99 99 99 99 99 ,transcrib]'s ,note3 ,! orig9al publication has be5 replicat$ fai?fully except z %[n 9 ! ,,transcrib]',s ,,am5dm5ts at ! end ( ! text4 ,?is etext presumes a mono-spac$ font on ! us]'s device1 su* z ,c\ri] ,new4 ,words 9 italics are indicat$ l ?is4 ,text emphasiz$ ) bold *>act]s or o!r treatm5t is %[n l ?is4 ,sup]scripts are indicat$ l ?is3 ,sta ,m>ia4 ,subscripts are indicat$ l ?is3 ,h#b,o4 ,footnotes are locat$ ne> ! end ( ! "w4 99 99 99 99 99 ,illu/ration ,illu/ration ,,! ,,?\ght ,,is ,,9 ,,! ,,"q ,,! ,,in=mation ,,is ,,9 ,,! ,,answ] ,,hawk9s ,,electrical ,,guide ,,numb] ,,"o ,,que/ions ,,answ]s ,,illu/rations ,a ,,progressive ,,c\rse ,,( ,,/udy ,,= ,,eng9e]s1 ,,electricians1 ,,/ud5ts ,,& ,,^? ,,desir+ ,,to ,,acquire ,a ,,work+ ,,k ,,( ,,electricity ,,& ,,its ,,applications ,a ,,practical ,,treatise by ,,hawk9s ,,& ,,/aff ,,!o4 ,,audel ,,co4 #gb ,,fif? ,,ave4 ,,new ,,york4 ,,copyright$1 #aiad1 ,,by ,,!o4 ,,audel ,,co41 ,,new ,,york4 ,pr9t$ 9 ! ,unit$ ,/ates4 ,,preface ,! ^w 8guide0 is def9$ z3 ,"o :o leads ano!r 9 any pa? or direction2 a p]son :o %[s or po9ts out ! way1 especially by accompany+ or go+ be=e2 m p>ticul>ly1 "o :o %[s /rang]s or t\ri/s ab\t2 a conductor2 lead]1 z 8let u foll[ our guide40 ,?is book1 or 8,guide10 is s call$ because x leads or po9ts out ! way to ! acquirem5t ( a !oretical & practical k ( ,electricity4 ,!re are sev]al guides1 ea* cov]+ 9 detail a c]ta9 phase ( ! broad subject ( ,electricity & lead+ ! read] progressively1 & 9 su* a way1 t he easily grasps1 n only ! simple fundam5tal facts1 b ! m complex problems1 enc\nt]$ 9 ! /udy ( ,electricity4 ,?is is accompli%$ by ! aid ( a v l>ge numb] ( illu/rations1 toge!r ) specific explanations1 word$ 9 concise & simple language4 ,! ,guides are writt5 p>tly 9 ! "q & answ] =m1 z ?is /yle ( pres5tation has met ) he>ty approval1 n only f ^? ( limit$ education1 b also f ! bett] in=m$4 ,:]e rec\rse is _h to ! "q & answ] =m1 ! special aim ( ! au?or has be5 to give %ort & direct answ]s1 9 su* pla9 language z to preclude a misconception ( ! mean+4 ,) ?is 9 view1 ! answ] gives simply ! in=mation s\ght by ! "q4 ,! answ] is limit$ to "o p>agraph s t ! read] may conc5trate ^u ! fact or facts dem&$ by ! "q4 ,any enl>gem5t ( ! answ] or specific explanations ( items conta9$ !re91 are pres5t$ 9 sep>ate p>agraphs pr9t$1 9 small] type4 ,) ?is plan ( sep>at+ ! answ]1 z x 71 f items ( second>y importance1 & mak+ x %ort & simple1 its cont5t is m =cibly impress$ ^u ! m9d ( ! read]4 ,9 a text book1 x is necess>y to illu/rate & expla9 ! v>i\s species ( comm]cial app>atus met ) 9 practice1 & 9 ?is connection ! ,publi%]s desire to call att5tion to ! mann] 9 :i* ! au?or has treat$ :at may be class$ z ! 8descriptive matt]40 ,contr>y to ! usual cu/om ( giv+ descriptions ( comm]cial ma*9es 9 ! ma9 text1 :]e !y w\ld occupy consid]able space1 to ! exclusion ( ! m important matt]1 all su* descriptions are plac$ 9 small type directly "u ! illu/rations1 leav+ space = an adequate pres5tation ( ! und]ly+ pr9ciples1 !ories1 & = ! l>ge am\nt ( practical in=mation t is ess5tial to obta9 a g5]al k ( ,electricity & its num]\s applications4 ,cr$it is l>gely due to ,frank ,d4 ,graham1 ,b4,s41 ,m4,s4 7,pr9ceton ,univ]sity71 & ,m4,e4 7,/ev5s ,in/itute71 practical eng9e]1 = ! au?or%ip ( ! ,guides1 & = orig9al sket*es illu/rat+ electrical pr9ciples & con/ruction4 ,,table ,,( ,,cont5ts ,,guide ,,no4 #a4 ,,introductory ,,*apt] ,,signs ,,& ,,symbols ,,electricity #a to #d ,nature & s\rce--k9ds ( electricity3 /atic1 curr5t1 dynamic1 radiat$1 positive1 negative1 atmosph]ic1 frictional1 res9\s1 vitre\s4 ,,/atic ,,electricity #e to #bf ,electrical attraction & repulsion--! *>ge--di/ribution ( ! *>ge--free & b\nd electricity--conductors & insulators--electroscopes--gold leaf electroscope--electric scre5s--electrification by induction--nature ( ! induc$ *>ge--! electrophorus--cond5s]s2 ,leyd5 j>--electric ma*9es--action ( ,toepl]-,holtz ma*9e--,wim%ur/ ma*9es4 ,,! ,,electric ,,curr5t #bg to #cd ,volt--amp]e--ohm--,ohm's law--production ( ! electric curr5t--curr5t /r5g?--voltage drop 9 an electric curr5t4 ,,prim>y ,,cells #ce to #fg ,! ^w 8batt]y0--action ( cell--*emical *anges2 pol>ization--effects ( pol>ization--me?ods ( depol>ization-- depol>iz]s--depol>iz] bag--,volta's contact law--contact s]ies ( metals--laws ( *emical action 9 cell-- requirem5ts ( a good cell--s+le & two fluid cells-- ! ,leclan*e cell--,full] bi*romate cell--! ,edison cell--,gr5et bi*romate cell--,daniell cell--directions = mak+ a ,daniell cell--gravity cells--,daniell gravity cell--s-call$ 8dry0 cells--po9ts relat+ to dry cells-- c>e ( cells--cleanl9ess--sep>at+ ! elem5ts--creep+-- amalgamat$ z9c--batt]y connections4 ,,conductors ,,& ,,insulators #fh to #gd ,! s-call$ 8non-conductors0--table ( conductors & insulators--mode ( transmission--effect ( heat--heat+ effect ( ! curr5t--insulators--impregnat+ comp\nds-- wat] z a conductor4 ,,resi/ance ,,& ,,conductivity #ge to #hb ,/&>d ( resi/ance--conductivity ( metals & liquids--effect ( heat--laws ( electrical resi/ance-- conductivity--specific conductivity--divid$ circuits4 ,,electrical ,,& ,,me*anical ,,en]gy #hc to #ib ,def9itions3 en]gy1 matt]1 molecule1 "w1 foot-p\nd1 volt-c\lomb1 amp]e-h\r1 p[]1 horse p[]1 watt1 kil[att1 watt-h\r--me*anical equival5t ( heat--,briti% !rmal unit--electrical horse p[]--! f>ad4 ,,effects ,,( ,,! ,,curr5t #ic to #ajd ,!rmal effect--use ( heat f ! curr5t--magnetic effect--*emical effect--electrolysis--electro-*emical s]ies--electric osmose--electric di/illation--muscul> contractions--electroplat+--electrotyp+4 ,,magnetism #aje to #abd ,two k9ds ( magnetism--nature ( ea*--poles--magnetic field--magnetic =ce--magnetic circuit--magnetic flux--! ,maxwell--! ,gauss--magnetic effect ( ! curr5t--corkscrew rule--sol5oids--p]meability--magnetic saturation--magnetomotive =ce--reluctance--analogy betwe5 electric & magnetic circuits--hy/]eses--residual magnetism4 ,,electromagnetic ,,induction #abe to #acf ,f>aday's discov]y--,f>aday's ma*9e--,f>aday's pr9ciple-- l9e ( =ce--induction ( curr5t--laws ( electromagnetic induction--rules = direction ( induc$ curr5t--,flem+'s rule--,amp]e's rule--! palm rule--self-induction4 ,,induction ,,coils #acg to #aed ,self-induction--mutual induction--prim>y induction coils-- second>y induction coils--pla9 second>y induction coils--second>y induction coils ) vibrator & cond5s]2 cycle ( action--magnetic vibrators--vibrator adju/m5t-- table ( induction coil dim5sions--table ( sp>k+ di/ances 9 air--po9ts relat+ to induction coils--wir+ diagram4 ,,! ,,dynamo #aee to #afj ,op]ation--ess5tial p>ts--field magnets--armature-- con/ruction ( dynamos--p>ts2 b$ plate1 field magnets1 armature1 commutator1 bru%es4 ,,! ,,dynamo3 ,,basic ,,pr9ciples #afa to #agj ,def9itions--ess5tial p>ts--elem5t>y alt]nator-- op]ation--direction ( induc$ curr5t--application ( ,flem+'s rule--cycle ( op]ation--! s9e curve2 its con/ruction & application4 ,,! ,,dynamo3 ,,curr5t ,,commutation #aga to #ahj ,h[ ! curr5t is produc$--h[ direct curr5t is obta9$-- ! commutator--inductors--8cont9u\s curr5t0--action ( f\r coil elem5t>y dynamo--conditions = /ead9ess ( ! curr5t4 ,,classes ,,( ,,dynamo #aha to #aih ,classification--bipol> & multi-pol> dynamos--diff]5ce betwe5 dynamo & magneto--self-excit+ dynamo--! s]ies dynamo--regulation ( s]ies dynamo2 difficulties exp]i5c$-- ! %unt dynamo--adaptation--op]ation--*>act]i/ic -- regulation--! comp\nd dynamo--s]vice int5d$ =-- regulation--ov] comp\nd+--usual degree ( ov] comp\nd+-- %ort %unt--long %unt--voltage ( %ort & long %unt ma*9es --sep>ately excit$ dynamos--,dobr[olski ?ree wire dynamo4 ,,field ,,magnets #aii to #bbj ,object--ess5tial p>ts--classes ( field magnet--multi-pol> field magnets--con/ruction--*oice ( mat]ials--design--pole pieces--eddy curr5t--lam9at$ fields--con/ruction to r$uce reluctance ( ! magnetic circuit--magnetiz+ coils--me?ods ( w9d+--coil ends--insulation--atta*m5t ( coils--coil connections--heat+--v5tilation4 ,,introductory ,,*apt] ,! subject matt] ( ?is "w relates to "o ( ! secrets ( creation :i* appe>s to h be5 int5d$ at ! v beg9n+ to be 8s\ght out40 ,?is idea is express$ 9 a c]ta9 say+ copi$ ?ree or f\r ?\s& ye>s ago by ! m5 ( ,hezekiah1 ,k+ ( ,judah3 f ,solomon's prov]bs3 8,x is ! glory ( ,god to conceal a ?+3 ,b ! glory ( ,k+s 7i4e41 wise m571 to se>* out a matt]40 ,9 all t may be said h]eaft] ?r\gh ! "w1 x is admitt$ t ! results record$ are ! det]m9ations ( exp]im5ts p]=m$ by an incr$ible numb] ( se>*]s ext5d+ ?r\gh _m ages4 ,^! inquiries h be5 pursu$ ) a g5]\s rivalry :i* has p]mitt$ discov]y to be add$ to discov]y1 until ! sum total has be5 wr\ght into su* exactness t x has be5 ?\ghtlessly /at$ t !re is no?+ m1 save its application4 ,x may be well1 h[ev]1 to /ate a few fundam5tal facts relat+ to electricity3 #a1 ,electricity & magnetism are "o & ! same ?+2 #b1 :at is really kn[n ab\t x has come z a discov]y & n z an inv5tion4 ,?us1 we say ! intrepid explor] discov]$ ! pole1 n t he inv5t$ x4 ,s ) electricity x has be5 a subject ( discov]y :ile its _m applications to useful purposes h be5 v]itable inv5tions2 #c1 ! e>? itself is a magnet4 ,?is la/ is %[n by ! fact t ! e>? affects a magnet j z "o magnet affects ano!r4 ,magnets are bodies1 ei!r natural or artificial1 :i* h ! prop]ty ( attract+ iron1 & ! p[]1 :5 freely susp5d$1 ( tak+ a direction t[>d ! poles ( ! e>?4 ,! natural magnet is sometimes call$ ! load/one4 ,?is ^w is said to be d]iv$ f lo$an1 a ,saxon ^w :i* signifies to guide4 ,x is an oxide ( iron ( a peculi> "*1 f\nd occasionally 9 b$s ( iron ore4 ,?\gh commonly met ) 9 irregul> masses only a few in*es 9 diamet]1 h[ev]1 load/ones ( l>g] sizes are sometimes f\nd4 ,by means ( simple exp]im5ts x may be asc]ta9$ t ! magnet has ! foll[+ g5]al prop]ties1 viz3 #a1 p[] ( attraction2 #b1 p[] ( repulsion2 #c1 p[] ( communicat+ magnetism to iron or /eel2 #d1 pol>ity1 or ! p[] ( tak+ a direction t[>d ! poles ( ! e>?2 #e1 p[] ( incl9+ itself t[>d a po9t bel[ ! horizon4 ,speak+ g5]ally we may say1 t magnetism is a dep>tm5t ( electrical sci5ce :i* treats ( ! prop]ties & effects ( ! magnet4 ,! same t]ms are also us$ to d5ote ! unkn[n cause ( magnetic ph5om5a1 z :5 we speak ( magnetism z excit$1 imp>t$1 & s on4 ,lightn+ & ! ,nor!rn ,lights are displays ( electricity on a gr& scale4 ,electricity is a t]m d]iv$ f ! ,greek ^w = amb]1 t be+ ! sub/ance 9 :i* a prop]ty ( ! ag5t n[ d5om9at$ electricity 0 fir/ obs]v$4 ,! anci5t ,greek philosoph]s 7 acqua9t$ ) ! fact t amb]1 :5 rubb$1 acquir$ ! prop]ty ( attract+ light bodies2 h5ce ! effect 0 d5om9at$ electrical & 9 lat] times1 ! t]m electricity has be5 us$ to d5ote ! unkn[n cause ( electrical ph5om5a1 & broadly ! sci5ce :i* treats ( electrical ph5om5a & _! causes4 ,electricity1 :atev] x may prove to be1 is n matt] nor is x en]gy2 x is h[ev] a means or m$ium ( transmitt+ en]gy4 ,if electricity is to transmit or convey en]gy along a wire1 ?is en]gy mu/ be imp>t$ to ! electricity f "s ext]nal s\rce1 t is to say1 be=e electricity c p]=m any "w x mu/ be set 9 motion1 aga9/ m or less resi/ance4 ,?is involves t pressure mu/ be appli$1 & to obta9 ?is pressure1 en]gy mu/ be exp5d$ f "s ext]nal s\rce4 ,accord+ly1 9 electrical eng9e]+1 ! fir/ pr9ciple to be grasp$ is t ( en]gy4 ,)\t ! exp5diture ( en]gy no useful "w c be accompli%$4 ,en]gy may be def9$ z ! capacity = p]=m+ "w4 ,al?