 & x c only happ5 :5 ! two metals are jo9$ 9 "s way4 ,?is peculi>1 invisible action 9 ! wire is call$ ! electric curr5t1 & su* an arrangem5t is call$ a ,galvanic cell4 #bfe4 ,s\rce ( ! ,electrification4 ,:5 two diff]5t metals are plac$ 9 acid !y are electrifi$ unequally by *emical action4 ,ea* has a high] pot5tial ?an ! acid1 b _! pot5tials are n ! same4 ,?is electrification t5ds to pass f ! place ( high] to ! place ( l[] pot5tial1 & ! conduct+ wire all[s ?is transf] to take place4 ,z ! diff]5ce ( pot5tial is kept up by ! cont9u$ *emical action1 ! curr5t is cont9u\s1 & n simply in/antane\s1 z 9 dis*>ges ( frictional electricity4 ,z heat is produc$ by ! burn+ ( coal1 s electrification is produc$ by ! *emical burn+ ( z9c4 ,*emical en]gy is ! s\rce ( electrification 9 ! ,galvanic cell1 j z muscul> en]gy 0 ! s\rce ( ! electrification 9 ! exp]im5ts ) frictional electricity4 #bff4 ,! ,electric ,circuit2 ,op5 & ,clos$ ,circuits4 ,! simple ,galvanic cell j us$1 toge!r ) ! wire :i* jo9$ ! metal /rips1 is call$ an electric circuit4 ,if ! curr5t %\ld pass ?r\gh a telegraph in/rum5t1 = example1 on its way f "o /rip to ! o!r1 ! telegraph in/rum5t w\ld also be 9 ! circuit4 ,:5 ! wire is cut or remov$ f "o metal /rip1 ! circuit is said to be op5--t is1 we h an op5 circuit4 ,:5 ! curr5t passes1 ! circuit is clos$4 ,we also say make & break ! circuit1 & t ! circuit has be5 brok54 #bfg4 ,plates or ,elem5ts4 ,! copp] & z9c /rips are call$ ! plates or elem5ts ( ! cell4 ,! z9c1 ,zn1 ,fig4 #hd1 is dissolv$ by ! acid1 & is call$ ! positive plate 7 plate74 ,! copp]1 ,cu1 is ! negative plate 7- plate74 ,! copp] is also call$ ! ca?ode1 & ! z9c ! anode4 #bfh4 ,direction ( ,curr5t4 ,x has be5 agre$1 = conv5i5ce1 t 9 ! cell ! curr5t passes f ! z9c ?r\gh ! liquid to ! copp]1 :]e ! hydrog5 bubbles are deposit$4 ,x !n passes ?r\gh ! wire1 or o!r conductor furni%$1 back to ! z9c1 ?r\gh ! liquid to ,cu aga91 & s on ar\nd & ar\nd ?\s&s ( times p] second4 ,! curr5t really />ts at ! surface ( ! z9c1 :]e ! *emical action is4 ,:5 c>bon & z9c are us$1 ! action & direction ( ! curr5t are ! same1 c>bon be+ ! - plate4 ,illu/ration3 ,fig4 #hd4 #bfi4 ,poles or ,electrodes4 ,if ! wire 7 cut1 ! electricity com+ f ! plate w\ld be /opp$ at ! end ( ! wire m>k$ 1 ,fig4 #hd1 aft] pass+ ?r\gh ! acid & up ,cu4 ,?is end ( ! wire is call$ ! pole or electrode 7positive74 ,! end ( ! wire jo9$ to ,zn is call$ ! - pole or electrode2 t is1 ! electrode is ! end ( ! wire atta*$ to ! - plate4 ,! tops ( ,cu & ,zn may be consid]$ electrodes4 ,! top ( ,cu is ! pole ( ! cell1 :ile ,cu is ! - plate4 #bgj4 ,*emical ,action 9 ! ,simple ,galvanic ,cell4 ,! *emical =mula ( sulphuric acid is ,h#b,,s#d 7read ,h1 #b1 ,s1 ,o1 #d74 ,?is means t x is a comp\nd ( hydrog5 7,h71 sulphur 7,s71 & oxyg5 7,o74 ,! ,h#b,,s#d /&s = molecule ( acid1 & ! small figures %[ t ! molecule is made up ( #b atoms ( hydrog5 7,h#b71 "o ( sulphur 7,s71 & #d ( oxyg5 7,o#d74 ,! atoms are held toge!r by *emical attraction or aff9ity4 ,!re is a /rong] *emical aff9ity betwe5 z9c 7,zn7 & ,,s#d ?an betwe5 ,h#b & ,,s#d2 s1 z soon z ! ,zn gets a *ance1 z x does 9 ! cell1 x drives out ! ,h#b1 & x takes its place 9 ! molecule4 ,?is *emical reaction may be %[n by ! foll[+ *emical equation3 ,zn ,h#b,,s#d ,zn,s,o#d ,h#b4 ,z9c & sulphuric acid produce z9c sulphate & hydrog54 ,! z9c sulphate produc$ weak5s ! effect ( ! acid2 9 fact1 ! acid has to be r5ew$ occasionally1 z x is *ang$ to ! sulphate :i* rema9s 9 solution4 #bga4 ,action 9 ,cell ,us+ ,impure ,z9c4 ,! above action takes place 9 ! cell :5 impure z9c is us$1 ev5 :5 no curr5t passes1 heat be+ produc$ by ! reaction in/ead ( useful electricity4 7,see ,local ,curr5ts47 ,action 9 ,cell ,us+ ,pure ,z9c4 ,:5 pure z9c 7or impure z9c t has be5 prop]ly amalgamat$7 is us$ 9 ! cell1 x dissolves1 or is eat5 away1 only :5 ! curr5t passes4 ,x %\ld be not$ t ! bubbles ( hydrog5 d n ev5 !n appe> at ! z9c2 !y are n se5 ?r\gh\t ! body ( ! liquid4 ,!re seems to be an unse5 transf] ( hydrog5 f ! z9c1 ?r\gh ! liquid1 to ! copp] 7or o!r - plate us$71 & x appe>s !re 9 ! %ape ( bubbles4 ,! l>g] ! quantity ( pure z9c dissolv$1 ! /rong] ! curr5t1 & ! l>g] ! am\nt ( hydrog5 produc$4 ,z ! z9c dissolves x p>ts ) its lat5t en]gy1 & ?is en]gy =ces ! electric curr5t ?r\gh ! circuit4 ,:ile ! hydrog5 ( ! decompos$ acid makes its way t[>ds ! - plate1 ! ,,s#d "p ( x travels t[>ds ! ,zn plate1 :]e ! ,,znso#d is =m$4 7,see #bgj47 ,,exp]im5t #aaa4 ,to see :at is meant by local curr5ts 9 ! cell4 ,app>atus4 ,tumbl] ( dilute sulphuric acid4 7 #beh72 /rip ( unamalgamat$ z9c2 cry/al ( copp] sulphate 7blue vitriol7 7,no4 #hf72 a galvaniz$ iron nail 7,no4 #fi71 ?is be+ iron cov]$ ) z9c4 #bgb4 ,directions4 7,a7 ,hold ! nail 9 ! acid = a few seconds1 & note result4 7,b7 ,rub ! copp] sulphate ^u ! z9c simply 9 "o spot1 !n place ! z9c 9 ! acid1 not+ ! result at ! spot4 #bgc4 ,local action2 ,local ,curr5ts4 ,ord9>y comm]cial z9c conta9s su* impurities z c>bon1 iron1 lead1 etc41 9 small quantities4 ,x 0 se51 ,exp4 #aji1 t :5 diff]5t metals 7 9 contact ) ! z9c1 ! z9c 0 rapidly dissolv$ by ! acid4 ,! impurities 9 ! z9c act l ! copp] plate 9 ! simple cell1 ?us produc+ local curr5ts 9 ! z9c1 :i* rapidly de/roy x )\t do+ any good4 ,^! curr5ts pass f z9c to impurities1 & back to ! z9c1 )\t go+ out into ! ma9 wire4 ,?is local action takes place ev5 :5 ! ma9 circuit is op54 #bgd4 ,reasons = ,amalgamat+ ,z9c ,plates4 ,pure z9c is n affect$ by dilute sulphuric acid1 b x is too exp5sive to use 9 cells2 s amalgamat$ z9c is us$ in/ead1 because x is *eap]1 & acts ! same z pure z9c4 ,! impurities are remov$ f ! surface ( ! z9c1 z ! z9c alone is dissolv$ by ! m]cury4 ,!re is1 !n1 a liquid lay] ( pure z9c ) m]cury ^u ! surface ( ! amalgamat$ plate4 ,?is is n act$ ^u by ! acid :5 ! circuit is op54 ,a /rong] & m regul> curr5t is produc$ ) amalgamat$ z9c ?an ) ! impure unamalgamat$ z9c4 ,,exp]im5t #aab4 ,to /udy ! s+le-fluid ,galvanic cell4 ,app>atus4 ,! galvanoscope ,g ,v 7,no4 #eh71 7,see #bdj1 etc472 ! simple cell arrang$ z describ$ 9 #bge1 ! z9c be+ amalgamat$4 #bge4 ,! ,simple ,cell %\ld be arrang$ s t ! plates w be held firmly 9 position4 ,! z9c1 ,zn 7,no4 #fj71 & copp]1 ,cu 7,no4 #fg71 %\ld be fa/5$ to ! wood5 cross-piece1 ,w ,c ,p 7,no4 #gj71 z %[n 9 ,fig4 #he4 ,c>e %\ld be tak5 n to use long] screws ?an ^? provid$ = 7,no4 #gb74 ,if ! screws t\* ea* o!r !y w %ort circuit ! cell4 ,p>tly fill ! tumbl] 7,no4 #fe7 ) dilute sulphuric acid 7 #beh71 jo9 wires ) connectors to ! plates4 ,! free ends ( ! wires are !n ready to jo9 to app>atus4 ,! ends ( wires may be fa/5$ "u ! screw-heads in/ead ( us+ connectors on ! plates4 ,d n put ! plates into ! acid until y read ! directions4 #bgf4 ,directions4 7,a7 ,arrange z 9 ,fig4 #hf4 ,place ! coil ( ,g ,v1 ,n & ,s 7 #bdd74 ,be=e putt+ ! plates 9 ! acid jo9 !m to ! #ae-turn coil ( ,g ,v 7 #bdb74 ,! compass-ne$le %\ld po9t to z]o4 ,see t ! ne$le sw+s freely4 7,b7 ,place ! plates 9 ! acid1 & quickly br+ ! ne$le to re/ ) ! aid ( ! h&1 s t y c take ! read+ at once be=e ! hydrog5 bubbles entirely cov] ! copp] plate4 ,wat* ! action ( ! ne$le = a few m9utes4 ,make a note ( ! read+1 9 degrees1 at ! beg9n+ ( ! exp]im5t & at ! end ( five m9utes4 7,see ,note47 ,illu/ration3 ,fig4 #he4 ,illu/ration3 ,fig4 #hf4 ,note4 ,if no *ange takes place 9 ! position ( ! ne$le1 ! *ange beg9n+ inside ( #aj seconds aft] ! plates are let d[n into ! acid1 )draw ! plates1 !n clean & ?or\ghly dry ! copp] to remove all traces ( hydrog54 ,?is may be done by heat+ ! copp] ov] a gas flame4 ,let ! copp] rema9 9 ! air #ae m9utes1 !n try aga94 ,9 tak+ ! fir/ read+ y mu/ "w quickly4 ,cat* ! ne$le dur+ its fir/ sw+4 ,if y all[ x to sw+ back & =? until x comes to re/1 y\r fir/ read+ w n be :at x %\ld be4 7,c7 ,aft] ! ne$le has rema9$ 9 "o position1 )\t *ange1 = #b or #c m9utes1 take hold ( ! wood5 cross-piece1 move ! plates back & =? 9 ! acid to dislodge ! hydrog5 bubbles1 & note c>efully ! action ( ! ne$le4 ,does ! curr5t seem /rong] :5 ! plates are mov$8 ,c y get ! ne$le back to ! fir/ read+8 7,d7 ,remove ! plates f ! acid1 dry & clean ! copp]1 let !m /& 9 ! air = #ae m9utes1 !n take ano!r quick read+ & comp>e x ) ! fir/4 #bgh4 ,pol>ization ( ,cells4 ,! acid gets a little weak]1 ( c\rse1 z x is decompos$ by ! z9c 7 #bgj71 b ! *ief cause ( ! weak5+ ( ! curr5t is hydrog51 :i* =ms a filmy coat+ ^u ! copp] plate4 ,?is coat+ ev5 seems to soak into ! copp]1 & x takes "s "t = x to be ?or\ghly remov$4 ,! z9c plate is kept comp>atively free f hydrog5 by amalgamation4 #bgi4 ,effects ( ,pol>ization4 ,! hydrog5 bubbles weak5 ! curr5t 9 at lea/ two ways4 ,9 ! fir/ place1 hydrog5 is n a conductor ( electricity2 s x holds ! curr5t back1 z any o!r resi/ance w\ld4 ,secondly1 acid acts ^u hydrog5 z x w\ld ^u ano!r metal4 ,:5 ! copp] plate becomes well cov]$ ) hydrog51 ! acid _c t\* x2 s we really h a hydrog5 plate 9 ! cell4 ,hydrog5 acts v mu* l z9c 9 ! acid2 we say t x is m electro-positive ?an copp]4 ,! result is1 !n1 t a new curr5t />ts up1 & z ?is is t[>ds ! z9c1 9 ! acid1 x p>tially de/roys or neutralizes ! ma9 z9c-to-copp] curr5t4 ,practical use is made ( ! pr9ciples ( pol>ization 7see ,second>y ,batt]ies74 #bhj4 ,rem$ies = ,pol>ization2 ,depol>iz]s4 ,any s*eme by :i* ! hydrog5 may be de/roy$ & kept f ! inactive1 or negative plate1 w prev5t pol>ization4 ,me*anical means h be5 employ$ to bru% away ! hydrog5 by keep+ up a con/ant circulation ( ! liquid4 ,*emical action is ano!r means by :i* ! hydrog5 may be side-track$ be=e x gets to ! - plate 9 s+le-fluid cells4 ,sub/ances l nitric acid & bi*romate ( pota%1 call$ depol>iz]s1 conta9 l>ge quantities ( oxyg51 &1 dur+ ! *emical *anges t take place1 ?is oxyg5 unites ) ! hydrog54 ,^! sub/ances are us$ 9 z9c-c>bon cells4 7,see #bhf1 etc4 = v>i\s =ms ( cells47 ,!re is ano!r =m ( cell1 ! two-fluid type1 9 :i* electro-*emical means are employ$1 & 9 :i* a metal is deposit$ ^u ! - plate in/ead ( hydrog54 ,! - plate is usually copp]1 copp] be+ deposit$ ^u x4 ,,exp]im5t #aac4 ,to /udy ! two-fluid ,galvanic cell4 ,app>atus4 ,! glass tumbl]1 ,g ,t1 7,no4 #fe72 por\s cup1 ,p ,c1 7,no4 #gc72 ! /rip ( z9c 7,no4 #fj71 well amalgamat$ 7 #beg71 or ! amalgamat$ z9c rod 7,no4 #gd72 piece ( %eet copp] 7,no4 #ge71 b5t s t x w surr\nd ,p ,c2 copp] wires1 ,c ,w1 ) connectors2 a saturat$ solution ( copp] sulphate1 commonly call$ blue vitriol or blue /one 7,see #bhc72 dilute sulphuric acid 7,see #beh74 ,) ! above1 set up ! two-fluid cell 7,see #bha74 ,! galvanoscope1 ,g ,v1 complete1 is also ne$$1 & if quantitative "w is to be done1 a pair ( scales weigh+ to #j4a gram is necess>y4 7,see ,app4 ,book1 ,*apt] ,i1 = ,home-,made ,two-,fluid ,cells47 ,illu/ration3 ,fig4 #hg4 #bha4 ,sett+ ,up ! ,two-,fluid ,cell4 ,fig4 #hg4 ,/& ! amalgamat$ z9c rod1 ,zn1 9 ,p ,c1 !n place ,p ,c 9 ! tumbl]1 ,g ,t2 put 9 ! copp] plate z %[n4 ,p\r dilut$ acid 7 #beh7 into ,p ,c until x /&s ab\t #b-a_/b 94 deep2 !n at once p\r ! copp] solution 7 #bhc7 into ,g ,t1 on ! outside ( ,p ,c1 until x /&s at ! same height z ! acid 9 ,p ,c4 ,z soon z ! liquids h soak$ into ,p ,c ! cell w be ready = use2 b x is bett] to connect x ) ! galvanoscope at once & note ! increase ( curr5t dur+ ! fir/ few m9utes :ile ! liquids soak ?r\gh ,p ,c4 ,a cry/al ( copp] sulphate %\ld be put outside ( ,p ,c to keep ! solution full /r5g?4 ,?is is a =m ( ! well-kn[n ,daniell cell4 ,fig4 #hg %[s a =m ( home-made two-fluid cell z describ$ 9 ,app>atus ,book4 ,if y h ! "o furni%$1 use ! rod in/ead ( %eet z9c1 & use connectors on ! plates4 #bhb4 ,c>e ( ,two-,fluid ,cell4 ,?is exp]im5tal cell %\ld be tak5 ap>t :5 n 9 use4 ,x %\ld n be left 9 op5 circuit1 ev5 = half an h\r4 ,ev5 aft] ! plates are remov$1 copp] may be deposit$ ^u ,p ,c 9 case !re are any metallic impurities on x4 ,remove ! plates & ,p ,c1 & ?or\ghly wa% !m4 ,! copp] solution %\ld be put into a bottle to prev5t evaporation2 ! dilute acid may be ?r[n away to be replac$ by fre% acid = ! next exp]im5t4 #bhc4 ,copp] ,sulphate ,solution is made by add+ ! blue cry/als to wat] until no m w dissolve--t is1 ! solution %\ld be saturat$1 extra cry/als always be+ left 9 ! /ock bottle4 ,an ounce ( ! cry/als to half a tumbl] ( wat] w be ab\t "r1 b a p9t or s %\ld be made at a "t & be kept bottl$ to save "t4 #bhd4 ,directions4 7,a7 ,9 case y h access to a pair ( scales t weigh to )9 #j4a gram1 c>efully weigh bo? copp] & z9c be=e proce$+4 ,!y %\ld be wa%$ & dri$ ) a clo?4 ,see t !re are no drops ( m]cury ^u ! z9c t may fall (f dur+ ! exp]im5t4 7,b7 ,replace ! plates 9 ! cell1 & connect !m ) ! #ae-turn coil ( ,g ,v1 plac$ ,n & ,s4 ,all[ ! circuit to rema9 clos$ = half an h\r1 & record ! position ( ! ne$le e #e m9utes4 7,c7 ,aga9 wa%1 dry ) a clo? )\t rubb+1 & weigh bo? ! z9c & copp]4 ,comp>e ! new weights ) ^? f\nd 9 7,a74 #bhe4 ,*emical ,action 9 ! ,two-,fluid ,cell4 ,9 ?is =m ( cell ! hydrog5 is n all[$ to collect ^u ! copp] plate4 ,! action inside ( ,p ,c is l t expla9$ 9 #bgj1 hydrog5 be+ set free4 ,z soon z ?is hydrog5 7,h#b7 comes 9 contact ) ! copp] sulphate 7,cu,s,o#d71 & x beg9s to d ?is 9 ! walls ( ,p ,c1 a new *emical reaction takes place4 ,hydrog5 has a /rong] attraction = ,,s#d ?an ,cu has1 s x unites ) ! ,,s#d1 =m+ ,h#b,,s#d 7sulphuric acid71 & ?is at ! same "t ?r[s out ! ,cu bodily4 ,?is ,cu is !n free1 in/ead ( hydrog51 to be deposit$ ^u ! copp] plate4 ,! curr5t is con/ant1 z !re is no pol>ization4 #bhf4 ,v>i\s ,galvanic ,cells2 ,op5 & ,clos$ ,circuit ,cells4 ,!re is no "o =m ( cell t is be/ = all k9ds ( "w4 ,if mom5t>y curr5ts only are want$1 su* z = bells1 telephones1 etc41 9 :i* ! cell has pl5ty ( "t to re/1 op5 circuit cells are us$4 ,^! cells pol>ize1 h[ev]1 :5 ! circuit has to be clos$ = any l5g? ( "t4 ,?is =m ( cell is always ready = use1 & may n ne$ att5tion = mon?s at a "t4 ,! mo/ common =ms ( ! op5 circuit cells are ! ,leclan* 7 #bhg7 & dry cell 7 #bhh74 ,op5 circuit cells pol>ize quickly1 because ! depol>iz] 7 #bhj7 is sl[ 9 de/roy+ ! hydrog54 ,:5 a /rong curr5t is ne$$ = a consid]able "t1 su* z = telegraph l9es1 motors1 etc41 a clos$ circuit cell is necess>y4 ,! depol>ization mu/ be rapid & con/ant4 ,! bi*romate 7 #bhi7 & ! ,daniell cell 7 #bij7 are v common =ms ( clos$ circuit cells4 7,see1 also1 ,/orage ,cells47 #bhg4 ,! ,leclan* ,cell is an op5 circuit cell 9 :i* c>bon & z9c are ! plates4 ,! c>bon is surr\nd$ ) dioxide ( manganese1 a depol>iz]2 ! two are ei!r pack$ toge!r 9 a por\s cup1 or ! latt] is compress$ into blocks1 :i* are fa/5$ to ! c>bon4 ,! por\s cup /&s 9 a j> conta9+ a solution ( sal ammoniac 7ammonium *loride71 :i* acts z ! excit+ fluid1 & 9 :i* /&s a z9c rod4 ,! z9c is n act$ ^u :5 ! circuit is op54 ,! hydrog5 giv5 (f by ! decomposition ( ! ammonium *loride is de/roy$ by ! oxyg5 conta9$ 9 ! manganese dioxide4 ,! ,e4 ,m4 ,f4 is ne>ly #a4e volts4 #bhh4 ,dry ,cells are = op5 circuit "w4 ,%eet z9c =ms at ! same "t ! active plate & ! outside cyl9d] or case4 ,a c>bon plate acts z ! inactive or - plate4 ,! excit+ fluid is kept f spill+ by its be+ absorb$ by "o ( ! v>i\s sub/ances us$ = t purpose4 #bhi4 ,! ,bi*romate ( ,pota% ,cell is a v common "o = laboratory use4 ,x gives a /rong curr5t1 & al?\gh a s+le fluid cell1 x does n readily pol>ize4 ,z9c & c>bon plates are us$4 ,9 ! sulphuric acid1 :i* is ! excit+ fluid1 is dissolv$ bi*romate ( pota%4 ,?is cell is us$ = runn+ small motors1 induction coils1 etc4 ,x has1 ) fre% solutions1 an ,e4 ,m4 ,f4 ( ab\t #b volts4 7,see ,app>atus ,book1 ,*apt] ,i41 = ,home-,made ,batt]ies47 #bij4 ,! ,daniell ,cell1 ( :i* ! two-fluid cell us$ 9 ,exp4 #aab is a =m1 is not$ = its con/ant curr5t4 ,! ,e4 ,m4 ,f4 is a little ov] #a volt1 & x %\ld be kept work+ ?r\gh a resi/ance :5 n 9 regul> use2 x %\ld n be left 9 op5 circuit4 ,! por\s cup keeps ! two fluids f mix+1 b x does n /op ! curr5t4 #bia4 ,! ,gravity ,cell is a =m ( ! above4 ,z "o ( ! fluids is heavi] ?an ! o!r1 no por\s cup is ne$$4 ,gravity1 toge!r ) ! action ( ! curr5t1 t5ds to keep ! fluids sep>at$4 ,a copp] plate is plac$ 9 ! bottom ( ! j>1 & ^u ?is is put ! copp] sulphate solution4 ,! z9c plate is support$ by ! top ( ! j> & re/s 9 a solution ( z9c sulphate1 :i* is light] ?an ! blue solution bel[4 ,an insulat$ wire ext5ds f ! copp] ?r\gh ! liquids4 ,?is cell is us$ = telegraph & simil> "w4 7,see ,app>atus ,book = ,home-,made ,gravity ,cell1 its ,regulation1 etc47 ,,*apt] ,,xvi4 ,,! ,,electric ,,circuit4 ,,exp]im5t #aad4 ,to see :at is meant by divid$ circuits or %unts4 ,app>atus4 ,! galvanoscope1 ,g ,v 7,no4 #eh72 a/atic galvanoscope1 ,a ,g 7,no4 #ei72 two-fluid cell1 #b-;,f ,c 7see #bha72 #f wires ) connectors2 small ?9 pieces ( t9 or o!r metal1 ,m ,p1 = rapidly mak+ connections 7 #bbf74 ,arrange z 9 ,fig4 #hh4 ,! wires1 #a & #d1 f #b-;,f ,c1 lead to ! metal plates ,m ,p-,a & ,m ,p-,b1 = conv5i5ce4 ,! wires1 #b & #c1 f ,g ,v1 are also connect$ ) ^! plates4 ,! wires1 #e & #f 7dott$ l9es71 lead f ,a ,g1 to be us$ z direct$ 9 "p 7,b7 ( ! exp]im5t4 ,see t ,g ,v is prop]ly plac$4 ,see t ,a ,g is adju/$4 ,illu/ration3 ,fig4 #hh4 #bib4 ,directions4 7,a7 ,)\t ,a ,g 9 place1 take ! read+ ( ,g ,v4 ,! curr5t n[ passes f ,cu ?r\gh #a1 ,m ,p-,b1 #b1 ,g ,v1 #c1 ,m ,p-,a1 #d to ,zn4 7,b7 ,connect wires #e & #f to ! plates1 z %[n by ! dott$ l9es4 ,aga9 take read+ ( ,g ,v1 & comp>e x ) ! fir/ read+4 ,does "s ( ! curr5t pass ?r\gh ,a ,g8 #bic4 ,divid$ ,circuits2 ,%unts4 ,! curr5t divides at ,m ,p-,b into two p>ts2 "o "p may be call$ a %unt ( ! o!r4 ,! circuit is said to be divid$2 x has two bran*es4 ,if ! two ends ( a wire be fa/5$ to ano!r z 9 ,fig4 #aja1 ! circuit is also divid$4 ,:5 two or m conductors lead side by side f "o po9t to ano!r1 !y are call$ p>allel circuits2 t is1 ! conductors are jo9$ 9 p>allel4 ,z /rong curr5ts w\ld injure delicate galvanomet]s1 a small "p only ( ! curr5t may be all[$ to pass ?r\gh ! galvanomet] by us+ a %unt4 ,fig4 #hi %[s su* an arrangem5t1 9 :i* mo/ ( ! curr5t passes ?r\gh ! %unt1 ,s4 ,!re are _m practical uses ( %unts4 ,illu/ration3 ,fig4 #hi4 ,,exp]im5t #aae4 ,to see :at is meant by %ort circuits4 ,app>atus4 ,ab\t ! same z 9 ,exp4 #aad1 ,fig4 #hh4 ,! a/atic galvanoscope is n ne$$2 9 place ( x provide a %ort piece ( metal1 su* z a batt]y-plate1 or ev5 a jack-knife4 ,arrange z 9 ,fig4 #hh1 b )\t ,a ,g4 #bid4 ,directions4 7,a7 ,) ! curr5t pass+ z describ$ 9 ,exp4 #aad 7,a71 take ! read+ ( ,g ,v4 7,b7 ,lay ! ends ( ! metal1 or o!r ?ick conductor1 ^u ,m ,p-,a & ,m ,p-,b4 ,comp>e ! new read+ ( ,g ,v ) t 9 "p 7,a74 7,c7 ,remove ! conductor us$ to %ort circuit ,g ,v1 take ! read+ 9 degrees1 !n t\* ,m ,p-,a to ,m ,p-,b2 wat* ,g ,v4 #bie4 ,%ort ,circuits are v apt to occur unless c>e is tak54 ,d n all[ un9sulat$ wires to t\* ea* o!r4 ,z %[n by ! above exp]im5t1 practically ! :ole ( ! curr5t may be side-track$ by a %unt ( l[ resi/ance4 ,a galvanic cell is %ort-circuit$ by connect+ ! plates directly by a wire or o!r conductor4 ,,*apt] ,,xvii4 ,,electromotive ,,=ce4 #bif4 ,electromotive ,=ce4 ,x has be5 /at$ t a galvanic cell has ! p[] to *>ge "o ( its plates positively & ! o!r negatively2 ?is p[] is call$ electromotive =ce1 &1 = %ort1 ,e4 ,m4 ,f4 is writt54 ,! ,e4 ,m4 ,f4 ( a cell dep5ds ^u ! k9ds ( plates us$ & _! condition1 ! *emicals us$ 9 ! excit+ fluids1 etc4 ,! great] ! ,e4 ,m4 ,f4 ( a cell ! great] its p[] to =ce ! curr5t ?r\gh wires1 etc4 ,! ,e4 ,m4 ,f4 ( a cell does n dep5d ^u ! size ( its plates1 z w be se5 by lat] exp]im5ts4 #big4 ,unit ( ,e4 ,m4 ,f42 ,! ,volt4 ,a c]ta9 am\nt ( ,e4 ,m4 ,f4 has be5 tak5 z ! /&>d1 &1 9 honor ( ,volta1 x has be5 call$ ! volt4 ,! ,e4 ,m4 ,f4 ( ! two-fluid cell us$ 9 ,exp4 #aac is n f> f #a volt4 ,if a c]ta9 cell has ! p[] to keep up twice ! diff]5ce ( pot5tial betwe5 its t]m9als t ! ,daniell cell has1 we say t x has an ,e4 ,m4 ,f4 ( ab\t #b volts4 ,voltmet]s are in/rum5ts to measure ,e4 ,m4 ,f4 ,,exp]im5t #aaf4 ,to see if ! ,e4 ,m4 ,f4 ( a cell dep5ds ^u ! mat]ials us$ 9 its con/ruction4 ,app>atus4 ,tumbl] two-?irds full ( dilute sulphuric acid 7#beh72 /rips ( z9c1 ,zn 7,no4 #fj72 copp] /rips1 ,cu 7,no4 #fg72 iron /rip1 ,i 7,no4 #gf72 lead /rip1 ,l 7,no4 #gg72 c>bon rod 7,no4 #fd72 ! galvanoscope1 ,g ,v 7,no4 #eh72 #b wires ) connectors 7 #bbf71 s t ! plates c be *ang$ quickly2 ! wood5 cross-piece1 ,w ,c ,p 7,no4 #gj74 ,arrange z 9 ,fig4 #ij4 ,! metal /rips are all ( ! same size2 !y may be held ) ! h& firmly aga9/ ,w ,c ,p1 9 ord] to h !m ! same di/ance ap>t 9 ea* trial4 ,!y %\ld be l[]$ to ! bottom ( ! tumbl] 9 ea* case1 9 ord] to h !m act$ ^u by ! same am\nt ( acid4 ,place ,g ,v prop]ly4 ,illu/ration3 ,fig4 #ij4 #bih4 ,directions4 7,a7 ,) ,zn & ,cu connect$ to ,g ,v z %[n 7,fig4 #ij71 take ! read+ 9 degrees1 & note 9 :i* direction 7ea/ or we/7 ! ,n end ( ! ne$le is deflect$4 ,tabulate results1 z %[n 9 ,fig4 #ia1 fill+ 9 ea* column ( y\r table made out on pap]4 7,b7 ,9 l mann] try ! foll[+ comb9ations 9 ! ord] giv51 9 ea* case connect+ ! fir/-m5tion$ plate ) ! left-h& b9d+-po/1 ,l1 ( ,g ,v4 ,= 7,b7 use z9c-iron4 7,c7 ,use z9c-lead2 7,d7 iron-copp]2 7,e7 iron-lead2 7,f7 lead-copp]2 7,g7 copp]-c>bon4 ,illu/ration3 ---------------------------------------- ------------------ ,,"p ,,plates4 ,,liquid4 ,,deflection4 ,,curr5t ,,9 ,,cell ,,f ---------------------------------------- ----------------- 7,a7 ,,z9c4 ,,copp]4 ,,dil4 ,,sulp4 #fe ,,we/4 ,,cu ,,to ,,zn ,,acid4 7,b7 7,c7 ,fig4 #ia4 #bii4 ,note4 ,"s ( ! comb9ations produce b slight curr5ts4 ,9 case ,g ,v is n delicate en\gh to %[ cle>ly :i* way ! curr5t passes1 use ! a/atic galvanoscope 9 its place = su* comb9ations4 #cjj4 ,discussion4 ,exp4 #aaf cle>ly %[$ t diff]5t comb9ations ( metals 9 ! acid h diff]5t p[]s ( pu%+ electricity ?r\gh ! galvanoscope4 ,al?\gh "s ( ! pairs ( metals furni%$ s weak a curr5t t x 0 necess>y to use ! a/atic galvanoscope to /udy ! curr5t1 all produc$ "s curr5t1 & f ! results c be =m$ an electromotive s]ies 7 #cja74 ,! /r5g? ( acid1 condition ( plates1 etc41 affect ! ,e4 ,m4 ,f4 ( a cell4 #cja4 ,electromotive ,s]ies4 ,all metals are n act$ ^u to ! same degree by dilute acid4 ,f ! results ( ,exp4 #aaf x is se51 "p 7,b71 t iron is electronegative to z9c2 t is1 ! curr5t 9 ! cell fl[s f z9c to iron4 ,"p 7,d7 %[$ t iron is electropositive to copp]1 z ! curr5t fl[$ f iron to copp] 9 ! cell4 ,x is possible to arrange ! metals 9 a s]ies1 "o bel[ ! o!r1 9 su* a way t any "o w be electronegative to ^? above x & electropositive to ^? bel[ x2 t is1 ! li/ %\ld h ! mo/ electropositive metal at ! top1 & ! "o lea/ act$ ^u by ! acid at ! bottom4 ,make su* a li/ f y\r results4 ,! f>!r ! metals us$ are ap>t 9 ! li/1 ! great] w be ! ,e4 ,m4 ,f4 ( ! cell4 ,good c>bon is act$ ^u ! lea/ ( all1 s z9c & c>bon are bett] ?an z9c & copp]4 ,,exp]im5t #aag4 ,to see :e!r ! electromotive =ce ( a cell dep5ds ^u its size4 ,app>atus4 ,galvanoscope2 two glass tumbl]s2 dilute acid2 two wood5 cross-pieces2 two copp] & two z9c /rips1 ! same size z ^? us$ = ,exp4 #aab4 7,see #bge74 ,^! mat]ials w =m two simple cells l ,fig4 #he4 ,h ab\t #c 94 ( acid 9 "o tumbl]1 & b #a 94 9 ! o!r4 ,! plates ( "o cell w !n be ab\t #b-a_/b 94 9 acid1 & ^? ( ! o!r cell only #a_/b 94 9 acid4 ,?is gives u ! same effect z a l>ge & a small cell4 #cjb4 ,directions4 7,a7 ,jo9 ! l>ge & small cells ) ,g ,v s t _! curr5ts w oppose ea* o!r4 ,to d ?is1 jo9 ! two z9c plates by means ( a wire & connectors4 ,) two o!r wires connect ! two copp] plates ) ! galvanoscope b9d+-po/s1 & wat* = any indication ( curr5t4 ,does "o cell oppose ! o!r8 #cjc4 ,discussion4 ,! ,e4 ,m4 ,f4 ( a cell1 !n1 does n dep5d ^u ! size ( its plates4 ,! small piece ( z9c--t is1 ! "o 9 b little acid--_h ! same pot5tial z ! l>ge piece2 !y mu/ h _h1 z !y 7 jo9$4 ,! l>ge cell w give a /rong] curr5t1 "u c]ta9 conditions1 ?an ! small "o2 b ?is dep5ds ^u o!r ?+s ?an ,e4 ,m4 ,f4 7,see exp]im5ts "u ,curr5t ,/r5g?47 ,a z9c-copp] cell1 l ! "o j us$ 7,exp4 #aag71 has ! same voltage z "o ( ! same k9d w\ld h1 ev5 ?\gh x 7 made z l>ge z a b>rel4 ,,*apt] ,,xviii4 ,,electrical ,,resi/ance4 #cje4 ,resi/ance4 ,x is h>d] = a horse to draw a wagon ?r\gh deep s& ?an ov] a smoo? pavem5t4 ,we may say t ! s& holds ! horse back--t is1 x (f]s a resi/ance4 ,! electric curr5t does n pass ?r\gh all sorts ( sub/ances ) ! same ease1 & :5 x succe$s 9 pu%+ its way ?r\gh a circuit ( consid]able resi/ance1 we _c expect x to arrive at ! end ( its j\rney )\t be+ weak] ?an :5 x />t$4 ,d we expect ?is ( a man or horse8 ,we %all soon see t !re is a def9ite relation betwe5 resi/ance & ! /r5g? ( ! curr5t at ! end ( its j\rney4 ,,exp]im5t #aah4 ,to /udy ! g5]al effect ( resi/ance ^u a curr5t4 ,app>atus4 ,galvanoscope1 ,g ,v 7,no4 #eh72 resi/ance coil1 ,r ,c 7,no4 #gi7 7 #caj72 two-fluid cell1 #b-;,f ,c 7 #bha72 #d wires ) connectors 7 #bbf74 ,arrange z 9 ,fig4 #ib4 ,! curr5t passes z %[n by ! arr[1 & ! circuit may be op5$ & clos$ at ! metal plate1 ,m ,p1 or by us+ a key 9 its place4 ,prop]ly place ,g ,v4 #cjf4 ,directions4 7,a7 ,take ! read+ ( ,g ,v 9 degrees1 ! curr5t pass+ ?r\gh ! entire l5g? ( ,r ,c4 7,see #caj47 7,b7 ,*ange ! end ( wire #d f b9d+-po/ ,r to ,m1 on ,r ,c1 s t ! curr5t w pass ?r\gh "o-half only ( ,r ,c4 ,note ! read+ ( ,g ,v4 7,c7 ,remove ,r ,c entirely & connect wires #c & #d by means ( a metal plate4 ,comp>e ! read+s ( 7,a71 7,b7 & 7,c74 ,:at d !y %[8 ,illu/ration3 ,fig4 #ib4 #cjg4 ,ext]nal ,resi/ance2 ,int]nal ,resi/ance4 ,:5 we consid] a circuit l t %[n 9 ,fig4 #ib we see t x is compos$ ( two p>ts1 & t we h two k9ds ( resi/ances4 ,! wires1 in/rum5ts1 etc41 make up :at is call$ ! ext]nal resi/ance ( ! circuit2 t is1 ! "p t is ext]nal to ! cell4 ,! liquids 9 ! cell (f] a resi/ance to ! curr5t2 ?is is call$ int]nal resi/ance4 7,see #cad47 ,! /r5g? ( ! curr5t dep5ds ^u ! relation betwe5 ^! two resi/ances1 z w be se5 by future exp]im5ts1 z well z ^u ! ,e4 ,m4 ,f4 ( ! cell4 ,z liquids are n z good conductors z metals1 ! int]nal resi/ance ( cells may be q high4 #cjh4 ,unit ( ,resi/ance2 ,! ,ohm4 ,:5ev] any?+ is to be measur$1 a /&>d1 or unit1 is necess>y4 ,! unit ( resi/ance is call$ ! ohm1 9 honor ( ,ohm1 :o made c>eful inve/igations ^u ?is subject4 ,a column ( m]cury hav+ a l5g? ( a little ov] #c feet has be5 tak5 z a unit4 7,! column tak5 is #ajf4c cm4 ) a weight ( #ad4deba grams2 x has a cross-section ( ab\t #a sq4 mm41 at a temp]ature ( #j;,c47 ,m]cury is a liquid1 & has no gra9 to affect ! resi/ance4 ,= ! use ( /ud5ts1 #i ft4 #i 94 ( ,no4 #cj copp] wire1 or #ci ft4 #a 94 ( ,no4 #bd copp] wire w make a fairly good ohm4 ,we might1 ( c\rse1 take any o!r l5g? z our /&>d2 ! above1 h[ev]1 w give results t are approximately correct4 7,see wire tables at ! end ( ?is book47 #cji4 ,resi/ance ,coils2 ,resi/ance ,boxes4 ,coils ( wire1 hav+ c>efully-measur$ resi/ances1 are call$ resi/ance coils4 ,! wire = any coil is d\bl$ at ! c5t] be=e x is w\nd into coils or ^u spools 7,fig4 #ic7 to avoid ! magnetic effect4 ,! ends ( ! coils are atta*$ to b9d+-po/s1 or to brass blocks1 9 regul> in/rum5ts1 s t "o or m coils c be us$ at a "t2 t is1 s t !y may be h&l$ 9 a mann] simil> to t 9 :i* ! diff]5t coils on ! galvanoscope are us$4 ,if we h #d coils ( #a1 #b1 #b1 & #e ohms resi/ance1 we %all be able to use any numb] ( ohms f #a to #aj by mak+ ! prop] connections4 7,see ,app>atus ,book1 *apt] ,,xvii1 = ,home-made ,resi/ance ,coils47 ,= protection & conv5i5ce1 coils are usually plac$ 9 a box1 ! :ole be+ call$ a resi/ance box4 ,! ends ( ! coils are jo9$ to brass blocks1 plac$ ne> ea* o!r on ! top ( ! box1 & betwe5 :i* may be press$ plugs :5 x is desir$ to %ort circuit ! coils4 ,by remov+ a plug1 ! coil1 ^: ends are jo9$ to ! blocks t\*+ x1 is br\ght into ! circuit4 ,illu/ration3 ,fig4 #ic4 ,illu/ration3 ,fig4 #id4 #caj4 ,simple ,resi/ance ,coil4 ,fig4 #id %[s a simple =m ( coil1 ,r ,c 7,no4 #gi74 ,! total resi/ance is #b ohms1 ,l 7left7 & ,r 7"r7 be+ b9d+-po/s to :i* ! ends ( ! coil1 ,c1 are jo9$4 ,m 7middle7 connects ) ! middle ( ! wire1 at :i* po9t ! wire is d\bl$4 ,! coil is fa/5$ to a /iff pa/ebo>d base1 ,b4 ,connections4 ,:5 #b ohms resi/ance are want$1 let ! curr5t ent] at ,l & leave at ,r 7or ! rev]se74 ,:5 #a ohm is want$1 let ! curr5t leave or ent] at ,m1 ! o!r wire be+ jo9$ to ,l or to ,r4 ,connections %\ld be made ) spr+ connectors4 ,see #bbi4 ,,exp]im5t #aai4 ,to te/ ! p[] ( v>i\s sub/ances to conduct galvanic electricity4 ,app>atus4 ,galvanoscope1 ,g ,v 7,no4 #eh72 dry cell1 ,d ,c1 or two-fluid cell1 #b-;,f ,c2 pieces ( diff]5t metals2 wood1 dry & damp2 tumbl] ( pure wat]2 rubb]2 ebonite2 silk2 glass1 etc41 etc4 ,arrange z 9 ,fig4 #ib1 leav+ out ,r ,c1 & in/ead ( hav+ ,m ,p betwe5 wires #a & #b1 use _! free ends to press firmly ^u ! ends ( ! sub/ance to be te/$2 t is1 ! body "u te/ %\ld take ! place ( ,m ,p 9 ! ,fig4 ,g ,v w %[ a deflection1 ( c\rse1 :5 ! p>ticul> ?+ "u te/ is a conductor4 #caa4 ,directions4 7,a7 ,make te/s ) ! above sub/ances1 & ) any o!rs at h&1 & note :i* are conductors & :i* are n4 #cab4 ,conductors & ,nonconductors4 ,x is evid5t1 f ! exp]im5ts1 t bodies :i* conduct /atic electricity d n necess>ily conduct galvanic electricity4 ,! great] ! ,e4 ,m4 ,f4 ( a curr5t1 ! great] its p[] to ov]come resi/ance4 ,"s bodies1 l dry wood1 t readily conduct ! high pot5tial /atic electricity1 make fairly good insulators = ! l[ pot5tial galvanic curr5ts4 ,= conv5i5ce1 sub/ances may be divid$ into good conductors1 p>tial conductors1 & insulators1 or nonconductors4 ,good ,conductors4 ,metals1 *>coal1 graphite1 acids1 etc4 ,p>tial ,conductors4 ,dry wood1 pap]1 cotton1 etc4 ,insulators4 ,oils1 porcela91 silk1 res91 %ellac1 ebonite1 p>aff9e1 glass1 dry air4 ,illu/ration3 ,fig4 #ie4 ,,exp]im5t #abj4 ,to f9d ! effect ( sulphuric acid ^u ! conductivity ( wat]4 ,app>atus4 ,galvanoscope1 ,g ,v2 cell2 #b-;,f ,c2 connect+ wires2 sauc] or tumbl]1 ,s2 a little sulphuric acid4 ,arrange z 9 ,fig4 #ie4 #cac4 ,directions4 7,a7 ,put a little pure wat] 9 ,s1 & see if en\gh curr5t c pass ?r\gh x to deflect ! ne$le ( ,g ,v4 ,! ends ( ! wires1 #a & #b1 %\ld be gradually mov$ t[>d ea* o!r1 ! ne$le be+ wat*$4 7,b7 ,put #d or #e drops ( conc5trat$ acid into ! wat]2 /ir x1 !n repeat ! te/4 ,:at effect has ! acid8 #cad4 ,int]nal ,resi/ance4 ,z f\nd 9 ,exp4 #abj1 pure wat] is n a good conductor ( galvanic electricity4 ,! acid 9 ! simple cell1 & 9 o!r s+le-fluid cells1 acts ^u ! z9c & at ! same "t makes x possible = ! curr5t to pass1 z x r$uces ! int]nal resi/ance4 ,z se5 lat]1 ?is resi/ance 9 cells is greatly dim9i%$ by br++ ! plates ne> ea* o!r1 & by increas+ ! surface ( ! plates t are 9 contact ) ! acid4 ,! l>g] ! plates ! less ! int]nal resi/ance1 o!r ?+s rema9+ ! same4 ,! int]nal resi/ance ( a batt]y c be *ang$ by connect+ ! cells diff]5tly4 7,see ,*ap4 on ,arrangem5t ( ,cells47 ,illu/ration3 ,fig4 #if4 ,,exp]im5t #aba4 ,to f9d :at effect ! l5g? ( a wire has ^u its electrical resi/ance4 ,app>atus4 ,a ,no4 #cj ,g]man-silv] wire1 ,g-,s ,w1 a little ov] two met]s long1 un-insulat$ 7,no4 #ha72 ! two-fluid cell1 #b-;,f ,c 7,exp4 #aac72 galvanoscope1 ,g ,v 7,no4 #eh72 plate b9d+-po/s1 ,x1 ,y & ,z 7,no4 #hc-hd-he72 copp] wa%]s 7,no4 #hg74 ,arrange z 9 ,fig4 #if1 s t ! curr5t w fl[1 at fir/1 z %[n by ! arr[4 ,! metal plates1 ,m ,p #a & ,m ,p #b1 are us$ s t ! connections may be *ang$ )\t di/urb+ ,g ,v4 ,! b9d+-po/s may be fa/5$ directly to ! top ( ! table2 b x w be m conv5i5t to p]man5tly fix !m to a bo>d1 ,b1 z %[n1 s t ! same arrangem5t c be us$ = future exp]im5ts4 ,! b9d+-po/s1 ,x & ,y1 %\ld be ab\t #a_/h 94 ap>t1 j f> en\gh s t _! edges d n t\* ea* o!r4 ,! b9d+-po/1 ,z1 %\ld be fa/5$ to ,b ) its inside end #a met]7#ajj c5timet]s1 cm47 f ! ends ( ,x & ,y4 ,m>ks %\ld be made ^u ,b1 #aj c5timet]s ap>t1 z indicat$ by ! cross l9es4 ,?is di/ance may be tak5 f ! scale on ! rule 7,no4 #hh74 ,fa/5 "o end ( ! ,no4 #cj wire1 ,g-,s ,w1 to ,x4 ,to d ?is twi/ its end ar\nd ! screw1 ,s1 betwe5 ,x & ! copp] wa%]1 !n turn ! screw 9 ) a screw-driv] until x firmly holds ,x to ! bo>d4 ,pass ! wire ar\nd ! screw 9 ,z1 & br+ its free end to ! o!r b9d+-po/1 ,y1 to be fa/5$ 7,fig4 #if74 ,two met]s ( wire !n =m a pa? = ! curr5t f ,x to ,y4 ,h ! bo>d wide en\gh s t ano!r set ( b9d+-po/s c be put by ! side ( ,y4 ,x w be be/ to p]man5tly leave ! ,no4 #cj wire ^u ! bo>d1 & to fa/5 ! ,no4 #bh wire 7next exp]im5t7 to ano!r set ( b9d+-po/s1 plac$ 9 ! same mann] z ^? 9 ,fig4 #if4 ,make holes 9 ! wood ) an awl be=e =c+ 9 ! screws4 #cae4 ,note4 ,?is exp]im5t is usually done ) a rev]s] 9 ! circuit1 fir/ tak+ read+s ) ! curr5t pass+ 9 "o direction1 & !n 9 ! opposite direction4 ,consid]able "t w be sav$ by tak+ all ! read+s = "o direction ( ! curr5t at a "t1 simply us+ diff]5t l5g?s ( ,g]man-silv] wire1 & all[+ ! curr5t to fl[ con/antly dur+ ea* "p4 ,?is obviates all dang] ( poor contacts 9 ! rev]s]1 etc42 x saves ! tr\ble ( h&l+ ! rev]s]1 & mu* ( ! "t ne$$ = ! ne$le to come to re/4 ,illu/ration3 ---------------------------------------- -------------- ,,l5g? ,,( ,,circ41 ,,cm4#bjj #ahj #afj #adjabjajj #hj #fjbjj ,o ---------------------------------------- -------------- ,,deflection2 ,,we/ #bf #bh #cj #bffg ---------------------------------------- -------------- ,,deflection2 ,,ea/ #be #bg #cj #befg ---------------------------------------- -------------- ,,av]age #be4ebg4e #cj #be4efg ---------------------------------------- -------------- ,fig4 #ig4 #caf4 ,directions4 7,a7 ,) ! circuit arrang$ z 9 ,fig4 #if1 & ) ,g ,v prop]ly plac$1 take ! read+ ( ,g ,v1 ! curr5t pass+ ?r\gh #bjj cm4 ( ,no4 #cj ,g-,s ,w4 ,record y\r results 9 a diagram made l ,fig4 #ig4 ,! r[ ( figures across ! top %[s ! l5g? ( ! circuit4 ,! table is />t$ ) results f "o exp]im5t4 ,y\r results w probably be diff]5t f ^!4 7,b7 ,get ! deflection ) ! curr5t pass+ ?r\gh #ahj cm4 ( wire4 ,to d ?is press a piece ( copp] 7,o1 ,fig4 #if7 ^u ! wire at ! m>k #aj cm4 f ,z1 ano!r ?9 piece ( metal1 ,u1 hav+ be5 slipp$ "u ! wire4 ,?is w all[ ! curr5t to pass across f "o wire to ! o!r4 ,record ! deflection 9 ! col4 m>k$ #ahj4 7,c7 ,record ! deflections = ! l5g?s1 #afj cm41 #adj1 #abj1 #ajj1 #hj1 & #fj2 !n repeat 7,a7 to be sure t ! cell has be5 work+ uni=mly4 ,?is deflection %\ld agree ) t 9 7,a74 7,d7 ,*ange ! direction ( ! curr5t ?r\gh ,g ,v2 to d ?is1 *ange wire1 #a1 f ,m ,p #b to ,m ,p #a1 & wire #e to ,m ,p #b4 ,?is mu/ be done )\t di/urb+ ,g ,v4 7,e7 ,repeat 7,a71 7,b71 & 7,c71 & record ! deflections = ! diff]5t l5g?s4 7,f7 ,get ! av]age deflections4 7,g7 ,take1 = future use1 ! deflection produc$ )\t ,g-,s ,w be+ 9 ! circuit4 ,sw+ ! end ( wire1 #c1 t is jo9$ to ,y1 ar\nd to ,m ,p #b4 ,! curr5t w !n pass simply ?r\gh ,g ,v4 ,record deflection 9 col4 m>k$ ,o4 ,note4 ,x is be/ to d ! next exp]im5t at once ) ! same cell1 s t ! results ( ! two exp]im5ts c be comp>$4 ,9 case ?is is impossible1 get y\r cell to produce ! same deflection :5 y use x aga91 z %[n 9 col4 ,o1 ,fig4 #ig4 ,y c regulate ! deflection ( ! ne$le ( ,g ,v by v>y+ ! /r5g? & quantity ( ! acid 9 ,p ,c4 #cag4 ,discussion4 ,! resi/ance ( a wire evid5tly dep5ds 7,exp4 #aba7 ^u its l5g?4 ,! exact relation betwe5 resi/ance & l5g? _c be se5 f ^! results1 h[ev]1 :i* are us$ 9 ! next exp]im5t4 ,x w be %[n lat] t 9 a wire1 o!r ?+s rema9+ ! same1 ! resi/ance v>ies directly z its l5g?4 ,,exp]im5t #abb4 ,to f9d :at effect ! size 7area ( cross-section7 ( a wire has ^u its electrical resi/ance4 ,app>atus4 ,same z 9 la/ exp]im5t1 ) "o *ange1 h[ev]4 ,replace ! ,no4 #cj ,g-silv] wire ) a ,no4 #bh ,g-silv] wire 7,no4 #hb71 or1 :at is bett] /ill1 fa/5 x to ano!r set ( b9d+-po/s on ! bo>d & leave ! ,no4 #cj = future use4 ,! two %\ld be /ret*$ side by side = con/ant use4 #cah4 ,directions4 7,a7 ,see t y\r cell is 9 ! same condition z = ,exp4 #aba2 t is1 x %\ld produce ! same deflection ( ! ne$le ( ,g ,v z be=e1 :5 ! two1 only1 are 9 ! circuit4 7,see ,exp4 #aba1 ,g47 ,! deflection may be *ang$ by *ang+ ! /r5g? & quantity ( ! dilute acid & copp] solution4 7,b7 ,f9d ! av]age deflection ( ! ne$le ) ! #b met]s ( ,no4 #bh ,g-s wire 9 ! circuit1 arrang$ z 9 ,fig4 #if4 7,c7 ,comp>e ?is av]age deflection ) ! results obta9$ 9 ,exp4 #aba1 9 ord] to f9d :at l5g? ( ! ,no4 #cj wire has ! same resi/ance z #b met]s ( ,no4 #bh wire4 ,to f9d h[ _m times great] "o l5g? is ?an ano!r1 we divide ! l>g] l5g? by ! small]2 h5ce1 to f9d ! relation betwe5 ! two l5g?s ( wire t gave ! same deflection1--l5g?s ( equal resi/ance1--we divide ! #bjj c5timet]s 7! l5g? ( ! ,no4 #bh7 by ! l5g? ( ,no4 #cj f\nd z direct$4 7,d7 ,f ! wire tables x w be f\nd t ! area ( cross-section ( ,no4 #bh wire is ab\t #a4ei times t ( ,no4 #cj wire4 ,h[ does ?is quoti5t1 or ratio1 comp>e ) t f\nd 9 "p 7,c78 ,:at is ! relation betwe5 ! area ( cross-section ( a wire & its resi/ance8 7,see #cai1 also ,exp4 #acf47 #cai4 ,discussion4 ,if we f9d t a c]ta9 wire1 ,x1 :i* is #egf feet long1 has ! same resi/ance z a %ort] "o1 ,y1 #cfj feet long1 we see 7#egf divid$ by #cfj7 t ! ratio ( _! l5g?s is #a4f4 ,?is means t ! long] "o1 ,x1 is #a4f times z good a conductor z ,y2 or1 9 o!r words1 t ! resi/ance ( ,y is #a4f times t ( ,x4 ,x is easi] = wat] to fl[ ?r\gh a l>ge pipe ?an x is ?r\gh a small "o4 ,! same g5]al pr9ciple is true ( electricity4 ,a l>ge wire (f]s less resi/ance to ! curr5t ?an a small "o ( ! same mat]ial4 ,if "o wire is twice ! size ( ano!r ( equal l5g?1 x w be twice z good a conductor z ! o!r2 t is1 x w h "o-half ! resi/ance ( ! small]1 provid$ !y are ( ! same mat]ial4 7,see ,laws47 ,,exp]im5t #abc4 ,to comp>e ! resi/ance ( a divid$ circuit ) ! resi/ance ( "o ( its bran*es4 ,app>atus4 ,same z 9 la/ exp]im5t4 ,arrange z 9 ,fig4 #ih4 #cbj4 ,directions4 7,a7 ,note ! deflection ( ! ne$le :5 ! curr5t passes ?r\gh #a met] ( ,g-s wire1 z %[n4 ,?is w be consid]$ z "o bran* ( ! divid$ circuit4 7,b7 ,/ill all[+ ! curr5t to pass z 9 "p 7,a71 press a piece ( copp] firmly across ! b9d+-po/s ,x & ,y1 to electrically connect !m1 & note ! read+ ( ! ne$le4 ,9 ?is case ! curr5t divides at ,z ?r\gh ! two bran*es4 ,:at is le>n$ f ! results ( 7,a7 & 7,b78 7,c7 ,see if y c %[ ! same results ) app>atus arrang$ z 9 ,fig4 #ii4 ,illu/ration3 ,fig4 #ih4 ,illu/ration3 ,fig4 #ii4 #cba4 ,discussion4 ,two wires plac$ side by side z 9 7,b71 ,exp4 #abc1 really =m a conductor hav+ twice ! size 7area ( cross section7 ( "o ( ! bran*es4 ,! m pa?s a curr5t has 9 go+ f "o place to ano!r1 ! less ! resi/ance4 7,see ,exp4 #ace47 ,! wires are said to be 9 p>allel or 9 multiple arc4 ,illu/ration3 ,fig4 #ajj4 ,illu/ration3 ,fig4 #aja4 ,,exp]im5t #abd4 ,to /udy ! effect ( decreas+ ! resi/ance 9 "o bran* ( a divid$ circuit4 ,app>atus4 ,galvanoscope1 ,g ,v 7,no4 #eh72 resi/ance coil1 ,r ,c 7,no4 #gi72 two-fluid cell1 #b-;,f ,c 7 #bha71 or a dry cell2 #f connect+ wires2 metal plates1 ,m ,p4 ,arrange z 9 ,fig4 #ajj1 s t ! curr5t divides into two bran*es at ,m ,p #a4 ,! bran*es unite at ,m ,p #b4 #cbb4 ,directions4 7,a7 ,take ! read+ ( ,g ,v ) #b ohms resi/ance 9 ! l[] bran*2 t is1 ) ! :ole ( ,r ,c 9 circuit4 7,b7 ,take ! read+ ( ,g ,v ) "o ohm 9 circuit2 t is1 ) ! end ( wire1 #e1 connect$ to ,m in/ead ( to ,r4 7,c7 ,cut out ,r ,c f ! l[] bran* by replac+ x ) a metal plate1 ?us jo9+ wires #c & #e4 ,comp>e ! results f 7,a71 7,b71 & 7,c71 & expla94 #cbc4 ,curr5t 9 ,divid$ ,circuits4 ,let u consid] a circuit l t %[n 9 ,fig4 #aja4 ,if ! po9ts1 ,c & ,z1 7 at ! same pot5tial1 no curr5t w\ld pass f ,c to ,z4 ,z ! curr5t does pass1 ,z mu/ be at a l[] pot5tial ?an ,c2 !re is a fall ( pot5tial f ,c to ,z4 ,if ! bran*1 ,a ,b1 has ! same resi/ance z ,r ,x1 ! same am\nt ( curr5t w pass ?r\gh ea*4 ,exp4 #abd has %[n t :5 ! bran*es h unequal resi/ances1 mo/ ( ! curr5t passes ?r\gh ! "o ( small resi/ance4 ,if ,r ,x has a great] resi/ance ?an ,a ,b1 mo/ ( ! curr5t w pass ?r\gh ,a ,b4 ,,*apt] ,,xix4 ,,measurem5t ,,( ,,resi/ance4 ,illu/ration3 ,fig4 #ajb4 ,,exp]im5t #abe4 ,to /udy ! con/ruction & use ( a simple ,:eat/one's ,bridge4 ,app>atus4 ,fig4 #ajb4 ,a ,:eat/one's bridge1 ,w ,b 7,no4 #hj71 7 #cbd72 a/atic galvanoscope1 ,a ,g 7,no4 #ei72 dry cell1 ,d ,c 7,no4 #ea72 key1 ,k 7,no4 #ee72 #g wires ) spr+ connectors1 two ( :i*1 ,r & ,x1 are equal 9 l5g?2 metal plate1 ,m ,p1 = connect+ wires4 ,arrange z 9 ,fig4 #ajb4 ,! c>bon ( ,d ,c is jo9$ to ,k1 & ?is to ! po9t1 ,c1 ( ! bridge4 ,! z9c ( ,d ,c connects ) ! po9t ,z on ,w ,b4 ,! ,a ,g is plac$ betwe5 ! bran*es = cle>ness4 ,wire #c is jo9$ to ! left-h& b9d+-po/ ( ,a ,g1 & wire #d jo9s ,m ,p ) ! "r-h& "o4 ,:5 ! end ( wire #c does n t\* ,g-s ,w1 x is evid5t t z soon z ,k is press$1 ! curr5t divides at ,c on its way to ,z1 :]e ! bran*es unite aga94 ,k is us$ s t ,d ,c w n be pol>iz$ by /eady use4 ,illu/ration3 ,fig4 #ajc4 #cbd4 ,! ,simple ,:eat/one's ,bridge 7,fig4 #ajc7 consi/s ( a wood5 base1 ,w1 at ! ends ( :i* are fa/5$ two alum9um conductors1 #a & #c4 ,at "o side ( ,w is fa/5$ ano!r conductor1 #b4 ,9 ,fig4 #ajd are side views ( ! conductors4 ,^! are us$ m]ely = conv5i5ce 9 mak+ connections1 & take ! place ( ! metal plates us$ 9 previ\s exp]im5ts4 ,a ,g]man-silv] wire1 ,g-s ,w1 is /ret*$ betwe5 #a & #c1 & "u ?is is a scale1 ,s1 divid$ into #ajj small p>ts1 ^! be+ t5?s ( ! l>g] divisions4 ,! ends ( ,g-s ,w are held betwe5 eyelets1 z %[n at ,e1 ,fig4 #ajd4 ,illu/ration3 ,fig4 #ajd4 ,read+ ! ,scale4 ,! value ( "p ,a c be read directly f ! scale1 us+ ! l[] r[ ( figures4 ,! po9t m>k$ ,p1 = example1 w\ld be read #c4g 7?ree & sev5-t5?s l>ge divisions72 ,b w\ld be #f4c1 f\nd by subtract+ #c4g f #aj4 ,! sum ( ,a & ,b mu/ always equal #aj4 ,! #f4c may also be read directly by us+ ! upp] r[ ( figures = ! :ole numb]s1 c\nt+ ! t5?s to ! left4 ,try to divide ! smalle/ divisions into halves1 at lea/2 t is1 if ,a #c4ge1 ,b #f4be4 ,take ! read+s c>efully4 #cbe4 ,directions4 7,a7 ,t\* ! free end ( wire1 #c1 to ! po9t1 ,c1 :i* has a high] pot5tial ?an ,m ,p4 ,press d[n ,k = an in/ant only4 ,"s curr5t %\ld pass ?r\gh ,a ,g1 z a %unt4 ,%\ld x pass f ,c to ,m ,p or ! rev]se8 ,note 9 :i* direction ! "r-h& end ( ! a/atic ne$le is deflect$4 7,b7 ,sw+ ! end ( #c ar\nd & t\* x to ! po9t1 ,z1 :i* has a l[] pot5tial ?an ,m ,p4 ,press ,k = an in/ant1 wat* ! ne$le1 & comp>e ) ! results 9 7,a74 7,c7 ,move ! free end ( #c along on ,g-s ,w1 t\*+ ,k at int]vals1 until a po9t is f\nd at :i* ! ne$le ( ,a ,g is n deflect$4 ,h[ does ! pot5tial ( ?is po9t comp>e ) t ( ,m ,p8 #cbf4 ,discussion2 ,equipot5tial ,po9ts4 ,s9ce "o end ( ! ,g-s ,w has a high]1 & its o!r end has a l[] pot5tial ?an ,m ,p1 !re mu/ be1 some:]e on x1 a po9t at :i* ! pot5tial is ! same z at ,m ,p4 ,?is place is quickly f\nd by slid+ ! free end ( wire1 #c1 along1 press+ ,k occasionally1 until ,a ,g %[s t no curr5t t5ds to pass ?r\gh x 9 ei!r direction1 :5 ! curr5t passes f ,c to ,z ?r\gh ! two bran*es ( ! divid$ circuit4 ,?is po9t & ,m ,p are call$ equipot5tial po9ts4 ,if ! resi/ance ( ! "p1 ,x1 be increas$1 x %\ld be evid5t t ! "p ( ! bridge-wire1 ,b1 %\ld be also increas$ to f9d a po9t hav+ ! same pot5tial z ,m ,p2 t is1 ! end ( #c %\ld be mov$ t[>ds ,c4 ,we h1 9 ! bridge-wire1 a simple means ( v>y+ ! resi/ance ( its p>ts1 ,a & ,b4 #cbg4 ,use ( ,:eat/one's ,bridge4 ,x w be f\nd1 ^u trial1 if we put a resi/ance ( #b ohms 9 place ( ,r1 ,fig4 #ajb1 & #b ohms 9 place ( ,x1 t ! free end ( wire #c w h to be at ! c5t] ( ! bridge-wire 9 ord] to get a balance2 t is1 to f9d ! place :]e ,a ,g is n affect$4 ,no matt] :at ! resi/ance ( ,r & ,x are1 provid$ !y are equal1 ?is w be true4 ,! value ( bo? ,a & ,b1 on ! scale1 w be #e :ole spaces1 no t5?s4 ,f ?is we see t ,a3 ,b33 ,r3 ,x1 :i* reads ,a is to ,b z ,r is to ,x2 ?is means t ,a ,x ,b ,r4 ,supply+ ! values ( ! lett]s1 we h #e #b #e #b4 ,if we did n "k ! value ( ,x1 t is1 if we 7 measur+ ! resi/ance ( a coil ( wire1 us+ a #b-ohm coil z ! /&>d1 or ,r1 we c\ld f9d ! value ( ,x1 kn[+ ! o!r #c p>ts ( ! proportion4 #e ,x #e #b1 :i* means t #e times ! value ( ,x is #aj2 h5ce ! value ( ,x is #aj #e #b ohms4 ,suppose t we h ,r #b ohms1 :i* is ! /&>d resi/ance coil 7,no4 #gi71 & are try+ to f9d ! resi/ance ( a coil1 ,x4 ,we slide ! end ( wire1 #c1 along on ! bridge-wire until ! correct place is f\nd4 7,see ,exp4 #abe1 #abf1 = details47 ,take ! values ( ,a & ,b 7 #cbd71 supply !m 9 ! equation giv51 & "w out ! value ( ,x4 #cbh4 ,,example4 ,r #b ohms2 ,a #c4g2 ,b #f4c2 to f9d ! value ( ,x 9 ohms4 ,a3 ,b33 ,r3 ,x1 :i* means t ,a ,x ,b ,r1 or #c4g ,x #f4c #b4 ,x mu/ equal1 !n 7#f4c #b7 #c4g #c4dje ohms4 ,note4 ,9 practice x is mo/ conv5i5t to make connections z %[n 9 ,fig4 #aje :5 measur+ resi/ances 7,exp4 #abf74 ,! arrangem5t giv5 9 ,fig4 #ajb is simply = explanation4 ,x w be se5 t ! small] ,a is1 comp>$ ) ,b1 ! l>g] ! unkn[n resi/ance comp>$ ) y\r /&>d4 ,illu/ration3 ,fig4 #aje4 ,,exp]im5t #abf4 ,to measure ! resi/ance ( a wire by means ( ,:eat/one's ,bridge2 ! bridge me?od4 ,app>atus4 ,same z 9 ,exp4 #abe2 ! two-ohm resi/ance coil1 ,r ,c 7,no4 #gi72 a coil ( wire1 ,x1 z1 = example1 ! #ae-turn coil on ! galvanoscope1 ,g ,v 7,no4 #eh74 ,arrange z 9 ,fig4 #aje4 ,y w obs]ve t ! c5tral conductor ( ! bridge 7#b1 ,fig4 #ajd7 takes ! place ( ,m ,p 9 previ\s explanations4 ,we /ill h ! same k9d ( a divid$ circuit z expla9$ 9 ,exp4 #abe1 ,a ,g be+ connect$ ) po9ts ( equal pot5tial4 ,x w be f\nd conv5i5t to h ,d ,c at ! "r1 & ,a ,g fac+ y at ! left1 ! key be+ 9 front4 7,see ,exp4 #ajg 9 reg>d to adju/+ ,a ,g47 ,notice t y h a /&>d resi/ance 7#b ohms7 9 place ( ,r1 ,fig4 #ajb1 & an unkn[n resi/ance 7galvanoscope coil7 9 place ( ,x4 7,see #ccj47 #cbi4 ,directions4 7,a7 ,t\* ! free end ( wire1 #c1 to ! left-h& side ( ! bridge-wire1 press ! key = an in/ant1 only1 & note ! direction tak5 by ! "r-h& end ( ! ne$le4 ,move ! end ( wire1 #c1 to ! "r-h& side ( ! bridge-wire1 t\* key1 wat*+ ne$le4 ,does ! ne$le move m or less ?an be=e8 ,9 ! same or opposite direction8 ,if ! deflections are opposite1 ! po9t t has ! same pot5tial z b9d+-po/1 #b1 mu/ be betwe5 ! two po9ts t\*$4 7,b7 ,be sure t all connections are good4 ,f9d ! po9t on ,g-s ,w1 at :i* !re is no deflection1 z direct$ 9 ,exp4 #abe 7,c74 ,note ! read+s on ! scale1 z expla9$ 9 #cbd4 7,c7 ,make ! prop] calculation1 #cbg1 #cbh1 & f9d ! resi/ance ( ! coil ( ,g ,v1 ! resi/ances ( ! wires jo9+ ,r ,c & ,g ,v to ! bridge be+ neglect$4 7,d7 ,make prop] all[ances = ! resi/ances ( ! wires j m5tion$ 7see #ccj71 & comp>e !m ) ! results f\nd 9 "p 7,c74 #ccj4 ,all[ances = connections4 ,x %\ld be rememb]$ t ! wires jo9+ ,r ,c & ,g ,v to ! bridge also h "s resi/ance4 ,su* connections1 9 regul> in/rum5ts1 are made by heavy copp] /raps or by ?ick1 %ort wires1 s t _! resi/ances c be neglect$4 ,9 case y use ! ord9>y ,no4 #bd copp] wire1 z direct$1 ! resi/ances ( ! pieces c be measur$ by means ( ! bridge1 or y c calculate _! resi/ances f ! wire tables4 ,! resi/ances %\ld be all[$ =4 ,x is evid5t t y\r /&>d resi/ance is #b ohms plus ! resi/ance ( ! connect+ wires1 & t ! resi/ance ( ! coil1 ,x1 is f\nd by d$uct+ ! resi/ance ( its connect+ wires f t f\nd f ! proportion previ\sly us$4 ,example4 ,we see f ! table t ! resi/ance ( ab\t #ci ft4 #a 94 ( ,no4 #bd1 ,b & ,s copp] wire is #a ohm4 ,?is equals #dfi 94 ,if #dfi 94 h a ,r 7resi/ance7 ( #a ohm1 #a 94 w h a ,r ( "o-#dfi? ( an ohm2 t is #a divid$ by #dfi1 :i* equals a little ov] 4#jjb ohm4 ,= e in* ( ,no4 #bd wire us$1 !n1 = connections1 we may all[ 4#jjb ohm4 ,?is w be ne> en\gh = our purposes4 ,suppose t ea* connection is #ah 94 long1 ! regul> wires ) connectors be+ us$4 ,! ,r ( ! #cf 94 jo9$ to ,r ,c w !n be #cf times 4#jjb 4#jgb ohm4 ,our /&>d ,r mu/ !n be consid]$ z #b4jgb ohm4 ,if we sub/itute ?is 9 ! example1 z /at$ 9 #cbh1 we h #c4g ,x #f4c #b4jgb4 ,x mu/ equal 7#f4c #b4jgb7_/c4g #c4ebh ohm1 :i* includes ! unkn[n resi/ance & #cf 94 ( connections1 ! ,r ( :i* is 4#jjb ohm2 #c4ebh - 4#jgb #c4def1 ! resi/ance ( ,x alone4 ,comp>e ?is ) ! answ] to example1 #cbh4 ,make all[ances accord+ to l5g? ( connectors us$4 ,note4--,c>efully keep all ! results ( ^! exp]im5ts 9 a note book = future ref]5ce4 ,be sure t connections are good4 ,,exp]im5ts #abg-acg4 ,to measure ! resi/ances ( v>i\s wires1 coils1 etc41 by ! bridge me?od4 ,app>atus4 ,! coils ( wire1 etc41 z /at$ 9 ! ,directions ( ea* exp]im5t4 ,! details ( ea* piece ( app>atus may be f\nd by ref]r+1 f ! numb]s giv51 to ! ,app>atus ,li/1 & to descriptions 9 ! p>agraphs m5tion$4 ,also all ! app>atus ( ,exp4 #abf4 ,note4 ,make prop] all[ances = connections 7 #ccj7 9 all exp]im5ts 9 measur+ resi/ances4 ,,exp]im5t #abg4 #cca4 ,directions4 7,a7 ,z expla9$ 9 ,exp4 #abf1 measure ! resi/ance ( ! #aj-turn coil ( ,g ,v1 all[+ = connections 7 #ccj74 ,read ! bridge-scale c>efully4 7,b7 ,use "o-half ( ! #b-ohm coil z /&>d & repeat4 ,,exp]im5t #abh4 #ccb4 ,directions4 7,a7 ,measure ! resi/ance ( ! #e-turn coil ( ,g ,v 7see ,exp4 #abf1 etc471 us+ #b ohms z /&>d4 7,b7 ,use #a ohm z /&>d1 repeat1 & comp>e results4 7,c7 ,add ! resi/ances ( ! #e & #aj-turn coils1 & comp>e ! sum ) ! resi/ance ( ! #ae-turn coil1 z f\nd 9 ,exp4 #abf1 ,d4 ,! diff]5ce %\ld be b a few hundr$?s ( an ohm4 ,,exp]im5t #abi4 #ccc4 ,directions4 7,a7 ,measure ! resi/ance ( ! coil ( ,no4 #bd copp] wire 7,no4 #hi74 ,?is coil is us$ = lat] exp]im5ts4 ,spr+ connectors are fa/5$ to ! ends ( ?is coil1 all[+ x to be directly connect$ to ! conductor on ! bridge1 s no all[ance %\ld be made = its connect+ wires4 7,see ,exp4 #abf = details47 ,m>k ! resi/ance ^u ! coil = future use4 7,see ,note47 ,note4 ,! /ud5t w be surpris$1 p]haps1 