\gh electricity is n en]gy1 electricity "u pressure is a =m ( en]gy spok5 ( z electrical en]gy4 ,9 an exp5diture ( en]gy 9 ?is =m1 ! electricity acts simply z a transmission ag5t or m$ium to transmit ! en]gy imp>t$ to x 9 caus+ x to fl[4 ,9 a simil> mann]1 /eam acts z a transmission ag5t or m$ium to transmit ! heat en]gy ( ! coal to ! /eam eng9e1 :]e x is conv]t$ into me*anical en]gy4 ,z j /at$1 electricity "u pressure is a =m ( en]gy1 & its g5]ation is simply a trans=mation ( en]gy f "o =m into ano!r4 ,usually1 me*anical en]gy is conv]t$ into electrical en]gy1 & a dynamo is employ$ = effect+ ! trans=mation4 ,9 trans=m+ ! me*anical en]gy ( wat]falls into electric en]gy1 ?is natural p[] ( wat] due to its weight & motion is fir/ conv]t$ into rot>y motion by a turb9e or wat] :eel1 & !n conv]t$ into electric en]gy by a dynamo1 or an alt]nator4 ,all dynamos are b ma*9es = conv]t+ into electric en]gy ! en]gy :i* is giv5 to !m by "s prime mov]1 z a /eam eng9e1 a gas eng9e1 by hydraulic or ev5 by w9d p[]4 ,all electric motors are m]ely ma*9es = reconv]t+ ! electric en]gy :i* !y receive by means ( ! conduct+ wires or ma9s1 into me*anical en]gy4 ,all electric lamps are contrivances = conv]t+ into lum9\s en]gy a p]c5tage ( ! electric en]gy t is suppli$ ?r\gh ! ma9s4 ,pot5tial & ,k9etic ,en]gy4--,pot5tial en]gy is ! capacity = p]=m+ "w :i* a body possesses by virtue ( its position4 ,k9etic en]gy is ! capacity = p]=m+ "w :i* a body possesses by virtue ( its motion4 ,x mu/ be evid5t t position or motion giv5 to a body enables x to p]=m "w4 ,9 ! fir/ in/ance1 = example1 a heavy weight at ! top ( a high t[] possesses pot5tial en]gy4 ,a t5 p\nd weight support$ "o foot above a plane has t5 foot p\nds ( pot5tial en]gy4 ,! fly:eel ( a /eam eng9e 9 motion is an example ( a body possess+ k9etic en]gy4 ,"s ( ?is k9etic en]gy :i* 0 /or$ up 9 ! fly :eel dur+ ! work+ /roke is exp5d$ 9 mov+ ! eng9e ov] ! 8dead c5t]10 & any o!r po9t :]e no torque is produc$ by ! pressure on ! pi/on4 ,*emical ,en]gy c be conv]t$ into electric en]gy to a limit$ ext5t by means ( ! electric batt]y1 b ! co/ ( ?is en]gy is s high t x is comm]cially feasible only :]e small quantities are requir$1 & ! co/ ( production is second>y to ! conv5i5ce ( g5]ation1 z = signall+ purposes1 ! op]ation ( bells & annunciators1 etc4 ,! *emical en]gy ( coal & o!r fuels _c be directly conv]t$ into electric en]gy4 ,= p[] produc+ purposes1 ! *emical en]gy ( a fuel is fir/ conv]t$ into heat by combu/ion1 & ! heat ?us obta9$ conv]t$ into me*anical en]gy by "s =m ( heat eng9e1 & ! me*anical en]gy subsequ5tly trans=m$ into electric en]gy 9 an electric g5]ator4 ,en]gy _c be creat$ or de/roy$4 ,?is is ! law kn[n z ! cons]vation ( en]gy :i* has be5 built up by ,helmholtz1 ,?omson1 ,j\le & o!rs4 ,x tea*es fur!r1 t en]gy c be transmitt$ f "o body to ano!r or trans=m$ 9 its manife/ations4 ,en]gy may be dissipat$1 t is1 conv]t$ into a =m f :i* x _c be recov]$1 z is ! case ) ! great p]c5tage ( heat escap+ f ! exhau/ nozzle ( a locomotive or 9 ! circulat+ wat] ( a /eam%ip1 b ! total am\nt ( en]gy 9 ! univ]se1 x is argu$1 rema9s con/ant & inv>iable4 ,foll[+ ?is law comes ! doctr9e ( ! cons]vation ( electricity z ann\nc$ by ,lippman1 be+ und\bt$ly ! outcome ( ! ideas ( ,maxwell & ( ,f>aday z to ! nature ( electricity4 ,accord+ to _! doctr9e1 electricity _c be creat$ or de/roy$1 al?\gh its di/ribution may be alt]$4 ,lippman /ates t e *>ge ( electricity has an opposite & equal *>ge some:]e 9 ! univ]se m or less di/ribut$2 t is1 ! sum ( positive *>ges is always equal to ! sum ( negative *>ges4 ,9 alt]+ ! di/ribution ( electricity1 we may cause m to appe> at "o place & less at ano!r1 or may *ange x f ! condition ( re/ to t ( motion1 or may cause x to sp9 r\nd 9 :irlpools or vortices1 :i* !mselves c attract or repel o!r vortices4 ,accord+ to ?is view all our electrical ma*9es & batt]ies are m]ely in/rum5ts = alt]+ ! di/ribution ( electricity by mov+ "s ( x f "o place to ano!r1 or = caus+ electricity1 :5 accumulat$ or heap$1 toge!r 9 "o place1 to d "w 9 return+ to its =m] di/ribution4 ,electrical eng9e]+ has develop$ l>gely & widely )9 a v %ort "t & its _m applications has creat$ s great a dem& = v>i\s k9ds ( electrical app>atus1 t _! manufacture =ms "o ( ! lead+ indu/ries4 ,electricity is v valuable z a m$ium = ! transmission ( en]gy1 especially to long di/ances2 x is also us$ to great advantage 9 light+1 be+ free f ! disagreeable prop]ties ( gas or oil4 ,aga91 electricity f9ds v>i\s applications1 9 extract+ gold f ! ore1 pump+ & v5tilation ( m9es1 traction1 telephone1 telegraph1 electroplat+1 !rapeutics1 etc4 ,^! few1 ( its _m applications w p]haps s]ve to indicate ! f> rea*+ int]e/ & importance ( electricity1 & possibly help to k9dle 9 ! /ud5t some?+ ( ! eag]ness 9 8 "w & en?usiasm )\t :i* he w fail to d ju/ice ei!r to 8 call+ or to himself4 ,,signs ,,& ,,symbols ,! foll[+ signs1 symbols & abbreviations are almo/ univ]sally employ$ 9 descriptive & te*nical works on electrical subjects4 ,al?\gh1 9 ! arrangem5t ( ! ,guides1 ! direct curr5t & alt]nat+ curr5t matt] has be5 kept sep>ate1 x is p]haps advisable 9 ! case ( signs & symbols1 to comb9e ^? relat+ to ! alt]nat+ curr5t ) ! direct curr5t & o!r symbols1 mak+ a s+le table1 r ?an h !m scatt]$ ?r\gh\t ! "w4 #a4 ,fundam5tal4 l1 ,l5g?4 cm4 c5timet]2 941 or in*1 ft4 or foot4 ,m1 ,mass4 gr4 mass ( #a gramme kg4 #a kilogramme4 ,t1 t1 ,"t1 s second4 #b4 ,d]iv$ ,geometric4 ,s1 s1 ,surface4 ,e1 ,volume4 1 1 ,angle4 #c4 ,d]iv$ ,me*anical4 v1 ,velocity4 1 ,angul> velocity4 r1 ,mom5tum4 a1 ,accel]ation4 g1 ,accel]ation due to gravity #cb4b feet p] second4 ,f1 f1 ,=ce4 ,w1 ,"w4 ,p1 ,p[]4 1 ,dyne4 1 ,ergs1 ft4 lb41 ,foot p\nd4 ,h4,p41 h4p4 ,horse p[]4 ,i4,h4,p41 ,indicat$ horse p[]4 ,b4,h4,p41 ,brake horse p[]4 ,e4,h4,p41 ,electrical horse p[]4 ,j1 ,j\le's equival5t4 p1 ,pressure4 ,k1 ,mom5t ( in]tia4 #d4 ,d]iv$ ,electro/atic4 e1 ,pressure diff]5ce4 i1 ,curr5t4 r1 ,resi/ance4 q1 ,quantity4 c1 ,capacity4 sc1 ,specific inductive capacity4 #e4 ,d]iv$ ,magnetic4 m1 ,/r5g? ( pole4 ,script ,j1 ,int5sity ( magnetization4 ,script ,m1 ,magnetic mom5t4 ,script ,h1 ,horizontal int5sity ( e>?'s magnetism4 ,script ,h1 ,field int5sity4 1 ,magnetic flux4 ,script ,b1 ,magnetic flux d5sity or magnetic induction4 ,script ,h1 ,magnetiz+ =ce4 ,script ,f1 ,magnetomotive =ce4 ,script ,r1 ,reluctance1 magnetic resi/ance4 1 ,magnetic p]meability4 1 ,magnetic susceptibility4 1 ,reluctivity 7specific magnetic resi/ance74 #f4 ,d]iv$ ,electromagnetic4 ,r1 ,resi/ance1 ohm4 ,o1 d1 megohm4 ,e1 ,volt1 pressure4 ,eim ,impress$ pressure4 ,ea1 ,eo ,active pressure2 ohmic drop4 ,ev ,virtual pressure4 ,emax ,maximum pressure4 ,eav ,av]age pressure4 ,eef ,effective pressure4 ,ei ,inductance pressure4 ,ec ,capacity pressure4 ,u1 ,diff]5ce ( pressure1 volt4 ,i1 ,int5sity ( curr5t1 amp]e4 ,iim ,impress$ curr5t4 ,ia ,active curr5t4 ,iv ,virtual curr5t4 ,imax ,maximum curr5t4 ,iav ,av]age curr5t4 ,ief ,effective curr5t4 ,q1 ,quantity ( electricity1 amp]e-h\r2 c\lomb4 ,c1 ,capacity1 f>ad4 ,w1 ,electric en]gy1 watt-h\r2 ,j\le4 ,p1 ,electric p[]1 watt2 kil[att4 p1 ,resi/ivity 7specific resi/ance7 ohm c5timet]4 ,g1 ,conductance1 mho4 1 ,conductivity 7specific conductivity74 ,y1 ,admittance1 mho4 ,z1 ,imp$ance1 ohm4 ,x1 ,reactance1 ohm4 ,xi ,inductance reactance4 ,xc ,capacity reactance4 ,b1 ,susceptance1 mho4 ,l1 ,inductance 7coeffici5t ( ,induction71 h5ry4 v1 ,ratio ( electromagnetic to electro/atic unit ( quantity #cajaj c5timet]s p] second approximately4 #g4 ,symbols 9 g5]al use4 ,d1 ,diamet]4 r1 ,radius4 t1 ,temp]ature4 1 ,deflection ( galvanomet] ne$le4 ,n1 n1 ,numb] ( any?