to f9d t diff]5t results are obta9$ = ! resi/ance ( a giv5 wire 9 case he uses diff]5t /&>d resi/ances 9 ! v>i\s te/s2 t is1 he w probably get a diff]5t result 9 ,exp4 #abg 7,a7 f ! result ( ,exp4 #abg 7,b74 ,! diff]5ce "h1 h[ev]1 may n be l>ge4 ,! be/ results are obta9$ by mak+ ! /&>d resi/ance z ne>ly equal z possible to ! resi/ance to be measur$1 s t a balance c be f\nd :5 ! end ( wire #c 7,fig4 #aje7 is ne> ! c5t] ( ! bridge-wire4 ,if ,r1 ,fig4 #aje1 is mu* l>g] or small] ?an ,x1 ! po9t desir$ on ,g-s ,w w be ne> "o ( its ends1 & l>ge errors !reby produc$4 ,! approximate resi/ance ( ,x c be f\nd by trial1 !n m or less resi/ance c be us$ = ,r to suit4 ,! /ud5t %\ld make sev]al coils z expla9$ 9 ,app>atus ,book1 ,*apt] ,,xvii4 ,! resi/ance ( ! diff]5t coils furni%$ %\ld be measur$ & m>k$4 ,^! c be us$ to v>y ! value ( ,r4 ,,exp]im5t #acj4 #ccd4 ,directions4 7,a7 ,measure ! resi/ance ( ! coil ( ,no4 #be copp] wire 7,no4 #ij74 7,see ,exp4 #abf = details & ! ,note1 ,exp4 #abi47 ,,exp]im5t #aca4 #cce4 ,directions4 7,a7 ,measure ! comb9$ resi/ance ( ! two coils us$ 9 ,exps4 #abi & #acj1 :5 !y are jo9$ 9 s]ies2 t is1 :5 "o end ( "o coil is jo9$ to "o end ( ! o!r by means ( a metal plate1 ! free ends be+ connect$ to ! bridge 7,exp4 #abf74 ,! curr5t has to travel ?r\gh ! entire l5g? ( bo? coils4 7,b7 ,comp>e ?is result ) ! sum ( _! sep>ate resi/ances f\nd 9 ,exps4 #abi & #acj4 7,see ,exp4 #abi1 ,note47 ,,exp]im5t #acb4 #ccf4 ,directions4 7,a7 ,measure ! resi/ance ( ! two coils 7,exp4 #aca7 :5 !y are jo9$ 9 p>allel4 7,see #bic47 ,!y may be jo9$ 9 p>allel by connect+ !m bo? to ! bridge at ! same "t1 "o end ( ea* be+ slipp$ onto #b 7,fig4 #ajc71 ! o!r end ( ea* be+ jo9$ to #c4 ,9 ?is way ! curr5t has two pa?s1 side-by-side1 to get f #b to #c4 7,see ,exp4 #abi1 ,note47 7,b7 ,comp>e ?is resi/ance ) t ( ,exp4 #aca4 ,,exp]im5t #acc4 #ccg4 ,directions4 7,a7 ,measure ! resi/ance ( #a met] ( ,no4 #bh ,g]man-silv] wire4 ,use ! wire z arrang$ on a bo>d1 ,exp4 #abb 7,figs4 #if & #ih71 mak+ ! connections ) ! bridge f b9d+-po/s1 ,x & ,z4 7,see ,exp4 #abi1 ,note47 ,! wires connect+ ! bridge ) ! ends ( ! ,g-s wire w ea* h to be ab\t #b ft4 long4 ,9 mak+ d$uctions 7 #ccj7 figure accord+ to ! l5g? us$4 7,b7 ,divide ! total resi/ance by #ajj to get ! resi/ance ( #a cm4 ( ! wire1 & c>efully m>k (f ! bo>d into cm4 ,?is w give #ajj p>ts betwe5 ,x & ,z4 ,,exp]im5t #acd4 #cch4 ,directions4 7,a7 ,us+ ! ,no4 #bh ,g-s wire on ! bo>d1 z arrang$ = ,exp4 #abb1 measure ! resi/ance ( ! #b met]s 9 s]ies1 ! connections be+ made ) ! bridge f ,x & ,y1 ,fig4 #ih4 7,b7 ,comp>e ! result ) t ( ,exp4 #acc4 ,:at is ! relation betwe5 ! l5g? ( a wire & its resi/ance8 ,see ,summ>y ( ,laws4 7,see ,exp4 #abi1 ,note47 ,,exp]im5t #ace4 #cci4 ,directions4 7,a7 ,measure ! resi/ance ( ! above two met]s ( ,no4 #bh ,g-s wire :5 jo9$ 9 p>allel4 7 #bic47 ,! b9d+-po/s1 ,x & ,y1 c be jo9$ by a %ort wire ) connectors on its ends1 or by clamp+ a ?9 /rip across by means ( spr+ connectors4 ,use ! #b-ohm coil z ! /&>d1 & make prop] all[ances4 7 #ccj47 7,b7 ,f ! results ( ,exps4 #acb & #ace :at c be said ab\t ! resi/ances ( p>allel circuits z comp>$ ) ! resi/ances ( ! sep>ate bran*es8 ,,exp]im5t #acf4 #cdj4 ,directions4 7,a7 ,arrange ! #b met]s ( ,no4 #cj ,g-s wire on ! table or bo>d1 aga9 7,exp4 #aba1 ,fig4 #if74 7,b7 ,measure ! resi/ance ( "o met]4 ,f9d ! value ( ,x approximately1 & use a resi/ance = ,r t w suit4 7,see ,exp4 #abi1 ,note47 7,c7 ,divide ! result by #ajj to get ! resi/ance ( #a cm4 ( ! wire4 7,d7 ,comp>e ! resi/ance ( "o met] ( ,no4 #bh ,g-s wire1 f\nd 9 ,exp4 #acc1 ) ! resi/ance ( #a met] ( ,no4 #cj ,g-s wire4 ,:at is ! relation1 !n1 betwe5 ! size 7area ( cross-section7 ( a wire & its resi/ance8 7,see ! results ( ,exp4 #abb1 & #cai1 also ,summ>y ( ,laws47 ,,exp]im5t #acg4 #cda4 ,directions4 7,a7 ,measure ! resi/ance ( #b met]s ( ,no4 #cj copp] wire1 arrang$ on a bo>d z 9 ,fig4 #if4 7,see ,exp4 #abi1 ,note47 ,get ! resi/ance ( #a met]4 7,b7 ,comp>e ! conductivities ( copp] & ,g]man silv] by /udy+ ! results ( ,exps4 #acf & #acg4 ,:i* has ! great] resi/ance8 ,to f9d out h[ _m times great] "o resi/ance is ?an ! o!r1 divide ! l>g] by ! small]4 ,,exp]im5t #ach4 ,to /udy ! effect ( heat ^u ! resi/ance ( metals4 ,app>atus4 ,same z = ,exp4 #abf2 ! coil ( ,no4 #bd wire 7,no4 #hi72 a lamp or o!r s\rce ( heat4 ,arrange z 9 ,fig4 #aje4 #cdb4 ,directions4 7,a7 ,measure ! resi/ance ( ! coil z be=e1 ,exp4 #abi4 ,! result %\ld ne>ly agree ) t ( ,exp4 #abi1 provid$ connections1 etc41 are ! same4 7,b7 ,remove ! coil f ! bridge1 hold x ab\t a foot above a lamp or /ove1 to w>m x ?or\ghly1 b d n heat x en\gh to injure ! cov]+4 ,x w take a m9ute or s to w>m x s t ! heat w get to ! inside also4 7,c7 ,replace ! coil1 measure its resi/ance1 & comp>e ! result ) its resi/ance :5 cold4 ,does heat increase or decrease ! resi/ance ( a copp] wire8 #cdc4 ,effect ( ,heat ^u ,resi/ance4 ,al?\gh !re 0 b ! fraction ( an ohm diff]5ce 9 ! resi/ances ( ! hot & cold coil1 x 0 evid5t t *anges ( temp]ature affect ! conduct+ p[] ( copp]4 ,?is is true ( all metals2 b ,g]man silv] & o!r alloys are mu* less affect$ ?an pure metals1 s !y are us$ 9 mak+ /&>d resi/ance coils4 ,! resi/ance ( liquids t c be decompos$ by ! electric curr5t decreases z ! temp]ature rises4 ,c>bon acts l ! liquids1 :ile ! resi/ance ( metals increases z _! temp]ature rises4 ,,exp]im5t #aci4 ,to measure ! resi/ance ( a wire by ! me?od ( sub/itution4 ,app>atus4 ,! coil ( ,no4 #bd wire 7,no4 #hi71 ! resi/ance ( :i* has be5 measur$1 b :i* w be consid]$ an unkn[n resi/ance1 ,x2 ,g ,v1 #b-;,f ,c1 ,m ,p1 connect+ wires1 etc41 previ\sly us$2 rheo/at 7 #cdd74 ,arrange z 9 ,fig4 #ajf fir/1 !n z 9 ,fig4 #ajg4 #cdd4 ,simple ,rheo/at4 ,! ,no4 #bh & ,no4 #cj ,g-s wires /ret*$ ^u ! bo>d 7,fig4 #if71 make a conv5i5t =m ( rheo/at4 ,! resi/ance p] cm4 be+ kn[n f ! results ( ,exp4 #acc & #acf1 ! resi/ance = any numb] ( cm4 is easily f\nd4 ,! #aj-;cm4 divisions %\ld be divid$ into c5timet]s4 ,^! spaces may be m>k$ (f f ! rule 7,no4 #hh74 ,illu/ration3 ,fig4 #ajf4 #cde4 ,directions4 7,a7 ,be sure t #b-;,f ,c gives a con/ant curr5t1 %[n by ! uni=m deflection at ,g ,v1 :5 arrang$ z 9 ,fig4 #ajf4 ,d n use a cell t quickly pol>izes4 ,! coil1 ,x1 =ms a "p ( ! circuit2 x is jo9$ to wires1 #a & #b1 by means ( metal plates1 s t x may be quickly remov$ )\t di/urb+ ei!r ,g ,v or #b-;,f ,c4 ,c>efully read ! deflection at ,g ,v4 7,b7 ,remove ,x f ! circuit1 & jo9 ! free end ( wire1 #b1 to b9d+-po/1 ,x1 & ! free end ( wire1 #a1 to a small piece ( %eet copp]1 :i* c be firmly press$ ^u ! ,g-s wire to make a contact4 ,move ?is along on ! ,g-s wire until ! deflection produc$ equals t ( "p 7,a71 rememb]+ t ! long] ! ,g-s wire 9 ! circuit ! less ! deflection4 ,make two or ?ree trials1 z "o or two cm4 diff]5ce 9 l5g? make b a little diff]5ce 9 ! deflection4 ,note ! numb] ( cm4 ( ,g-s wire us$1 ! resi/ance ( :i* mu/ equal t ( ! coil1 ,x4 7,c7 ,f9d ! resi/ance ( ,x by multiply+ ! l5g? j f\nd by ! resi/ance ( ea* cm41 & comp>e ! result ) ! value f\nd by us+ ! bridge me?od directly4 ,illu/ration3 ,fig4 #ajg4 ,,exp]im5t #adj4 ,to measure ! ,e4 ,m4 ,f4 ( a cell by comp>ison ) ! two-fluid cell4 ,app>atus4 ,rheo/at 7 #cdd72 ! two-fluid cell1 #b-;,f ,c 7,exp4 #aac71 ! ,e4 ,m4 ,f4 ( :i* may be tak5 z #a volt2 dry cell1 ,d ,c2 galvanoscope1 ,g ,v4 ,arrange fir/ z 9 ,fig4 #ajg4 #cdf4 ,directions4 7,a7 ,be sure t #b-;,f ,c gives a con/ant curr5t4 ,take ! read+ ( ,g ,v )\t ! rheo/at 9 ! circuit2 t is1 ) wires1 #b & #a1 jo9$ directly4 ,! deflection %\ld be #ej or #fj degrees at lea/1 & be con/ant4 7,b7 ,atta* a small piece ( copp] to ! end ( #a1 & firmly rub x along ^u ! ,g-s wire1 ?us introduc+ resi/ance into ! circuit1 until ! deflection is1 say1 #fj 7#ej or #ee degrees w d74 ,note ! l5g? ( ,g-s wire us$ & call x 7,b74 7,c7 ,gradually add m resi/ance by mov+ ! end ( #a along until ! deflection is #ej1 #aj degrees less ?an be=e4 7,if ! orig9al 0 #ej make ! new #dj74 ,call ! numb] ( cm4 ( wire us$ 7,c74 7,d7 ,replace #b-;,f ,c ) ! dry cell ,d ,c4 ,add resi/ance1 z be=e1 until ,g ,v indicates a deflection ( #fj1 be+ c>eful n to keep ! circuit clos$ long en\gh to p>tially pol>ize ,d ,c4 ,make #b or #c trials1 all[+ ,d ,c to re/ a few m9utes betwe5 ea*4 ,call ! numb] ( cm4 ( ,g-s wire us$ 7,d74 7,e7 ,aga9 add m resi/ance1 z 9 7,c71 until ! deflection is r$uc$ to #ej4 ,call ! l5g? us$ 7,e74 #cdg4 ,calculation4 ,x is kn[n t resi/ances t are able to r$uce ! /r5g? ( ! curr5ts equally are proportional to ! electromotive =ces2 t is1 ! electromotive =ces ( ! two cells are to ea* o!r z ! two resi/ances necess>y to produce equal *anges 9 ! deflections1 :i*1 ( c\rse1 indicate equal *anges 9 ! /r5g? ( ! curr5ts4 ,s9ce ! resi/ances us$ 9 ! two cases are directly proportional to ! l5g?s us$1 we h3 ,l5g? 7,c-,b73 ,l5g? 7,e-,d733 ,e4 ,m4 ,f4 ( #b-;,f ,c3 ,e4 ,m4 ,f4 ( ,d ,c4 ,sub/itute ! values f\nd & f9d ! ,e4 ,m4 ,f4 ( ,d ,c4 ,,exp]im5t #ada4 ,to measure ! int]nal resi/ance ( a cell by ! me?od ( opposition4 ,app>atus4 ,all ! app>atus ( ,exp4 #abf4 ,two simple cells 7 #bge71 ! plates ( :i* %\ld be ( ! same size1 ! same di/ance ap>t1 & imm]s$ 9 acid to ! same ext5t 9 bo?4 ,! acid 9 bo? %\ld be ( ! same /r5g?4 #cdh4 ,directions4 7,a7 ,connect ! two cells 9 opposition1 s t no curr5t w be g5]at$ by !m1 & s t ! two c be treat$ z a dead resi/ance4 ,d ?is by jo9+ ! two z9c plates by a wire ) connectors1 & use wires to connect ! copp] plates to ! bridge l any o!r unkn[n resi/ance4 7,b7 ,measure ! resi/ance ( ! two by ! regul> bridge me?od1 all[+ = wires us$ = connections4 ,"o-half ( ! resi/ance f\nd w give ! int]nal resi/ance ( "o cell4 7,see ,note47 ,note4--,! /&>d resi/ance w h to be arrang$ to suit ea* p>ticul> case to make ! calculations ev5 approximately correct4 7,see ,exp4 #abi1 ,note47 ,! /&>d resi/ance may be increas$ by add+ ! v>i\s coils & rheo/at wires1 _! values be+ kn[n4 #cdi4 ,summ>y ( ,laws ( ,resi/ance4 #a4 ,! resi/ance ( a wire is directly proportional to its l5g?1 provid$ its cross-section1 mat]ial1 etc41 are uni=m4 ,,example4 ,if #ci4a ft4 ( ,no4 #bd copp] wire has a resi/ance ( #a ohm1 #gh4b ft4 w h a resi/ance ( #b ohms1 because #gh4b is twice #ci4a2 #gj4ch ft4 w h a resi/ance ( #a4h ohms1 z 7#gj4ch #ci4a #a4h7 x is #a4h times #ci4a4 #b4 ,! resi/ance ( a wire is inv]sely proportional to its area ( cross-section4 ,! areas ( cross-section ( r\nd wires v>y z ! squ>es ( _! diamet]s2 s ! resi/ance ( a wire is also inv]sely proportional to ! squ>e ( its diamet]1 o!r ?+s be+ equal4 ,,example4 ,a ,no4 #cj wire has a diamet] ( ab\t 4#ja in*1 :ile ! diamet] ( a ,no4 #bd wire is ab\t 4#jb 942 t is1 ! ,no4 #bd has twice ! diam4 t ! ,no4 #cj has4 ,! area ( cross-section ( ! ,no4 #bd1 h[ev]1 is f\r times t ( ! ,no4 #cj1 s its resi/ance is b #a_/d t ( ! ,no4 #cj1 ! l5g?s1 etc41 be+ ! same4 7,see ,wire ,tables47 #c4 ,! resi/ance ( a wire dep5ds ^u its mat]ial1 z well z ^u its l5g?1 size1 etc4 #d4 ,! resi/ance ( a wire dep5ds ^u its temp]ature4 7,see ,elem5t>y ,electrical ,examples47 ,,*apt] ,,xx4 ,,curr5t ,,/r5g?4 #cej4 ,/r5g? ( ,curr5t4 ,! wat] 9 a c]ta9 tank may be "u great pressure1 b if x is oblig$ to pass ?r\gh long tubes be=e x c turn a wat]-:eel1 = example1 x is evid5t t ! "w done w dep5d n only ^u ! pressure 9 ! tank1 b ^u ! resi/ance to be ov]come be=e ! wat] gets to ! :eel4 ,! "w t ! wat] c d dep5ds ^u its rate ( fl[1 & may be us$ to measure ! /r5g? ( ! curr5t4 ,! /r5g? ( a curr5t ( electricity is measur$ also by ! "w t x c d1 & x dep5ds ^u its rate ( fl[ at ! po9t measur$4 ,! /r5g? may be det]m9$ f its magnetic1 heat+1 or *emical effects4 #cea4 ,unit ( ,curr5t ,/r5g?2 ,! ,amp]e4 ,a curr5t hav+ ! /r5g? ( #a amp]e1 :5 pass$ ?r\gh a solution ( silv] nitrate "u prop] conditions1 w deposit #j4jjaaah gramme ( silv] 9 "o second2 if pass$ ?r\gh a solution ( copp] sulphate1 copp] plates be+ us$ = ! electrodes1 9 ! solution1 #j4jjjcbgg gramme ( copp] w be deposit$ 9 "o second4 7,see ,*emical ,effects ( ! ,curr5t47 ,! ?\s&? ( an amp]e is call$ ! milliamp]e4 ,! /r5g? ( a curr5t is proportional to ! am\nt ( *emical "w t x c d p] second4 7,see #ceg47 #ceb4 ,measurem5t ( ,curr5t ,/r5g?4 ,! galvanoscope previ\sly describ$ simply %[s ! pres5ce ( a curr5t1 or :e!r "o curr5t is l>g] or small] ?an ano!r4 ,:5 ! degree-c>d is us$ to get ! relative deflections1 ! in/rum5t may be call$ a galvanomet]4 ,! ,tang5t ,galvanomet] is made on ! same g5]al idea z our galvanoscope1 ! diamet] ( ! coil be+ tw5ty times1 or m1 ! l5g? ( ! ne$le4 ,9 ^! ! /r5g?s ( ! two curr5ts comp>$ are proportional to ! tang5ts ( ! angles ( deflection produc$4 7,see ,elem5t>y ,electrical ,examples47 ,!re are sev]al v>ieties ( galvanomet]s1 ea* design$ = its special "w4 ,!y are (t5 calibrat$ or /&>diz$ s t ! amp]es ( curr5t pass+ ?r\gh !m c be read (f directly f ! scale4 #cec4 ,! ,ammet] is really a galvanomet] f :i* may be read directly ! /r5g? ( a curr5t4 ,! coil has a l[ resi/ance s t x w n greatly r$uce ! /r5g? ( ! curr5t to be te/$4 ,! ,voltamet] measures ! /r5g? ( a curr5t by *emical means4 #ced4 ,unit ( ,quantity2 ,! ,c\lomb4 ,a curr5t hav+ a /r5g? ( #a amp]e w d m *emical "w by fl[+ "o h\r ?an x c d 9 #a second4 ,9 speak+ ( ! quantity ( electricity we introduce ! elem5t ( "t4 ,! unit ( quantity is call$ ! c\lomb1 j z a cubic foot ( wat] may be tak5 z a unit ( quantity = wat]4 ,a c\lomb is ! quantity ( electricity giv51 9 "o second1 by a curr5t hav+ a /r5g? ( #a amp]e4 ,c\lombs are f\nd by multiply+ amp]es by seconds2 ?us1 a curr5t ( #e amp]es w give #bj c\lombs 9 #d seconds4 #cee4 ,electrical ,horse-p[]2 ,! ,watt4 ,! electric curr5t has p[] to d "w1 & we speak ( ! horse-p[] ( an electric motor 9 ! same way z = a /eam-eng9e4 ,a curr5t ) ! /r5g? ( #a amp]e & an ,e4 ,m4 ,f4 ( #a volt has a unit ( p[] call$ ! watt4 #gdf watts make an electrical horse-p[]4 ,watts amp]es volts4 ,watts #gdf ! numb] ( horse-p[]4 7,see ,trans=m]s1 also ,elem5t>y ,electrical ,examples47 #cef4 ,ohm's ,law4 ,x 0 fir/ %[n by ,ohm t ! /r5g? ( a curr5t is equal to its ,e4 ,m4 ,f4 divid$ by ! resi/ance 9 ! circuit2 t is1 ,/r5g? ( curr5t 7amp]es7 ,e4 ,m4 ,f4 7volts74 _/ resi/ance 7ohms74 ,if we let ,c /& = ! /r5g? 9 amp]es1 ,e = ! ,e4 ,m4 ,f4 9 volts1 & ,r = ! resi/ance 9 ohms1 we h ! %ort =mula1 easily rememb]$1 ,c ,e_/,r #ceg4 ,an ,amp]e w\ld be produc$ by a curr5t ( #a volt pu%+ its way ?r\gh a resi/ance ( #a ohm4 ,kn[+ any two ( ! ?ree1 ,c1 ,e1 or1 ,r1 ! o!r may be f\nd4 ,! resi/ance1 ,r1 x mu/ be rememb]$1 is ! total resi/ance 9 ! circuit1 & is compos$ ( ! total int]nal & ext]nal resi/ances4 7,see ,elem5t>y ,electrical ,examples47 #ceh4 ,int]nal ,resi/ance & ,curr5t ,/r5g?4 ,x is evid5t t ! int]nal resi/ance ( a cell v>ies ) ! position & size ( ! plates4 ,we %all n[ /udy ! effects ( ^! *anges ^u ! /r5g? ( ! curr5t4 ,illu/ration3 ,fig4 #ajh4 ,,exp]im5t #adb4 ,hav+ a cell ) ,,l>ge ,,plates1 to f9d h[ ! /r5g? ( ! curr5t is affect$ by *anges 9 ! position ( ! plates1 ! ext]nal resi/ance be+ small4 ,app>atus4 ,galvanoscope1 ,g ,v2 mat]ials = simple cell 7,exp4 #aaj72 connect+ wires4 ,arrange z 9 figure #ajh1 omitt+ ! wood5 cross-piece4 #cei4 ,directions4 7,a7 ,connect ! wires ) ! #e-turn coil ( ,g ,v1 :i* has b little resi/ance4 ,h ! tumbl] ne>ly full ( dilute acid to get ! effect ( l>ge plates2 t is1 ! curr5t has a l>ge liquid conductor to pass ?r\gh 9 ! cell1 & ! int]nal resi/ance w be small4 ,g ,v %\ld be prop]ly plac$ ,n & ,s4 7,b7 ,place ! copp] & z9c plates z f> ap>t z possible 9 ! acid1 & press !m aga9/ ! bottom ( ! tumbl]4 ,note ! read+ ( ,g ,v4 ,x is n necess>y to take read+s ) rev]s$ curr5t4 7,c7 ,/ill press+ !m aga9/ ! bottom ( ! glass1 to keep ! same am\nt ( surface "u acid1 sl[ly br+ !m ne> ea* o!r & wat* ! ne$le4 7,d7 ,hold ! plates ab\t an in* ap>t1 & aga9/ ! bottom1 & note ! read+ ( ,g ,v4 ,sl[ly raise ! plates1 keep+ !m ! same di/ance ap>t until !y are out ( ! acid4 ,wat* ! action ( ! ne$le4 ,make a note ( y\r read+s 9 degrees & write y\r conclusions4 ,does a *ange 9 int]nal resi/ance affect ! /r5g? ( ! curr5t8 ,,exp]im5t #adc4 ,hav+ a cell ) ,,small ,,plates to f9d h[ ! /r5g? ( ! curr5t is affect$ by *anges 9 ! position ( ! plates1 ! ext]nal resi/ance be+ small4 ,app>atus4 ,same z 9 ,exp4 #adb1 ! acid1 h[ev]1 be+ b #a 94 deep 9 ! tumbl]2 t is1 we h ! effect ( a cell ) small plates1 ea* be+ ab\t #a 94 by #a_/b 94 #cfj4 ,directions4 7,a7 ,repeat 7,b7 & 7,c7 ( ,exp4 #adb1 record+ ! read+ ( ,g ,v 9 ea* case4 7,b7 ,comp>e ! results ) ^? ( ,exp4 #adb1 rememb]+ t ! int]nal resi/ance is l>g] ?an be=e4 ,is ! curr5t z /rong ) small plates z ) l>ge plates :5 ! ext]nal resi/ance is small8 ,:5 ! ext]nal resi/ance is small 7! #e-turn coil1 = example71 %\ld ! cell h a high or l[ int]nal resi/ance to produce ! greate/ effect ^u ! ne$le8 ,illu/ration3 ,fig4 #aji4 ,,exp]im5t #add4 ,to f9d :e!r ! *anges 9 curr5t /r5g?1 due to *anges 9 int]nal resi/ance1 are z great :5 ! ext]nal resi/ance is l>ge1 z !y are :5 ! ext]nal resi/ance is small4 ,app>atus4 ,same z = ,exp4 #adb1 #adc1 also ! rheo/at conta9+ ! two met]s ( ,g-s wire 7,exp4 #aba74 #cfa4 ,directions4 7,a7 ,arrange z 9 ,fig4 #aji1 ! ext]nal resi/ance be+ #b met]s ( ,no4 #cj ,g-s wire 9 s]ies ) ,g ,v4 ,! #b-;,f ,c 9 ! ,fig4 is replac$1 h[ev]1 by ! simple cell z 9 ,exp4 #adc4 7,b7 ,f9d ! effect ^u ! /r5g? ( ! curr5t ( mov+ ! plates ab\t :5 b #a 94 ( acid is 9 ! tumbl]4 7,c7 ,ne>ly fill ! tumbl] ) acid & repeat 7,b71 tak+ read+s ) plates ne> ea* o!r & z f> ap>t z possible4 ,lift !m ne>ly out ( ! acid & take ! read+4 7,d7 ,/ill increase ! ext]nal resi/ance ( ! circuit by add+ coils ( wire or ! met] ( ,no4 #bh ,g-s wire & repeat4 ,is ! /r5g? ( ! curr5t greatly affect$ by slight *anges 9 ! int]nal resi/ance :5 ! ext]nal resi/ance is l>ge8 #cfb4 ,discussion4 ,we %all /udy1 by means ( figures1 h[ *anges 9 int]nal resi/ance affect ! /r5g? ( ! curr5t4 ,let ,r /& = ! total ext]nal resi/ance ( a circuit1 & r = ! total int]nal resi/ance ( ! cell or cells2 ohm's law1 !n1 w be express$ by ,c ,e _/ 7,r r7 ,,example4 ,let u take a circuit 7,a7 :5 ! ext]nal resi/ance1 ,r1 is small1 & 7,b7 :5 ,r is l>ge comp>$ ) r1 ,e be+ tak5 z #a volt 9 bo? cases4 7,a7 ,let ,r #a1 & r #b2 sub/itut+ ^! values 9 ! =mula above1 we h3 ,c #a _/ 7#a #b7 #a _/ #c 4#cc amp]e4 ,n[ let ! int]nal resi/ance1 r1 be slightly increas$ f #b to #c ohms2 ! value ( ,c !n becomes #a_/d amp]e1 z ,r r #d4 ,! *ange 9 ,c1 !n1 is ! diff]5ce betwe5 #a_/c & #a_/d2 & ?is express$ 9 decimals becomes 4#cc - 4#be 4#jh amp]e4 7,b7 ,let ,r #bjj ohms1 & r #b ohms z 9 7,a74 ,sub/itut+ ^! values we h1 ,c #a _/ 7#bjj #b7 #a _/ #bjb 4#jjdie amp]e4 ,increas+ r f #b to #c1 z be=e1 etc41 we f9d t ,c #a divid$ by #bjc 4#jjdib amp]e4 ,! above %[s cle>ly 7,a7 t ! value ( ,c is *ang$ consid]ably by *anges 9 r :5 ,r is small1 & 7,b7 t *anges 9 r produce v slight *anges 9 ,c :5 ,r is l>ge4 ,review y\r results ( ,exps4 #adb-add4 7,see ,elem5t>y ,electrical ,examples47 #cfc4 ,arrangem5t ( ,cells & ,curr5t ,/r5g?4 ,we h se5 t int]nal resi/ance affects curr5t /r5g?4 ,9 jo9+ cells1 !n1 att5tion mu/ be giv5 to ! int]nal resi/ance z well z to ! ,e4 ,m4 ,f4 ( ! comb9ation4 #cfd4 ,cells 9 ,s]ies4 ,x has be5 %[n by c>eful exp]im5ts t ! ,e4 ,m4 ,f4 ( two cells jo9$ 9 s]ies 7,fig4 #aaj7 is equal to ! sum ( ! ,e4 ,m4 ,f4 ( ea*4 ,t5 cells1 jo9$ 9 s]ies1 h t5 times ! ,e4 ,m4 ,f4 ( "o cell1 provid$ !y h ! same ,e4 ,m4 ,f4 ,z ! ,zn ( "o is jo9$ to ! ,cu ( ! o!r1 ! curr5t is oblig$ to pass ?r\gh "o solution aft] ! o!r2 t is1 ! int]nal resi/ance ( ! two 9 s]ies is equal to ! sum ( _! int]nal resi/ances4 ,t5 cells1 jo9$ 9 s]ies1 h t5 times ! int]nal resi/ance ( "o cell1 provid$ !y h equal int]nal resi/ances4 ,illu/ration3 ,fig4 #aaj4 ,illu/ration3 ,fig4 #aaa4 #cfe4 ,cells ,abrea/4 ,:5 ! positive plates are jo9$ toge!r & ! negative plates are also jo9$ toge!r 7,fig4 #aaa71 ! cells are said to be abrea/1 9 p>allel1 or 9 multiple arc4 ,x has be5 %[n t two cells ( equal /r5g?1 jo9$ abrea/1 h ! same ,e4 ,m4 ,f4 z "o cell4 ,! two ,cu plates1 be+ jo9$1 mu/ h ! same pot5tial2 all ! ,zn plates h ! same pot5tial1 s ! diff]5ce ( pot5tial at ! t]m9als ( ! comb9ation is ! same z t at ! t]m9als ( a s+le cell4 ,9 two cells abrea/ 7,fig4 #aaa7 ! curr5t has two liquid pa?s1 side by side1 to get f ,cu to ,zn2 ?is makes ! int]nal resi/ance "o-half t ( "o cell1 provid$ _! int]nal resi/ances are equal4 ,t5 cells1 ( equal int]nal resi/ance1 :5 jo9$ abrea/1 h "o-t5? ! int]nal resi/ance ( "o cell4 ,,exp]im5t #ade4 ,to f9d ! be/ way to jo9 two simil> cells :5 ! ext]nal resi/ance is small4 ,app>atus4 ,two simple cells us+ dilute sulphuric acid1 ) copp] & z9c elem5ts1 z 9 ,exp4 #aab2 galvanoscope1 ,g ,v2 connect+ wires1 etc4 ,h ! z9cs well amalgamat$4 ,remove !m f ! acid z soon z read+s are tak54 #cff4 ,directions4 7,a7 ,p>tly fill ! tumbl]s ) ! acid4 ,jo9 ! cells 9 s]ies 7,fig4 #aaj71 !n connect wire #a 7,fig4 #aaj7 ) ! left-h& b9d+-po/ ( ,g ,v1 & wire #b ) ! middle "o1 ?us putt+ ! #e-turn coil into ! circuit4 ,take ! read+ ( ,g ,v4 7,b7 ,jo9 ! cells 9 multiple arc 7,fig4 #aaa71 connect+ !m z 9 7,a7 ) ,g ,v4 ,write d[n ! read+1 & comp>e x ) t f\nd 9 7,a74 7,c7 ,take ! read+ ) b #a cell jo9$ to ,g ,v4 ,,exp]im5t #adf4 ,to f9d ! be/ way to jo9 two simil> cells :5 ! ext]nal resi/ance is l>ge4 ,app>atus4 ,same z = ,exp4 #ade1 also ! rheo/at conta9+ #b metres ( ,no4 #bh or #cj ,g-s wire4 ,arrange ! ,g-s wire 9 s]ies ) ! #ae-turn coil ( ,g ,v1 z %[n 9 ,fig4 #aji1 two simple cells be+ us$1 h[ev]1 in/ead ( #b-;,f ,c z %[n4 #cfg4 ,directions4 7,a7 ,take ! read+ ( ,g ,v :5 ! two cells are 9 s]ies 7,exp4 #ade71 ! ext]nal resi/ance be+ ! #ae-turn coil & ,g-s wire4 7,b7 ,jo9 ! cells 9 p>allel & take ! read+1 us+ ! same ext]nal resi/ance z 9 7,a74 7,c7 ,increase ! ext]nal resi/ance by add+ coils ( wire or #b metres ( ,no4 #bh ,g-s wire & repeat 7,a7 & 7,b74 ,:at does ! exp]im5t %[8 7,d7 ,take ! read+ ) #a cell & l>ge ext]nal resi/ance4 #cfh4 ,be/ ,arrangem5t ( ,cells4 ,x w be se5 by exp]im5ts t ) a giv5 numb] ( cells ! /ronge/ curr5t is produc$ :5 !y are arrang$ s t ! int]nal resi/ance ( ! batt]y ne>ly equals ! ext]nal resi/ance ( ! circuit4 ,:5 ! ext]nal resi/ance is small1 ! int]nal resi/ance may be kept d[n by jo9+ ! cells 9 p>allel2 &1 al?\gh ! ,e4 ,m4 ,f4 is also kept small1 ! value ( ,c w be l>g] ?an x w\ld be ) a l>g] int]nal resi/ance & a l>g] ,e4 ,m4 ,f4 ,:5 ! ext]nal resi/ance is l>ge1 ! int]nal resi/ance c be made l>ge by jo9+ ! cells 9 s]ies4 ,! advantage comes1 h[ev]1 f hav+ a l>ge value ( ,e4 ,a l>ge resi/ance c n hold back a curr5t ( l>ge ,e4 ,m4 ,f4 ,by jo9+ ! cells 9 s]ies ! value ( ,e is made l>ge1 & ! value ( ,c becomes l>ge ev5 ?\gh !re is an increas$ int]nal resi/ance4 7,see ,elem5t>y ,electrical ,examples47 ,,*apt] ,,xxi4 ,,*emical ,,effects ,,( ,,! ,,electric ,,curr5t4 #cfi4 ,*emical ,action & ,electricity4 ,we h le>n$ t ! electric curr5t is produc$1 9 ! cell1 by *emical action4 ,!re is a def9ite relation betwe5 ! *emical action & ! curr5t produc$4 ,we are n[ to /udy ! *ang+ ( electrical en]gy back1 aga91 to *emical en]gy4 ,illu/ration3 ,fig4 #aab4 #cgj4 ,electrolysis is ! "n giv5 to ! process ( decompos+ *emical comp\nds by pass+ ! electric curr5t ?r\gh !m4 ,! comp\nd decompos$ is ! electrolyte4 ,fig4 #aab %[s a tumbl] ( liquid 7electrolyte7 ?r\gh :i* ! curr5t is to pass 9 ! direction ( ! arr[4 ,two c>bon plates1 ,a & ,c1 are 9 ! liquid1 & are jo9$ to ! s\rce ( electricity4 ,! curr5t ent]s at ,a 7anode7 & leaves at ,c 7ca?ode74 ,illu/ration3 ,fig4 #aac4 ,,exp]im5t #adg4 ,to /udy ! electrolysis ( wat]4 ,app>atus4 ,! two simple cells 7 #bge7 jo9$ 9 s]ies 7 #cfd71 al?\gh two ,daniell or two dry cells w be bett]4 ,a tumbl] ( wat] conta9+ a few drops ( sulphuric acid to make ! wat] a conductor4 ,two pieces ( %eet copp] w s]ve z ! electrodes4 ,! galvanoscope may also be put into ! circuit z 9 ,fig4 #aac4 #cga4 ,directions4 7,a7 ,all[ ! curr5t to pass1 & note 7#a7 :e!r gas is set free at bo? electrodes1 ,a & ,c1 & 7#b7 at :i* ! quantity ( gas is ! great]4 ,if v little gas is produc$ use m cells4 7,b7 ,remove ,a & ,c f ! liquid1 to remove ! gas1 !n wat* ! action ( ! ne$le ( ,g ,v z ! wat] is aga9 decompos$4 #cgb4 ,composition ( ,wat]4 ,! two gases lib]at$ 9 ,exp4 #adg 7 hydrog5 7,h7 & oxyg5 7,o74 ,! *emical =mula = wat] is ,h#b,o1 :i* means t x is compos$ ( two p>ts1 by volume1 ( ,h & "o "p ( ,o4 ,) prop] app>atus ^! gases may be collect$1 te/$1 & ! am\nts measur$4 #cgc4 ,electromotive ,=ce ( ,pol>ization4 ,we "k t ,h & ,o h a /rong *emical attraction1 or aff9ity1 = ea* o!r4 ,9 ord]1 !n1 = ! curr5t to decompose wat]1 ?is attraction betwe5 ! gases mu/ be ov]come2 & z soon z ! curr5t ceases1 ^! gases try to ru% toge!r aga9 to =m wat]4 ,?is sets up an electromotive =ce ( almo/ #a4e volts2 9 fact1 a curr5t is produc$ if ! ,h & ,o be all[$ to =m wat] aga9 7,see ,/orage ,cells74 ,to decompose wat] ! curr5t mu/ h an ,e4 ,m4 ,f4 ( ov] #a4e volts to ov]come ?is ,e4 ,m4 ,f4 ( pol>ization4 ,x 0 se5 9 ! /udy ( simple cells t ! curr5t became rapidly weak] z hydrog5 0 deposit$ ^u ! copp] plate1 on acc\nt ( ?is oppos+ electromotive =ce4 ,9 decompos+ o!r comp\nds1 ! anode is made ( ! metal :i* is to be deposit$ at ! ca?ode4 ,if copp] is to be deposit$ f a solution ( copp] sulphate ! anode %\ld be a copp] plate2 ?is keeps ! solution at same /r5g?1 & avoids ! oppos+ ,e4 ,m4 ,f4 ( pol>ization2 t is1 a v weak curr5t w d ! "w 7,see ,exp4 #adi71 because ! electrodes are ( ! same metal4 ,,exp]im5t #adh4 ,to coat iron ) copp]4 ,app>atus4 ,iron nail1 solution ( copp] sulphate 7 #bhc74 #cgd4 ,directions4 7,a7 ,clean ! nail ) s&pap]1 !n hold x 9 ! copp] solution = a few seconds4 ,ma*9i/s (t5 cov] iron or /eel tools ) a ?9 coat+ ( copp] 9 ?is way4 ,illu/ration3 ,fig4 #aad4 ,,exp]im5t #adi4 ,to /udy ! electrolysis ( a solution ( copp] sulphate4 ,app>atus4 ,galvanoscope1 ,g ,v2 two-fluid cell1 #b-;,f ,c2 a tumbl]1 ,t1 conta9+ ab\t an in* ( copp] sulphate solution 7 #bhc72 a wood5 cross-piece to :i* is fa/5$ a copp] /rip2 c>bon rod1 ,c2 wire #b is held to ,c by a rubb] b&4 ,arrange z 9 ,fig4 #aad1 s t ,cu w be ! anode 7 #cgj71 ! curr5t pass+ z %[n by arr[4 ,a dry cell may be us$ = %ort exp]im5ts in/ead ( ! #b-;,f ,c4 #cge4 ,directions4 7,a7 ,! c>bon be+ clean1 all[ ! curr5t to pass1 ,c & ,cu be+ kept ab\t #a_/b 94 ap>t4 ,wat* ! surface ( ,c1 & note ! beautiful color ( ! deposit$ copp]4 ,save ! coat$ rod = ! next exp]im5t4 ,has ! ,cu plate be5 act$ ^u8 #cgf4 ,electroplat+ is ! "n giv5 to ! process ( coat+ sub/ances ) metal ) ! aid ( ! electric curr5t4 ,! copp] sulphate1 ,cu,s,o#d1 is brok5 up into ,cu & ,,s#d by ! curr5t4 ,! ,cu goes to ! ca?ode1 & ! ,,s#d attacks ! anode1 gradually dissolv+ x if x be copp]2 t is1 ! metal "p ( ,cu,s,o#d is c>ri$ 9 ! direction ( ! curr5t4 ,mo/ metals are coat$ ) copp] be=e !y are silv] or gold plat$4 ,a solution ( silv] is us$ = silv] plat+1 silv] be+ us$ z ! anode4 ,,exp]im5t #aej4 ,to /udy ! *emi/ry ( electroplat+4 ,app>atus4 ,same z 9 la/ exp]im5t1 b use two c>bon rods = ! electrodes4 ,arrange z 9 ,fig4 #aad1 ) ! ,cu replac$ by ano!r c>bon4 ,two simple cells 7 #bge7 are also ne$$4 #cgg4 ,directions4 7,a7 ,all[ ! curr5t to pass z be=e4 ,is copp] /ill deposit$8 ,does any?+ occur n[ at ! surface ( ! anode8 ,is ! copp] deposit$ z rapidly z be=e8 7,b7 ,try ! effect ( ! two simple cells jo9$ 9 s]ies1 ,in/ead ( ! two-fluid cell4 7,c7 ,aft] a fair coat+ ( copp] has be5 deposit$ ^u ! c>bon ca?ode1 rev]se ! direction ( ! curr5t ?r\gh ! copp] solution2 t is1 use ! coat$ rod = ! anode4 ,all[ ! curr5t to pass until a *ange takes place 9 ! anode4 #cgh4 ,discussion4 ,ions are ! names giv5 to ! p>ts into :i* an electrolyte is decompos$ by ! electric curr5t4 ,9 ! case ( ,cu,s,o#d1 ! ions are ,cu & ,,s#d1 :i* is call$ an acid radical4 ,?is ,,s#d c n dissolve c>bon or plat9um1 s ^! are us$ :5 wat] is to be electrolyz$4 ,:]e copp] is us$ z ! anode = copp] plat+1 ! ,,s#d attacks x1 =m+ ,cu,s,o#d aga91 & ?is keeps ! solution /rong4 ,if c>bon 7 us$ in/ead1 ! ,,s#d w\ld take ,h#b f ! wat] ar\nd ! anode & ,h#b,,s#d 7sulphuric acid7 w\ld be =m$1 ! oxyg5 ( ! wat] be+ set free at ! anode4 ,! am\nt ( ,cu dissolv$ f ! copp] anode equals ne>ly ! am\nt deposit$ ^u ! ca?ode4 ,exp4 #aej %[s t ! metal is c>ri$ 9 ! direction ( ! curr5t4 ,z hydrog5 is produc$ at ! ca?ode x is *emically consid]$ a metal4 #cgi4 ,electrotyp+ consi/s 9 mak+ a copy 9 metal1 ( a woodcut1 page ( type1 etc4 ,a m\ld or impression ( ! type is fir/ made 9 wax1 or o!r suitable mat]ial 7! pages ( ?is book1 = example1 z set up by ! pr9t]74 ,^! m\lds are1 ( c\rse1 ! rev]se ( ! type4 ,!y are coat$ ) graphite to make !m conduct electricity1 & hung z ! ca?ode1 9 a ba? ( copp] sulphate4 ,aft] a ?9 coat ( copp] has be5 deposit$ by an electric curr5t1 ! wax is remov$ & ! ?9 copp] back$ ) s(t metal4 ,! metal surface next to ! wax w be j l ! type1 only made ( copp]4 ,^! plates or electrotypes c be pr9t$ f1 ! orig9al type be+ us$ to set up ano!r page4 7,see ,?+s a ,boy ,%\ld ,"k ,ab\t ,electricity47 #chj4 ,voltamet]s are cells us$ to measure ! /r5g? ( an electric curr5t4 ,9 ! ,wat] ,voltamet] ! hydrog5 & oxyg5 produc$ are measur$4 ,! ,h acts l a metal & goes to ! ca?ode1 two p>ts ( ,h be+ =m$ to "o ( ,o4 ,copp] ,voltamet]4 ,?is cell measures ! am\nt ( copp] deposit$ 9 a giv5 "t by a curr5t4 ,! copp] ca?ode is weigh$ be=e & aft] ! curr5t fl[s4 ,! weight ( ,cu deposit$ is !n divid$ by ! numb] ( seconds dur+ :i* ! curr5t pass$1 & ?is result1 9 turn1 by 4#jjjcbh1 :i* w give ! av]age /r5g? ( ! curr5t 9 amp]es4 7,see #cea47 ,o!r =ms ( voltamet]s are also us$4 ,9 all voltamet]s ! quantity ( metal deposit$ is proportional to ! "t t ! curr5t fl[s1 & to its /r5g?4 ,illu/ration3 ,fig4 #aae4 ,,exp]im5t #aea4 ,to /udy ! con/ruction & action ( a simple /orage cell4 ,app>atus4 ,two lead plates1 ,l ,p1 7,nos4 #gg1 #gh7 fa/5$ to a wood5 cross-piece 7 #bge74 ,! spr+-connectors %\ld n be =c$ ^u ! ?ick lead4 ,fa/5 "o end ( ! wire "u ! screw-head4 ,a tumbl] two-?irds full ( dilute sulphuric acid 7 #beh72 ! a/atic galvanoscope1 ,a ,g2 wires to =m connections2 ! two simple cells jo9$ 9 s]ies4 ,arrange z 9 ,fig4 #aae4 ,"o ,l ,p is jo9$ to b9d+-po/1 ,l1 ( ,a ,g by ! wire m>k$ #a2 wire #b connects ! o!r ,l ,p to ! copp] ,cu4 ,wire #c jo9s ! z9c to any ?9 metal plate1 ,m ,p1 :i* is us$ = conv5i5ce1 s t ! spr+ connectors c be quickly slipp$ on or (f4 ,wire #d jo9s ,m ,p ) b9d+-po/ ,r ( ,a ,g4 #cha4 ,directions4 7,a7 ,get cle>ly 9 m9d ! direction 9 :i* ! "r-h& end ( ! a/atic ne$le is deflect$ :5 ! curr5t passes1 rememb]+ t x passes into ,a ,g at ,l & leaves at ,r4 ,all[ ! curr5t to fl[ = #aj or #ae m9utes ?r\gh ! circuit1 at ! same "t wat*+ ! ne$le to see :e!r ! /r5g? ( ! curr5t rema9s con/ant4 7,b7 ,remove ! connector f ,cu1 sw+ x ov] into ! position ( ! dott$ l9e 7,fig4 #aae71 slip ! connector ^u ,m ,p & wat* ! ne$le4 ,?is cuts ! cells out ( ! circuit2 b1 if y desire1 also remove wire #c f ,m ,p4 ,does ! /orage cell1 ,s ,c1 produce any curr5t8 ,does x pass ?r\gh ,a ,g 9 ! same direction z t :i* came directly f ! two cells8 7,c7 ,try ! dry cell 9 place ( ! two simple cells4 ,try #b o!r cells 9 s]ies if y h !m4 #chb4 ,second>y or ,/orage ,cells mu/ be *>g$ by a curr5t be=e !y c give out a curr5t4 ,electricity is n really /or$4 ,*emical *anges are produc$ 9 ! /orage cell by ! *>g+ curr5t1 z 9 ! voltamet] or electroplat+ ba?2 & x is1 !n1 pot5tial *emical en]gy t is /or$4 ,:5 ! new comp\nds are all[$ to g back to _! orig9al condition by jo9+ ! electrodes ( ! *>g$ cell a curr5t is produc$4 ,9 o!r words1 an electric curr5t produces *emical *anges 9 ! cell by electrolysis1 & ^! new comp\nds h an ,e4 ,m4 ,f4 ( pol>ization because !y are con/antly will+ & anxi\s to get back to _! old /ate4 ,! plates are lead & are usually coat$ ) comp\nds ( lead4 ,hydrog5 & oxyg5 are giv5 out at ! electrodes4 ,! curr5t f a dynamo is us$ to *>ge second>y batt]ies4 7,see ,?+s a ,boy ,%\ld ,"k ,ab\t ,electricity47 ,,*apt] ,,xxii4 ,,electromagnetism4 #chc4 ,electromagnetism is ! "n giv5 to magnetism t is develop$ by electricity4 ,y h already se5 t if a magnetic ne$le be plac$ 9 ! magnetic field ( a magnet1 its ,n pole w po9t 9 ! direction 9 :i* ! l9es ( =ce pass on _! way f ! ,n to ! ,s pole ( ! magnet4 ,y h also se5 t 9 ! galvanoscope1 etc41 a coil ( wire acts l a magnet :5 a curr5t passes ?r\gh x4 ,c we n1 !n1 use ! ne$le to /udy ! l9es ( =ce ab\t wires & coils8 ,illu/ration3 ,fig4 #aaf4 ,illu/ration3 ,fig4 #aag4 ,,exp]im5t #aeb4 ,to /udy ! l9es ( magnetic =ce ab\t a /raight wire c>ry+ a curr5t4 ,app>atus4 ,! compass1 ,o ,c2 key1 ,k2 dry cell1 ,d ,c4 ,arrange z 9 ,fig4 #aaf4 #chd4 ,directions4 7,a7 ,arrange ! wire s t ! curr5t w fl[ ?r\gh x f ,n to ,s ov] ! compass-ne$le z soon z ! circuit is clos$ 7,fig4 #aag1 ,a74 ,press ,k = an in/ant only1 & note ! direction 9 :i* ! ,n pole is deflect$4 ,repeat two or ?ree times until y get cle>ly 9 m9d ! direction tak5 by ! ne$le4 ,sket* ! result 9 y\r note-book1 & comp>e ) ,fig4 #aah1 ,a4 ,! arr[ %[s ! direction ( ! curr5t4 7,b7 ,let ! curr5t pass = an in/ant f ,n to ,s & "u ! ne$le1 z %[n 9 ,fig4 #aag1 ,b4 ,sket* result4 7,c7 ,let ! curr5t pass = an in/ant f ,s to ,n above ! ne$le 7,fig4 #aag1 ,c74 ,sket* result4 7,d7 ,let x pass f ,s to ,n "u ! ne$le 7,fig4 #aag1 ,d74 ,sket* result4 7,e7 ,let x pass ?r\gh ! wire f ea/ to we/ 7,fig4 #aag1 ,f7 above ! ne$le1 !n "u x1 & note result4 ,comp>e ! results ) ^? indicat$ 9 ,fig4 #aah4 ,illu/ration3 ,fig4 #aah4 ,illu/ration3 ,fig4 #aai4 #che4 ,l9es ( ,=ce ,ab\t a ,wire4 ,:5 a curr5t passes ?r\gh a wire1 ! ne$le1 ov] or "u x1 t5ds to take a position at "r angles to ! wire4 ,?is %[s t ! l9es ( =ce pass ar\nd ! wire & n 9 ! direction ( its l5g?4 ,! ne$le does n sw+ entirely p]p5dicul> to ! wire2 t is1 to ! ,e & ,w l9e1 because ! e>? is at ! same "t pull+ its ,n pole t[>ds ! ,n4 ,if ! ne$le _h no po9t+ p[]1 & at ! same "t reta9$ its magnetic field1 x w\ld po9t exactly at "r angles to ! wire z soon z ! curr5t pass$4 ,if y look along ! wire1 ,fig4 #aai1 f ! po9t1 ,c1 t[>ds ! positions1 ,a & ,b1 y w see 7,a7 t "u ! wire ! l9es ( =ce pass to ! left1 & t above ! wire 7,b7 !y pass t[>ds ! "r4 ,?is is because ! ,n pole po9ts 9 ! directions m5tion$4 7,see ,fig4 #aah47 ,look+ along ! wire f ,z t[>ds position1 ,d & ,c1 y w see j ! opposite to ! above1 z ! curr5t comes t[>ds y4 ,rule4--,:5 ! curr5t goes f y1 ! l9es ( =ce pass ar\nd ! wire 9 a clockwise direction1 & :5 ! curr5t comes t[>d y !y pass ar\nd x 9 an anti-clockwise direction4 #chf4 ,amp]e's ,rule may be us$ to rememb] :at has be5 le>n$ 9 ,exp4 #aeb4 ,if y imag9e y\rself swimm+ 9 ! wire ) ! curr5t1 always fac+ ! ne$le1 ! ,n-seek+ pole ( ! ne$le w always be deflect$ t[>ds y\r left h&4 ,:5 ! ne$le is above ! wire y mu/ imag9e t y swim ^u y\r back1 9 ord] to face ! ne$le4 ,ano!r ,rule4--,hold ! "r h& ) ! ?umb ext5d$ & ) ! f+]s po9t+ 9 ! direction ( ! curr5t1 ! palm be+ t[>ds ! ne$le & on ! opposite side ( ! wire f ! ne$le4 ,! ,n-seek+ pole w !n be deflect$ 9 ! direction 9 :i* ! ?umb po9ts4 #chg4 ,if a wire c>ry+ a /rong curr5t be dipp$ 9 iron fil+s1 ! magnetic field ab\t ! wire acts by induction ^u ! p>ticles ( fil+s1 mak+ magnets ( !m4 ,^! cl+ to ea* o!r simply because !y are little magnets4 #chh4 ,l9es ( ,=ce ab\t ,p>allel ,wires4 ,:5 a curr5t passes 9 ! same direction 9 two p>allel wires ! l9es ( =ce pass ar\nd ! wires 9 ! same direction 9 bo?1 & ! magnetic fields attract ea* o!r4 ,:5 ! curr5ts fl[ 9 opposite directions ! magnetic fields repel ea* o!r4 ,,exp]im5t #aec4 ,to /udy ! l9es ( =ce ab\t a coil ( wire l t ^u ! galvanoscope4 ,app>atus4 ,galvanoscope1 ,g ,v2 dry cell2 key2 compass4 ,arrange z 9 ,fig4 #aaf1 us+ ,g ,v in/ead ( ! compass %[n4 ,! coil ( ,g ,v %\ld be plac$ 9 ! ,e & ,w l9e4 ,! curr5t c pass only :5 ! key is press$4 ,connect ! wires ) ,g ,v1 s t ! curr5t w pass ?r\gh ! #ae-turn coil f ,w to ,e on top ( ! coil2 t is1 s t ! curr5t w h a clockwise motion4 ,fig4 #abj repres5ts a front view ( ! coil4 ,illu/ration3 ,fig4 #abj4 ,illu/ration3 ,fig4 #aba4 #chi4 ,directions4 7,a7 ,hold ! compass 9 ! v>i\s places m>k$ ) a dot 7,fig4 #abj7 & note ! directions tak5 by its ,n pole4 ,make a circle simil> to ! "o %[n to repres5t ! coil1 & sket* ^u x ! way 9 :i* ! l9es ( =ce pass ar\nd x accord+ to y\r obs]vations4 7,b7 ,make a diagram l ,fig4 #aba1 :i* repres5ts a cross-section ( ! coil ?r\gh ! c5t]4 ,imag9e t y h remov$ ! top half ( ! coil & t y are look+ d[n ^u ! ends ( ! wire ( ! l[] half4 ,draw curv$ arr[s ab\t ! coil at ,w & ,e to %[ :i* way ! l9es ( =ce are pass+4 ,comp>e y\r results ) ^? 9 ,fig4 #aai1 rememb]+ t at ,e1 ,fig4 #aba1 ! curr5t is go+ away f y4 7,c7 ,move ,o ,c back & =? on ! c5t]-l9e t runs ,n & ,s ?r\gh ! coil1 & note ! positions ( ! compass-ne$le4 ,does ! coil seem to h poles8 7,d7 ,rev]se ! curr5t ?r\gh ! coil & repeat y\r obs]vations4 ,,exp]im5t #aed4 ,to /udy ! magnetic field ab\t a small coil ( wire4 ,app>atus4 ,a coil ( wire 7,no4 #hi71 describ$ 9 #cij2 curr5t rev]s]1 ,c ,r 7,no4 #eg72 dry cell2 connect+ wires1 etc4 #cij4 ,coils ( wire = "s ( ! foll[+ exp]im5ts %\ld be w\nd ^u wood5 spools t h be5 turn$ d[n ?91 s t ! wire w be z ne> ! c5tral hole z possible4 ,!y %\ld be w\nd ) a w9d]4 7,see ,app>atus ,book1 ,*apt] ,x47 ,= conv5i5ce we %all call ! />t+ end ( ! coil1 t is1 ! end t comes f ! wire t is ne> ! c5t]1 ! inside end1 ,i ,e4 ,! end ( ! la/ lay] ( ! coil we %all call ! outside end1 ,o ,e4 ,^! lett]s %\ld be not$ 9 ! diagrams4 ,see ,app>atus ,li/ = details ( ! special coils us$ 9 ^! exp]im5ts4 ,illu/ration3 ,fig4 #abb4 #cia4 ,directions4 7,a7 ,arrange z 9 ,fig4 #abb1 s t ! axis ( ! coil w lie 9 ! ,e & ,w l9e4 ,place ,o ,c ab\t #b 94 f ! ,e end ( ! coil4 ,press "o lev] ( ,c ,r s t ! curr5t w pass ar\nd ! coil = an in/ant 9 a clockwise direction2 t is1 s t x w ent] ! coil at ,o ,e4 ,note ! action ( ! ne$le4 ,if ! ne$le is n affect$ move x ne>] ! coil & press ! lev] aga94 ,get cle>ly 9 m9d ! connections1 ! direction 9 :i* ! ,n end ( ! ne$le is deflect$1 etc4 ,is ! ,e end ( ! coil a ,n or a ,s pole8 7,b7 ,rev]se ! curr5t ?r\gh ! coil4 ,:at effect has x ^u ! pol>ity ( ! ,e end ( ! coil8 7,c7 ,place ,o ,c at ! we/ end ( ! coil & repeat 7,a7 & 7,b74 7,d7 ,place ,o ,c 9 v>i\s positions ab\t ! coil & note ! action ( ! ne$le :5 ! curr5t passes4 ,does ?is coil act l a magnet1 hav+ poles1 magnetic field1 etc48 ,illu/ration3 ,fig4 #abc4 #cib4 ,pol>ity ( ,coils4 ,x is evid5t f ,exps4 #aec & #aed t a coil$ conductor has poles1 magnetic field1 etc41 :5 a curr5t passes1 & t x /rongly resembles a magnet1 ev5 ?\gh no iron ent]s into its con/ruction4 ,we may say t ! coil becomes magnetiz$ by ! electric curr5t4 ,fig4 #abc %[s a "r h&$ coil or helix ( wire1 ! curr5t pass+ z %[n by ! small arr[s4 ,! left-h& end is a ,s pole because ! curr5t passes ar\nd x 9 a clockwise direction4 ,:5 y face ! "r-h& end ( ! coil ! curr5t is se5 to pass ar\nd x 9 an anti-clockwise direction2 ?is produces a ,n pole4 ,z ! ,n pole ( ! magnetic ne$le is attract$ t[>d ! ,s pole ( ! coil1 x is cle> t ! l9es ( =ce pass ?r\gh ! inside ( ! coil z %[n by ! l>ge arr[s4 ,!y !n curve ?r\gh ! air & return to ! ,s pole z ) magnets4 ,,exp]im5t #aee4 ,to te/ ! attract+ & suck+ p[] ( a magnetiz$ coil or helix4 ,app>atus4 ,! coil1 batt]y1 etc41 us$ 9 ,exp4 #aed1 ,fig4 #abb2 a sew+-ne$le4 ,illu/ration3 ,fig4 #abd4 #cic4 ,directions4 7,a7 ,arrange ! coil1 etc41 z describ$ 9 ,exp4 #aed4 ,! coil ne$ n lie 9 ! ,e & ,w l9e1 h[ev]1 & a key may be us$ in/ead ( ! curr5t rev]s]4 7,b7 ,magnetize ! ne$le s t its po9t w be a ,n pole4 7,c7 ,tie a ?read ab\t ! c5t] ( ! magnetiz$ ne$le1 hold ! ?read 9 ! h& s t ! ,s pole ( ! ne$le w sw+ freely at ! hole at ! "r-h& end ( ! coil 7,fig4 #abd74 ,if ! curr5t passes z direct$1 ! "r-h& end ( ! coil w be a ,n pole4 ,:at happ5s to ! ne$le :5 ! key is press$ = an in/ant4 7,d7 ,*ange ! ne$le to ! left end ( ! coil & repeat4 7,e7 ,try a nail1 p51 iron1 etc41 in/ead ( ! ne$le4 ,,exp]im5t #aef4 ,to f9d :e!r a piece ( /eel c be p]man5tly magnetiz$ by an electric curr5t4 ,app>atus4 ,same z = la/ exp]im5t2 an unmagnetiz$ sew+-ne$le2 ! compass4 #cid4 ,directions4 7,a7 ,be sure t ! ne$le is n magnetiz$4 ,x %\ld attract bo? ends ( ! compass-ne$le4 ,h[ c any magnetism 9 ! ne$le be remov$8 7,b7 ,place ! ne$le inside ( ! coil ) its po9t to ! ea/2 t is1 ) its po9t at ! ,n pole ( ! coil1 & its head at ! ,s pole4 ,close ! circuit = an in/ant4 ,te/ ! ne$le aga9 = poles4 ,is ! po9t a ,n or a ,s pole8 7,c7 ,turn ! ne$le end = end 9 ! coil1 & see :e!r its pol>ity c be rev]s$4 7,d7 ,exp]im5t ) iron wire1 nails1 /eel p5s1 spr+ /eel1 etc4 ,illu/ration3 ,fig4 #abe4 ,,exp]im5t #aeg4 ,to /udy ! effect ( a piece ( iron plac$ inside ( a magnetiz$ coil ( wire4 ,app>atus4 ,same z 9 ,exp4 #aed2 a %ort rod or iron core1 ,i ,c1 ( s(t iron 7,no4 #ib7 t w fit inside ( ! coil4 ,?is comb9ation is call$ an electromagnet4 #cie4 ,directions4 7,a7 ,arrange fir/ z = ,exp4 #aed1 ,fig4 #abb1 ) ! coil 9 ! ,e & ,w l9e1 no core be+ us$1 & place ,o ,c ab\t #f 94 f ! "r-h& end ( ! coil4 7,b7 ,press ! lev] = an in/ant to see :e!r ! field ( ! coil is /rong en\gh to move ! compass-ne$le at t di/ance4 ,move ,o ,c a little ne>] or f>!r f ! coil until ! ne$le j moves1 :5 ! circuit is clos$4 7,c7 ,place ,i ,c inside ( ! coil 7,fig4 #abe71 & repeat 7,b7 to see :e!r ! magnetic field ( ! coil is /rong] or weak] ?an be=e4 7,d7 ,/udy ! location ( ! poles4 ,c !y be rev]s$8 ,,*apt] ,,xxiii4 ,,electromagnets4 #cif4 ,electromagnets are important to ! /ud5t ( electricity4 ,!y =m ! pr9cipal "p ( ne>ly e electrical in/rum5t4 ,y h se5 t a wire has a magnetic field ab\t x ! in/ant a curr5t passes ?r\gh x4 ,a coil1 or helix ( wire1 has a /rong] field ?an a /raight wire c>ry+ ! same curr5t1 because ea* turn1 or convolution1 adds its field to ! fields ( ! o!r turns4 ,by hav+ a core ( s(t iron in/ead ( air1 wood1 or o!r non-magnetic mat]ial1 ! /r5g? ( ! magnet is greatly increas$4 ,! c5tral core may be p]man5tly fix$ 9 ! coil1 or x may be removable4 7,see ,app>atus ,book1 ,*apt] ,,ix1 = ,home-made ,electromagnets47 #cig4 ,cores ( ,electromagnets4 ,a /rong magnet has m l9es ( =ce pass+ f its ,n pole ?r\gh ! air to its ,s pole ?an a weak magnet4 ,by increas+ ! numb] ( l9es ( =ce we increase ! /r5g? ( a magnet4 ,x has be5 se51 9 exp]im5ts ) p]man5t magnets1 t l9es ( =ce d n pass z readily ?r\gh air z ?r\gh s(t iron1 & t l9es ( =ce w g out ( _! way to pass ?r\gh iron4 ,x 0 le>n$ 9 ,exp4 #aed t inside ( a helix 7,fig4 #abc7 ! l9es ( =ce pass f ! ,s to ! ,n pole2 !y !n spread out ?r\gh ! air & pass back on all sides ( ! coil to its ,s pole1 z 9 ! case ( p]man5t magnets4 ,! air ar\nd & inside ( a helix (f]s a great resi/ance to ! l9es ( =ce1 & t5ds to weak5 ! magnetic field4 ,:5 "p ( ! circuit consi/s ( an iron core1 :i* is a spl5did conductor ( l9es ( =ce1 ! magnetic field is greatly increas$ 9 /r5g?4 ,,exp]im5ts #aeh-afc4 ,to /udy /raight electromagnets4 ,app>atus4 ,a good dry cell or o!r s\rce ( a fairly /rong curr5t2 coil ) s(t iron core2 key2 wires ) connectors1 etc42 small nails2 iron-fil+s2 compass2 l>ge wire nail2 t9 box 7,no4 #id7 to act z a base = ! electromagnets4 ,,exp]im5t #aeh4 ,lift+ p[]4 #cih4 ,directions4 7,a7 ,jo9 ! cell1 key1 & coil1 z expla9$ 9 ,exp4 #aed1 s t ! curr5t w pass only :5 ! key is press$4 ,place ! core inside ( ! coil 7,fig4 #abe74 ,two good cells 9 s]ies c be us$ to advantage4 7,b7 ,hold ! coil 9 a v]tical position ne> small nails1 iron fil+s1 t9 boxes1 etc42 !n press ! key & raise coil2 c>ry ! cl++ iron to ano!r place1 break ! circuit at ! key1 & expla9 ! result4 ,:y d nails cl+ m /rongly to ! core ?an fil+s aft] ! circuit is brok58 ,,exp]im5t #aei4 ,residual magnetism ( core4 #cii4 ,directions4 7,a7 ,aft] ! curr5t has pass$ ?r\gh ! coil ) ! core 9 place1 remove ! core & te/ x = magnetism ) ! compass4 ,w ! small end ( ! core attract bo? poles ( ! compass-ne$le1 or is x slightly magnetiz$8 7,b7 ,if !re is any residual magnetism1 /rike ! core ) a hamm] & te/ aga94 7,c7 ,use a s(t /eel wire nail = ! core1 & repeat 7,a7 & 7,b74 ,:y does s(t iron make a bett] core ?an /eel = electromagnets8 ,:i* %\ld be ! m easily magnetiz$8 ,,exp]im5t #afj4 ,magnetic tick4 #djj4 ,directions4 7,a7 ,jo9 ! electromagnet ) ! cell & key z be=e 7,exp4 #aed74 ,hold "o end ( ! core firmly aga9/ ! top ( a t9 box :i* %\ld /& ^u ! table & :i* %\ld act z a s\nd+-bo>d4 ,! flat boxes us$ 9 ! exp]im5ts on /atic electricity are good = ?is1 or use ! t9 box1 ,no4 #id1 = a base4 ,rapidly op5 & close ! circuit by means ( ! key & li/5 = any clicks made by ! core4 7,b7 ,li/5 = ?is s\nd 9 telegraph s\nd]s1 electric bells1 etc41 if y h !m4 ,! armature %\ld be held1 ( c\rse1 s t slight s\nds c be he>d4 #dja4 ,discussion4 ,a b> ( iron becomes slightly long] :5 x is magnetiz$1 ! p>ticles ( iron be+ made to po9t 9 ! same direction4 ,z soon z ! curr5t ceases to fl[ ?r\gh ! coil ! p>ticles ( ! s(t core ne>ly all resume _! mix$ positions4 ,! click he>d is suppos$ to be due to ! *anges 9 ! molecules ( iron4 ,! core becomes gradually w>m] :5 x is rapidly magnetiz$ & demagnetiz$ by a /rong curr5t4 ,illu/ration3 ,fig4 #abf4 ,,exp]im5t #afa4 ,magnetic figures4 #djb4 ,directions4 7,a7 ,arrange z 9 ,fig4 #abf4 ,! key %\ld be us$ 9 case a dry cell acts z ! s\rce ( ! curr5t4 ,two good cells jo9$ 9 s]ies c be us$ to advantage4 ,lay ! coil flat ^u ! table & place on x a piece ( /iff1 smoo? pap]1 or a %eet ( glass4 7,b7 ,spr9kle a few iron fil+s ^u ! glass1 :i* may be held 9 place by books4 ,g5tly tap ! glass ) a p5cil :ile y close ! circuit at ! key4 ,d ! fil+s arrange !mselves z 9 ! case ( p]man5t magnets8 ,make a sket* ( ! field1 rememb]+ t y h bo? ,n & ,s poles1 & comp>e x ) previ\s results4 ,illu/ration3 ,fig4 #abg4 ,,exp]im5t #afb4 ,magnetic figures4 #djc4 ,directions4 7,a7 ,arrange z 9 ,fig4 #abf1 b /& ! coil on end1 us+ ! base z direct$ 9 #djg1 to hold x firmly 9 position4 ,jo9 ! ends1 ,o ,e & ,i ,e1 to ! key z be=e4 ,fig4 #abg %[s a top view ( ! coil & base4 7,b7 ,) books1 etc41 fix a piece ( /iff1 smoo? pap]1 or glass j ov] ! top ( ! core1 & proce$ z 9 ,exp4 #afa to /udy ! field4 ,see #dag = mak+ p]man5t pictures ( magnetic fields4 ,,exp]im5t #afc4 ,magnetic field4 #djd4 ,directions4 7,a7 ,use same arrangem5t z = ,exp4 #afb1 except fil+s & glass1 :i* are replac$ by ! compass4 7,b7 ,hold ! compass ab\t #b 94 f ! top pole ( ! electromagnet1 close ! circuit = a second or two & note action ( ne$le4 ,is ! top ,n or ,s1 :5 ! curr5t ent]s ! coil at ,o ,e8 ,comp>e result ) #cib4 7,c7 ,move ! compass quickly ab\t ! pole1 ! circuit be+ clos$1 & note action ( ne$le4 ,comp>e result ) directions tak5 by p>ticles ( iron fil+s 9 ,exp4 #afc4 7,d7 ,rev]se ! direction ( ! curr5t ?r\gh ! coil & te/ ! nature ( ! pole at ! top4 ,illu/ration3 ,fig4 #abh4 ,illu/ration3 ,fig4 #abi4 #dje4 ,horse%oe ,electromagnets4 ,fig4 #abh %[s a simple =m ( electromagnet ) two coils :i* h a b5t piece ( iron z a core = bo?4 ,! coils h to be w\nd on by h& 9 ?is =m4 ,z ?is is tr\blesome1 ! coils are g5]ally w\nd on two sep>ate cores :i* are jo9$ by a yoke 7 #djf71 :i* takes ! place ( ! curv$ "p 9 ,fig4 #abh4 ,! sep>ate coils c be quickly made ) a w9d] & jo9$ to suit4 7,see ,app>atus ,book1 ,*apt] ,,ix1 = ,home-made ,electromagnets47 ,fig4 #abi %[s a top view ( a home-made exp]im5tal horse%oe electromagnet4 ,! coils are jo9$ by an iron /rap1 call$ ! yoke1 :i* is screw$ to a wood5 base4 ,a /rip ( iron plac$ above ! magnets to be attract$ by !m1 :5 ! curr5t passes1 is call$ ! armature4 7,see ,telegraph ,s\nd]s47 #djf4 ,use ( ,yoke4 ,x has be5 expla9$ 7 #hb7 :y horse%oe magnets are1 9 g5]al1 bett] ?an /raight ones4 ,! same is true ( electromagnets2 !re are two poles to attract1 & two to induce4 ,! l9es ( =ce pass ?r\gh ! yoke on _! way f "o core to ! o!r1 & ?is r$uces ! resi/ance to !m4 ,! /r5g? ( ! horse%oe magnet w\ld be greatly r$uc$ if ! l9es ( =ce 7 oblig$ to pass ?r\gh two air spaces in/ead ( "o2 9 fact1 if !re 7 no yoke we %\ld h simply two /raight magnets4 ,! yoke %\ld be made ( s(t iron4 ,illu/ration3 ,fig4 #acj4 ,illu/ration3 ,fig4 #aca4 #djg4 ,exp]im5tal ,magnets are quickly jo9$ to a t9 base 7,no4 #id71 :i* has #c holes pun*$ 91 ?r\gh :i* screws c be put to hold ! cores 9 place4 ,fig4 #abg %[s plan ( t94 ,fig4 #acj %[s h[ removable cores are fa/5$ to ! base1 ! coils be+ on ! spools1 & ,fig4 #aca %[s h[ home-made coils on bolts c be us$4 ,! coils on bolts %\ld be w\nd z direct$ 9 ,app>atus ,book1 ,*apt] ,x4 ,! t9 base also s]ves z ! yoke4 ,removable ,cores4 ,fig4 #acj4 ,^! are ( s(t iron 7,no4 #ib1 #ic74 ,9 "o end ( ea* is a hole = ! screws1 ,s4 ,"p ( ! t9 has be5 cut away 9 ! ,fig4 ,! copp] wa%]1 ,c ,w1 %\ld be us$4 7,see #djh47 ,connectors are fa/5$ to ! ends ( ! coils 7 #bbf-bcj74 ,bolt ,cores4 ,fig4 #aca4 ,aft] w9d+ on ! coils1 z direct$ 9 ,app>atus ,book1 remove ! nut & put on an extra wa%]1 ,e ,w1 s t ! ends ( ! coils w n be press$ aga9/ ! t91 b come out betwe5 ! two wa%]s4 ,pu% ! screw-end ( ! bolt ?r\gh holes 7ab\t #b 94 ap>t7 pun*$ 9 ! t91 !n put on ! nut1 z %[n4 ,d n =ce ! nut on too f>1--j f> en\gh to hold ! cores 9 place4 ,! ends ( ! wires are n %[n 9 ,figs4 #acj1 #aca4 ,connectors are fa/5$ to !m 7 #djh74 ,illu/ration3 ,fig4 #acb4 #djh4 ,me?od ( ,jo9+ ,coils4 ,to produce ! be/ results ! poles ( ! horse%oe electromagnet %\ld be unlike4 ,z ! coils are w\nd alike1 _! ends mu/ be jo9$ 9 su* a mann] t ! curr5t w pass ar\nd !m 9 opposite directions2 t is1 if ! curr5t ent]s "o coil at ! outside end1 ,o ,e1 x mu/ ent] ! o!r coil at ! inside end1 ,i ,e4 ,fig4 #acb %[s a plan ( ! connections1 spr+ connectors be+ fa/5$ to ! coil-ends1 to all[ rapid & easy *anges 9 ! arrangem5t4 ,l1 ,m1 & ,r are pieces ( metal fa/5$ to a /rip ( wood 7,no4 #ie71 us$ to make connections f cells or o!r app>atus4 ,!y are turn$ up at ea* end z 9 ,fig4 #ajd1 #c4 ,c>e %\ld be tak5 n to get %ort circuits by all[+ two wires to t\* ! t9 base4 ,by *ang+ ! ends ( ! coils ^u ,l1 ,m1 & ,r 7left1 middle1 & "r71 & by *ang+ ! direction 9 :i* ! curr5t ent]s ! comb9ation connect+ plates 7,no4 #ie71 x is evid5t t ! nature ( ! poles c be regulat$ to suit4 ,,exp]im5ts #afd-agc4 ,to /udy horse%oe electromagnets4 ,app>atus4 ,coils ( wire ) cores & yoke l ^? expla9$ 9 ?is *apt]4 ,coils fa/5$ to t9 base or yoke ) wires lead+ f !m to ! comb9ation connect+ plates 7,no4 #ie1 ,fig4 #acb71 are v h&y4 ,cells2 iron fil+s2 compass2 iron /rip 7,no4 #gf74 ,,exp]im5t #afd4 ,to te/ ! poles4 #dji4 ,directions4 7,a7 ,arrange z 9 ,fig4 #abf1 b use ! exp]im5tal magnets & comb9ation connections 7,fig4 #acb7 9 place ( ! s+le coil %[n 9 ,fig4 #abf4 ,jo9 ,o ( ! key ) ,l1 & ,zn ( ! cell ) ,r ( ,fig4 #acb4 ,:5 ! key is press$ ! curr5t w ent] ! magnets f ,l & leave at ,r4 7,b7 ,) ! compass te/ ! pol>ity ( ! cores z 9 ,exp4 #afc1 ,b1 ,c4 ,make a sket* ( ! arrangem5t1 & note :i* pole is ,n & :i* ,s4 7,c7 ,see :i* way ! curr5t mu/ pass ar\nd ea* coil1 by ! way x is w\nd1 & comp>e ! results ( 7,b7 ) ,exp4 #aed1 ,fig4 #abc4 ,,exp]im5t #afe4 ,to te/ ! poles4 #daj4 ,directions4 7,a7 ,arrange z 9 ,exp4 #afd1 b rev]se ! direction ( ! curr5t ?r\gh ! coils4 ,d ?is by jo9+ ,o ( ! key 7,fig4 #abf7 ) ,r ( ,fig4 #acb1 & ,zn ( ! cell ) ,l4 7,b7 ,repeat 7,b7 & 7,c7 ( ,exp4 #afd & /udy results4 ,illu/ration3 ,fig4 #acc4 ,,exp]im5t #aff4 ,to te/ ! poles4 #daa4 ,directions4 7,a7 ,arrange all connections z 9 ,exp4 #afd1 !n rev]se ! positions ( ,o ,e & ,i ,e ( coil ,a2 t is1 jo9 ,o ,e to ,m1 & ,i ,e to ,l1 ,fig4 #acb4 ,?is w make unlike ends come toge!r at ,m2 9 o!r words1 :5 ! curr5t ent]s at ,l & leaves at ,r x w pass ar\nd bo? coils 9 ! same direction4 7,b7 ,/udy ! nature ( ! poles1 z 9 ,exps4 #afd1 #afe1 & note results4 ,note4--,fig4 #acc %[s simply ! two cores ( a horse%oe electromagnet ) arr[s to indicate 9 :i* direction ! curr5t is pass+ 9 ea* coil to produce ,n & ,s poles4 ,,exp]im5t #afg4 ,to /udy ! inductive action ( "o core ^u ! o!r4 #dab4 ,directions4 7,a7 ,arrange z = ,exp4 #afd1 b jo9 ! wire f ,zn ( ! cell to ,m 7,fig4 #acb74 ,9 ?is way coil ,b w be cut out ( ! circuit4 ,place ! coils 9 ! ,e & ,w l9e4 7,b7 ,f9d ab\t h[ f> ! residual magnetism ( ! core ( ,b c act ^u ! compass-ne$le1 hold+ ! compass on ! side away f coil ,a1 no curr5t pass+4 7,c7 ,press ! key = an in/ant1 & note :e!r ! magnetism ( coil ,b has be5 made /rong] or weak]4 ,expla9 ! action ( core ,a on core ,b4 ,,exp]im5t #afh4 ,magnetic figures4 #dac4 ,directions4 7,a7 ,arrange z 9 ,exp4 #afd4 ,) books1 etc41 fix a piece ( smoo?1 /iff pap]1 or a %eet ( glass1 j above ! poles ( ! electromagnets4 7,b7 ,spr9kle iron fil+s ^u ! glass1 & g5tly tap x :ile ! circuit is clos$ at ! key = a few seconds4 ,make a sket* ( ! magnetic figure produc$4 ,d ! l9es ( =ce f ! opposite poles attract or repel ea* o!r8 ,see #dag = mak+ p]man5t figures4 7,see ,?