+4 1 ,circumf]5ce diamet] #c4adaeib4 1 #b;f #f4bhca frequ5cy1 9 alt]nat+ curr5t4 1 f1 ,frequ5cy1 p]iodicity1 cycles p] second4 1 ,phase angle4 ,g1 ,galvanomet]4 ,s1 ,%unt4 ,n1 n1 ,nor? pole ( a magnet4 ,s1 s1 ,s\? pole ( a magnet4 ,a4,c4 ,alt]nat+ curr5t4 ,d4,c4 ,direct curr5t4 ,p4,d4 ,pressure diff]5ce4 ,p4,f4 ,p[] factor4 ,c4,g4,s4 ,c5timet]1 ,gramme1 ,second sy/em4 ,b4,s4 ,br[n ,%>pe wire gauge4 ,b4,w4,g4 ,birm+ham wire gauge4 ,r4p4m4 ,revolutions p] m9ute4 ,c4,p4 ,c&le p[]4 --o--1 ,inc&esc5t lamp4 --,x--1 ,arc lamp4 ,symbol3 ,cond5s] ,,or ,symbol3 ,cond5s] ,cond5s]4 ,symbol3 ,batt]y ( cells ,batt]y ( cells4 ,symbol3 ,dynamo ,dynamo1 or direct curr5t motor4 ,symbol3 ,alt]nator ,alt]nator1 or alt]nat+ curr5t motor4 ,symbol3 ,conv]t] ,conv]t]4 ,symbol3 ,/atic trans=m] ,/atic trans=m]4 ,symbol3 ,inductive resi/ance ,inductive resi/ance4 ,symbol3 ,non-inductive resi/ance ,non-inductive resi/ance4 ,,*apt] ,i ,,electricity ,nature & ,s\rce ( ,electricity4--,:at is electricity8 ,?is is a "q t is frequ5tly ask$1 b has n yet be5 satisfactorily answ]$4 ,x is a =ce1 subject to control "u well kn[n laws4 ,:ile ! nature & s\rce ( electricity /ill rema9 a my/]y1 _m ?+s ab\t x h become kn[n1 ?us1 x is positively assur$ t electricity nev] manife/s itself except :5 !re is "s me*anical di/urbance 9 ord9>y matt]4 ,! true nature ( electricity has n yet be5 discov]$4 ,_m ?9k x a quality inh]5t 9 ne>ly all ! sub/ances1 & accompani$ by a peculi> movem5t or arrangem5t ( ! molecules4 ,"s assume t ! ph5om5a ( electricity are due to a peculi> /ate ( /ra9 or t5sion 9 ! e!r :i* is pres5t ev]y:]e1 ev5 9 & betwe5 ! atoms ( ! mo/ solid bodies4 ,if ! latt] !ory be ! true "o1 & if ! atmosph]e ( ! e>? be surr\nd$ by ! same e!r1 x may be possible to e/abli% ^! assumptions z facts4 ,! mo/ mod]n supposition reg>d+ ?is matt]1 by ,maxwell1 is t light itself is f\nd$ on electricity1 & t light waves are m]ely electromagnetic waves4 ,! !ory 8t electricity is relat$ to1 or id5tical )1 ! lum9if]\s e!r10 has be5 accept$ by ! mo/ prom95t sci5ti/s4 ,b :ile electricity is /ill a my/]y1 mu* is kn[n ab\t ! laws gov]n+ its ph5om5a4 ,man has ma/]$ ?is mighty =ce & made x 8 p[]ful s]vant2 he c produce x & use x4 ,electricity1 x is also conc$$1 is )\t weight1 &1 :ile x is )\t d\bt1 "o & ! same1 x is = conv5i5ce sometimes classifi$ accord+ to its motion1 z3 #a4 ,/atic electricity1 or electricity at re/2 #b4 ,curr5t electricity1 or electricity 9 motion2 #c4 ,magnetism1 or electricity 9 rotation2 #d4 ,electricity 9 vibration 7radiation74 ,o!r useful divisions are3 #a4 ,positive2 #b4 ,negative electricity2 #c4 ,/atic2 #d4 ,dynamic electricity4 ,/atic ,electricity4--,?is is a t]m employ$ to def9e electricity produc$ by friction4 ,x is prop]ly employ$ 9 ! s5se ( a /atic *>ge :i* %[s itself by ! attraction or repulsion betwe5 *>g$ bodies4 ,:5 /atic electricity is dis*>g$1 x causes m or less ( a curr5t1 :i* %[s itself by ! passage ( sp>ks or a bru% dis*>ge2 by a peculi> prickl+ s5sation2 by a peculi> smell due to its *emical effects2 by heat+ ! air or o!r sub/ances 9 its pa?2 & sometimes 9 o!r ways4#a ,curr5t ,electricity4--,?is may be def9$ z ! quantity ( electricity :i* passes ?r\gh a conductor 9 a giv5 "t--or1 electricity 9 ! act ( be+ dis*>g$1 or electricity 9 motion4 ,an electric curr5t manife/s itself by heat+ ! wire or conductor2 by caus+ a magnetic field ar\nd ! conductor & by caus+ *emical *anges 9 a liquid ?r\gh :i* x may pass4 ,dynamic ,electricity4--,?is t]m is us$ to def9e curr5t electricity to di/+ui% x f /atic electricity4 ,radiat$ ,electricity4--,electricity 9 vibration4 ,:]e ! curr5t oscillates or vibrates back & =? ) extreme rapidity1 x takes ! =m ( waves :i* are simil> to waves ( light4 ,positive electricity4--,?is t]m expresses ! condition ( ! po9t ( an electrifi$ body hav+ ! high] en]gy f :i* x fl[s to a l[] level4 ,! sign :i* d5otes ?is phase ( electric excitem5t is 2 all electricity is ei!r positive or negative4 ,negative ,electricity4--,?is is ! rev]se condition to ! above & is express$ by ! sign or symbol -4 ,^! two t]ms are us$ 9 ! same s5se z hot & cold4 ,atmosph]ic ,electricity is ! free electricity ( ! air :i* is almo/ always pres5t 9 ! atmosph]e4 ,its exact cause is unkn[n4 ,! ph5om5a ( atmosph]ic electricity are ( two k9ds2 !re are ! well kn[n manife/ations ( ?und]/orms2 & !re are ! ph5om5a ( cont9ual slight electrification 9 ! air1 be/ obs]v$ :5 ! wea!r is f9e2 ! ,aurora con/itutes a ?ird bran* ( ! subject4 ,illu/ration3 ,,fig4 #a4--,! electric eel4 ,!re are sev]al species inhabit+ ! wat]1 & :i* h ! p[] ( produc+ electric dis*>ges by c]ta9 portions ( _! organism4 ,! be/ kn[n ( ^! are ! ,torp$o1 ! ,gymnotus1 & ! ,silurus1 f\nd 9 ! ,nile & ! ,tig]4 ,! ,electric ,ray1 ( :i* !re are ?ree species inhabit+ ! ,m$it]ranean & ,atlantic is provid$ ) an electric organ on ! back ( its head1 z %[n 9 ! illu/ration4 ,?is organ consi/s ( lam9 compos$ ( polygonal cells to ! numb] ( #hjj or #ajjj1 or m1 suppli$ ) f\r l>ge bundles ( n]ve fibres2 ! "u surface ( ! fi% is -1 ! upp] 4 ,9 ! ,sur9am eel1 ! electric organ goes ! :ole l5g? ( ! body along bo? sides4 ,x is able to give a v sev]e %ock1 & is a =midable antagoni/ :5 x has atta9$ its full l5g? ( #e or #f feet4 ,frictional ,electricity is t produc$ by ! friction ( "o sub/ance aga9/ ano!r4 ,res9\s ,electricity4--,! k9d ( electricity produc$ ^u a res9\s sub/ances su* z seal+ wax1 res91 %ellac1 rubb] or amb] :5 rubb$ ) wool or fur4 ,res9\s electricity