+s a ,boy ,%\ld ,"k ,ab\t ,electricity = draw+s ( magnetic figures47 ,note4--,if possible1 use two or ?ree good cells 9 s]ies = mak+ magnetic figures1 z a fairly /rong field is be/4 ,,exp]im5t #afi4 ,magnetic figures4 #dad4 ,directions4 7,a7 ,arrange app>atus z = ,exp4 #afe1 & make ! magnetic figure = ?is comb9ation1 z direct$ 9 ,exp4 #afh4 ,sket* & /udy ! results4 ,,exp]im5t #agj4 ,magnetic figures4 #dae4 ,directions4 7,a7 ,arrange ! app>atus & connections z 9 ,exp4 #aff1 & make ! magnetic figure ( ?is comb9ation z direct$ 9 ,exp4 #afh4 ,9 ?is case ! poles are alike4 ,sket* & /udy ! results4 ,,exp]im5t #aga4 ,magnetic figures4 #daf4 ,directions4 7,a7 ,arrange app>atus & connections z 9 ,exp4 #afg1 & make ! magnetic figure ( ! comb9ation z direct$ 9 ,exp4 #afh4 ,comp>e ! figure produc$ ) t ( ,exp4 #afh4 ,9 ?is case ! curr5t passes ?r\gh b "o coil4 #dag4 ,p]man5t ,magnetic ,figures c be made 9 sev]al ways = future /udy & comp>ison4 7,a7 ,p>aff9e pap] figures4 ,make p>aff9e pap] z direct$ 9 ,app>atus ,book1 page #ace4 ,= ?is purpose smoo?1 /iff1 :ite pap] is be/1 s t ! fil+s w %[ pla9ly1 & b a ?9 coat+ ( p>aff9e %\ld be giv54 ,place ! magnets ^u ! table1 lay ov] !m a piece ( unp>aff9$ pap]1 & fix ! p>aff9e pap] directly ov] ?is4 ,?is is necess>y1 z ! coat$ pap] /icks :5 heat$4 ,= electromagnets x w be necess>y to support ! edges ( ! pap] ) books1 etc4 ,spr9kle on ! fil+s & tap ! pap] to make !m arrange !mselves :ile ! circuit is clos$4 ,aft] ! l9es ( =ce %[ pla9ly1 ! curr5t ne$ n be us$ aga91 provid$ ! pap] be kept p]fectly /ill4 ,pass ! flame ( a ,buns5 burn] ov] ! pap] to melt ! coat+4 ,?is w1 no d\bt1 make ! two pieces ( pap] /ick toge!r1 & p]man5tly fix ! p>ticles ( fil+s 9 place4 ,d n heat ! pap] too mu*--j en\gh to melt ! p>aff9e4 ,if y h no gas1 hold a fire-%ovel1 conta9+ hot coals1 ov] ! pap]4 ,z soon z ! p>aff9e cools1 ! figures w /& consid]able h&l+4 ,blue pr9t figures are v pretty1 & la/ indef9itely4 ,get "s blue-pr9t pap] at a photograph]'s1 :o w give y directions ab\t develop+ x ) wat]4 ,keep ?is 9 ! d>k1 & take out b "o %eet at a "t = exp]im5ts4 ,to make ! figures1 take y\r app>atus ne> a w9d[ :]e bright sunlight comes 94 ,pull d[n ! curta9 s t y h b a dim light :5 y make ! magnetic figure1 z direct$ be=e4 ,aft] ! l9es ( =ce %[ pla9ly1 raise ! curta91 & let ! bright sunlight %9e on x = #e or #f m9utes1 or until ! surface ( ! pap] has a ri*1 bronze color4 ,! pap] _c be act$ ^u by ! light "u ! p>ticles ( fil+s4 ,quickly %ake ! fil+s f ! pap]1 & wa% x 9 #c *anges ( wat] to develop x1 !n p9 ! pap] up to dry4 ,,exp]im5t #agb4 ,lift+ p[]4 #dah4 ,directions4 7,a7 ,arrange ! app>atus z 9 ,exp4 #afd4 ,hold an iron /rip 7,no4 #gf71 a screw-driv]1 or o!r iron b> directly ov] & ne> ! poles ( ! exp]im5tal electromagnet4 ,close ! circuit at ! key1 !n lift ! magnets by ! armature1 z ! iron /rip may be call$1 ! circuit be+ kept clos$ = a few seconds4 ,if y\r cell is good !re %\ld be no tr\ble 9 lift+ ! magnets by ! armature4 ,op5 ! circuit1 & see :e!r ! magnets drop4 7,b7 ,hold ! magnets upside d[n directly ov] nails1 t9 boxes1 iron fil+s1 or o!r pieces ( iron4 ,close ! circuit1 move ! attract$ iron to ano!r place on ! table1 & op5 ! circuit4 ,c ?is pr9ciple be us$ = practical purposes8 ,note4--,"s exp]im5ts illu/rat+ practical uses ( electromagnets w be giv5 9 a future *apt]4 ,,exp]im5t #agc4 ,residual magnetism :5 magnetic circuit is clos$4 #dai4 ,directions4 7,a7 ,arrange z 9 ,exp4 #afd4 ,y h already se5 t ea* core reta9s "s magnetism aft] ! circuit is clos$4 ,place ! iron /rip firmly across ! poles1 close ! circuit = an in/ant1 op5 ! circuit1 !n see :e!r ! armature /ill cl+s to ! cores ) "s /r5g?4 ,! armature %\ld fit well ^u ! cores = ?is exp]im5t4 7,b7 ,aga9 press ! armature ^u ! cores1 no curr5t be+ us$2 !n lift x z 9 7,a74 ,comp>e ! attraction ) t f\nd 9 7,a74 #dbj4 ,clos$ ,magnetic ,circuits4 ,x 0 se5 9 ! /udy ( ! p]man5t horse%oe magnet1 t ! armature clung /rongly to ! magnet4 ,! armature clos$ ! magnetic circuit1 ! l9es ( =ce hav+ almo/ no resi/ance4 ,9 ! case ( electromagnets ! magnetic circuit becomes clos$ :5 ! armature t\*es bo? poles at ! same "t4 ,! armature cl+s /rongly to ! poles ev5 aft] ! curr5t ceases to fl[4 ,z soon z ! magnetic circuit is brok51 h[ev]1 b little residual magnetism rema9s4 ,! armatures ( electromagnets are usually arrang$ s t !y c n q t\* ! cores1 to avoid ?is /ick+4 ,,*apt] ,,xxiv4 ,,!rmoelectricity4 ,illu/ration3 ,fig4 #acd4 ,,exp]im5t #agd4 ,to f9d :e!r electricity c be produc$ by heat4 ,app>atus4 ,! home-made !rmopile describ$ 9 #dba2 a/atic galvanoscope2 connect+ wires2 c&le or alcohol lamp4 #dba4 ,home-made ,!rmopile4 7,fig4 #acd47 ,= ?is y ne$ #c hairp9s1 copp] wire1 a piece ( wood ab\t #c 94 long & #a 94 squ>e on ! ends1 #b pieces ( t91 & "s small nails4 ,/raight5 ! hairp9s & scrape ! coat+ (f ) s&pap] or a file4 ,scrape ! insulation f #d pieces ( copp] wire1 ea* ab\t #h 94 long4 ,twi/ ! ends ( ! copp] wire ab\t ! ends ( ! hairp9s 7,fig4 #acd71 & !n fa/5 ! hairp9s to ! block4 ,!y may be held firmly by small nails :i* %\ld be driv5 p>tly into ! block & b5t ov]4 ,! hairp9s at ! "r-h& side ( ! ,fig4 are %[n to be ne> b n t\*+ ea* o!r4 ,?is all[s all to be heat$ at ! same "t4 ,! t9 b9d+-po/s may be nail$ or screw$ to ! block1 & if ! b>e copp] wires #a & #d be plac$ "u ,x & ,y be=e !y are screw$ d[n !y w be electrically connect$4 ,! ends ( #a & #d may be held "u ! screw-heads4 ,! block may be support$ ^u o!r blocks to raise x to ! prop] height1 :i* w dep5d ^u ! l5g? ( ! c&le4 ,illu/ration3 ,fig4 #ace4 ,a !rmopile 9 ! =m ( a circle ) sev]al pairs ( metals1 c easily be made by fa/5+ ! hairp9s to a piece ( c>dbo>d 7,fig4 #ace7 ) a hole at ! c5t]4 ,?is may be support$ by blocks1 ! heat be+ appli$ "u ! c5t]4 #dbb4 ,directions4 7,a7 ,arrange ! app>atus z 9 ,fig4 #acd4 ,see t ! a/atic ne$le is prop]ly adju/$1 no magnets be+ ne> x4 7,b7 ,heat ! jo9ts z %[n1 & wat* ! ne$le4 ,c a curr5t be produc$ by heat8 7,c7 ,remove ! connector on wire #f f ,y to ,m1 ?us cutt+ "o pair out ( ! circuit4 ,heat ! jo9ts aga9 & comp>e ! /r5g? ( ! curr5t ) t produc$ 9 7,b74 7,d7 ,see :e!r mu* curr5t is produc$ by "o pair4 ,f results obta9$ d y see any relation betwe5 ! /r5g? ( ! curr5t & ! numb] ( pairs8 #dbc4 ,!rmoelectricity is produc$ by heat+ ! junction betwe5 two metals4 ,diff]5t pairs ( metals produce diff]5t results4 ,antimony & bismu? are (t5 us$4 ,if ! end ( a /rip ( bismu? be sold]$ to ! end ( a simil> /rip ( antimony1 & ! free ends be connect$ to a galvanomet] ( l[ resi/ance1 ! pres5ce ( a curr5t w be %[n :5 ! po9t ( contact becomes hott] ?an ! re/ ( ! circuit4 ,! curr5t w fl[ f ! bismu? to antimony across ! jo9t4 ,by cool+ ! junction bel[ ! temp]ature ( ! re/ ( ! circuit a curr5t w be produc$ 9 ! opposite direction4 ,!rmoelectric curr5ts h a l[ pot5tial4 ,! en]gy ( ! curr5t is kept up by ! heat absorb$4 #dbd4 ,pelti] ,effect4 ,! action not$ 9 #dbc c be rev]s$2 t is1 if a curr5t f a batt]y be s5t ?r\gh ! metals1 ! p>ts at ! junction become slightly w>m] or cool] ?an be=e1 dep5d+ ^u ! direction ( ! curr5t4 ,?is is kn[n z ! ,pelti] ,effect1 ! heat n be+ due to ! resi/ance to ! curr5t4 #dbe4 ,!rmopiles4 ,z ! ,e4 ,m4 ,f4 ( ! curr5t produc$ by a s+le pair ( metals is small1 sev]al pairs are usually jo9$ 9 s]ies 9 su* a way t ! diff]5t curr5ts help ea* o!r & fl[ 9 ! same direction4 ,su* comb9ations1 usually made ( antimony & bismu?1 are call$ !rmoelectric piles1 or simply !rmopiles4 ,!y are useful 9 detect+ v small diff]5ces 9 temp]ature4 ,! heat ( a mat*1 or ! cold ( a piece ( ice1 w produce a curr5t ev5 at "s di/ance1 ! !rmopile be+ connect$ ) a s5sitive %ort-coil a/atic galvanomet]4 7,see ,?+s a ,boy ,%\ld ,"k ,ab\t ,electricity47 ,,*apt] ,,xxv4 ,,induc$ ,,curr5ts4 #dbf4 ,electromagnetic ,induction4 ,y h se51 by exp]im5ts1 t a magnet has ! p[] to induce ano!r piece ( iron or /eel to become a magnet4 ,y h also se51 9 ! /udy ( /atic electricity1 t an electrifi$ body has ! p[] to act ?r\gh space ^u ano!r conductor4 ,a body may be pol>iz$ & *>g$ ) /atic electricity by induction4 ,sev]al que/ions n[ come up4 ,c a curr5t ( electricity 9 a conductor induce a curr5t 9 ano!r conductor n 9 any way connect$ ) ! fir/8 ,c curr5t electricity produce effects ?r\gh space8 ,is !re an electromagnetic induction8 ,x has be5 se5 t a curr5t-c>ry+ wire has a magnetic field1 & t magnetic fields c act ?r\gh space4 ,x is evid5t1 !n1 t a conductor w be surr\nd$ & cut by l9es ( =ce :5 x is plac$ 9 a magnetic field1 or ne> a wire or coil ?r\gh :i* a curr5t passes4 ,let u /udy ?is by exp]im5ts4 ,,exp]im5ts #age-ahb4 ,to /udy induc$ curr5ts4 ,app>atus4 ,! two coils ( wire 7,nos4 #hi1 #ij72 two %ort1 s(t iron cores 7,nos4 #ib1 #ic72 long iron core 7,no4 #if72 b> magnet 7,no4 #ig72 a/atic galvanoscope 7,no4 #ei72 dry cell 7,no4 #ea72 key 7,no4 #ee72 horse%oe magnet2 connect+ wires ) spr+ connectors 7,no4 #ed7 on ! ends 7 #bbf-bcj72 coil ( wire 7,no4 #ih7 w\nd on an iron core2 compass4 ,illu/ration3 ,fig4 #acf4 ,,exp]im5t #age4 ,to f9d :e!r a curr5t c be g5]at$ ) a b> magnet & a holl[$ coil ( wire4 #dbg4 ,directions4 7,a7 ,arrange z 9 ,fig4 #acf4 ,! coil 7,no4 #ij7 ( f9e wire is jo9$ to ,a ,g 7,no4 #ei7 z %[n4 ,small pieces ( t9 or copp]1 #a & #b1 are us$ to make connections betwe5 ! coil ends & wires1 #c & #d1 :i* are atta*$ to ! galvanoscope4 ,x is be/ to use ! wires1 #c & #d1 s t ! coil w be #b feet at lea/1 f ,a ,g2 o!rwise ! ne$le ( ,a ,g might be affect$ by ! magnet1 ,m 7,no4 #ig74 7,b7 ,get cle>ly 9 m9d 9 :i* direction ! "r-h& end ( ! ne$le is deflect$ :5 a curr5t ent]s ,a ,g at ,l1 ! left-h& b9d+-po/4 ,if y h =gott5 ! results ( previ\s exp]im5ts1 use ! cell = an in/ant1 t\*+ ! wire f ! c>bon to ,l & t f ! z9c to ,r4 ,if any curr5ts come f ! coil1 lat]1 y %\ld be able to tell 9 :i* direction !y fl[1 ! coil & ,a ,g =m+ a clos$ circuit4 7,c7 ,hold ! magnet1 ,m1 z %[n1 & quickly pu% x into ! coil until x has ! place ( a core1 at ! same "t wat*+ ! ne$le4 ,if a curr5t is produc$1 9 :i* direction does x fl[ f ! coil8 ,does ! ne$le rema9 deflect$8 ,is ! curr5t con/ant or tempor>y8 7,d7 ,aft] ! magnet1 ,m1 has be5 plac$ 9 ! coil1 z 9 7,c71 & ! ne$le has come to re/1 quickly pull ,m f ! coil1 wat*+ ! ne$le4 ,if a curr5t is produc$1 does x pass f ! coil 9 ! same direction z be=e1 9 7,c78 7,e7 ,turn ,m end = end1 repeat 7,c7 & 7,d71 & /udy ! results4 ,are l9es ( =ce made to cut ! turns ( ! coil8 7,f7 ,repeat 7,c7 & 7,d71 mov+ ,m sl[ly4 #dbh4 ,discussion4 ,an induc$ curr5t1 produc$ z 9 ! above exp]im5t1 is a mom5t>y "o4 ,no curr5t passes :5 ! magnet & coil are /ill2 at lea/ "o ( !m has to be 9 motion4 ,:5 ! magnet is ins]t$1 ! induc$ curr5t is said to be an inv]se "o1 z x passes 9 a direction opposite to t :i* w\ld be necess>y to give ! magnet its poles1 x be+ consid]$ a core magnetiz$ by ! curr5t4 ,a direct curr5t is produc$ :5 ! magnet is )drawn f ! coil4 ,rapid movem5ts produce /rong] curr5ts ?an sl[ ones4 7,see #dci47 #dbi4 ,induc$ ,curr5ts & ,"w4 ,x takes =ce to move a magnet ?r\gh ! c5t] ( a coil1 & x is ?is "w t is ! s\rce ( ! induc$ curr5t4 ,:5 ! coil is pu%$ on to ! magnet1 or :5 x is mov$ ?r\gh a magnetic field1 =ce is also requir$4 ,we h1 9 ?is simple exp]im5t1 ! key to ! action ( ! dynamo & o!r important electrical ma*9es4 ,^! w be discuss$ lat]4 ,,exp]im5t #agf4 ,to f9d :e!r a curr5t c be g5]at$ ) a b> magnet & a coil ( wire hav+ an iron core4 #dcj4 ,directions4 7,a7 ,arrange z 9 ,exp4 #age1 ,fig4 #acf1 &1 9 addition1 place an iron core 7,no4 #ib7 inside ( ! coil 7,no4 #ij74 7,b7 ,hold ! b> magnet 7,no4 #ig7 z 9 ,fig4 #acf1 & quickly l[] x until x t\*es ! core1 at ! same "t wat*+ ! ne$le4 ,/udy results1 direction ( curr5t1 etc41 z be=e4 7,c7 ,sudd5ly )draw ,m f ! core4 ,is ! curr5t produc$ 9 ! same direction z t f 7,b78 7,d7 ,turn ,m end = end & repeat 7,b7 & 7,c74 7,e7 ,repeat 7,c7 & 7,d71 mov+ magnet sl[ly4 ,h[ does ! /r5g? ( ! curr5t comp>e ) t ( ,exp4 #age8 ,are l9es ( =ce made to cut ! turns ( ! coil8 ,illu/ration3 ,fig4 #acg4 ,,exp]im5t #agg4 ,to f9d :e!r a curr5t c be g5]at$ ) a horse%oe magnet & a coil ( wire hav+ an iron core4 #dca4 ,directions4 7,a7 ,arrange ! app>atus z 9 ,exp4 #agf1 b use ! horse%oe magnet1 ,h ,m1 in/ead ( ! b> magnet4 ,fig4 #acg %[s ! coil 7,no4 #ij7 ) "o pole ( ,h ,m held ov] ! core4 7,b7 ,/udy ! effect ( quickly l[]+ & rais+ fir/ "o pole & !n ! o!r ov] ! core1 z ) ! b> magnet4 ,get cle>ly 9 m9d ! direction 9 :i* ! induc$ curr5t fl[s 9 ea* case4 #dcb4 ,induc$ ,curr5ts & ,l9es ( ,=ce4 ,9 ! exp]im5ts j giv51 x %\ld be rememb]$ t ! p]man5t magnets are s5d+ out ?\s&s ( l9es ( =ce f _! ,n poles1 & receiv+ !m aga9 at _! ,s poles4 ,z ! magnet is pu%$ into ! coil 7,exp4 #age71 ! l9es ( =ce n only cut ?r\gh ! turns ( ! coil1 b ! numb] ( l9es ( =ce t cut ! coil at any in/ant v>ies rapidly z ! magnet is mov$4 ,motion is necess>y1 ) ?is arrangem5t1 to make a *ange 9 ! numb] ( cutt+ l9es ( =ce4 ,! curr5t passes only :ile ! magnet moves2 & ! direction ( ! curr5t at any mom5t dep5ds ^u :e!r ! numb] ( l9es ( =ce is increas+ or decreas+ at t mom5t4 7,see #dch1 #dci47 ,illu/ration3 ,fig4 #ach4 ,,exp]im5t #agh4 ,to f9d :e!r a curr5t c be g5]at$ ) an electromagnet & a holl[ coil ( wire4 #dcc4 ,directions4 7,a7 ,! holl[ coil 7,no4 #ij7 %\ld be jo9$ to ! a/atic galvanoscope1 z %[n 9 ,fig4 #acf4 ,in/ead ( ! b> magnet 9 ,fig4 #acf1 an electromagnet is to be us$1 & ?is %\ld be jo9$ 9 s]ies ) a cell & key1 z %[n 9 ,fig4 #ach4 ,! curr5t f ! cell w pass only :5 ,k is press$4 7,b7 ,note f ! w9d+ :i* way ! curr5t mu/ pass ar\nd ! coil :5 ! circuit is clos$ at ,k1 & det]m9e :e!r ! l[] end ( ! long iron core1 ,l ,i ,c 7,no4 #if7 %\ld be ,n or ,s4 ,) ! compass te/ ! poles ( ! core to be sure y are "r4 7,c7 ,quickly l[] ! end ( ,l ,i ,c into ! holl[ coil 7,h1 ,fig4 #acf71 ! circuit be+ kept clos$ long en\gh to all[ ! ne$le to p>tially come to re/ aga94 ,)draw ,l ,i ,c be=e y op5 ! circuit4 ,expla9 action ( ne$le4 7,d7 ,rev]se ! direction ( ! curr5t ?r\gh ! electromagnet1 by *ang+ ! connections1 & repeat 7,c74 ,does any induc$ curr5t pass ?r\gh ,a ,g :5 ! core is held /ill 9 ! coil ,h1 ev5 ?\gh a curr5t passes ?r\gh coil ,e8 ,illu/ration3 ,fig4 #aci4 ,,exp]im5t #agi4 ,to f9d :e!r a curr5t c be g5]at$ ) an electromagnet & a coil ( wire hav+ an iron core4 #dcd4 ,directions4 7,a7 ,fig4 #aci %[s simply ! arrangem5t ( coils4 ,coil ,h 7,no4 #ij7 ) core1 is jo9$ to ! galvanoscope z 9 ,fig4 #acf4 ,coil ,e1 ) %ort core1 %\ld be jo9$ to key & cell z %[n 9 ,fig4 #ach4 7,b7 ,keep+ 9 m9d ! pol>ity ( ! l[] end ( core ,e1 quickly l[] x to ! core ( ,h1 ! circuit be+ kept clos$ = a few seconds4 ,does ! ne$le rema9 deflect$ aft] ! motion ceases8 7,c7 ,quickly raise ,e1 ! circuit be+ /ill clos$1 !n op5 ! circuit4 ,comp>e ! directions tak5 by ! induc$ curr5ts 9 7,b7 & 7,c74 #dce4 ,discussion ( ,exps4 #agh1 #agi4 ,?is motion 9 /raight l9es is n suitable = produc+ curr5ts /rong en\gh = comm]cial purposes4 ,9 ord] to produce curr5ts ( consid]able /r5g?1 ! coils ( wire h to be pu%$ pa/ magnets ) great spe$4 ,special ma*9es 7see ,dynamos7 are con/ruct$ 9 :i* ! coils are w\nd s t !y c be giv5 a rapid rot>y motion z !y fly pa/ /rong electromagnets4 ,9 ?is way ! coil c keep on pass+ ! same magnets1 9 ! same direction1 z long z =ce is appli$ to ! %aft t c>ries !m4 ,illu/ration3 ,fig4 #adj4 ,,exp]im5t #ahj4 ,to /udy ! effect ( />t+ or /opp+ a curr5t ne> a coil ( wire or o!r clos$ circuit4 #dcf4 ,directions4 7,a7 ,arrange z 9 ,fig4 #adj4 ,place ! two coils1 ,h & ,e1 on ! same core1 ,l ,i ,c4 ,connect ,e ) ! key & cell z be=e 7,fig4 #ach74 ,connect ,h ) ! a/atic galvanoscope1 ,a ,g1 z 9 ,fig4 #acf4 ,keep ! coils #b or #c feet f ,a ,g1 s t ! ne$le w n be affect$ by !m4 7,b7 ,close ! circuit at ! key1 wat*+ ! ne$le1 !n z soon z ! ne$le rega9s its =m] position1 op5 ! circuit aga94 ,comp>e ! direction ( ! induc$ curr5t 9 ,h ) t ( ! curr5t 9 ,e1 7#a7 :5 ! ma9 circuit is clos$1 & 7#b7 :5 x is op5$4 ,is any curr5t induc$ 9 ,h by a /eady curr5t 9 ,e8 7,see ,trans=m]s47 ,illu/ration3 ,fig4 #ada4 ,,exp]im5t #aha4 ,to /udy ! effect ( />t+ or /opp+ a curr5t 9 a coil plac$ inside ( ano!r coil4 #dcg4 ,directions4 7,a7 ,arrange z 9 ,fig4 #ada4 ,jo9 coil ,h ) ! a/atic galvanoscope1 ,a ,g4 ,place ! small coil ,p 7,no4 #ih7 ) core1 inside ( ,h1 & connect ! ends ( ,p ) ! key & cell1 z %[n4 7,b7 ,close ! circuit at ,k2 wat* ! ne$le1 & z soon z x rega9s its position1 op5 ! circuit aga94 ,comp>e ! direction ( ! induc$ curr5t 9 ,h ) t ( ! induc+ curr5t 9 ,p1 7#a7 :5 ! induc+ circuit is clos$1 & 7#b7 :5 x is brok54 7,see ,induction ,coils47 #dch4 ,discussion ( ,exps4 #ahj1 #aha4 ,:5 a curr5t sudd5ly beg9s to fl[ ?r\gh a coil1 ! effect ^u a neighbor+ coil is ! same z t produc$ by sudd5ly br++ a magnet ne> x2 & :5 ! curr5t /ops1 ! opposite effect is produc$4 ,we may consid] t :5 ! induc+ circuit is clos$1 ! l9es ( =ce %oot out ?r\gh ! turns ( ! outside coil4 ,^u op5+ ! circuit ! l9es ( =ce cease to exi/2 t is1 we may imag9e !m drawn 9 aga94 ,illu/ration3 ,fig4 #adb4 #dci4 ,direction ( ,induc$ ,curr5t4 ,fig4 #adb %[s ! magnet on its way into ! coil2 ! numb] ( l9es ( =ce is increas+ 9 ! coil1 & ! induc$ curr5t passes 9 an anti-clockwise direction :5 look+ d[n into ! coil along ! l9es ( =ce4 ,?is produces an indirect curr5t4 ,if a curr5t f a cell 7 pass$ ?r\gh ! coil 9 ! direction ( ?is indirect curr5t1 ! l[] end ( a b> ( iron w\ld become a ,s pole4 7,see #dbh47 #ddj4 ,laws ( ,induction4 7#a7 ,an increase 9 ! numb] ( l9es ( =ce t pass ?r\gh a clos$ circuit produces an indirect induc$ curr5t2 :ile a decrease produces a direct "o4 7,see #dbh47 7#b7 ,! ,e4 ,m4 ,f4 ( ! induc$ curr5t is equal to ! rate ( increase or decrease 9 ! numb] ( l9es ( =ce t pass ?r\gh ! circuit4 7#c7 ,a con/ant curr5t produces no induc$ curr5t1 provid$ !re is no motion4 7#d7 ,clos+ a circuit produces an indirect curr5t4 7#e7 ,op5+ a circuit produces a direct curr5t4 7#f7 ,l5z's ,law4 ,induc$ curr5ts h a direction t t5ds to /op ! motion t produces !m4 #dda4 ,prim>y & ,second>y ,curr5ts4 ,9 ! prec$+ exp]im5ts 9 induction1 x mu/ be kept 9 m9d t ! curr5t f ! cell did n pass ?r\gh ! galvanoscope4 ,!re 7 two entirely sep>ate circuits1 9 no way connect$4 ,! prim>y curr5t comes f ! cell1 :ile ! second>y curr5t is an induc$ "o4 ,illu/ration3 ,fig4 #adc4 ,,exp]im5t #ahb4 ,to see :at is meant by alt]nat+ curr5ts4 #ddb4 ,directions4 7,a7 ,arrange z 9 ,fig4 #adc4 ,connect coil ,h ) ,a ,g1 z be=e4 ,place "o pole ( ,h ,m aga9/ ! end ( ! core ,i ,c1 hold ,h ) "o h&1 & ) ! o!r quickly pu% ! o!r pole ( ,h ,m onto ! core4 ,?is %\ld produce a mom5t>y curr5t ?r\gh ,a ,g1 fir/ 9 "o direction1 & !n 9 ! o!r4 ,let ! ne$le come to re/4 7,b7 ,move ,h ,m back & =? ^u ! end ( ,i ,c1 *ang+ its pol>ity rapidly4 ,a m9ute's practice w enable y to slide ! core f "o pole ( ,h ,m to ! o!r & back aga9 rapidly--#c complete vibrations p] second be+ ab\t "r4 ,! ne$le %\ld be p>allel to ! coil ( ,a ,g1 & if prop]ly done1 ! ne$le w be made to vibrate back & =? slightly at ea* *ange 9 ! pol>ity ( ,i ,c4 #ddc4 ,direct & ,alt]nat+ ,curr5ts4 ,a curr5t t fl[s /eadily 9 "o direction is said to be a direct curr5t4 ,a cell gives a direct curr5t :5 ! circuit is clos$4 ,:5 ! curr5t passes 9 "o direction = an in/ant1 & !n rev]ses imm$iately & fl[s 9 ! opposite direction1 x is said to alt]nate4 ,! induc$ curr5t :i* fl[$ ?r\gh ! galvanoscope 9 ,exp4 #ahb 0 an alt]nat+ "o4 ,curr5ts ( ?is class h great practical uses4 #ddd4 ,self-,induction2 ,extra ,curr5ts4 ,x has be5 %[n t a magnetiz$ coil c act ?r\gh space & induce a curr5t 9 a neighbor+ coil4 ,! l9es ( =ce :i* rea* out f an electromagnet w g5]ate a curr5t 9 any conductor :i* happ5s to be 9 ! field1 or :i* is mov$ across ! l9es4 ,x is evid5t1 !n1 s9ce ! l9es ( =ce f ea* turn ( a coil cut all ! o!r turns ( ! same coil1 t ea* turn acts z a conductor plac$ 9 ! field ( e o!r turn4 ,! in/ant a curr5t beg9s to fl[ ?r\gh a coil1 !re is an inv]se curr5t ( self-induction />t$ 9 ! coil1 :i* opposes ! curr5t 9 ! cell4 ,:5 ! circuit is brok51 ?is extra curr5t1 z x is also call$1 is a direct "o & adds its /r5g? to t ( ! curr5t f ! cell2 z ?is takes place at ! in/ant ! circuit is brok51 a bright sp>k is se5 at ! key1 & ?is %[s t ! ,e4 ,m4 ,f4 ( ?is extra curr5t is high4 ,practical uses are made ( x4 ,,*apt] ,,xxvi4 ,,! ,,production ,,( ,,motion ,,by ,,curr5ts4 #dde4 ,curr5ts & ,motion4 ,we h se51 9 ! exp]im5ts on induc$ curr5ts1 t a curr5t ( electricity c be g5]at$ by prop]ly mov+ magnets ne> coils ( wire4 7,see ,dynamo-electric ,ma*9es47 ,c we rev]se ?is process8 ,c motion be produc$ by ! electric curr5t8 ,,exp]im5ts #ahc-aij4 ,to /udy ! production ( motion by means ( ! electric curr5t4 ,app>atus4 ,! support1 includ+ base1 rod1 & support wire1 ,s ,w 7,fig4 #add47 ,coils ( wire 7,no4 #hi1 #ij72 iron cores = coils2 cell2 key2 connect+ wires2 compass2 curr5t rev]s]2 b> magnet2 horse%oe magnet4 ,illu/ration3 ,fig4 #add4 ,,exp]im5t #ahc4 ,motion produc$ ) a holl[ coil & a piece ( iron4 #ddf4 ,directions4 7,a7 ,arrange z 9 ,fig4 #add4 ,coil ,h 7,no4 #ij7 is to be us$ z a p5dulum1 & c be support$ by fa/5+ a /r+ to x1 ! upp] end ( :i* %\ld be ti$ to ,s ,w4 ,connect ! ends ( ,h ) ,k & ,d ,c4 ,!re w be a slight magnetic