is negative electricity4 ,vitre\s ,electricity4--,a t]m appli$ to ! positive electricity develop$ 9 a glass rod by rubb+ x ) silk4 ,?is electric *>ge w attract to itself bits ( pi? or pap] :i* h be5 repell$ f a rod ( seal+ wax or o!r res9\s sub/ance :i* _h be5 rubb$ ) wool or fur4 ,,*apt] ,,ii ,,/atic ,,electricity ,/atic electricity may be def9$ simply z electricity at re/2 ! t]m prop]ly applies to an isolat$ *>ge ( electricity produc$ by friction4 ,! pres5ce ( /atic electricity manife/s itself by attraction or repulsion4 ,electrical ,attraction & ,repulsion4--,:5 a glass rod1 or a /ick ( seal+ wax or %ellac is held 9 ! h& & rubb$ ) a piece ( flannel or cat sk91 ! p>ts w be f\nd to h ! prop]ty ( attract+ bodies1 su* z pieces ( silk1 wool1 fea!rs1 gold leaf1 etc42 !y are !n said to be electrifi$4 ,9 ord] to asc]ta9 :e!r bodies are electrifi$ or n1 in/rum5ts call$ electroscopes are us$4 ,!re are two opposite k9ds ( electrification3 #a4 ,positive2 #b4 ,negative4 ,frankl9 call$ ! electricity excit$ ^u glass by rubb+ x ) silk positive electricity1 & t produc$ on res9\s bodies by friction ) wool or fur1 negative electricity4 ,! electricity develop$ on a body by friction dep5ds on ! rubb] z well z ! body rubb$4 ,?us glass becomes negatively electrifi$ :5 rubb$ ) catsk91 b positively electrifi$ :5 rubb$ ) silk4 ,illu/ration3 ,,figs4 #b & #c4--,pi? ball p5dulum or electroscope2 ! figures illu/rate also electrical attraction & repulsion4 ,! nature ( ! electricity set free by friction dep5ds on ! degree ( poli%1 ! direction ( ! friction1 & ! temp]ature4 ,if two glass discs ( diff]5t degrees ( poli% be rubb$ aga9/ ea* o!r1 t :i* is mo/ poli%$ is positively1 & t :i* is lea/ poli%$ is negatively electrifi$4 ,if two silk ribbons ( ! same k9d be rubb$ across ea* o!r1 t :i* is transv]sely rubb$ is negatively & ! o!r positively electrifi$4 ,if two bodies ( ! same sub/ance1 ( ! same poli%1 b ( diff]5t temp]atures1 be rubb$ toge!r1 t :i* is mo/ heat$ is negatively electrifi$4 ,g5]ally speak+1 ! p>ticles :i* are mo/ readily displac$ are negatively electrifi$4 ,9 ! foll[+ li/1 :i* is ma9ly due to ,f>aday1 ! sub/ances are arrang$ 9 su* ord] t ea* becomes positively electrifi$ :5 rubb$ ) any ( ! bodies foll[+1 b negatively :5 rubb$ ) any ( ^? :i* prec$e x3 #a4 ,catsk94 #b4 ,flannel4 #c4 ,ivory4 #d4 ,rock cry/al4 #e4 ,glass4 #f4 ,cotton4 #g4 ,silk4 #h4 ,! h&4 #i4 ,wood4 #aj4 ,metals4 #aa4 ,ca\t*\c4 #ab4 ,seal+ wax4 #ac4 ,res94 #ad4 ,sulphur4 #ae4 ,gutta-p]*a4 #af4 ,gun cotton4 ,! ,*>ge4--,! quantity ( electrification ( ei!r k9d produc$ by friction or o!r means ^u ! surface ( a body is spok5 ( z a *>ge1 & a body :5 electrifi$ is said to be *>g$4 ,x is cle> t !re may be *>ges ( diff]5t values z well z ( ei!r k9d4 ,:5 ! *>ge ( electricity is remov$ f a *>g$ body x is said to be dis*>g$4 ,good conductors ( electricity are in/antane\sly dis*>g$ if t\*$ by ! h& or by any conductor 9 contact ) ! gr\nd1 ! *>ge ?us f9d+ a means ( escap+ to e>?4 ,a body t is n a good conductor may be readily dis*>g$ by pass+ x rapidly ?r\gh ! flame ( a lamp or c&le2 = ! flame in/antly c>ries (f ! electricity & dissipates x 9 ! air4 ,di/ribution ( ! ,*>ge4--,:5 an insulat$ sph]e ( conduct+ mat]ial is *>g$ ) electricity1 ! latt] passes to ! surface ( ! sph]e1 & =ms !re an extremely ?9 lay]4 ,! di/ribution ( ! *>ge !n1 dep5ds on ! ext5t ( ! surface & n on ! mass4 ,boit prov$ t ! *>ge resides on ! surface by ! foll[+ exp]im5t3 ,a copp] ball 0 electrifi$ & insulat$4 ,two holl[ hemisph]es ( copp] ( a l>g] size1 provid$ ) glass h&les1 7 !n plac$ ne> ! sph]e1 z 9 fig4 #d4 ,s long z !y did n t\* ! sph]e1 ! *>ge rema9$ on ! latt]1 b if ! hemisph]es t\*$ ! inn] sph]e1 ! :ole ( ! electricity pass$ to ! ext]ior1 & :5 ! hemisph]es 7 sep>at$ & remov$ ! inn] globe 0 f\nd to be completely dis*>g$4 ,! di/ribution ( a *>ge ov] an insulat$ sph]e ( conduct+ mat]ial is uni=m1 provid$ ! sph]e is remote f all o!r conductors & electrifi$ bodies4 ,illu/ration3 ,,fig4 #d4--;,boit's exp]im5t :i* prov$ t ! *>ge resides on ! surface4 ,figs4 #e to #h %[1 by ! dott$ l9es1 ! di/ribution ( a *>ge = bodies ( v>i\s %apes4 ,fig4 #f %[s t = elongat$ bodies1 ! *>ge collects at ! ends4 ,! effects ( po9ts is illu/rat$ 9 fig4 #i2 :5 a *>g$ body is provid$ ) a po9t z "h %[n1 ! curr5t accumulates at ! po9t to su* a high degree ( d5sity t x passes (f into ! air1 & if a light$ c&le be held 9 front ( ! po9t1 ! flame w be visibly bl[n aside4 ,fig4 #aj %[s an electric w9dmill or exp]im5tal device = illu/rat+ ! escape ( electricity f po9ts4 ,x consi/s ( a vane ( sev]al po9t$ wires b5t at ! tips 9 ! same direction1 radiat+ f a c5t] :i* re/s ^u a pivot4 ,:5 m\nt$ ^u ! conductor ( an electro/atic ma*9e1 ! vane rotates 9 a direction opposite t ( ! po9ts4 ,! movem5t ( ! vane is due to ! repulsion ( ! electrifi$ air p>ticles ne> ! po9ts & ! electricity on ! po9ts !mselves4 ,! motion ( ! air is call$ electric w9d4 ,?is device is also call$ electric fly]1 & electric :irl4 ,illu/ration3 ,,figs4 #e to #h4--;,illu/rat+ ! di/ribution ( ! *>ge on conductors ( v>i\s %apes4 8,free0 & 8,b\nd0 ,electricity4--,^! t]ms may be def9$ z foll[s3 ,! expression free electricity relates to ! ord9>y /ate ( electricity ^u a *>g$ conductor1 n 9 ! pres5ce ( a *>ge ( ! opposite k9d4 ,a free *>ge w fl[ away to ! e>? if a conduct+ pa? be provid$4 ,a *>ge ( electricity ^u a conductor is said to be b\nd1 :5 x is attract$ by ! pres5ce ( a neighbor+ *>ge ( ! opposite k9d4 ,conductors & ,insulators4--,! t]m conductors is appli$ to ^? bodies :i* readily all[ electricity to fl[ ?r\gh !m1 9 di/9ction f insulators or s-call$ non-conductors1 :i* practically all[ no fl[ ( electricity4 ,/rictly speak+1 !re is no sub/ance :i* w prev5t ! passage ( electricity1 h5ce1 ! t]m non-conductors1 ?\gh ext5sively us$1 is n correct4 ,illu/ration3 ,,fig4 #i4--;,exp]im5t to illu/rate ! effect ( po9t$ conductors4 ,illu/ration3 ,,fig4 #aj4--;,electric w9dmill :i* op]ates by ! reaction due to ! escape ( ! electric *>ge f ! po9ts4 ,electroscopes4--,^! are in/rum5ts = detect+ :e!r a body be electrifi$ or n1 & indicat+ also :e!r ! electrification be positive or negative4 ,! e>lie/ electroscope devis$ consi/$ ( a /iff /raw balanc$ lightly ^u a %>p po9t2 a ?9 /rip ( brass or wood1 or ev5 a goose quill1 balanc$ ^u a sew+ ne$le w s]ve equally well4 ,ano!r =m ( electroscope is ! pi? ball p5dulum1 %[n 9 figs4 #b & #c4 ,:5 an electrifi$ body is held ne> ! electroscope x is attract$ or repell$ ?us indicat+ ! pres5ce & nature ( ! *>ge4 ,gold ,leaf ,electroscope4--,?is =m ( electroscope1 :i* is v s5sitive1 0 inv5t$ by ,b5net4 ,its op]ation dep5ds on ! fact t l *>ges repel ea* o!r4 ,illu/ration3 ,,fig4 #aa4--;,gold leaf electroscope2 x consi/s ( two /rips ( gold foil susp5d$ f a brass rod )9 a glass j>4 ,us$ to detect ! pres5ce & sign ( an electric *>ge4 ,! gold leaf electroscope z %[n 9 fig4 #aa1 is conv5i5tly made by susp5d+ ! two n>r[ /rips ( gold leaf )9 a wide m\!d glass j>1 :i* bo? s]ves to protect !m f draughts ( air & to support !m f contact ) ! gr\nd4 ,a piece ( v>ni%$ glass tube is pu%$ ?r\gh ! cork1 :i* %\ld be v>ni%$ ) %ellac or ) p>aff9 wax4 ,?r\gh ?is passes a /iff brass wire1 ! l[] end ( :i* is b5t at a "r angle to receive ! two /rips ( gold leaf1 :ile ! upp] end is atta*$ to a flat plate ( metal1 or may be furni%$ ) a brass knob4 ,:5 kept dry & free f du/ x w indicate excessively small quantities ( electricity4 ,a rubb$ glass rod1 ev5 :ile two or ?ree feet f ! in/rum5t1 w cause ! leaves to repel "o ano!r4 ,if ! knob be bru%$ ) only a small camel's hair bru%1 ! slight friction produces a p]ceptible effect4 ,) ?is in/rum5t all k9ds ( friction c be %[n to produce electrification4 ,! gold leaf electroscope c be fur!r us$ to indicate ! k9d ( electricity on an excit$ body4 ,?us1 if a piece ( br[n pap] be rubb$ ) a piece ( india rubb]1 ! nature ( ! *>ge is det]m9$ z foll[s3 ,illu/ration3 ,,fig4 #ab4--;,di/ribution ( electrification on a *>g$ holl[ sph]e4 ,if an insulat$ conductor d be ins]t$ ?r\gh ! op5+ 9 ! sph]e & br\ght 9 contact ) ! int]ior surface & aft]w>ds c>efully remov$1 x w be f\nd1 by te/+ ) ! gold leaf electroscope1 t x has receiv$ no *>ge4 ,if t\*$ to ! outside1 h[ev]1 ! conductor w receive "p ( ! *>ge4 ,fir/ *>ge ! gold leaves ( ! electroscope by t\*+ ! knob ) a glass rod rubb$ on silk4 ,! leaves div]ge1 be+ electrifi$ ) positive electrification4 ,:5 !y are ?us *>g$ ! approa* ( a body :i* is positively electrifi$ w cause !m to div]ge /ill m widely2 :ile1 on ! approa* ( "o negatively electrifi$1 !y w t5d to close toge!r4 ,if n[ ! br[n pap] be br\ght ne> ! electroscope1 ! leaves w be se5 to div]ge m1 prov+ ! electrification ( ! pap] to be ( ! same k9d z t ) :i* ! electroscope is *>g$4 ,! gold leaf electroscope w also indicate r\ghly ! am\nt ( electricity on a body plac$ 9 contact ) x1 = ! gold leaves op5 out m widely :5 ! quantity ( electricity ?us imp>t$ to !m is great]4 ,illu/ration3 ,,figs4 #ac & #ad4--;,electrification produc$ by rubb+ dissimil> bodies toge!r & !n sep>at+ !m4 ,if ! insulat$ glass & lea!r discs ,a & ,b be rubb$ toge!r1 b n sep>at$1 no signs ( electrification c be detect$2 b if ! discs be drawn ap>t a little di/ance ! space betwe5 !m is f\nd to be an electric field1 & z !y sep>ate f>!r & f>!r1 electric =ces w be f\nd to exi/ 9 m & m ( ! surr\nd+ space1 ! electrification be+ indicat$ by 8l9es ( =ce40 ,x %\ld be not$ t "w has to be done 9 sep>at+ ! *>g$ discs to ov]come ! attraction :i* t5ds to hold !m toge!r4 ,! /ress indicat$ by ! l9es ( =ce consi/s ( a t5sion or pull 9 ! direction ( _! l5g? & a pressure or ?ru/ at "r angles to t direction4 ,electric ,scre5s4--,t ! *>ge on ! outside ( a conductor always di/ributes itself 9 su* a way t !re is no electric =ce )9 ! conductor 0 fir/ prov$ exp]im5tally by ,f>aday4 ,he cov]$ a l>ge box ) t9 foil & w5t inside ) ! mo/ delicate electroscopes obta9able4 ,f>aday f\nd t ! outside ( ! box c\ld be *>g$ s /rongly t long sp>ks w\ld fly f x )\t any electrical effects be+ obs]vable any:]e inside ! box4 ,to repeat ! exp]im5t 9 modifi$ =m1 let an electroscope be plac$ b5ea? a bird cage or wire nett+1 z 9 fig4 #ae4 ,let *>g$ rods or o!r p[]fully *>g$ bodies be br\ght ne> ! electroscope outside ! cage4 ,! leaves w be f\nd to rema9 undi/urb$4 ,illu/ration3 ,,fig4 #ae4--,! electric scre54 ,a scre5 ( wire gauze surr\nd+ a delicate electrical in/rum5t w protect x f ext]nal electro/atic induction4 ,electrification by ,induction4--,an insulat$ conductor1 *>g$ ) ei!r k9d ( electricity1 acts on bodies 9 a neutral /ate plac$ ne> x 9 a mann] analog\s to t ( ! action ( a magnet on s(t iron2 t is1 x decomposes ! neutral electricity1 attract+ ! opposite & repell+ ! l k9d ( electricity4 ,! action ?us ex]t$ is said to take place by influ5ce or induction4 ,! ph5om5on ( electrification by induction may be demon/rat$ by ! foll[+ exp]im5t3 ,9 fig4 #af1 let ! ebonite rod be electrifi$ by friction & sl[ly br\ght t[>d ! knob ( ! gold leaf electroscope4 ,! leaves w be se5 to div]ge1 ev5 ?\gh ! rod does n approa* to )9 a foot ( ! electroscope4 ,illu/ration3 ,,fig4 #af4--;,exp]im5t to illu/rate electro/atic induction4 ,! leaves w div]ge1 ev5 ?\gh ! *>g$ ebonite rod does n approa* to )9 a foot ( ! electroscope4 ,?is exp]im5t %[s t ! m]e influ5ce :i* an electric *>ge ex]ts ^u a conductor plac$ 9 its vic9ity is able to produce electrification 9 t conductor4 ,?is me?od ( produc+ electrification is call$ electro/atic induction4 ,z soon z ! *>g$ rod is remov$ ! leaves w collapse1 indicat+ t ?is =m ( electrification is only a tempor>y ph5om5on :i* is due simply to ! pres5ce ( ! *>g$ body 9 ! neighborhood4 ,nature ( ! ,induc$ ,*>ge4--,?is is %[n by ! exp]im5t illu/rat$ 9 fig4 #ag4 ,let a metal ball ,a be *>g$ by rubb+ x ) a *>g$ rod1 & let x !n be br\ght ne> an insulat$ metal cyl9d] ,b :i* is provid$ ) pi? balls on /rips ( pap] ,c1 ,d1 ,e1 z %[n4 ,! div]g5ce ( ,c & ,e w %[ t ! ends ( ,b h receiv$ electrical *>ges because ( ! pres5ce ( ,a1 :ile ! failure ( ,d to div]ge w %[ t ! middle ( ,b is un*>g$4 ,fur!r1 ! rod :i* *>g$ ,a w be f\nd to repel ,c b to attract ,e4 ,illu/ration3 ,,fig4 #ag4--;,exp]im5t illu/rat+ ! nature ( an induc$ *>ge4 ,! app>atus consi/s ( a metal ball & cyl9d]1 bo? m\nt$ on insulat$ /&s1 pi? balls be+ plac$ on ! cyl9d] at po9ts ,c1 ,d1 & ,e4 ,f ^! exp]im5ts1 ! conclusion is t :5 a conductor is br\ght ne> a *>g$ body1 ! end away f ! induc+ *>ge is electrifi$ ) ! same k9d ( electricity z t on ! induc+ body1 :ile ! end t[>d ! induc+ body receives electricity ( opposite sign4 ,! ,electrophorus4--,?is is a simple & +5i\s in/rum5t1 inv5t$ by ,volta 9 #agge = ! purpose ( procur+1 by ! pr9ciple ( induction1 an unlimit$ numb] ( *>ges ( electricity f "o s+le *>ge4 ,x consi/s ( two p>ts1 z %[n 9 fig4 #ai1 a r\nd cake ( res9\s mat]ial ,b1 ca/ 9 a metal di% or 8sole0 ab\t "o foot 9 diamet]1 & a r\nd disc ,a1 ( slightly small] diamet] made ( metal or ( wood cov]$ ) t9foil1 & provid$ ) a glass h&le4 ,%ellac1 or seal+ wax1 or a mixture ( res9 %ellac & ,v5ice turp5t9e1 may be us$ to make ! cake4 ,illu/ration3 ,,figs4 #ah & #ai4--,! electrophorus & me?od ( us+4 ,*>ge ,b2 place ,a 9 contact ) ,b1 & t\* ,a 7fig4 #ah74 ,! disc is n[ *>g$ by induction & w yield a sp>k :5 t\*$ by ! h&1 z 9 fig4 #ai4 ,to use ! electrophorus1 ! res9\s cake ,b mu/ be fir/ beat5 or rubb$ ) fur or a wool5 clo?1 ! disc ,a is !n plac$ on ! cake1 t\*$ ) ! f+] & !n lift$ by ! h&le4 ,! disc w n[ be f\nd to be *>g$ & w yield a sp>k :5 t\*$ ) ! h&1 z 9 fig4 #ai4 ,! 8cov]0 may be replac$1 t\*$1 & once m remov$1 & w ?us yield any numb] ( sp>ks1 ! orig9al *>ge on ! res9\s plate mean:ile rema9+ practically z /rong z be=e4 ,! !ory ( ! electrophorus is v simple1 provid$ ! /ud5t has cle>ly grasp$ ! pr9ciple ( induction4 ,illu/ration3 ,,figs4 #bj to #bc4--;,illu/rat+ 8h[ ! electrophorus works40 ,:5 ! res9\s cake is fir/ beat5 ) ! cat's sk9 its surface is negatively electrifi$1 z indicat$ 9 fig4 #bj4 ,aga91 :5 ! metal disc is plac$ d[n ^u x1 x re/s really only on ?ree or f\r po9ts ( ! surface1 & may be reg>d$ z an insulat$ conductor 9 ! pres5ce ( an electrifi$ body4 ,! negative electrification ( ! cake !re=e acts inductively on ! metallic disc or 8cov]10 attract+ a positive *>ge to its "u side1 & repell+ a negative *>ge to its upp] surface1 z %[n 9 fig4 #ba4 ,if1 n[1 ! cov] be t\*$ = an in/ant ) ! f+]1 ! negative *>ge ( ! upp] surface 7:i* is ^u ! upp] surface be+ repell$ by ! negative *>ge on ! cake7 w be neutraliz$ by electricity fl[+ 9 f ! e>? ?r\gh ! h& & body ( ! exp]im5t]4 ,! attract$ positive *>ge w1 h[ev] rema9 be+ b\nd z x 7 by its attraction t[>ds ! negative *>ge on ! cake4 ,illu/ration3 ,,fig4 #bd4--,l9es ( =ce ( a *>g$ sph]e & a conductor "u induction4 ,! negative electrification on ! end a ( ! cyl9d] indicates t a c]ta9 numb] ( l9es end !re1 :ile ! positive electrification on ! end b simil>ly indicates t an equal numb] ( l9es set out f t end4 ,x is "o ( ! fundam5tal prop]ties ( a conductor t x yields in/antly to ! smalle/ electric =ce1 & t no electric =ce c be p]man5tly ma9ta9$ )9 ! sub/ance ( a conductor 9 :i* no curr5t is pass+4 ,!re c1 !re=e1 be no electro/atic /ra9 & no l9es ( =ce )9 ! mat]ial ( a conductor :]e ! electric field has become /eady4 ,h5ce ! l9es />t+ f b are entirely di/9ct f ^? end+ at a4 ,! two sets are equal 9 numb] because no *>ge has be5 giv5 to ! cyl9d]1 ei!r positive or negative1 & !re=e ! sum ( all ! positive electrifications 7or l9es />t+ f b7 mu/ be equal to ! sum ( all ! negative electrifications 7or ! l9es end+ at a74 ,9 all n9e l9es h be5 drawn at ea* end ( ! cyl9d]1 leav+ ! ?irte5 l9es emanat+ f ! sph]e :i* d n run on to ! cyl9d]4 ,if ! cyl9d] be )drawn to a di/ance f ,k1 x 7! cyl9d]7 w be f\nd to %[ no signs ( electrification4 ,fig4 #bb %[s ! result aft] ! cov] has be5 t\*$4 ,if1 f9ally1 ! cov] be lift$ by its h&le1 ! rema9+ positive *>ge w no long] be 8b\nd0 on ! l[] surface by attraction1 b w di/ribute itself on bo? sides ( ! cov]1 & may be us$ to give a sp>k4 ,x is cle> t no "p ( ! orig9al *>ge has be5 consum$ 9 ! process1 :i* may be repeat$ z (t5 z desir$4 ,z a matt] ( fact1 ! *>ge on ! cake sl[ly dissipates--especially if ! air be damp4 ,h5ce x is ne$ful sometimes to r5ew ! orig9al *>ge by aga9 beat+ ! cake ) ! cat's sk94 ,illu/ration3 ,,fig4 #be4--;,f>aday's ice-pail exp]im5t4 ,an ice-pail ,p connect$ ) ! gold leaves ( an electroscope ,c1 is plac$ on an insulat+ /& ,s4 ,a *>g$ conductor ,k1 c>ri$ by a silk ?read1 is l[]$ into ! pail1 & f9ally t\*es x at ! bottom4 ,:ile x is be+ l[]$ ! leaves ( ! electroscope div]ge f>!r & f>!r1 until ,k is well )9 ! pail1 aft] :i* !y div]ge no m1 ev5 :5 ,k t\*es ! pail or is aft]w>ds )drawn by ! insulat+ ?read4 ,aft] )drawal1 ,k is f\nd to be completely dis*>g$4 ,! labor ( t\*+ ! cov] ) ! f+] at ea* op]ation may be sav$ by hav+ a p9 ( brass or a /rip ( t9foil project+ f ! metallic 8sole0 on to ! top ( ! cake1 s t x t\*es ! plate ea* "t1 & ?us neutralizes ! negative *>ge by all[+ electricity to fl[ 9 f ! e>?4 ,illu/ration3 ,,figs4 #bf to #bi4--;,explanation ( ,f>aday's ice pail exp]im5t4 ,= simplicity ! electroscope1 insulat+ /& & silk ?read h be5 omitt$4 ,only ! ?ree pr9cipal conductors ,k1 ,p1 & ! e>? ,e are %[n4 ,9 fig4 #bf ! ball ,k is suffici5tly close to ,p to act inductively on x2 six l9es are %[n z fall+ on ,p1 & ! o!r six z pass+ to ,e by diff]5t pa?s4 ,correspond+ to ! six l9es fall+ on ,p f ,k1 six o!rs pass to ,e f ! l[] surfaces4 ,9 fig4 #bg :]e ,k is j ent]+ ! pail1 two l9es only pass f ,k to ,e ?r\gh ! dielectric2 ! rema9+ t5 fall on ,p1 & t5 o!rs />t+ f ! di/ant p>ts ( ,p pass to ,e4 ,9 fig4 #bh1 ,k is s f> )9 ,p t none ( its l9es c rea* ,e ?r\gh ! dielectric2 !y all fall on ,p & f ! outside ( ,p an equal numb] />t & pass ?r\gh ! dielectric to ,e4 ,x is evid5t t 9 ?is position ,k c be mov$ ab\t )9 ,p1 )\t affect+ ! outside di/ribution 9 ! slighte/1 & t ev5 :5 ,k t\*es ,p z %[n 9 fig4 #bi1 & :51 !re=e1 all l9es betwe5 !m disappe>1 ! l9es 9 ! dielectric outside rema9 j z !y are 9 fig4 #bh4 ,k is n[ completely dis*>g$1 s9ce l9es no long] emanate f x1 h5ce x c be remov$ by ! silk cord )\t di/urb+ ! electrification ( ,p4 ,if ,k be aga9 *>g$ & introduc$ into ,p x w be aga9 dis*>g$1 = ! fact t ,p is already *>g$ w h no effect on ! f9al result1 provid$ :5 ,k t\*es ,p x is well "u cov]4 ,s9ce ! electricity ?us yield$ by ! electrophorus is n obta9$ at ! exp5se ( any "p ( ! orig9al *>ge1 x is a matt] ( "s int]e/ to inquire :5ce is ! s\rce f :i* ! en]gy ( ?is app>5tly unlimit$ supply is drawn2 = x _c be call$ into exi/5ce )\t ! exp5diture ( "s o!r =m ( en]gy4 ,! fact is1 m "w is done 9 lift+ ! cov] :5 x is *>g$ ) ! positive electricity ?an :5 x is n *>g$2 = :5 *>g$1 !re is ! =ce ( ! electric attraction to be ov]come z well z ! =ce ( gravity2 ?is excess =ce is ! real orig9 ( ! en]gy /or$ up 9 ! sep>ate *>ges4 ,illu/ration3 ,,figs4 #cj & #ca4--,! ,leyd5 j> & dis*>g]4 ,its discov]y is attribut$ to ! attempt ( ,muss*5brock & 8 pupil ,cuneus to collect ! suppos$ electric 8fluid0 9 a bottle half fill$ ) wat]4 ,! bottle 0 held 9 ! h& & 0 provid$ ) a nail to lead ! 