field ab\t ,h z soon z ! circuit is clos$4 7,b7 ,hold ,i ,c ne> ! end ( ! coil4 ,close ! circuit = an in/ant4 ,is !re any motion produc$ 9 ,h8 ,:ile ! motion w be slight1 !re %\ld be en\gh to be notic$ if ! cell is /rong4 7,c7 ,sw+ ! susp5d$ coil back & =? l a p5dulum = a m9ute1 until y get 9 m9d ! rapidity ( its vibrations4 ,/op x1 !n repeat 7,b71 clos+ & op5+ ! circuit at regul> int]vals1 s t ! little impulses giv5 by ! attraction = ,i ,c w gradually cause ,h to vibrate4 ,! wires lead+ f ,h %\ld n drag ^u ! table4 ,,exp]im5t #ahd4 ,motion ) holl[ coil & b> magnet4 #ddg4 ,directions4 7,a7 ,sub/itute ! b> magnet ,m 7,no4 #ig7 = ! iron ( ,exp4 #ahc 7,fig4 #add74 ,get cle>ly 9 m9d ! pol>ity ( ! coil f ! way ! curr5t fl[s ?r\gh x1 !n te/ x ) ! compass to f9d :e!r y are "r4 7,b7 ,hold ! ,n pole ( ,m ne> ! left-h& end ( ! coil1 close ! circuit = an in/ant & /udy results4 7,c7 ,rev]se ! magnet & repeat 7,b74 ,comp>e ! results ) ^? ( ,exp4 #ahc4 ,try to make ! coil vibrate4 ,,exp]im5t #ahe4 ,motion ) electromagnet & piece ( iron4 #ddh4 ,directions4 7,a7 ,arrange z describ$ 9 ,exp4 #ahc1 ,fig4 #add4 ,place a %ort core inside ( ! coil & repeat4 7,see #ddf = directions47 ,:y is ! motion produc$ mu* l>g] ?an t giv5 by a holl[ coil8 7,b7 ,! coil c gradually be made to sw+ ?r\gh q a little space by clos+ & op5+ ! circuit regul>ly 7 #ddf1 ,c74 ,c\ld any use be made ( su* a motion1 if x 7 on a l>ge scale8 ,c\ld x be made to run a ma*9e8 ,illu/ration3 ,fig4 #ade4 ,,exp]im5t #ahf4 ,motion ) electromagnet & b> magnet4 #ddi4 ,directions4 7,a7 ,arrange z 9 ,fig4 #ade1 ! coil be+ susp5d$ & connect$ z 9 ,exp4 #ahc 7,fig4 #add74 7,b7 ,/udy ! effect ( clos+ ! circuit :5 ! ,n pole ( ,m is held ne> ! core ( ,h4 ,rev]se ,m1 & repeat4 ,illu/ration3 ,fig4 #adf4 ,,exp]im5t #ahg4 ,motion ) electromagnet & horse%oe magnet4 #dej4 ,directions4 7,a7 ,arrange z 9 ,fig4 #adf4 ,! ends ( ,h 7,no4 #hi7 are jo9$ to ,x & ,y ( ! curr5t rev]s] ,c ,r 7,no4 #eg74 ,x is evid5t1 !n1 t ! direction ( ! curr5t ?r\gh ,h c be easily & rapidly rev]s$ by ,c ,r4 7,see ,exp4 #ajc47 ,ei!r pole ( ! horse%oe magnet ,h ,m w attract ,i ,c :5 x is n magnetiz$4 7,b7 ,place ! end ( ,i ,c ne> ! ,n pole ( ,h ,m s t x w be attract$ to x4 ,y h le>n$ t l poles repel ea* o!r1 s press ! lev] ( ,c ,r t w produce a ,n pole at ! left-h& end ( ,i ,c4 ,! core ,i ,c %\ld be repell$ by ! ,n pole ( ,h ,m & be in/antly attract$ by its ,s pole4 7,c7 ,rapidly rev]se ! curr5t & make ,i ,c jump back & =? f "o pole to ! o!r4 ,! results ( ?is exp]im5t %\ld be rememb]$1 z !y w aid 9 und]/&+ motors4 ,a core #a_/d 94 9 diamet] c be plac$ 9 betwe5 ! poles & be made to vibrate rapidly z ! curr5t is rev]s$4 ,illu/ration3 ,fig4 #adg4 ,,exp]im5t #ahh4 ,motion ) two electromagnets4 #dea4 ,directions4 7,a7 ,arrange z 9 ,fig4 #adg4 ,jo9 ! two coils1 ,h & ,e1 9 p>allel4 ,connect _! two outside ends ,o ,e to a metal plate ,a1 & _! inside ends ,i ,e to ,b4 ,jo9 wires #a & #f to ,k1 ,d ,c1 ,a & ,b1 z %[n4 ,:5 ! circuit is clos$ at ,k1 ! curr5t w pass along wire #a & divide at ,a1 ent]+ ,e & ,h at ! same "t by wires #b & #d & return+ ?r\gh #c & #e to ,b1 & !nce to ,d ,c4 7,b7 ,close ! circuit = an in/ant ) wires arrang$ z 9 ,fig4 #adg4 ,d ! electromagnets attract or repel ea* o!r8 ,/udy out ! direction 9 :i* ! curr5t passes ar\nd ! coils1 & see :e!r !y %\ld attract or repel4 7,c7 ,*ange wire #d to ,b1 & wire #e to ,a4 ,! pol>ity ( ,h1 only1 w be *ang$ :5 ?is circuit is clos$4 ,press ! key = an in/ant & /udy ! results4 #deb4 ,discussion ( ,exps4 #ahc-ahh4 ,f ! results x is evid5t t motion c be produc$ ) ! aid ( ! electric curr5t 9 _m diff]5t ways4 ,x c be produc$ at ! ends ( wires :i* simply rea* across ! room1 or :i* rea* miles f ! s\rce ( ! curr5t4 ,to get practical results = comm]cial purposes we require a prop] s\rce ( curr5t1 prop] conductors1 & prop] app>atus to conv]t ! motions into useful "w4 ,! motions giv5 to ! p>ts ( ! app>atus 9 ! previ\s exp]im5ts are n suitable = comm]cial purposes1 z !y are 9 /raight l9es4 ,a rot>y motion is ne$$ to d good "w2 & :5 ?is is appli$ to a %aft1 belts c be us$ to run all sorts ( ma*9]y4 7,see ,electric ,motors47 ,illu/ration3 ,fig4 #adh4 ,,exp]im5t #ahi4 ,rot>y motion ) a holl[ coil ( wire & a p]man5t magnet4 #dec4 ,directions4 7,a7 ,arrange z 9 ,fig4 #adh4 ,a key c be us$ in/ead ( ! rev]s]4 ,! coil ( ! galvanoscope1 ,g ,v1 has a magnetic field ab\t x :5 ! circuit is clos$4 ,! ne$le has a p]man5t field4 7,b7 ,close ! circuit = an in/ant1 let ! ne$le sw+ back pa/ ! z]o m>k1 close ! circuit aga91 etc41 until ! add$ impulses give ! ne$le a complete turn4 7,c7 ,keep ! ne$le turn+ on its axis by op5+ & clos+ ! circuit at ! prop] "t4 ,) a little practice y c make x turn rapidly4 7,d7 ,rev]se ! motion ( ! ne$le4 7,see #dee47 ,illu/ration3 ,fig4 #adi4 ,,exp]im5t #aij4 ,rot>y motion ) an electromagnet & a p]man5t magnet4 #ded4 ,directions4 7,a7 ,arrange z 9 ,fig4 #adi4 ,place ! compass a %ort di/ance f ! end ( ! core ( ! coil ,h 7,no4 #hi74 ,close ! circuit1 & z soon z ! ne$le gets "p way ar\nd op5 x aga91 clos+ x at ! prop] "t to give ! ne$le a new impulse4 ,! spe$ c be regulat$1 some:at1 by *ang+ its di/ance f ! core4 ,a key may be us$ 9 place ( a rev]s]4 7,b7 ,rev]se ! direction ( rotation4 #dee4 ,discussion ( ,exps4 #ahi-aij4 ,we h1 9 ^! exp]im5ts1 ! key to ! action ( electric motors4 ,by prop]ly op5+ & clos+ ! circuit1 ! rot>y motion c be kept up z long z curr5t is suppli$4 ,if a small pulley 7 atta*$ to ! top ( ! compass-ne$le 9 ,exp4 #aij1 a t9y belt c\ld be atta*$1 & we %\ld h a ma*9e t c\ld d1 p]haps1 a fly-p[] ( "w4 7,see ,electric ,motors47 ,,*apt] ,,xxvii4 ,,applications ,,( ,,electricity4 #def4 ,?+s ,electricity ,c ,d4 ,among ! almo/ c\ntless ?+s t electricity c d are ! foll[+3 ,x signals )\t wires4 ,x drills rock1 coal1 & tee?4 ,x cures diseases & kills crim9als4 ,x protects1 heats1 & v5tilates h\ses4 ,x photographs ! bones ( ! human body4 ,x r+s *ur* bells & plays *ur* organs4 ,x lights /reets1 c>s1 boats1 m9es1 h\ses1 etc4 ,x pumps wat]1 cooks food1 & fans y :ile eat+4 ,x runs all sorts ( ma*9]y1 elevators1 c>s1 boats1 & wagons4 ,x s5ds messages ) ! telegraph1 telephone1 & se>*-light4 ,x cuts clo?1 irons clo!s1 wa%es di%es1 black5s boots1 welds metals1 pr9ts books1 etc41 etc4 ,z ?is book deals almo/ exclusively ) exp]im5ts1 to be p]=m$ ) simple1 home-made app>atus1 space _c be giv5 = a discussion ( ! _m in/rum5ts & ma*9es :i* make electricity a practical e-day ?+4 7,see ,?+s ,a ,boy ,%\ld ,"k ,ab\t ,electricity47 ,! pr9ciples ^u :i* a few important in/rum5ts dep5d1 h[ev]1 w be giv54 ,illu/ration3 ,fig4 #aej4 ,,exp]im5t #aia4 ,to /udy ! action ( a simple telegraph s\nd]4 #deg4 ,directions4 7,a7 ,arrange z 9 ,fig4 #aej4 ,! electromagnet is support$ ^u its base1 z direct$ 9 #djg4 ,coil ,h1 ,k1 & ,d ,c are jo9$ 9 s]ies4 ,! iron /rip1 ,i1 c be held by ! left h&1 :ile ,k is work$ ) ! "r4 7,b7 ,press ! key1 clos+ ! circuit = diff]5t l5g?s ( "t1 & note t ! armature1 ,i1 responds exactly to ! motions at ,k4 #deh4 ,discussion4 ,! d[nw>d click makes a di/9ct s\nd1 & 9 regul> in/rum5ts ! armature is all[$ to make an upw>d click1 also4 ,! "t betwe5 ! two clicks c be %ort or long to repres5t dots or da%es1 :i*1 toge!r ) spaces1 repres5t lett]s4 7,= telegraph alphabet1 & complete directions = mak+ & connect+ a home-made telegraph l9e1 see ,app>atus ,book47 ,illu/ration3 ,fig4 #aea4 #dei4 ,telegraph ,l9e2 ,connections4 ,fig4 #aea %[s complete connections = a home-made telegraph l9e4 ,! capital lett]s are us$ = ! "r side1 ,r1 & small lett]s = ! left side1 ,l4 ,gravity cells1 ,b & b1 are us$4 ,! s\nd]s ,s & s1 & ! keys1 ,k & k1 are %[n by a top view1 or plan4 ,! broad black l9es ( ,s & s repres5t ! armatures1 :i* are directly ov] ! electromagnets4 ,! keys h swit*es1 ,e & e4 ,! two /ations1 ,r & ,l1 may be ne> ea* o!r or 9 diff]5t h\ses4 ,! return wire1 ,r ,w1 passes f ! copp] ( b to ! z9c ( ,b4 ,?is is important1 z ! cells mu/ help ea* o!r2 t is1 !y are 9 s]ies4 ,! l9e wire1 ,l ,w1 passes f "o /ation to ! o!r1 & ! return may be ?r\gh a wire1 ,r ,w1 or ?r\gh ! e>?2 b = %ort l9es a return wire is be/4 #dfj4 ,op]ation ( ,l9e4 ,suppose ,r 7"r7 & ,l 7left7 h a l9e4 ,fig4 #aea %[s t ,r's swit*1 ,e1 is op51 :ile e is clos$4 ,! entire circuit1 !n1 is brok5 at b "o po9t4 ,z soon z ,r presses 8 key1 ! circuit is clos$1 & ! curr5t f bo? cells ru%es ar\nd f ,b ?r\gh ,k1 ,s1 ,l ,w1 s1 k1 b1 ,r ,w & back to ,b4 ,?is makes ! armatures ( ,s & s come d[n ) a click at ! same "t4 7,see ,exp4 #aia47 ,z soon z ! key is rais$1 ! armatures raise1 mak+ ! up-click4 7,see #deh47 ,z soon z ,r has f9i%$1 he closes 8 swit*1 ,e4 ,l !n op5s e & answ]s ,r4 ,bo? ,e & e are clos$ :5 ! l9e is n 9 use1 s t ei!r c op5 8 swit* at any "t & call up ! o!r4 ,clos$ circuit cells are us$ = su* l9es4 ,on l>ge l9es ! curr5t f a dynamo is us$4 ,illu/ration3 ,fig4 #aeb4 ,,exp]im5t #aib4 ,to /udy ! action & use ( ! relay on telegraph l9es4 #dfa4 ,directions4 7,a7 ,arrange z 9 ,fig4 #aeb4 ,place ,k & ,d ,c at "o end ( ! table to repres5t ! s5d+ /ation4 ,at ! o!r end ( ! table place ,e1 :i* is ! electromagnet ( ! relay1 & ,h1 ! electromagnet ( ! s\nd]4 ,connect ! ends ( ,e ) ,k & ,d ,c1 ,l ,w be+ ! l9e wire1 & ,r ,w ! return4 ,9 practice1 ! return is ?r\gh ! e>?4 ,! relay armature1 ,r ,a1 %\ld vibrate t[>ds ,e e "t ,k is press$4 ,c is a piece ( copp] aga9/ :i* ,r ,a presses ea* "t x is attract$ by ,e1 & ?is closes :at is call$ ! local circuit4 ,connect ! poles ( ano!r batt]y1 ,l ,b1 ) ,c & ,h1 & ! o!r end ( coil ,h ) ,r ,a4 ,! s\nd] armature1 ,s ,a1 %\ld be arrang$ z 9 ,exp4 #aia4 ,small spr+s are %[n on ! two armatures1 & ^! keep !m away f ! cores :5 ! circuits are op54 7,b7 ,fa/5 ! p>ts to a bo>d1 & /udy ! connections & action ( ?is home-made outfit4 #dfb4 ,! ,relay replaces ! s\nd] 9 ! l9e wire circuit1 & its coils are usually w\nd ) _m turns ( f9e wire1 s t a feeble curr5t w move its nicely adju/$ armature4 ,ow+ to ! l>ge resi/ance ( long telegraph l9es1 ! curr5t is weak :5 x rea*es a di/ant /ation1 & n /rong en\gh to "w an ord9>y s\nd]4 ,! curr5t passes back f ! relay to ! s5d+ /ation ?r\gh ! e>?4 ,! relay armature acts z an automatic key to op5 & close ! local circuit1 :i* includes also a batt]y & s\nd]4 ,! l9e curr5t does n ent] ! s\nd]4 7,see ,?+s ,a ,boy ,%\ld ,"k ,ab\t ,electricity47 ,illu/ration3 ,fig4 #aec4 ,,exp]im5t #aic4 ,to /udy ! action ( a two-pole telegraph in/rum5t4 #dfc4 ,directions4 7,a7 ,arrange z 9 ,fig4 #aec4 ,connect ! two coils to ! connect+ plates1 z describ$ 9 #djh4 ,jo9 a /rip ( copp] ,cu ) wire #b lead+ f ,d ,c1 & jo9 ! z9c ( ,d ,c to ,m4 ,! ends ( wires #a & #c %\ld be ne> ,cu b !y mu/ n t\* x4 ,if ,cu be slightly curv$ s t its ends are rais$ above ! table1 ! ends ( wires #a & #c may be put directly "u ! ends ( ,cu2 ea* half ( ,cu c !n be us$ z a key4 ,two armatures1 ,a & ,b1 %\ld be held z %[n4 ,d ,c c be plac$ at "o side1 ( c\rse1 its t]m9als be+ jo9$ to ,m & ,cu4 7,b7 ,press fir/ "o end & !n ! o!r ( ,cu1 s t ! curr5t w pass ?r\gh ,h or ,e at w4 7,c7 ,pa/e pieces ( pap] to ! armatures1 ! left "o be+ m>k$ ) a dot1 & ! o!r ) a da%4 ,! "o :o s5ds ! message c make dots or da%es at ! in/rum5t by press+ ! prop] key4 ,?is =m ( in/rum5t c be easily made by boys1 & ! messages are m easily read by ! eye ?an by ! e>1 z 9 regul> s\nd]s4 ,illu/ration3 ,fig4 #aed4 ,,exp]im5t #aid4 ,to /udy ! action ( a simple s+le ne$le telegraph in/rum5t4 #dfd4 ,directions4 7,a7 ,arrange z 9 ,fig4 #aed4 ,/ick a p9 on ea* side ( ! ,n pole ( ! galvanoscope-ne$le ?r\gh ! degree-c>d1 s t ! ne$le c make b "p ( a turn :5 ! circuit is clos$4 7,b7 ,t\* "o lev] ( ! rev]s] ,c ,r1 !n ! o!r1 to see :e!r connections are "r4 ,! ne$le %\ld be =c$ aga9/ "o p9 & !n aga9/ ! o!r4 ,if motions to ! left repres5t dots1 & ^? to ! "r da%es1 comb9ations ( dots & da%es c be us$ = lett]s z 9 ! s\nd] 7,exp4 #aia74 7,c7 ,arrange ! app>atus %[n 9 ,fig4 #abb s t messages c be s5t4 ,illu/ration3 ,fig4 #aee4 ,,exp]im5t #aie4 ,to /udy ! action ( a simple automatic contact break]1 or curr5t int]rupt]4 #dfe4 ,directions4 7,a7 ,arrange z 9 ,fig4 #aee4 ,slip a spr+ connector atta*$ to wire #a ^u ! iron /rip ,i1 a %ort di/ance f its end4 ,hold ! left-h& end ( ,i firmly 9 "o h&1 & ) ! o!r hold ! connector on wire #b j above t on #a4 ,! "r-h& end ( ,i %\ld be j above ! core ( ,h4 7,b7 ,all[ ! curr5t to pass ?r\gh ! circuit by t\*+ ! two connectors toge!r g5tly4 ,does ! armature make "o click1 z 9 ! telegraph s\nd]1 or does x vibrate rapidly8 7,c7 ,try ! connectors 9 v>i\s positions on ,i4 #dff4 ,automatic ,curr5t ,int]rupt]s are us$ on bells1 buzz]s1 induction coils1 etc4 ,! pr9ciple ^u :i* !y "w is %[n 9 ! above exp]im5t 7,fig4 #aee74 ,! curr5t1 z x comes f ! c>bon ( ,d ,c1 is oblig$ to /op :5 x rea*es ,i1 unless ! two connectors t\*4 ,z soon z ! curr5t passes1 ,i is pull$ d[n & away f ! upp] connector1 & ?is breaks ! circuit4 ,i1 be+ held firmly 9 ! h&1 imm$iately spr+s back to its =m] position1 clos+ ! circuit4 ,! rapidity ( ! vibrations dep5ds some:at ^u ! position ( ! connectors ^u ,i4 ,9 regul> in/rum5ts1 a plat9um po9t is us$ :]e ! circuit is brok52 ?is /&s ! con/ant sp>k+ at t po9t4 ,illu/ration3 ,fig4 #aef4 ,,exp]im5t #aif4 ,to /udy ! action ( a simple electric bell1 or a buzz]4 #dfg4 ,directions4 7,a7 ,fig4 #aef %[s ! circuit expla9$ 9 ,exp4 #aie1 ) a key or pu%-button put 91 s t ! circuit c be clos$ at a di/ance f ! vibrat+ armature4 7,b7 ,h a fri5d "w ! key :ile y hold ,i & wires #a & #b z direct$ 9 ,exp4 #aie4 ,! circuit mu/ n be brok5 at two places1 ( c\rse1 s beg9 by hold+ ! two connectors toge!r4 ,! armature %\ld vibrate rapidly ea* "t ,k is press$4 #dfh4 ,electric ,bells & ,buzz]s are v ne>ly alike 9 con/ruction2 9 fact1 y w h a buzz] by remov+ ! bell f an ord9>y electric bell4 ,buzz]s are us$ 9 places :]e ! l\d s\nd ( a bell w\ld be objectionable4 ,by plac+ a bell ne> ! end ( ! vibrat+ armature 7,fig4 #aef71 s t ! bell w\ld be /ruck by x at ea* vibration1 we %\ld h an electric bell4 ,by mak+ ! wires #a & #c long1 ! bell or buzz] c be work$ at a di/ance4 7,see ,app>atus ,book1 ,*apt] ,,xv1 = ,home-made ,bells & ,buzz]s47 ,illu/ration3 ,fig4 #aeg4 ,,exp]im5t #aig4 ,to /udy ! action ( a simple telegraph record]4 #dfi4 ,directions4 7,a7 ,cut f a t9 box1 or c1 a piece ( t9 ab\t #d 94 long & #a-a_/b 94 wide4 ,b5d ?is d\ble to make two ?icknesses4 ,?is w s]ve z an armature ,i 7,fig4 #aeg74 ,nail to "o end ( ,i a small spool1 ,s1 & into ?is put a %ort l5g? ( lead-p5cil1 ,p1 :i* may be held firmly 9 ,s by wrapp+ a little pap] ar\nd x4 ,connect ! ends ( coil ,h to a key & cell z 9 ,fig4 #aef4 7,b7 ,hold or fa/5 ,i 9 place1 & h a fri5d make dots & da%es at ! key1 :ile y draw a piece ( pap] pa/ ! end ( ,p4 ,a little adju/+ w be necess>y to get ! p5cil to write only :ile ! circuit is clos$4 ,9 regul> ma*9es all ! p>ts are automatic4 ,illu/ration3 ,fig4 #aeh4 ,,exp]im5t #aih4 ,to /udy ! action ( a simple annunciator4 #dgj4 ,directions4 7,a7 ,arrange z 9 ,fig4 #aeh4 ,fa/5 ! two electromagnets1 ,h & ,e1 to a bo>d or a piece ( /iff c>dbo>d4 ,!y may be held 9 place by pass+ /r+s ov] !m & ?r\gh ! bo>d1 ty+ on ! o!r side4 ,! ends ( coils ,h & ,e %\ld be jo9$ to pieces ( t91 ,a1 ,b1 ,c1 by means ( connectors4 ,k & ,k are keys or pu%-buttons1 :i* 9 real in/rum5ts are 9 diff]5t rooms4 ,two /eel p5s may be swung on p9s a %ort di/ance f ! ends ( ! cores1 s t _! l[] ends w be attract$ to ! cores ! in/ant ! curr5t passes ?r\gh !m4 ,! residual magnetism %\ld hold !m aga9/ ! cores until remov$4 ,hairp9s1 nails1 or ne$les c be us$ in/ead ( p5s4 7,b7 ,press fir/ "o ,k & !n ! o!r to see :e!r y\r connections are correct4 #dga4 ,annunciators4 ,!re are _m =ms ( annunciators 9 use to indicate1 9 a hotel = example1 a c]ta9 room :5 a bell r+s at ! (fice4 ,if a bell be includ$ 9 ! circuit betwe5 ,d ,c & ,a 9 ,fig4 #aeh1 x w r+ ea* "t a key is pu%$4 ,?is w call att5tion to ! fact t "s "o has rung1 & ! annunciator w %[ ! location ( ! special call4 ,l>ge in/rum5ts are made ) hundr$s ( electromagnets1 ea* "o answ]+ to a special room4 ,! in/rum5t %\ld be set1 ( c\rse1 aft] ea* call4 ,a nail or screw w\nd ) insulat$ wire c be us$ = ! electromagnets ( a home-made annunciator4 ,,exp]im5t #aii4 ,to /udy ! %ock+ effects ( ! extra curr5t4 #dgb4 ,directions4 7,a7 ,use ! two electromagnets jo9$ to ! connect+ plates 7,fig4 #acb71 to g5]ate a self-induc$ or extra curr5t4 ,connect ,r ( ,fig4 #acb ) ! z9c ( a dry cell1 & betwe5 ,l & ! c>bon ( ! cell place a key2 9 o!r words1 jo9 ! electromagnets1 cell1 & key 9 s]ies4 ,two good cells 9 s]ies c be us$ to advantage4 7,b7 ,wet ! ends ( two f+]s ( ! left h&1 press "o ^u ,l & ! o!r on ,r1 ?us mak+ a %unt ) y\r h&4 ,) ! "r h& "w ! key rapidly4 ,if ! curr5t is /rong en\gh y %\ld feel a slight %ock 9 ! f+]s ea* "t ! circuit is brok54 ,! extra curr5t 7 #ddd7 causes ! %ock z x %oots ?r\gh ! f+]s4 7,c7 ,if y h electric bells or telegraph s\nd]s use !m = ?is exp]im5t4 #dgc4 ,induction ,coils are in/rum5ts = produc+ induc$ curr5ts ( high ,e4 ,m4 ,f4 ,! app>atus %[n 9 ,fig4 #ada =ms a simple induction coil4 ,! prim>y coil is made ( co>s] wire & has less turns ( wire ?an ! second>y coil4 ,! curr5t 9 ! prim>y circuit is usually int]rupt$ by an automatic int]rupt] 7,exp4 #aie71 ?us produc+ an alt]nat+ curr5t 9 ! second>y coil1 ! voltage ( :i* dep5ds ^u ! relative numb] ( turns 9 ! two coils4 ,induction coils are us$ 9 telephone "w1 = m$ical purposes1 = ,x-ray "w1 etc41 etc4 7,= ,home-made ,induction ,coils see ,app>atus ,book1 ,*apt] ,,xi47 ,illu/ration3 ,fig4 #aei4 #dgd4 ,action ( ,induction ,coils4 ,fig4 #aei %[s a top view ( "o ( ! home-made induction coils describ$1 9 full1 9 ! ,app>atus ,book4 ,wires #e & #f are ! ends ( ! prim>y coil1 :ile wires #g & #h are ! t]m9als ( ! second>y coil4 ,! batt]y wires %\ld be jo9$ to b9d+-po/s ,w & ,x1 & ! h&les to ,y & ,z4 ,fig4 #afj %[s ! details ( ! automatic int]rupt] :i* is plac$ 9 ! prim>y circuit4 ,illu/ration3 ,fig4 #afj4 ,if ! curr5t ent]s at ,w1 x w pass ?r\gh ! prim>y coil & out at ,x1 aft] go+ ?r\gh #e1 ,r1 ,f1 ,s ,i1 ,b1 ,e & ,c4 ,! in/ant ! curr5t passes1 ! bolt becomes magnetiz$2 ?is attracts ,a1 :i* pulls ,b away f ! end ( ,s ,i1 ?us automatically op5+ ! circuit4 ,b at once spr+s back to its =m] position aga9/ ,s ,i1 z ,a is no long] attract$2 ! circuit be+ clos$1 ! op]ation is rapidly repeat$4 7,= comm]cial =ms & uses ( induction coils see ,?+s ,a ,boy ,%\ld ,"k ,ab\t ,electricity47 #dge4 ,trans=m]s1 l induction coils1 are in/rum5ts = *ang+ ! ,e4 ,m4 ,f4 & /r5g? ( curr5ts4 ,!re is v little loss ( en]gy 9 well-made trans=m]s4 ,!y consi/ ( two coils ( wire on ! same core2 9 fact1 an induction coil may be consid]$ a trans=m]4 ,if ! second>y coil has #ajj times z _m turns ( wire z ! prim>y1 a curr5t ) an ,e4 ,m4 ,f4 ( #ajj volts c be tak5 f ! second>y coil1 :5 ! ,e4 ,m4 ,f4 ( ! curr5t pass+ ?r\gh ! prim>y is #a volt2 b ! /r5g? 7amp]es7 ( ! second>y curr5t w be b "o-hundr$? t ( ! prim>y curr5t4 ,by us+ ! coil ( f9e wire z ! prim>y1 ! ,e4 ,m4 ,f4 ( ! curr5t t comes f ! o!r coil w be b "o-hundr$? t 9 ! f9e coil4 ,x w h #ajj times its /r5g?1 h[ev]4 ,cont9u\s curr5ts f cells or dynamos mu/ be int]rupt$1 z 9 induction coils1 to be trans=m$ f "o ,e4 ,m4 ,f4 to ano!r4 ,trans=m]s are n[ l>gely us$ 9 light+ & p[] circuits1 etc4 7,see ,?+s ,a ,boy ,%\ld ,"k ,ab\t ,electricity47 #dgf4 ,! ,dynamo4 ,we saw 9 ! ,exps4 ( ,*apt] ,,xxv4 t curr5ts ( electricity c be g5]at$ 9 a coil ( wire 7clos$ circuit7 by rapidly mov+ x ?r\gh ! field ( a magnet4 ,z %[n by ! exp]im5ts1 ?is c be accompli%$ 9 _m ways4 ,! dynamo is a ma*9e = do+ ?is on a l>ge scale1 ! coils be+ giv5 a rot>y motion 9 a v /rong magnetic field2 & z ! numb] ( l9es ( =ce t cut ! coil is con/antly *ang+1 !re is a curr5t 9 ! coil z long z p[] is appli$1 & ?is curr5t is l$ f ! ma*9e by prop] devices4 ,! dynamo is a ma*9e = conv]t+ me*anical en]gy into an electric curr5t1 ?r\gh electromagnetic induction4 ,if a loop ( wire 7,fig4 #afa7 be s arrang$ on be>+s at its ends t x c be made to revolve1 a curr5t w fl[ ?r\gh x 9 "o direction dur+ "o-half ( ! revolution1 & 9 ! opposite direction dur+ ! o!r half1 x be+ insulat$ f all ext]nal conductors4 ,su* a curr5t inside ( ! ma*9e w\ld be ( no value2 x mu/ be l$ out to ext]nal conductors4 ,"s sort ( slid+ contact is necess>y to connect a revolv+ conductor ) a /ation>y "o4 ,illu/ration3 ,fig4 #afa4 ,illu/ration3 ,fig4 #afb4 ,fig4 #afb %[s ! ends ( a coil jo9$ to two r+s1 ,x1 ,y1 :i* are insulat$ f ea* o!r1 & :i* rotate ) ! coil4 ,two /ation>y pieces ( c>bon1 ,a1 ,b1 call$ bru%es1 press aga9/ ! r+s1 & to ^! are jo9$ wires :i* complete ! circuit1 & :i* lead out :]e ! curr5t c d "w4 ,! arr[s %[ ! direction ( ! curr5t dur+ "o-half ( a revolution4 ,! r+s =m a collector1 & ?is arrangem5t gives an alt]nat+ curr5t4 ,illu/ration3 ,fig4 #afc4 ,9 ,fig4 #afc ! ends ( ! coil are jo9$ to ! two halves ( a cyl9d]4 ,^! halves1 ,x & ,y1 are insulat$ f ea* o!r & f ! axis4 ,! curr5t fl[s f ,x onto ! bru% ,a1 ?r\gh "s ext]nal circuit :]e x does "w1 & !nce back ?r\gh bru% ,b onto ,y4 ,by ! "t t ,y gets ar\nd to ,a ! direction ( ! curr5t 9 ! loop has rev]s$1 s t x passes t[>ds ,y2 b x /ill ent]s ! outside circuit ?r\gh ,a because ,y is !n 9 contact ) ,a4 ,?is device is call$ a commutator1 & x all[s a con/ant or direct curr5t to leave ! ma*9e4 ,9 regul> ma*9es !re are _m loops ( wire & sev]al segm5ts to ! commutator4 ,! rotat+ coils are w\nd ^u an iron core1 s t ! l9es ( =ce1 9 pass+ f "o pole to ! o!r1 w meet ) z little resi/ance z possible4 ,! coils1 core1 & commutator1 tak5 toge!r1 are call$ ! armature4 ,! magnets :i* furni% ! field are call$ ! field-magnets4 ,^! are electromagnets1 ! curr5t f ! dynamo1 or a "p ( x1 be+ us$ to excite !m4 ,!re are _m =ms ( dynamos1 & _m ways ( w9d+ ! armature & field-magnets1 b space w n p]mit a discussion ( !m "h4 7,see ,?+s a ,boy ,%\ld ,"k ,ab\t ,electricity47 #dgg4 ,! ,electric ,motor4 ,exp]im5ts h %[n t motion c be produc$ by ! electric curr5t 9 _m ways4 ,! galvanoscope may be consid]$ a t9y motor4 ,an electric motor is a ma*9e = trans=m+ electric en]gy into me*anical p[]4 ,:ile ! electric motor is simil> 9 con/ruction to ! dynamo1 x is opposite to x 9 action4 ,motors receive curr5t & produce motion4 ,! motion is a rot>y "o1 ! p[] be+ appli$ to o!r ma*9es by means ( belts or ge>s4 ,illu/ration3 ,fig4 #afd4 ,,exp]im5t #bjj4 ,to /udy ! action ( ! telephone4 #dgh4 ,directions4 7,a7 ,jo9 ! ends ( coil ,h 7,fig4 #afd7 to ! a/atic galvanoscope4 ,move magnet ,m back & =? 9 front ( ! s(t iron core1 :ile ,h is held 9 position4 ,wat* ! ne$le4 ,imag9e t vibrations 9 ! air caus$ by ! voice are /rong en\gh to give ,m a slight motion to & fro1 & y c see h[ a curr5t w\ld be s5t ?r\gh ! galvanoscope by speak+ aga9/ ,m4 #dgi4 ,! ,telephone is an in/rum5t = reproduc+ s\nds at a di/ance1 & electricity is ! ag5t by :i* ?is is g5]ally accompli%$4 ,! "p spok5 to is call$ ! transmitt]1 & ! "p :i* gives ! s\nd out aga9 is call$ ! receiv]4 ,s\nd itself does n pass ov] ! l9e4 ,al?\gh ! same app>atus may be us$ = bo? transmitt] & receiv]1 !y are g5]ally diff]5t 9 con/ruction4 ,illu/ration3 ,fig4 #afe4 #dhj4 ,! ,bell or ,magneto-transmitt] g5]ates its own curr5t1 & is1 /rictly speak+1 a dynamo t is run by ! voice4 ,y h se51 by exp]im5ts1 t a curr5t c be g5]at$ 9 a coil ( wire by mov+ a magnet back & =? 9 front ( its s(t iron core4 ,9 ! telephone ?is process is rev]s$1 s(t iron 9 ! %ape ( a ?9 disc 7,d1 ,fig4 #afe7 be+ made to vibrate by ! voice imm$iately 9 front ( a coil hav+ a p]man5t magnet1 ,m1 = a core4 ,! s(t iron diaphragm is fix$ ne>1 b x does n t\* ! magnet4 ,! coil consi/s ( _m turns ( f9e insulat$ wire4 ,! curr5t g5]at$ is an alt]nat+ "o & exce$+ly feeble2 9 fact1 x c n be detect$ by a galvanoscope4 #dha4 ,! ,receiv] has ! same con/ruction z ! bell transmitt]1 & receives ! curr5ts f ! l9e4 ,z ! diaphragm is always attract$ by ! magnet1 x is "u a con/ant /ra94 ,?is /ra9 is increas$ :5 a curr5t passes ?r\gh ! coil 9 a direction t adds /r5g? to ! magnet1 & decreas$ :5 ! curr5t weak5s ! magnet4 ,:5 ! curr5t ?r\gh ! coil is always 9 ! same direction1 b v>ies 9 /r5g?1 ! diaphragm w vibrate on acc\nt ( ! v>y+ pull ^u x4 ,illu/ration3 ,fig4 #aff4 ,:5 ! curr5t ?r\gh ! coil is an alt]nat+ "o1 ! same result is obta9$1 z ! magnet gets weak] & /rong] _m times p] m9ute4 ,fig4 #aff %[s two bell in/rum5ts jo9$1 ei!r be+ us$ z ! transmitt] & ! o!r z ! receiv]4 #dhb4 ,! ,c>bon ,transmitt] does n 9 itself g5]ate a curr5t l ! magneto-transmitt]2 x m]ely produces *anges 9 ! /r5g? ( a curr5t t fl[s ?r\gh x1 & t comes f "s outside s\rce4 ,9 ,fig4 #afg1 ,x & ,y are two c>bon buttons1 ,x be+ atta*$ to ! diaphragm1 ,d4 ,button ,y presses g5tly aga9/ ,x4 ,:5 ,d is caus$ to vibrate by ! voice1 ,x is made to press m or less aga9/ ,y1 & ?is all[s m or less curr5t to pass ?r\gh ! circuit1 9 :i* also is ! receiv]1 ,r4 ,?is direct undulat+ curr5t *anges ! pull ^u ! diaphragm ( ,r1 caus+ x to vibrate & reproduce ! orig9al s\nds spok5 into ! transmitt]4 ,illu/ration3 ,fig4 #afg4 #dhc4 ,induction ,coils 9 ,telephone ,"w4 ,z ! resi/ance ( telephone l9es is l>ge1 a curr5t ) a fairly high ,e4 ,m4 ,f4 is desir$4 ,:ile ! curr5t f "o or two cells is suffici5t to "w ! transmitt]1 x is n /rong en\gh to =ce its way ov] a long l9e4 ,to get ar\nd ?is difficulty an induction coil is us$ to trans=m ! batt]y curr5t1 t fl[s ?r\gh ! transmitt] & prim>y coil1 into a curr5t ) a high ,e4 ,m4 ,f4 t c g into ! ma9 l9e & =ce its way to a di/ant receiv]4 ,! batt]y curr5t 9 ! prim>y coil is undulat+1 b always 9 ! same direction1 ! magnetic field ar\nd ! core gett+ weak] & /rong]4 ,?is causes an alt]nat+ curr5t 9 ! second>y coil & ma9 l9e4 ,illu/ration3 ,fig4 #afh4 ,fig4 #afh %[s ! two coils1 ,p1 ,s1 ( ! induction coil4 ,! prim>y1 ,p1 is jo9$ 9 s]ies ) a cell & transmitt]4 ,! second>y coil1 ,s1 is jo9$ to ! receiv]4 ,"o end ( ,s c be gr\nd$1 ! curr5t complet+ ! circuit ?r\gh ! e>? & into ! receiv] ?r\gh ano!r wire ent]+ ! e>?4 ,!re are _m =ms ( transmitt]s4 7,see ,?+s a ,boy ,%\ld ,"k ,ab\t ,electricity47 #dhd4 ,electric ,light+ & ,heat+4 ,:5ev] resi/ance is (f]$ to ! electric curr5t1 heat is produc$4 ,by prop] appliances1 ! heat ( resi/ance c be appli$ j :]e x is ne$$1 & _m comm]cial processes dep5d ^u electricity = _! success4 ,dynamos are us$ to g5]ate curr5ts = light+ & heat+ purposes4 ,!re are two great sy/ems ( light+1 ! "o by arc lamps & ! o!r by inc&esc5t lamps4 7,see ,?+s a ,boy ,%\ld ,"k ,ab\t ,electricity47 #dhe4 ,arc ,lamps produce a light :5 a curr5t passes f "o c>bon rod to ! o!r across an air-space4 ,z ! curr5t />ts ?r\gh ! lamp1 ! ends ( ! c>bons t\*1 & ! imp]fect contact causes resi/ance en\gh to heat ! ends r$-hot4 ,!y are !n automatically sep>at$1 & ! curr5t passes f "o to ! o!r1 caus+ ! arc4 ,! resi/ance ( ! air-space is r$uc$ by ! int5sely heat$ vapor & fly+ p>ticles ( c>bon4 #dhf4 ,! ,inc&esc5t ,lamp consi/s ( a glass bulb1 9 :i* is a vacuum1 & ! light is caus$ by ! passage ( a curr5t ?r\gh a ?9 fibre ( vegetable c>bon1 enclos$ 9 ! vacuum4 ,! fibre w\ld burn in/antly if all[$ to come 9 contact ) ! air4 ,! fibres h a high resi/ance1 & are easily heat$ to inc&esc5ce4 ,,*apt] ,,xxviii4 ,,wire ,,tables4 ,copp] ,wire ,tables are v conv5i5t1 & a necessity :5 work+ electrical examples4 ,! tables "h giv5 are tak5 f a deal]'s catalogue1 & w be f\nd suffici5tly accurate = ord9>y "w4 ,explanation ( ,tables4 ,9 ! fir/ column are giv5 ! sizes ( wires by numb]s4 ,! ,b ,s or ,am]ican gauge is us$4 ,9 ! table bel[ is giv5 a comp>ison betwe5 ! ,b ,s & ! ,birm+ham gauges4 ,! second column gives ! diamet]s ( wires4 ,! diamet] ( ,no4 #cf wire is #e ?\s&?s ( an in*2 ! diamet] ( ,no4 #bd wire is a little ov] #bj ?\s&?s or #b hundr$?s ( an in*4 ,! ?ird column conta9s :at is call$ circul> mils1 a mil be+ a ?\s&? ( an in*4 ,! figures 9 ?is column are obta9$ by squ>+ ^? 9 ! second2 ?us1 = ,no4 #cf wire1 #e #e #be4 ,?is column is useful :5 work+ examples :]e ! squ>es ( ! diamet]s are want$4 ,! re/ ( ! table expla9s itself4 ,! table at ! bottom gives a comp>ison betwe5 ! fractional & decimal p>ts ( an in*4 ,space c n be giv5 "h = a s]ies ( examples %[+ ! _m uses ( ?is table4 7,see ,elem5t>y ,electrical ,examples47 ,,copp] ,,wire ,,tables4 7,bas$ on ! ,b4 ,a4 ,unit47 ,gauge ,,diam- ,sectional,capac- ,,ohms ,,et]4 ,,area ity4 ---------------------------------------- --------------------- ,b4,s4 ,9 ,9 ,9 ,amp- ,p] ,p] ,p] ,no4 #ajjj?s,circul> eres4 #a1jjj ,mile4 ,p\nd4 ,mils4 feet4 ---------------------------------------- --------------------- #jjjj4dfj #baafjj4 #cab4 4#jdijf 4#beijc 4#jjjjgg #jjj4djifd #afghje4 #bfb4 4#jfahf 4#cbffd 4#jjjab #jj4cfdh #accjgi4 #bbj4 4#jghja 4#daahg 4#jjjai #j4cbdhf #ajeecd4 #ahe4 4#jihca 4#eaiji 4#jjjca #a4bhic #hcfid4 #aef4 4#abdjd 4#fedij 4#jjjdi #b4begfc #ffcgc4 #aca4 4#aefdj 4#hbeh 4#jjjgh #c4bbidb #ebfcd4 #aaj4 4#aigbc #a4jdad 4#jjabe #d4bjdca #dagdc4 #ib4c 4#bdhfi #a4cac 4#jjaih #e4ahaid #ccajb4 #gg4f 4#cacfa #a4fee 4#jjcad #f4afbjb #bfbea4 #fe4b 4#ciedf #b4jhh 4#jjdii #g4addbh #bjhag4 #ed4h 4#dihga #b4fcc 4#jjgib #h4abhdi #afeaj4 #df4a 4#febi #c4c 4#jabe #i4aaddc #acjid4 #ch4g 4#ghib #d4a 4#jaig #aj4ajahi #ajchb4 #cb4e 4#hdda #d4d 4#jbgj #aa4jijgdb #hbcd4 #bg4c #a4bed #f4d 4#jeja #ab4jhjhjh #fecj4 #bc4 #a4ehj #h4c 4#jgi #ac4jgaifa #eagh4 #ai4c #a4iie #aj4d 4#abg #ad4jfdjhd #dajg4 #af4b #b4ejd #ac4b 4#bjj #ae4jegjfh #cbeg4 #ac4f #c4agb #af4g 4#cbj #af4jejhb #behc4 #aa4e #d4jja #bc4 4#eab #ag4jdebeg #bjdh4 #i4f #e4jd #bf4 4#haa #ah4jdjcjc #afbd4 #h4a #f4cf #cc4 #a4bi #ai4jcehi #abhh4 4444 #h4be #dc4 #b4aa #bj4jcaifa #ajba4 4444 #aj4ab #ec4 #c4bg #ba4jbhdfb #haj4 4444 #ab4gf #fh4 #e4bj #bb4jbecdg #fdb4 4444 #af4be #he4 #h4ce #bc4jbbega #eji4 4444 #bj4cj #ajh4 #ac4c #bd4jbja #djd4 4444 #be4fj #ace4 #bj4i #be4jagi #cbj4 4444 #cb4b #agj4 #cc4b #bf4jaeid #bed4 4444 #dj4g #bad4 #eb4i #bg4jadaie #bja4 4444 #ea4c #bgj4 #hd4b #bh4jabfda #aei4h 4444 #fd4h #cdc4 #acd4 #bi4jaabeg #abf4g 4444 #ha4f #dhb4 #bac4 #cj4jajjbe #ajj4e 4444 #ajc4 #ech4 #cch4 #ca4jjhibh #gi4g 4444 #acj4 #fhe4 #eci4 #cb4jjgie #fc4 4444 #afd4 #hfe4 #hef4 #cc4jjgjh #ej4a 4444 #bjf4 #ajcc4 #aceg4 #cd4jjfcjd #ci4gd 4444 #bfj4 #achi4 #baff4 #ce4jjefad #ca4e 4444 #cbh4 #ahbj4 #ceba4 #cf4jje #be4 4444 #dad4 #bbjj4 #edfi4 #cg4jjddec #ai4h 4444 #ebc4 #bgfe4 #hgdb4 #ch4jjcife #ae4gb 4444 #ffj4 #cdhf4 #acggb4 #ci4jjceca #ab4dg 4444 #hcb4 #dcie4 #bahif4 #dj4jjcadd #i4hh 4444 #ajdi #eedb4 #cdhbc4 ---------------------------------------- --------------------- ,gauge ,,feet4 ,,p\nds4 ---------------------------------------- ---------- ,b4,s4 ,p] ,p] ,p] ,p] ,no4 ,p\nd4 ,ohm4 #a1jjj feet4 ,ohm4 ---------------------------------------- ---------- #jjjj #a4efabbbjdig4g #fdj4ea #abihg4 #jjj #a4ifhg #afbee4bg #ejg4ie #hccc4 #jj #b4dhbd #abhia4cg #djb4hc #ebfc4 #j #c4acjc #ajbbc4jh #cai4de #cbbe4 #a #c4idgad #hajg4di #bec4cd #bjda4 #b #d4iggbb #fdbi4eh #bjj4ia #abhb4 #c #f4bgfe #ejih4fa #aei4cb #hjj4 #d #g4iada #djdc4f #abf4ce #eje4 #e #i4igihc #cbjf4fa #ajj4bj #cah4 #f #ab4ehdg #bedb4hi #gi4dfb #bjj4 #g #ae4hfif #bjae4ea #fc4jac #abf4 #h #bj4jjig #aeii4c #di4igf #hj4 #i #be4bbi #abfh4dd #ci4fcf #ej4 #aj #ca4hbab #ajee4ff #ca4dbf #cg4 #aa #dj4abjb #gig4fdi #bd4ibd #bj4 #ab #ej4eijf #fcb4eee #ai4gff #ab4fe #ac #fc4gidh #eja4fc #ae4fgd #g4hg #ad #hj4ddae #cig4hbb #ab4dce #e4jj #ae #aja4dcfe #cae4dhb #i4hei #c4ab #af #abg4ab #bej4ahd #g4hai #a4ie #ag #afa4bi #aih4dji #f4aii #a4bc #ah #bjc4cgd #aeg4ce #d4iaf 4#gge #ai #bef4dfh #abd4ggg #c4hii 4#dgc #bj #cbc4cii #ih4iecc #c4jid 4#cje #ba #djg4hae #gh4dgc #b4deb 4#aib #bb #ead4aic #fb4bcf #a4ide 4#aai #bc #fdh4deb #di4cejd #a4edb 4#jge #bd #hag4fhh #ci4acfe #a4bbc 4#jdg #be #ajca4jch #ca4jcha 4#ifii 4#jcj #bf #acjj4ahj #bd4faca 4#gfib 4#jahg #bg #afci4di #ai4eaia 4#fjii 4#jaah #bh #bjfg4cfd #ae4dgic 4#dhcg 4#jjgd #bi #bfjf4iei #ab4bhed 4#chce 4#jjdg #cj #cbhg4jhd #i4gcee 4#cjjb 4#jjbi #ca #ddad4di #g4gbadc 4#bdac 4#jjah #cb #ebbf4iae #f4abbdc 4#aiac 4#jjaa #cc #feij4da #d4heege 4#aeag 4#jjjgf #cd #hcab4h #c4hdiff 4#abjd 4#jjjdf #ceajdha4gg #c4jecje 4#jief 4#jjjbh #cfacbad4af #b4dbag 4#jgeg 4#jjjah #cgaffei4ig #a4ibjhf 4#jfjjc 4#jjjaa #chbajac4be #a4ebbib 4#jdgeh 4#jjjjg #cibfdif4bcg #a4bjggg 4#jcgee 4#jjjjd #djccdbj4fc #j4igihd 4#jbiib 4#jjjjbi ---------------------------------------- ---------- ,comp>ative ,table ( ! ,fractional & ,decimal ,p>ts ( an ,in*4 ----------------- #a_/fd 4#jaefbe #a_/cb 4#jcabej #c_/fd 4#jdfhge #a_/af 4#jfbejj #e_/fd 4#jghabe #c_/cb 4#jicgej #g_/fd 4#ajicge #a_/h 4#abejjj #i_/fd 4#adjfbe #e_/cb 4#aefbej #aa_/fd 4#agahge #c_/af 4#ahgejj #ac_/fd 4#bjcabe #g_/cb 4#bahgej #ae_/fd 4#bcdcge #a_/d 4#bejjjj #ag_/fd 4#bfefbe #i_/cb 4#bhabej #ai_/fd 4#bifhge #e_/af 4#cabejj #ba_/fd 4#cbhabe #aa_/cb 4#cdcgej #bc_/fd 4#ceicge #c_/h 4#cgejjj #be_/fd 4#cijfbe #ac_/cb 4#djfbej #bg_/fd 4#dbahge #g_/af 4#dcgejj #bi_/fd 4#decabe #ae_/cb 4#dfhgej #ca_/fd 4#dhdcge #a_/b 4#ejjjjj ----------------- ,comp>ative ,table ( ,b4 & ,s4 & ,b4 ,w4 ,gauges 9 ,decimal ,p>ts ( an ,in*4 --------------------------------------- ,birm+ham ,am]ican ,no4 ( ,wire ,gauge4 7,b4 & ,s47 ,wire ,gauge4 ,wire ,gauge4 --------------------------------------- #jjjj 4#df 4#ded #jjj 4#djifd 4#dbe #jj 4#cfdh 4#ch #j 4#cbdhf 4#cd #a 4#bhic 4#c #b 4#begfc 4#bhd #c 4#bbidb 4#bei #d 4#bjdca 4#bch #e 4#ahaid 4#bb #f 4#afbjb 4#bjc #g 4#addbh 4#ah #h 4#abhdi 4#afe #i 4#aaddc 4#adh #aj 4#ajahi 4#acd #aa 4#jijgdb 4#ab #ab 4#jhjhjh 4#aji #ac 4#jgaifa 4#jie #ad 4#jfdjhd 4#jhc #ae 4#jegjfh 4#jgb #af 4#jejhb 4#jfe #ag 4#jdebeg 4#jeh #ah 4#jdjcjc 4#jdi #ai 4#jcehi 4#jdb #bj 4#jcaifa 4#jce #ba 4#jbhdfh 4#jcb #bb 4#jbecdg 4#jbh #bc 4#jbbega 4#jbe #bd 4#jbja 4#jbb #be 4#jagi 4#jb #bf 4#jaeid 4#jah #bg 4#jadaie 4#jaf #bh 4#jabfda 4#jad #bi 4#jaabeg 4#jac #cj 4#jajjbe 4#jab #ca 4#jjhibh 4#ja #cb 4#jjgie 4#jji #cc 4#jjgjh 4#jjh #cd 4#jjfcjd 4#jjg #ce 4#jjefad 4#jje #cf 4#jje 4#jjd #cg 4#jjddec #ch 4#jjcife #ci 4#jjceca #dj 4#jjcaad --------------------------------------- ,,li/ ,,( ,,app>atus ,,= ,! ,/udy ( ,elem5t>y ,electricity & ,magnetism by ,exp]im5t4 ,! #ajj pieces ( app>atus 9 ! foll[+ li/ are ref]r$ to1 by numb]1 9 ! exp]im5ts conta9$ 9 ,! ,/udy ( ,elem5t>y ,electricity & ,magnetism by ,exp]im5t4 ,?is li/ is furni%$ to give ^? :o wi% to make _! own app>atus an idea ( ! approximate size1 etc41 ( ! v>i\s articles us$4 ,! au?or is prep>+ a price catalogue ( ! articles includ$ 9 ?is li/1 & ( odds & ends ne$$ 9 ! con/ruction ( simple1 home-made app>atus4 ,no4 #a4 ,a package ( #be /eel sew+-ne$les4 ,to be suitable = exp]im5ts 9 magnetism1 ^! %\ld be ( good1 h>d /eel1 & n too ?ick4 ,no4 #b4 ,a flat cork1 ab\t #a 94 9 diamet] & #c_/h 94 ?ick4 ,no4 #c4 ,a c&le = anneal+ /eel4 ,no4 #d-ae4 ,"o doz5 assort$ anneal$ iron wires1 f #a 94 to #f 94 9 l5g?4 ,! iron %\ld be v s(t4 ,no4 #af4 ,"o ,engli% horse%oe magnet1 #b-a_/b 94 long1 be/ quality4 ,no4 #ag4 ,a small box ( iron fil+s f s(t iron4 ,no4 #ah4 ,a compass 7,fig4 #e74 ,! ne$le sw+s v freely2 x is enclos$ 9 a wood5 pill box1 ! cov] ( :i* =ms ! support4 ,no4 #ai1 #bj4 ,two s(t /eel wire nails1 #b 94 long4 ,no4 #ba1 #bb4 ,two pieces ( spr+ /eel1 ab\t #c 94 long & #c_/h 94 wide1 to be magnetiz$ by ! /ud5t & us$ z b> magnets4 ,no4 #bc4 ,an iron r+1 or wa%]1 ab\t #g_/h 94 9 diamet]4 ,no4 #bd4 ,a sift] = iron fil+s4 ,?is consi/s ( a pa/ebo>d pill box3 ,prick holes ?r\gh ! bottom ) a p94 ,no4 #be4 ,a ?91 flexible piece ( spr+ /eel1 ab\t #c 94 long & #a_/h 94 wide4 ,no4 #bf1 #bg4 ,two ebonite %eets 7,e ,s1 ,fig4 #cd71 ea* #d 94 squ>e4 ,^! are made ) a special surface4 ,!y are v mu* bett] ?an ! ord9>y smoo? ebonite4 ,no4 #bh4 ,"o ebonite rod 7,e ,r1 ,fig4 #cd71 #c-a_/b 94 long1 ) special surface4 ,no4 #bi4 ,"o ebonite rod1 #a-c_/d 94 long1 ) special surface1 us$ to support ! insulat+ table1 ,no4 #dc 7,i ,t1 ,fig4 #cb74 ,no4 #cj4 ,"o piece ( flannel clo?1 #g 94 squ>e4 ,no4 #ca4 ,six %eets ( tissue-pap]1 ea* #d 94 squ>e4 ,no4 #cb4 ,a few feet ( :ite cotton ?read4 ,no4 #cc4 ,a few feet ( black silk ?read4 ,no4 #cd4 ,"o support base 7,s ,b1 ,fig4 #ef74 ,?is is ( ?9 wood1 ab\t #c-c_/d 94 by #f-a_/b 941 to "o end ( :i* is fa/5$ a spool = hold+ ! support rod 7,no4 #ce74 ,no4 #ce4 ,"o support rod 7,s ,r1 ,fig4 #ef71 #g 94 long & #e_/af 94 9 diamet]4 ,?is rod has a hole 9 ea* end4 ,! small hole is = hold+ ! support wire 7,no4 #cf72 ! l>ge hole is = ! ebonite rod 7,no4 #bi74 ,no4 #cf4 ,"o support wire 7,s ,w1 ,fig4 #add74 ,no4 #cg4 ,"o wire sw+ 7,w ,s1 ,fig4 #bi74 ,no4 #ch4 ,"o %eet ( glass1 #d 94 squ>e4 ,no4 #ci4 ,"o b5t hairp9 7,h ,p1 ,fig4 #cb74 ,no4 #dj4 ,bottom ( flat box 7,b ,f ,b1 ,fig4 #cb71 #c-e_/h 94 9 diamet]4 ,no4 #da4 ,top ( flat box 7,t ,f ,b1 ,fig4 #cc74 ,no4 #db4 ,"o electrophorus cov] 7,e ,c1 ,fig4 #cd71 #c-e_/h 94 9 diamet]4 ,?is has r\nd$ edges1 & a small tube is rivet$ into ! top ( x to hold ! insulat+ h&le1 ,e ,r4 ,no4 #dc4 ,"o insulat+ table 7,i ,t1 ,fig4 #cb74 ,?is is made ! same z ,no4 #db1 & is support$ by ,no4 #bi4 ,no4 #dd4 ,"o insulat$ copp] wire1 #b-a_/b feet long4 ,no4 #de4 ,"o rubb] b& 7,r ,b1 ,fig4 #cc74 ,no4 #df4 ,six b5t wire clamps 7,b ,c1 ,fig4 #cg74 ,no4 #dg4 ,"o t9 box conductor 7,t ,b1 ,fig4 #db74 ,?is cyl9drical conductor is ab\t ! size ( an ord9>y bak+ p[d] box4 ,no4 #dh4 ,"o hairp9 dis*>g] = ! cond5s]4 ,no4 #di4 ,two %eets ( alum9um-leaf = ! leaf electroscope 7,fig4 #eg7 & o!r exp]im5ts4 ,no4 #ej4 ,"o b5t wire 7,h ,p1 ,fig4 #eg7 us$ 9 connection ) ! leaf electroscope4 ,no4 #ea4 ,a dry cell1 ord9>y size ab\t #g 94 high & #b-a_/b 94 9 diamet]4 ,no4 #eb4 ,en\gh m]cury to amalgamate batt]y z9cs4 ,a wood5 pill box conta9+ ab\t half a ?imbleful w d4 ,no4 #ec4 ,a coil conta9+ #be feet ( ,no4 #bd insulat$ copp] wire = connections4 ,no4 #ed4 ,"o doz5 spr+ connectors 7,fig4 #fa7 = mak+ connections4 ,^! are made ( brass1 nickel plat$1 & d n affect ! compass-ne$le4 ,no4 #ee4 ,a telegraph key 7,fig4 #fh7 )\t swit*4 ,! metal /raps are made ( alum9um2 !y are #a_/b 94 wide1 & are fa/5$ to a neat wood5 base4 ,no4 #ef4 ,?ree metal plates1 ea* ab\t #b 94 by #c_/d 941 on :i* spr+ connectors 7,no4 #ed7 are to be pu%$ 9 ord] to jo9 two wires4 ,no4 #eg4 ,a curr5t rev]s] 7,fig4 #fi74 ,! /raps are made ( alum9um & are fa/5$ to a neat wood5 base4 ,no4 #eh4 ,a galvanoscope 7,fig4 #gb7 includ+ a degree-c>d 7,no4 #ii74 ,! c>dbo>d coil-support1 ,c ,s1 is #e #f-a_/d 941 & ! hole 9 x is #c-c_/h 94 9 diamet]4 ,! coil is #d-a_/d 94 9 diamet]1 made ( ,no4 #bd insulat$ copp] wire4 ,no4 #ei4 ,an a/atic galvanoscope 7,fig4 #gg74 ,! :ole may be tak5 ap>t & mail$ 9 ! conta9+ box1 ,b1 :i* is #d-c_/h #c-a_/h #a 94 ,! coil is made ( ,no4 #ca wire1 & has a resi/ance ( ab\t #e ohms4 ,spr+ connectors are us$ to jo9 a wire to ! app>atus by pu%+ ! connectors into ! tubul> b9d+-po/s1 ,l & ,r4 ,no4 #fj-fc4 ,f\r /rips ( %eet z9c1 #d 94 by #a_/b 941 n amalgamat$4 ,no4 #fd4 ,a c>bon rod1 #d 94 long 7,fig4 #ha74 ,no4 #fe1 #ff4 ,two glass tumbl]s 7,fig4 #ha74 ,no4 #fg1 #fh4 ,two /rips ( %eet copp]1 #d 94 by #a_/b 94 7,fig4 #he74 ,no4 #fi4 ,"o galvaniz$ iron nail4 ,no4 #gj1 #ga4 ,two wood5 cross-pieces 7,fig4 #he74 ,no4 #gb4 ,"o doz5 brass screws1 #e_/h 94 long1 size ,no4 #e1 ) r\nd heads4 ,no4 #gc4 ,a por\s cup 7,p ,c1 ,fig4 #hg7 t w /& inside ( ! tumbl]s 7,no4 #fe74 ,no4 #gd4 ,a z9c rod1 ab\t #c_/h 94 9 diamet]1 l ^? us$ 9 ,leclan* cells4 ,no4 #ge4 ,a %eet copp] plate = ! two-fluid cell 7,c1 ,fig4 #hg74 ,?is is #b 94 wide2 x ne>ly surr\nds ! por\s cup1 & is support$ ^u ! edge ( ! tumbl] by a n>r[ /rip1 ,a1 ) :i* connections are made by spr+ connectors 7,no4 #ed74 ,no4 #gf4 ,"o /rip ( %eet iron1 #d 94 by #a_/b 94 ,no4 #gg1 #gh4 ,two /rips ( %eet lead1 #d 94 by #a_/b 94 ,no4 #gi4 ,a resi/ance coil 7,fig4 #id74 ,! coil is made ( ,no4 #bd insulat$ copp] wire2 x has a resi/ance ( #b ohms 7ne>ly7 & is fa/5$ to a c>dbo>d base4 ,x is s arrang$ t ei!r "o or two ohms c be us$ at w4 ,no4 #hj4 ,a ,:eat/one's bridge 7,fig4 #ajc71 includ+ a scale 7,no4 #ajj74 ,! alum9um /raps1 #a1 #b1 #c1 are fa/5$ to a neat wood5 base1 #aj 94 long by #b 94 wide4 ,a ,no4 #bh ,g]man-silv] wire is us$ = ! bridge4 ,no4 #ha4 ,a piece ( ,no4 #cj uncov]$ ,g]man-silv] wire1 #b4a met]s long1 us$ = resi/ance 7,fig4 #if74 ,no4 #hb4 ,a piece ( ,no4 #bh uncov]$ ,g]man-silv] wire1 #b4a met]s long4 ,no4 #hc-he4 ,?ree plate b9d+-po/s1 consi/+ ( b5t /raps ( %eet alum9um 7,x1 ,y1 ,z1 ,fig4 #if74 ,no4 #hf4 ,two ounces ( copp] sulphate1 commonly call$ blue/one4 ,! cry/als may be kept 9 a l>ge wood5 pill box4 ,no4 #hg4 ,"o doz5 copp] wa%]s4 ,no4 #hh4 ,"o comb9ation rule1 #a ft4 long1 m>k$ ) ,engli% & metric sy/ems4 ,no4 #hi4 ,a holl[ coil ( ,no4 #bd insulat$ copp] wire 7,fig4 #acj74 ,! spool1 on :i* ! wire is w\nd1 has a hole = a five-sixte5?s in* core4 ,x is turn$ d[n ?91 s t ! wire is ne> ! core4 ,! coil is ab\t #a-a_/h 94 long & #a 94 9 diamet]4 ,spr+ connectors are jo9$ to ! ends ( ! coil4 ,no4 #ij4 ,a holl[ coil ( ,no4 #be insulat$ copp] wire1 simil> to ,no4 #hi1 ) spr+ connectors atta*$ to its ends4 ,no4 #ia4 ,c>bon rod = electroplat+4 ,no4 #ib1 #ic4 ,two s(t iron cores1 ) screws 7,i ,c1 ,fig4 #acj74 ,^! cores are #e_/af 94 9 diamet]1 & h a ?read$ hole 9 "o end = fa/5+ !m to ,no4 #id4 ,no4 #id4 ,a t9 box ) ?ree holes pun*$ 9 its top 7,fig4 #acb74 ,?is s]ves z a base1 z well z a yoke1 = ! two electromagnets1 ,a1 ,b1 %[n 9 plan4 ,no4 #ie4 ,comb9ation connect+ plates 7,fig4 #acb74 ,?ree alum9um /raps are fa/5$ to a wood5 base4 ,!y are turn$ up at _! ends s t spr+ connectors c be easily pu%$ ^u !m4 ,no4 #if4 ,"o long iron core 7,l ,i ,c1 ,fig4 #adj74 ,?is is ( s(t iron1 #e_/af 94 9 diamet]1 & long en\gh to pass ?r\gh bo? coils 7,no4 #hi1 #ij74 ,no4 #ig4 ,b> magnet1 ab\t #d 94 long & #e_/af 94 9 diamet]4 ,no4 #ih4 ,coil ( insulat$ wire w\nd on a s(t iron core1 to act z a prim>y coil = induction exp]im5ts4 ,?is coil fits inside ( ! holl[ coils 7,nos4 #hi1 #ij74 ,no4 #ii4 ,a pr9t$ degree-c>d = ! galvanoscope 7,no4 #eh74 ,?is is pr9t$ on /iff c>dbo>d1 ab\t #c 94 9 diamet]4 ,no4 #ajj4 ,a pr9t$ scale = ! ,:eat/one's bridge 7,no4 #hj74 ,?is is pr9t$ on /iff pap]4 ,! scale is #h 94 long1 & is divid$ into #aj l>ge divisions1 ea* ( :i* is subdivid$ into #aj p>ts1 ?us mak+ #ajj p>ts 9 all4 ,,index4 ,numb]s ref] to p>agraphs4 ,see ,table ( ,cont5ts = ! v>i\s exp]im5ts4 ,abrea/1 arrangem5t ( cells1 #cfe4 ,accumulators4 7,see /orage cells47 ,action1 local1 #bgc4 ,air1 z insulator1 #add1 a4 ,alt]nat+ curr5ts1 #ddc4 ,amalgamat+1 #beg1 #bgd4 ,amb]1 #ajg4 ,ammet]1 #cec4 ,amp]e1 !1 #cea1 #ceg4 ,amp]e's rule1 #chf4 ,anneal+1 #f4 ,annunciators1 #dga4 ,anode1 #cgc1 #cgh4 ,applications ( electricity1 ,*ap4 ,,xxvii4 ,arc lamp1 #dhe4 ,arrangem5t1 ( cells1 #cfc to #cfh4 ,armature1 !1 #aa1 #gh1 #dgf4 ,a/atic ne$les1 #bea1 #bec1 #bed2 galvanoscope1 #beb1 #bef4 ,atmosph]ic electricity1 ,*ap4 ,,xiii41 #bag2 causes (1 #bba4 ,attraction1 mutual1 #aaa2 & repulsion1 laws ( magnetic1 #bi2 electric1 laws (1 #aba4 ,aurora borealis1 #bbc4 ,batt]ies1 ,*ap4 ,,xv42 /orage1 #chb4 ,bell1 electric1 #dfh4 ,bell telephone1 #dhj4 ,bi*romate cell1 #bhi4 ,b\nd electrification1 #afb1 #aia4 ,break+ a magnet1 #ea4 ,bridge1 ,:eat/one's1 #cbd to #ccj4 ,bru%es1 #dgf4 ,buzz]s1 electric1 #dfh4 ,cable1 subm>9e1 z cond5s]1 #ahb4 ,capacity1 inductive1 #afi2 electrical1 #agf1 #agh4 ,c>bon1 transmitt]1 #dhb2 electroscope1 #aad4 ,ca?ode1 #cgc4 ,cell1 galvanic1 ,*ap4 ,,xv42 arrangem5t (1 #cfc1 #cfd1 #cfe1 #cfh2 *emical action 91 #bgj1 #bga2 direction ( curr5t 91 #bfh2 local action 91 #bgc2 op5 & clos$ circuit1 #bhf2 pol>ization (1 #bgh2 poles (1 #bfi2 simple1 #bge2 second>y1 #chb2 s+le-fluid1 #bge2 two-fluid1 #bha1 #bhe2 v>i\s galvanic1 #bhf to #bia4 ,*>ge1 9 cond5s]1 #aie2 residual ( cond5s]s1 #aig4 ,*>g+ conductors1 ,*ap4 ,,viii4 ,*emical action1 #cfi4 ,*emical effects ( curr5t1 ,*ap4 ,,xxi4 ,circuit1 electric1 #bff2 divid$1 #bic2 %ort1 #bie4 ,co]cive =ce1 #dd1 #df4 ,coils1 #cij2 induction1 #dgc1 #dgd2 me?od ( jo9+1 #djh2 pol>ity (1 #cib2 resi/ance1 #cji2 simple resi/ance1 #caj4 ,commutator1 #dgf4 ,compass1 #bf2 our1 #cb2 ne$le1 #bdc1 #bdi4 ,comp\nd magnets1 #gc4 ,cond5sation ( electrification1 ,*ap4 ,x41 #agh4 ,cond5s]s1 #agh2 action (1 #ahf1 #aia2 induction coil1 #aha2 subm>9e cables1 #ahb4 ,conductive dis*>ge1 #adi1 #ahd4 ,conductors1 #abf1 #abi1 #acc2 holl[ & solid1 #aec2 & insulators1 relation betwe51 #acc2 & non-conductors1 #cab4 ,connections1 electrical1 #bbf to #bcj4 ,contact break]1 ,exp4 #aie2 #dff4 ,convective dis*>ge1 #adi4 ,copp] sulphate solution1 #bhc4 ,cores1 ( electromagnets1 #cig4 ,c\lomb1 !1 #ced4 ,curr5t electricity1 ,"p ,,iii4 ,curr5t1 #add1 a1 #bfd2 detectors1 #bcb1 #bci2 direction ( 9 cell1 #bfh2 direct & alt]nat+1 #ddc2 extra1 #ddd2 int]rupt]s1 #dff2 prim>y & second>y1 #dda2 measurem5t (1 #ceb2 rev]s]1 #bce1 #bcg2 /r5g? (1 ,*ap4 ,,xx41 #cej1 #ceh1 #cfb to #cfe2 unit (1 #cea4 ,daniell cell1 #bij4 ,decl9ation1 #hd4 ,depol>iz]s1 #bhj1 #bhb4 ,detectors1 curr5t1 #bcb1 #bci4 ,diamagnetic bodies1 #ae4 ,dielectric1 #ahd1 #aia1 #aie4 ,dielectrics1 #aff4 ,dip1 #hf4 ,direct curr5ts1 #dbh1 #ddc4 ,dis*>g]s1 #ahh4 ,dis*>ges1 k9ds (1 #adi4 ,divid$ circuits1 #bic1 #cbc4 ,dry cells1 #bhh4 ,dynamo1 #dce1 #dgf4 ,e>?'s magnetism1 #hc1 #ib1 #ic4 ,electric1 bells1 #dfh2 *ime1 #aic2 circuit1 #bff1 ,*ap4 ,,xvi42 curr5t1 #add1 a1 #bfd2 d5sity1 #aee2 field1 #aef2 horse-p[]1 #cee2 light+1 #dhd2 ma*9es1 /atic1 #baf2 motor1 #dgg2 pol>ization1 #aei2 resi/ance1 ,*ap4 ,,xviii42 w9d1 #aee4 ,electricity1 /atic1 ,"p ,,ii42 ,curr5t1 ,"p ,,iii42 ,applications (1 ,*ap4 ,,xxvii41 #def2 k9ds (1 #ajj2 d]ivation ( "n1 #ajg2 ,atmosph]ic1 ,*ap4 ,,xiii41 #bag4 ,electrification1 ,*ap4 ,,vi41 #ajc1 #aaf1 #acb1 #acd2 & heat1 #ajd2 cond5sation (1 ,*ap4 ,x42 escape (1 #aee2 free & b\nd1 #afb2 induc$1 ,*ap4 ,,ix42 k9ds (1 #abj2 ( e>?1 #bbb2 s\rce ( 9 cells1 #bfe2 !ories ab\t1 #ade2 two k9ds (1 #abj1 #baa4 ,electrics & non-electrics1 #acd4 ,electrifi$ bodies1 #ajb1 #ajg4 ,electrodes1 #bfi4 ,electromagnetism1 ,*ap4 ,,xxii41 #chc4 ,electromagnets1 ,*ap4 ,,xxiii41 #cif2 cores (1 #cig2 horse%oe1 #dje4 ,electromotive =ce1 #add1 ,*ap4 ,,xvii41 #bif1 #cjj1 #cjc2 measurem5t (1 ,exp4 #adj2 ( pol>ization1 #cgc1 #chb2 s]ies1 #cja2 unit (1 #big4 ,electrophorus1 #ach2 action (1 #aga1 #agb2 our1 #aci4 ,electrolysis1 #cgj4 ,electrolyte1 #cgj4 ,electroplat+1 #cgf1 #cgh4 ,electroscope1 action (1 #bjf1 #bjh2 c>bon1 #aad2 pi?-ball1 #bjj2 our leaf1 #bja1 #bjb4 ,electroscopes1 ,*ap4 ,,xi4 ,electrotyp+1 #cgi4 ,equator ( magnet1 #ac4 ,equipot5tial po9ts1 #cbf4 ,ext]nal resi/ance1 #cjg1 #cfh4 ,extra curr5t1 #ddd2 ,exp4 #aii4 ,field1 electric1 #aef2 magnetic1 ,*ap4 ,,iv41 #fb1 #hj2 magnets1 #dgf4 ,figures1 magnetic1 #fd2 p]man5t1 #dag4 ,=ce1 #ajc2 l9es ( magnetic1 #fd1 #gc1 #hj1 #aef2 l9es ( electric1 #aef2 l9es ( ab\t a wire1 #che4 ,frankl91 ,b5jam91 #bah4 ,free electrification1 #afb4 ,frictional electricity1 ,"p ,,ii4 ,fulm9at+ panes1 #ahj4 ,galvanic cells1 ,*ap4 ,,xv41 #bfe2 *emical action 91 #bgj2 v>i\s k9ds (1 #bhf to #bia4 ,galvanoscope1 #bdj to #bdi4 ,glass1 z insulator1 #acf4 ,gold-leaf electroscope1 #bjj1 #bji4 ,gravity cell1 #bia4 ,h>d5+ /eel1 #h1 #aj4 ,heat1 effect on resi/ance1 #cdc2 effect on magnet1 #di4 ,horse-p[]1 electric1 #cee4 ,horse%oe magnet1 #aa2 advantages (1 #hb2 electromagnets1 #dje4 ,hydrog51 #bfj1 #bfb1 #bga1 #bgh1 #bgi1 #cgc4 ,incl9ation ( ne$le1 #hf4 ,induc$ curr5ts1 ,*ap4 ,,xxv42 & "w1 #dbi2 & l9es ( =ce1 #dcb1 #dce1 #dch2 direction (1 #dci4 ,induc$ magnetism1 ,*ap4 ,,iii4 ,induction coils1 #dgc2 action (1 #dgd2 cond5s]s (1 #aha2 ) telephone1 #dhc4 ,induction1 electromagnetic1 #dbf2 laws (1 #ddj2 /atic1 !ory (1 #aei2 successive1 #afh4 ,inductive capacity1 #afi4 ,insulators1 ,*ap4 ,,vii41 #abe4 ,int]nal resi/ance1 #cjg1 #cad1 #ceh1 #cfb1 #cfh4 ,iron & /eel1 ,*ap4 ,i4 ,iron1 h>d5+ prop]ties (1 ,exp4 #d2 impurities (1 #a2 k9ds (1 #b2 s(t1 #aj4 ,j>1 ,leyd51 #agi4 ,key1 #bcc1 #bcd4 ,lamp1 arc1 #dhe2 inc&esc5t1 #dhf4 ,laws1 ( electrification1 #aba2 ( induction1 #ddj2 ( magnetism1 #bi2 ( resi/ance1 #cdi4 ,leclan* cell1 #bhg4 ,leyd5 j>1 #agi4 ,light+1 #dhd1 #dhe1 #dhf4 ,lightn+1 #add1 a2 #bah2 rods1 #bbj4 ,l9es ( =ce1 ab\t a wire1 #che1 #chh2 electric1 #aef2 & induc$ curr5ts1 #dcb1 #dch2 magnetic1 #fd1 #gc1 #gd1 #hj1 #aef2 resi/ance to1 #gh1 #cig4 ,local action1 #bgc4 ,local curr5ts1 #bgc4 ,lode/one1 #ic4 ,magnetic1 bodies1 #ae2 circuits1 clos$1 #dbj2 field1 #fb1 #hj2 figures1 p]man5t1 #dag2 figures1 #fd1 ,exp4 #afa1 #afb1 ,exps4 #afh to #aga2 =ce1 l9es (1 #fd1 #hj1 #aef2 induction ( ! e>?1 #ib2 ne$le1 #bf2 ne$les1 balanc+ (1 #hh2 ne$le1 dip (1 #hf2 problems1 #cc2 saturation1 #db2 scre5s1 #ah2 tick1 ,exp4 #afj2 transp>5cy1 #ah4 ,magnetism1 ,"p ,i42 induc$1 ,*ap4 ,,iii41 #ec2 residual1 #dd1 #ec2 tempor>y1 #ec2 t]re/rial1 ,*ap4 ,v42 !ory (1 #db2 ( e>?1 #hc2 laws (1 #bi4 ,magnets1 b>1 #ba2 comp\nd1 #gc2 effect ( break+1 #ea2 equator (1 #ac1 #ea2 exp]im5tal1 #djg2 k9ds (1 #aa2 natural1 #ic2 poles (1 #ac1 #be2 practical uses (1 #af4 ,m]cury1 #bgd4 ,motion1 production (1 ,*ap4 ,,xxvi41 #dde1 #deb1 #dee4 ,motors1 electric1 #dgg4 ,mutual attractions1 #aaa4 ,natural magnets1 #ic4 ,ne$le1 a/atic1 #bea1 #bec1 #bed2 magnetic1 #bf1 #cb4 ,negative electrification1 #abj4 ,neutral bodies1 #ajb4 ,non-conductors1 #cab4 ,non-electrics1 #acd4 ,nor?-seek+ poles1 #be4 ,ohm1 !1 #cjh4 ,ohm's law1 #cef4 ,"o-fluid !ory1 #ade4 ,op5 & clos$ circuits1 #bff2 cells1 #bhf4 ,oxyg51 #cgb1 #cgc1 #chb4 ,pelti] effect1 #dbd4 ,pi?-ball electroscope1 #bjj4 ,plates or elem5ts1 #bfg4 ,pol>ization ( cells1 #bgh2 effects (1 #bgi2 electric1 #aei1 #afd2 electromotive =ce (1 #cgc2 magnetic1 #ef2 rem$ies =1 #bhj4 ,poles1 #ac1 #be1 #fd1 #ib2 consequ5t1 #ci2 ( coils1 #cib2 ( electrodes1 #bfi2 rev]sal (1 #ce2 rule =1 #ca4 ,pole pieces1 #ef4 ,positive electrification1 #abj4 ,pot5tial1 #acc1add2 en]gy1 #ajc4 ,prim>y curr5t1 #dda4 ,pro(-plane1 #bji4 ,quantity1 unit (1 #ced4 ,record]1 ,exp4 #aig4 ,relay1 telegraph1 #dfb4 ,repulsion1 laws ( electro/atic1 #aba2 laws ( magnetic1 #bi4 ,residual1 *>ge 9 cond5s]1 #aig2 magnetism1 #dd2 magnetism ( core1 ,exp4 #aei4 ,resi/ance1 coils1 #cji2 effect ( heat on1 #cdc2 electrical1 ,*ap4 ,,xviii41 #cje1 #cai1 #cba2 ext]nal & int]nal1 #cjg1 #cfb1 #cfh2 int]nal1 #cad1 #ceh2 laws (1 #cdi2 to l9es ( =ce1 #gh2 measurem5t (1 ,*ap4 ,,xix42 unit (1 #cjh4 ,ret5tivity1 #dd1 #df4 ,rev]s]1 curr5t1 #bce1 #bcg4 ,rheo/at1 simple1 #cdd4 ,saturation1 magnetic1 #db4 ,second>y cells1 #chb2 curr5t1 #dda4 ,self-induction1 #ddd4 ,s]ies arrangem5t ( cells1 #cfd4 ,%ocks1 #ahh4 ,%ort circuits1 #bie4 ,%unts1 #bic4 ,silk1 z insulator1 #acf4 ,s+le-fluid cell1 #bge4 ,s+le ne$le telegraph1 ,exp4 #aid4 ,s\nd]1 telegraph1 #deh4 ,sp>k1 #add1 a4 ,/atic electricity1 ,"p ,,ii4 ,/atic electric ma*9es1 #baf4 ,/eel1 ,*ap4 ,i42 k9ds (1 #b2 magnetism (1 #db1 #df1 #di4 ,/4 ,elmo's fire1 #bbb4 ,/orage cells1 #chb4 ,successive1 induction1 #afh2 cond5sation1 #aii4 ,sulphuric acid1 #beh1 #bfb1 #cad4 ,tang5t galvanomet]1 #ceb4 ,telegraph1 l9e1 #dei1 #dfj2 relay1 #dfb2 s+le ne$le in/rum5t1 ,exp4 #aid2 s\nd]1 #deh2 /atic1 #acj4 ,telephone1 !1 #dgi2 ,bell1 #dhj2 c>bon transmitt]1 #dhb2 ) induction coils1 #dhc2 receiv]1 #dha4 ,temp]+ /eel1 #h4 ,tempor>y magnetism1 #ec4 ,t]re/rial magnetism1 ,*ap4 ,v4 ,!rmoelectricity1 ,*ap4 ,,xxiv41 #dbc4 ,!rmopile1 #dbe2 home-made1 #dba4 ,?und]1 #bai4 ,trans=m]s1 #dge4 ,transmitt]s1 #dhj1 #dhb4 ,two-fluid cell1 #bhj1 #bha2 c>e (1 #bhb2 *emical action 91 #bhe4 ,two-fluid !ory ( electrification1 #adf4 ,unit (1 curr5t /r5g?1 #cea2 ,e4 ,m4 ,f41 #big2 ( p[]1 #cee2 quantity1 #ced2 resi/ance1 #cjh4 ,v>iation1 angle (1 #hd4 ,v>ieties ( electricity1 #ajj4 ,volt1 !1 #big4 ,voltamet]s1 #big1 #cec1 #chj4 ,wat]1 composition (1 #cgb4 ,watt1 !1 #cee4 ,:eat/one's bridge1 #cbd to #ccj4 ,w9d1 electric1 #aee4 ,wire tables1 ,*ap4 ,,xxviii4 ,yoke1 use (1 #djf4 ,z]o1 pot5tial1 #add1 a4 ,z9c1 *emical action )1 #bga2 ) comm]cial1 #bgc4 ,z9c plates1 reasons = amalgamat+1 #bgd4 ,notes4 ,notes4 ,,electrical ,,books ,,electrical ,,app>atus ,,games ,,puzzles ,,educational ,,amusem5ts ,illu/ration ,,?omas ,m4 ,,/4 ,,john1 ,met4 ,e4 ,a ,^w to ,p>5ts ,ab\t ,games & ,educational ,amusem5ts4 ,sy/ematic play is z important z sy/ematic "w4 ,! be/ games & home amusem5ts are z valuable to a *ild z s*ool-/udies2 9 fact1 !y br+ out & /imulate qualities 9 a *ild1 :i* no s*ool-/udy c4 ,fasc9at+ home amusem5ts are z necess>y z s*ool-books4 ,boys & girls l to be busy4 ,_! amusem5ts %\ld be ent]$ into z he>tily1 *os5 z c>efully1 & pur*as$ z will+ly z s*ool-books4 ,games4--,,j+o & ,,hu/le-,,ball are good games4 ,!y are int]e/+ & full ( action4 ,!y ar\se a *ild's common-s5se4 ,!y cultivate an ability to ?9k rapidly1 judge correctly1 & decide quickly4 ,!y educate ! eye & h& at ! same "t4 ,!y are v simple1 & may be play$ at once4 ,educational ,amusem5ts4--,!re is a peculi> fasc9ation ab\t ,electricity & ,magnetism1 :i* makes ^! subjects appeal to e boy & girl4 ,!re is no?+ bett] ?an sci5ce /udies1 to tea* *ildr5 to obs]ve & to see :at !y look at2 besides1 x is fun to exp]im5t4 ,fun ,) ,electricity & ,fun ,) ,magnetism are educational amusem5ts4 ,!y conta9 fasc9at+ exp]im5ts & are sy/ematically arrang$4 ,juv5ile ,"w 9 ,electricity4 ,f ,! ,electrical ,eng9e]1 ,may #ai1 #ahih4 ,! position t ,"y ,am]ica is n[ tak+ 9 ! electric & magnetic field is v cle>ly %[n at ! ,electrical ,%[ n[ be+ held at ,madison ,squ>e ,g>d51 by an exhibit ( simple exp]im5tal app>atus made by "y boys f ! ,br[n+ ,s*ool1 ( ?is city4 ,! models %[n cov] e v>iety ( app>atus t is de> to ! he>t ( a boy1 & yet1 along ! :ole l9e f pu%-buttons to motors1 "o is /ruck by ! extreme simplicity ( design & ! +5i\s uses made ( old t9 tomato cans1 crack] boxes1 bolts1 screws1 wire1 & ! wood t a boy c get f a soap box4 ,! app>atus 9 ?is exhibit 0 made by boys #ac1 #ad & #ae ye>s ( age1 f designs made by ,mr4 ,?omas ,m4 ,/4 ,john1 ( ! ,br[n+ ,s*ool4 ,x cle>ly %[s t good1 practical app>atus c be made f *eap mat]ials by an av]age boy4 ,! :ole exhibit is wir$ & 9 work+ ord]1 & x attracts ! att5tion ( a l>ge numb] ( p>5ts & boys :o hov] ar\nd to see1 9 op]ation1 ! telegraph in/rum5ts1 buzz]s1 %ock+ coils1 curr5t detectors1 motors1 etc4 ,mr4 ,/4 ,john des]ves ! ?anks ( e boy :o wants to build 8 own electrical app>atus = amusem5t or = exp]im5tal purposes1 z he has made ! designs extremely simple1 & has kept con/antly 9 m9d ! fact t ! av]age boy has b a limit$ supply ( pocket money1 & an equally limit$ supply ( tools4 ,h[ ,two ,boys ,made ,_! ,own ,electrical ,app>atus4 ,,cont5ts3 ,*apt] ,i4 ,cells & ,batt]ies4--,,ii4 ,batt]y ,fluids & ,solutions4--,,iii4 ,miscellane\s ,app>atus & ,me?ods ( ,con/ruction4--,,iv4 ,swit*es & ,cut-,outs4--,v4 ,b9d+-,po/s & ,connectors4--,,vi4 ,p]man5t ,magnets4--,,vii4 ,magnetic ,ne$les & ,compasses4--,,viii4 ,yokes & ,armatures4--,,ix4 ,electro-,magnets4--,x4 ,wire-,w9d+ ,app>atus4--,,xi4 ,induction ,coils & ,_! ,atta*m5ts4--,,xii4 ,contact ,break]s & ,curr5t ,int]rupt]s4--,,xiii4 ,curr5t ,detectors & ,galvanomet]s4--,,xiv4 ,telegraph ,keys & ,s\nd]s4--,,xv4 ,electric ,bells & ,buzz]s4--,,xvi4 ,commutators & ,curr5t ,rev]s]s4--,,xvii4 ,resi/ance ,coils4--,,xviii4 ,app>atus = ,/atic ,electricity4--,,xix4 ,electric ,motors4--,,xx4 ,odds & ,ends4--,,xxi4 ,tools & ,mat]ials4 ,! au?or ( ?is book is a tea*] & writ] ( great +5uity1 & we imag9e t ! effect ( su* a book z ?is fall+ into ,juv5ile h&s mu/ be highly /imulat+ & b5eficial4 ,x is full ( explicit details & in/ructions 9 reg>d to a great v>iety ( app>atus1 & ! mat]ials requir$ are all )9 ! compass ( v mode/ pocket-money4 ,moreov]1 x is sy/ematic & entirely )\t rhetorical frills1 s t ! /ud5t c g "r along )\t be+ div]t$ f good helpful "w t w lead him to build useful app>atus & make him und]/& :at he is ab\t4 ,! draw+s are pla9 & excell5t4 ,we he>tily comm5d ! book4--,electrical ,eng9e]4 ,^? :o visit$ ! electrical exhibition la/ ,may _c h fail$ to notice on ! s\? gall]y a v int]e/+ exhibit1 consi/+1 z x did1 ( electrical app>atus made by boys4 ,! v>i\s devices !re %[n1 compris+ electro-magnets1 telegraph keys & s\nd]s1 resi/ance coils1 etc41 7 turn$ out by boys foll[+ ! in/ructions giv5 9 ! book ) ! above title1 :i* is unque/ionably "o ( ! mo/ practical little works yet writt5 t treat ( simil> subjects1 = ) b a limit$ am\nt ( me*anical k1 & by closely foll[+ ! in/ructions giv51 almo/ any electrical device may be made at v small exp5se4 ,t su* a book fills a long-felt want may be inf]r$ f ! numb] ( inquiries we are con/antly receiv+ f p]sons desir+ to make _! own induction coils & o!r app>atus4--,electricity4 ,at ! electrical %[ 9 ,new ,york la/ ,may "o ( ! mo/ int]e/+ exhibits 0 t ( simple electrical app>atus made by ! boys 9 "o ( ! private s*ools 9 ! city4 ,?is app>atus1 made by boys ( ?irte5 to fifte5 ye>s ( age1 0 f designs by ! au?or ( ?is clev] little book1 & x 0 rem>kable to see :at an +5i\s use _h be5 made ( old t9 tomato-cans1 crack]-boxes1 bolts1 screws1 wire1 & wood4 ,) ^! simple mat]ials telegraph in/rum5ts1 coils1 buzz]s1 curr5t detectors1 motors1 swit*es1 armatures1 & an almo/ endless v>iety ( app>atus 7 made4 ,9 8 book ,mr4 ,/4 ,john has giv5 directions 9 simple language = mak+ & us+ ^! devices1 & has illu/rat$ ^! directions ) admirable diagrams & cuts4 ,! little volume is unique1 & w prove exce$+ly helpful to ^? ( our "y read]s :o are =tunate en\gh to possess !mselves ( a copy4 ,= s*ools :]e a c\rse ( elem5t>y sci5ce is taught1 no bett] text-book 9 ! fir/-/eps 9 electricity is obta9able4--,! ,great ,r\nd ,_w4 ,exhibit ( ,exp]im5tal ,electrical ,app>atus ,,at ,,! ,,electrical ,,%[1 ,,madison ,,squ>e ,,g>d51 ,,new ,,york4 ,:ile only #dj pieces ( simple app>atus 7 %[n 9 ?is exhibit1 x gave visitors some?+ ( an idea ( :at "y boys c d if giv5 prop] designs4 ,illu/ration3 ,,h[ ,,two ,,boys ,,made ,,_! ,,own ,,electrical ,,app>atus ,gives ,prop] ,designs--,designs = ov] #aej ,?+s4 ,,j ,,publi%$4 ,h[ ,two ,boys ,made ,_! ,own ,electrical ,app>atus4 ,conta9+ complete directions = mak+ all k9ds ( simple electrical app>atus = ! /udy ( elem5t>y electricity4 ,by ,,pr(essor ,,?omas ,m4 ,,/4 ,,john1 ,new ,york ,city4 ,! book measures #e #g-a_/b 941 & is beautifully b\nd 9 clo?4 ,x conta9s #ada pages & #abe illu/rations4 ,complete directions are giv5 = mak+ #aeb diff]5t pieces ( ,app>atus = ! practical use ( /ud5ts1 tea*]s1 & o!rs :o wi% to exp]im5t4 ,,price1 ,,po/-,,paid1 #a4jj4 ,! %ock+ coils1 telegraph in/rum5ts1 batt]ies1 electromagnets1 motors1 etc41 etc41 are s simple 9 con/ruction t any boy ( av]age ability c make !m2 9 fact1 ! illu/rations h be5 made directly f app>atus con/ruct$ by "y boys4 ,! au?or has be5 work+ along ?is l9e = sev]al ye>s1 & he has be5 able1 ) ! help ( boys1 to devise a complete l9e ( simple electrical app>atus4 ,,! ,,app>atus ,,is ,,simple because ! designs & me?ods ( con/ruction h be5 work$ out practically 9 ! s*ool-room1 absolutely no ma*9e-"w be+ requir$4 ,,! ,,app>atus ,,is ,,practical because x has be5 design$ = real use 9 ! exp]im5tal /udy ( elem5t>y electricity4 ,,! ,,app>atus ,,is ,,*eap because mo/ ( ! p>ts c be made ( old t9 cans & crack] boxes1 bolts1 screws1 wires & wood4 ,address1 ,,?omas ,m4 ,,/4 ,,john1 #djg ,we/ #ea/ ,/reet1 ,new ,york4 ,fun ,) ,magnetism4 ,,book ,,& ,,complete ,,outfit ,,= ,,sixty-,,"o ,,exp]im5ts ,,9 ,,magnetism4444 ,illu/ration ,*ildr5 l to d exp]im5ts2 & 9 ?is way1 bett] ?an 9 any o!r1 a practical k ( ! elem5ts ( magnetism may be obta9$4 ,^! exp]im5ts1 al?\gh arrang$ to amuse boys & girls1 h be5 f\nd to be v useful 9 ! class-room to supplem5t ! ord9>y ex]cises giv5 9 text-books ( sci5ce4 ,to secure ! be/ possible quality ( app>atus1 ! horse%oe magnets 7 made at ,%effield1 ,engl&1 especially = ^! sets4 ,!y are new & /rong4 ,o!r p>ts ( ! app>atus h also be5 select$ & made ) great c>e1 to adapt !m p>ticul>ly to ^! exp]im5ts4--,f ! au?or's preface4 ,,cont5ts4--,exp]im5ts ,) ,horse%oe ,magnet4--,exp]im5ts ,) ,magnetiz$ ,ne$les4--,exp]im5ts ,) ,ne$les1 ,corks1 ,wires1 ,nails1 etc4--,exp]im5ts ,) ,b> ,magnets4--,exp]im5ts ,) ,float+ ,magnets4--,miscellane\s ,exp]im5ts4--,miscellane\s ,illu/rations %[+ :at v small *ildr5 c d ) ! ,app>atus4--,diagrams %[+ h[ ,magnetiz$ ,ne$les may be us$ by little *ildr5 to make hundr$s ( pretty designs ^u pap]4 ,,amus+ ,,exp]im5ts4--,some?+ = ,n]v\s ,p to ,try4--,! ,j]sey ,mosquito4--,! ,/amp$e4--,! ,runaway4--,! ,dog-fight4--,! ,:irligig4--,! ,naval ,battle4--,a ,/r+ ( ,fi%4--,a ,magnetic ,gun4--,a ,top ,upsid$[n4--,a ,magnetic ,w9dmill4--,a ,compass ,upsid$[n4--,! ,magnetic ,acrobat4--,! ,busy ,ant-hill4--,! ,magnetic ,bridge4--,! ,m]ry-g-,r\nd4--,! ,tight-rope ,walk]4--,a ,magnetic ,motor ,us+ ,attractions & ,repulsions4 ,! ,book & ,complete ,outfit w be s5t1 ,po/-paid1 ^u receipt ( #ce ,c5ts1 by ,,?omas ,m4 ,,/4 ,,john1 #djg ,w4 #ea/ ,/41 ,new ,york4 ,a ,few ,(f-,h& ,/atem5ts t h be5 made ab\t ,fun ,) ,magnetism & ,fun ,) ,electricity 9 lett]s ( inquiry to ! au?or4 7,^! /atem5ts 7 absolutely unsolicit$47 ,my little boy has y\r ',fun ,) ,magnetism' & enjoys x s mu* t if ! ',fun ,) ,electricity' is ready ,i w\ld l to h x = him4 ,please let me "k1 etc4 ,i h _h mu* fun ) ',fun ,) ,magnetism4' ,my boy has ',fun ,) ,magnetism' & has enjoy$ x v mu* & w\ld l ! o!r4 ,w y1 etc4 ,please let me "k :5 ',fun ,) ,electricity' is ^u ! m>ket1 = if x is z good z ?is1 ,i %all c]ta9ly want x4 ,i h j receiv$ ',fun ,) ,magnetism' & am delight$ ) x4 ,please s5d me #ab sets1 etc4 ,i h ',fun ,) ,magnetism' & ',fun ,) ,electricity' & h enjoy$ !m v mu*4 ,please s5d1 etc4 ,i am mu* pleas$ ) ',fun ,) ,electricity' & w\ld l to h1 etc4 ',fun ,) ,electricity' is f9e & ,i h _h lots ( fun ) x4 ,please s5d1 etc4 ,hav+ exp]im5t$ ) bo? ( y\r app>atus ',fun ,) ,magnetism' & ',fun ,) ,electricity1' & hav+ f\nd !m bo? amus+ & in/ructive1 ,i wi% to ask1 etc4 ,i h pur*as$ y\r outfits ',fun ,) ,electricity' & ',fun ,) ,magnetism1' & ?\gh !y are design$ = amusem5t1 ,i f9d !m a great help 9 my /udies4 ,w y please1 etc4 ,i h "o ( y\r outfits ( ',fun ,) ,electricity1' & ,i enjoy x v mu*1 "s ( ! exp]im5ts be+ v a/oni%+4 ,w y please1 etc4 ,i h enjoy$ ',fun ,) ,magnetism' & ',fun ,) ,electricity' v mu*4 ,my little boy has y\r book ',fun ,) ,electricity1' :i* has giv5 him mu* amusem5t4 ,he w\ld l to h1 etc4 ,i am v mu* pleas$ ) bo? outfits4 ,i am v mu* 9 favor ( su* ?+s = boys2 x keeps !m occupi$ ) some?+ t is bo? amus+ & in/ructive4 ,s5d me1 etc4 ,fun ,) ,electricity4 ,,book ,,& ,,complete ,,outfit ,,= ,,sixty ,,exp]im5ts ,,9 ,,electricity4444 ,illu/ration ,en\gh ( ! pr9ciples ( electricity are br\ght out to make ! book in/ructive z well z amus+4 ,! exp]im5ts are sy/ematically arrang$1 & make a fasc9at+ sci5ce c\rse4 ,no *emicals1 no dang]4 ,! book is conv]sational & n at all s*ooly1 ,h>ry & ,n$ be+ two boys :o p]=m ! exp]im5ts & talk ov] ! results z !y g along4 ,! book reads l a /ory4--,an appropriate pres5t = a boy or girl4--,intellig5t p>5ts w appreciate ',fun ,) ,electricity4'--,v complete1 because x conta9s bo? book & app>atus4--,!re is no end to ! fun :i* a boy or girl c h ) ?is fasc9at+ amusem5t4 ,,!re ,,is ,,fun ,,9 ,,^! ,,exp]im5ts4--,*a9 ,lightn+4--,an ,electric ,:irligig4--,! ,baby ,?und]/orm4--,a ,race ) ,electricity4--,an ,electric ,frog ,pond4--,an ,electric ,d+-,dong4--,! ,magic ,f+]4--,daddy ,long-,legs4--,jump+ ,sally4--,an ,electric ,kite4--,v ,%ock+4--,cond5s$ ,lightn+4--,an ,electric ,fly-,trap4--,! ,m]ry ,p5dulum4--,an ,electric ,f]ry-,boat4--,a ,funny ,piece ( ,pap]4--,a ,joke on ! ,family ,cat4--,electricity ,plays ,leap-,frog4--,lightn+ ,goes ,ov] a ,bridge4--,electricity ,c>ries a ,lant]n4--,& #dj ,o!rs4 ,! ,,outfit conta9s #bj diff]5t articles4 ,! ,,book ,,( ,,in/ruction measures #e #g-a_/b in*es1 & has #ch illu/rations1 #ee pages1 good pap] & cle> type4 ,! ,book & ,complete ,outfit w be s5t1 by mail or express1 ,*>ges ,prepaid1 ^u receipt ( #fe ,c5ts1 by ,,?omas ,m4 ,,/4 ,,john1 #djg ,w4 #ea/ ,/41 ,new ,york4 ,fun ,) ,puzzles4 ,,book1 ,,key1 ,,& ,,complete ,,outfit ,,= ,,f\r ,,hundr$ ,,puzzles4444 ,! ,,book measures #e #g-a_/b in*es4 ,x is well pr9t$1 nicely b\nd1 & conta9s #ae *apt]s1 #hj pages1 & #abh illu/rations4 ,! ,,key is illu/rat$4 ,x is b\nd ) ! book1 & conta9s ! solution ( e puzzle4 ,! ,,complete ,,outfit is plac$ 9 a neat box ) ! book4 ,x consi/s ( numb]s1 c\nt]s1 figures1 pictures1 etc41 = do+ ! puzzles4 ,,cont5ts3 ,*apt] 7#a7 ,secret ,writ+4 7#b7 ,magic ,triangles1 ,squ>es1 ,rectangles1 ,hexagons1 ,crosses1 ,circles1 etc4 7#c7 ,dropp$ ,lett] & ,dropp$ ,^w ,puzzles4 7#d7 ,mix$ ,prov]bs1 ,prose & ,rhyme4 7#e7 ,^w ,diamonds1 ,squ>es1 ,triangles1 & ,rhomboids4 7#f7 ,num]ical ,enigmas4 7#g7 ,jumbl$ ,writ+ & ,magic ,prov]bs4 7#h7 ,dissect$ ,puzzles4 7#i7 ,hidd5 & ,conceal$ ,words4 7#aj7 ,divid$ ,cakes1 ,pies1 ,g>d5s1 ,f>ms1 etc4 7#aa7 ,bicycle & ,boat ,puzzles4 7#ab7 ,v>i\s ,^w & ,lett] ,puzzles4 7#ac7 ,puzzles ) ,c\nt]s4 7#ad7 ,comb9ation ,puzzles4 7#ae7 ,mazes & ,labyr9?s4 ,fun ,) ,puzzles is a book t e boy & girl %\ld h4 ,x is amus+1 in/ructive1--educational4 ,x is j ! ?+ to wake up boys & girls & make !m ?9k4 ,!y l x1 because x is real fun4 ,?is sort ( educational play %\ld be giv5 9 e s*ool-room & 9 e home4 ,fun ,) ,puzzles w puzzle y\r fri5ds1 z well z y\rself2 x conta9s "s real bra9-splitt]s4 ,ov] #cjj new & orig9al puzzles are giv51 besides _m t are hundr$s ( ye>s old4 ,secret ,writ+4 ,among ! _m ?+s t ,f4 ,w4 ,p4 conta9s1 is ! key to secret writ+4 ,x %[s y a v simple way to write lett]s to y\r fri5ds1 & x is simply impossible = o!rs to read :at y h writt51 unless !y "k ! secret4 ,?is1 alone is a valuable ?+ = any boy or girl :o wants to h "s fun4 ,! ,book1 ,key1 & ,complete ,outfit w be s5t1 po/paid1 ^u receipt ( #ce c5ts1 by ,,?omas ,m4 ,,/4 ,,john1 #djg ,we/ #ea/ ,/41 ,new ,york ,city4 ,fun ,) ,soap-,bubbles4 ,,book ,,& ,,complete ,,outfit ,,= ,,fancy ,,bubbles ,,& ,,films4444 ,illu/ration ,,! ,,outfit conta9s ev]y?+ necess>y = ?\s&s ( beautiful bubbles & films4 ,all highly color$ articles h be5 c>efully avoid$1 z *eap pa9ts & dyes are positively dang]\s 9 *ildr5's m\?s4 ,! outfit conta9s ! foll[+ articles3 ,"o ,book ( ,in/ructions1 call$ ,fun ,) ,soap-,bubbles1 #a ,metal ,base = ,bubble ,/&1 #a ,wood5 ,rod = ,bubble ,/&1 #h ,l>ge ,wire ,r+s = ,bubble ,/&1 #a ,small ,wire ,r+1 #c ,/raws1 #a ,package ( ,prep>$ ,soap1 #a ,bubble ,pipe1 #a ,wat]-pro( ,bubble ,horn4 ,! complete outfit is plac$ 9 a neat box ) ! book4 7,extra ,horns1 ,soap1 etc41 furni%$ at slight co/47 ,,cont5ts ,,( ,,book4--,tw5ty-"o ,illu/rations4--,introduction4--,! ,colors ( ,soap-bubbles4--,! ,outfit4--,soap ,mixture4--,useful ,h9ts4--,bubbles ,bl[n ,) ,pipes4--,bubbles ,bl[n ,) ,/raws4--,bubbles ,bl[n ,) ! ,horn4--,float+ ,bubbles4--,baby ,bubbles4--,smoke ,bubbles4--,bomb%ell ,bubbles4--,danc+ ,bubbles4--,bubble ,games4--,support$ ,bubbles4--,bubble ,clu/]4--,susp5d$ ,bubbles4--,bubble ,lamp ,*imney4--,bubble ,l5ses4--,bubble ,basket4--,bubble ,bell[s4--,to ,draw a ,bubble ,?r\gh a ,r+4--,bubble ,acorn4--,bubble ,bottle4--,a ,bubble ,)9 a ,bubble4--,ano!r ,way4--,bubble ,%ade4--,bubble ,hammock4--,wre/l+ ,bubbles4--,a ,smok+ ,bubble4--,soap ,films4--,! ,t5nis ,racket ,film4--,fi%-net ,film4--,pan-%ap$ ,film4--,b[ & ,arr[ ,film4--,bubble ,dome4--,d\ble ,bubble ,dome4--,pyramid ,bubbles4--,turtle-back ,bubbles4--,soap-bubbles & ,frictional ,electricity4 ,!re is no?+ m beautiful ?an ! airy-fairy soap-bubble ) its ev]*ang+ colors4 ,,! ,,be/ ,,possible ,,amusem5t ,,= ,,old ,,& ,,"y4 ,! ,book & ,complete ,outfit w be s5t1 ,,po/-,,paid1 ^u receipt ( #ce c5ts1 by ,,?omas ,m4 ,,/4 ,,john1 #djg ,we/ #ea/ ,/41 ,new ,york ,city4 ,?+s ,a ,boy ,%\ld ,"k ,ab\t ,electricity4 7,9 ,prep>ation47 ,?is book expla9s1 9 simple1 /raight=w>d language1 _m ?+s ab\t electricity2 ?+s 9 :i* ! ,am]ican boy is int5sely int]e/$2 ?+s he wants to "k2 ?+s he %\ld "k4 ,x is free f te*nical language & rhetorical frills1 b x tells h[ ?+s "w1 & :y !y "w4 ,x is brimful ( illu/rations--! be/ t c be _h--illu/rations t are tak5 directly f app>atus & ma*9]y1 & t %[ :at !y are int5d$ to %[4 ,?is book does n conta9 exp]im5ts1 or tell h[ to make app>atus2 our o!r books d t4 ,aft] expla9+ ! simple pr9ciples ( electricity1 x %[s h[ ^! pr9ciples are us$ & comb9$ to make electricity d e-day "w4 ,! foll[+ are ,"s ( ! ,?+s ,electricity ,c ,d3 ,x signals )\t wires4 ,x drills rock1 coal1 & tee?4 ,x cures diseases & kills crim9als4 ,x protects1 heats1 & v5tilates h\ses4 ,x photographs ! bones ( ! human body4 ,x r+s *ur* bells & plays *ur* organs4 ,x lights /reets1 c>s1 boats1 m9es1 h\ses1 etc4 ,x pumps wat]1 cooks food1 & fans y :ile eat+4 ,x runs all sorts ( ma*9]y1 elevators1 c>s1 boats1 & wagons4 ,x s5ds messages ) ! telegraph1 telephone1 telautograph1 & se>*-light4 ,x cuts clo?1 irons clo!s1 wa%es di%es1 black5s boots1 welds metals1 pr9ts books1 etc41 etc4 ,ev]yone ,%\ld ,"k ,ab\t ,electricity4 ,?+s ,a ,boy ,%\ld ,"k ,ab\t ,electricity w int]e/ y4 ,we %all be glad to s5d y complete in=mation z soon z x is ready4 ,s5d u y\r address n[4 ,dewey ,flag ,poles ,,are ,,little ,,models ,,( ,,real ,,flag ,,poles4444 ,illu/ration ,!y are appropriate = any occasion1 & suitable = any k9d ( decoration4 ,!y %\ld /& on tables1 mantels1 pianos1 etc42 9 fact1 !re is no bett] ornam5t = g5]al use4 ,!y %\ld be 9 e home & 9 e s*ool-room 9 ! ,unit$ ,/ates4 ,no toy =t complete )\t a ,dewey ,flag ,pole4 ,! *ildr5 c fa/5 !m on ! w9d[sill & wat* !m flutt] by ! h\r4 ,!y hoi/ l big flags1 at half-ma/1 etc4 ,invaluable = /ore-w9d[ decoration4 ,illu/ration ,,prices ,,small ,,size3 height #ah in*es1 fitt$ ) ,unit$ ,/ates or ,cuban ,silk ,flag 7#df 947 po/-paid1 #cj;c4 ,,l>ge ,,size3 height #bd in*es1 fitt$ ) ,unit$ ,/ates ,silk ,flag 7#g #aj 9471 po/-paid1 #dj;c4 ,,l>ge ,,size3 fitt$ ) ,cuban or ,briti% ,silk ,flag 7#hab 9471 po/-paid1 #ej;c4 ,,dewey ,,flag ,,poles are beautifully made ( h>d wood1 & fitt$ ) be/ ,silk ,flags4 ,,games4 ,hu/le,ball4 ,a quick1 %>p1 decisive game t is ?or\ghly ,am]ican4 ,play$ by means ( ,magic ,w&s1 & ,poli%$ ,balls ( ,/eel4 ,ne$$3 ,a quick eye & a nimble h&4--,%akespe>e4 ,! ,rule3 ,j keep cool--& hu/le4 ,f\r ,games ) ,"o ,outfit3 ,hu/le ,ball1 ,leap-,frog1 ,cross-,c\ntry ,race1 ,magnetic ,potato-,race4 ,! game-bo>d is new & orig9al1 z well z ! me?ods ( play+4 ,! game is put up 9 a /rong box hav+ a beautifully li?ograph$ cov]1 & measures #h #ae-a_/b in*es4 ,) ! game-bo>d are furni%$1 magic w&s1 poli%$ /eel balls1 an extra /r5g? horse%oe magnet1 & a complete set ( illu/rat$ rules & directions = play+4 ,unlike all o!r games4 ,any "o c play ,hu/le-,ball4 ,j ! ?+ = progressive p>ties4 ,hu/le-,ball games are int5sely excit+4 ,no wait+ = "s "o to play4 ,y w9 or lose a po9t 9 a few seconds4 ,by h&icapp+ ! be/ play]s1 all games are made equally int]e/+ & excit+4 ,a game = ,gr&p>5ts1 z well z = ,gr&*ildr54 ,a ,br&-,new ,idea 9 ,games4 ,illu/ration ,illu/ration ',a ,,hu/le ,,f ,,! ,,^w ,,g4' ,?is ,excit+ ,game w be s5t1 ,*>ges ,prepaid1 by mail or express1 ^u receipt ( #fe ,c5ts4 ,address ,,?omas ,m4 ,,/4 ,,john1 #djg ,we/ #ea/ ,/reet1 ,new ,york ,city4 ,,j+o ,,! ,,great ,,w> ,,game ,social ,excit+ ,int]e/+ ,simple4 ,a ,?or\gh ,w> ,game3--,infantry ,aga9/ ,infantry1 ,cavalry ,aga9/ ,cavalry1 ,etc4 ,j+o is really a great w> conte/ betwe5 ,engl& & ,am]ica4 ,^u ! game-bo>d are #ad beautiful w> sc5es1 ea* li?ograph$ 9 #h colors4 ,am]ican & ,engli% flags1 coats ( arms1 cannon1 torp$oes1 etc41 aid 9 mak+ ?is game arti/ic1 h&some & attractive4 ,! foll[+ companies1 %ips1 etc41 are %[n3--,am]ican1 #ab? ,u4 ,s4 ,infantry1--#f? ,u4 ,s4 ,cavalry1--#b;d ,u4 ,s4 ,light ,artill]y1--,u4 ,s4 ,mort> ,batt]y1--,u4 ,s4 ,monitor ,miantonomoh1--,u4 ,s4 ,ram ,katahd91--,u4 ,s4 ,battle%ip ,indiana1--,u4 ,s4 ,torp$o ,boat ,cu%+1--,u4 ,s ,dynamite ,cruis] ,vesuvius4 ,engli%1 #cj? ,ea/ ,lanca%ire1--#a/ ,royal ,dragoons1--,royal ,horse ,artill]y1--,royal ,artill]y1--,h4 ,m4 ,s4 ,?und]]1--,h4 ,m4 ,s4 ,seagull1--,h4 ,m4 ,s4 ,nile1--,h4 ,m4 ,s4 ,au/ralia1--,h4 ,m4 ,s4 ,d>t4 ,! game bo>d is ov] #af in*es squ>e :5 op5$4 ,j+o is made & f9i%$ 9 a mann] :i* makes x ! mo/ beautiful1 arti/ic1 & practical game ev] publi%$4 ,j :at e boy likes4 ,a good idea well c>ri$ out4 ,! ,game-bo>d is a "w ( art4 ,any *ild c play ,j+o at once4 ,x is ! h&some/ game on ! m>ket4 ,,j+o ,,junior is ! ,greate/ ,game ev] ,inv5t$ = ,little ,folks4 ,x is play$ ^u ! ,j+o bo>d ) ! extra ammunition furni%$4 ,^! ,two ,great ,games make a mo/ complete & beautiful outfit = home amusem5t4 ,,j+o ,,& ,,j+o ,,junior4 ,two ,fasc9at+ & ,entirely ,diff]5t ,games1 ,play$ ) ,"o ,outfit1 & ,complete 9 ,"o ,box4 ,illu/ration ,,?is ,,h&some ,,outfit = play+ ! ,,two ,,great ,,w> ,,games w be s5t ,,*>ges ,,prepaid ^u receipt ( #a4jj4 ,address ,,?omas ,m4 ,,/4 ,,john1 #djg ,we/ #ea/ ,/reet1 ,new ,york ,city4 ,transcrib]'s ,notes ,9 ! text v]sion1 ,italic text is d5ot$ by und]scores & bold text by equal signs4 ,obvi\s punctuation errors h be5 repair$4 ,! book conta9s "s inconsi/5t hyph5ation :i* has be5 left z pr9t$4 p4 xi4 7,,toc7 con/ructi\ *ang$ to con/ruction p4 xiv4 7,,toc7 ,! ,prodution ( ,motion *ang$ to ,! ,production ( ,motion p4 #bg4 p>a4 #gc4 ?ick p]mam5t magnets *ang$ to ?ick p]man5t magnets p4 #ii4 p>a #bec4 wabble may be a typo = wobble b has be5 left on ! (f *ance t ?is c\ld be :at 0 int5d$4 p4 #aah4 ,fig #ia4 ,! f9al column has be5 scor$ ?r\gh b appe>s to read ,,cu to ,,zn p4 #aca4 p>a4 #cbd1 #cbe4 ,g]man-silv] ,wire1 ,g-s ,w us$ "h b previ\sly ,g ,s ,w us$4 p4 #afd4 p>a #cie4 circuit 9 clos$ *ang$ to circuit is clos$ p4 #aff4 p>a #cih4 core inside ( ! c l *ang$ to core inside ( ! coil aft] *eck+ orig9al scans4 p4 #afi-agj4 ,x appe>s t a ^w has be5 omitt$ across ! page break4 ,! copp] wa%]1 ,c ,w1 be us$4 has be5 *ang$ to ,! copp] wa%]1 ,c ,w1 %\ld be us$44 7,alt]native words are possible67 p4 #baa4 ,no4 #ce4 #e-af 94 *ang$ to #e_/af 94 p4 #bac4 ,no4 #ib1 #ic4 #e-af 94 *ang$ to #e_/af 94 p4 #bad4 ,no4 #if4 & ,no4 #ig4 #e-af 94 *ang$ to #e_/af 94 p4 #baf4 ,entry = ,c\lomb mov$ f end ( ,c to above ,curr5t4