8fluid0 d[n ?r\gh ! cork to ! wat] f ! electric ma*9e4 ,! inv5tion ( ! ,leyd5 j> is also claim$ by ,klei/1 ,bi%op ( ,pom]ania4 ,cond5s]s2 ,leyd5 ,j>4--,a cond5s] is an app>atus = cond5s+ a l>ge quantity ( electricity on a comp>atively small surface4 ,! =m may v>y consid]ably1 b 9 all cases x consi/s ess5tially ( two insulat$ conductors1 sep>at$ by an insulator & ! work+ dep5ds on ! action ( induction4 ,a =m ( cond5s] g5]ally us$ 9 mak+ exp]im5ts on /atic electricity is ! ,leyd5 j>1 s nam$ f ! t[n ( ,leyd5 :]e x 0 inv5t$4 ,x consi/s ( a glass j> coat$ inside & out to a c]ta9 height ) t9foil1 hav+ a brass rod t]m9at+ 9 a knob pass$ ?r\gh a wood5 /opp]1 & connect$ to ! inn] coat by a loose *a91 z %[n 9 fig4 #cj4 ,! j> may be *>g$ by repeat$ly t\*+ ! knob ) ! *>g$ plate ( ! electrophorus or by connect+ ! inn] coat+ to "o knob ( an electrical ma*9e & ! out] coat+ to ! o!r knob4 ,! dis*>ge ( a cond5s] is effect$ by connect+ ! plates hav+ an opposite *>ge4 ,?is may be done by use ( a wire or a dis*>g]1 z %[n 9 fig4 #ca2 ! connection is made betwe5 ! out] coat & ! knob4 ,:5 ! knob ( ! dis*>g] is suffici5tly close to ! knob ( ! j>1 a bright sp>k w be obs]v$ betwe5 ! knobs4 ,?is dis*>ge occurs :5ev] ! diff]5ce ( pot5tial betwe5 ! coats is great en\gh to ov]come ! resi/ance ( ! air betwe5 ! knobs4 ,let a *>g$ j> be plac$ on a glass plate s z to insulate ! out] coat4 ,let ! knob be t\*$ ) ! f+]4 ,no appreciable dis*>ge w be notic$4 ,let ! out] coat be 9 turn t\*$ ) ! f+]4 ,aga9 no appreciable dis*>ge w appe>4 ,b if ! inn] & out] coat+s be connect$ ) ! dis*>g]1 a p[]ful sp>k w pass4 ,electric ,ma*9es4--,v>i\s ma*9es h be5 devis$ = produc+ electric *>ges su* z h be5 describ$4 ,! ord9>y 8/atic0 or electric ma*9e1 is no?+ b a cont9u\sly act+ electrophorus4 ,fig4 #cb repres5ts ! s-call$ ,toepl]-,holtz ma*9e4 ,^u ! back ( ! /ation>y plate ,e1 are pa/$ pap] sectors1 b5ea? :i* are /rips ( t9foil ,,ab & ,,cd call$ inductors4 ,9 front ( ,e is a revolv+ glass plate c>ry+ discs l1 m1 n1 o1 p & q1 call$ c>ri]s4 ,to ! inductors ,,ab & ,,cd are fa/5$ metal arms t & u1 :i* br+ ,b & ,c into electrical contact ) ! discs l1 m1 n1 o1 p & q1 :5 ^! discs pass b5ea? ! t9sel bru%es c>ri$ by t & u4 ,a /ation>y metallic rod rs c>ries at its ends /ation>y bru%es z well z %>p po9t$ metallic combs4 ,! two knobs ,r & ,s h _! capacity increas$ by ! ,leyd5 j>s ,l & ,l4 ,illu/ration3 ,,fig4 #cb4--,! ,toepl]-,holtz electric ma*9e4 ,illu/ration3 ,,fig4 #cc4--,pr9ciple ( ,toepl]-,holtz electric ma*9e4 ,action ( ! ,toepl]-,holtz ,ma*9e4--,! action ( ! ma*9e describ$ above is be/ und]/ood f ! diagram ( fig4 #cc4 ,suppose t a small *>ge is orig9ally plac$ on ! inductor ,,cd4 ,induction takes place 9 ! metallic sy/em consi/+ ( ! discs l & o & ! rod rs1 l becom+ negatively *>g$ & o positively *>g$4 ,z ! plate c>ry+ l1 m1 n1 o1 p1 q rotates 9 ! direction ( ! arr[ ! negative *>ge on l is c>ri$ ov] to ! position m1 :]e a "p ( x passes ov] to ! inductor ,,ab1 ?us *>g+ x negatively4 ,:5 l rea*es ! position n ! rema9d] ( its *>ge1 be+ repell$ by ! negative electricity :i* is n[ on ,,ab1 passes ov] into ! ,leyd5 j> ,l4 ,:5 l rea*es ! position o x aga9 becomes *>g$ by induction1 ?is "t positively1 & m /rongly ?an at fir/1 s9ce n[ ! negative *>ge on ,,ab1 z well z ! positive *>ge on ,,cd1 is act+ inductively ^u ! rod rs4 ,:5 l rea*es ! position u1 a "p ( its n[ /rong positive *>ge passes to ,,cd1 ?us increas+ ! positive *>ge ^u ?is inductor4 ,9 ! position v ! rema9d] ( ! positive *>ge on l passes ov] to ,l4 ,?is completes ! cycle = l4 ,?us z ! rotation cont9ues ,,ab & ,,cd acquire /rong] & /rong] *>ges1 ! inductive action ^u rs becomes m & m int5se1 & positive & negative *>ges are cont9u\sly imp>t$ to ,l & ,l until a dis*>ge takes place betwe5 ! knobs ,r & ,s4 ,!re is usually suffici5t *>ge on "o ( ! inductors to />t ! ma*9e1 b 9 damp wea!r x w (t5 be f\nd necess>y to apply a *>ge to "o ( ! inductors by means ( ! ebonite or glass rod be=e ! ma*9e w "w4 ,! ,wim%ur/ ,ma*9e4--,! ess5tial p>ts ( an ord9>y ,wim%ur/ ma*9e1 z %[n 9 fig4 #cd1 are two insulat+ plates or drums4 ,on ea* plate are fix$ a l>ge numb] ( /rips ( conduct+ mat]ial1 :i* are equal 9 size & are equally spac$--radially if on a plate1 & circumf]5tially if on a drum4 ,! plates1 or drums1 are made to rotate 9 opposite directions4 ,! capacity ( ! inductors !re=e v>ies f a maximum :5 ea* /rip on "o plate is fac+ a /rip on ! o!r1 to a m9imum :5 ! conduct+ /rips on ea* plate are fac+ blank or insulat+ portions ( ! o!r plate4 ,!re are ?ree pairs ( contact bru%es1 ! memb]s ( two ( ! pairs be+ at opposite ends ( diametrical conduct+ rods plac$ at "r angles to "o ano!r2 ! ?ird pair are insulat$ f "o ano!r & =m ! pr9cipal collectors1 ! "o giv+ positive & ! o!r negative electricity4 ,! plates are revolv+ 9 opposite directions2 ?us if !re be a *>ge on "o ( ! conduct+ segm5ts ( "o plate & an opposite *>ge on "o ( ! conduct+ segm5ts on ! o!r plate ne> x1 _! pot5tial w be rais$ z ! rotation ( ! plates sep>ates !m4#b ,illu/ration3 ,,fig4 #cd4--,! ,wim%ur/ ,electric ,ma*9e4 ,,*apt] ,,iii ,,! ,,electric ,,curr5t ,! ord9>y /atem5t t an electric curr5t is fl[+ along a wire is only a conv5tional way ( express+ ! fact t ! wire & ! space ar\nd ! wire are 9 a diff]5t /ate f t 9 :i* !y are :5 no electric curr5t is said to be fl[+4 ,9 ord] to make laym5 und]/& ! action ( ?is s call$ curr5t1 x is g5]ally comp>$ ) ! fl[ ( wat]4 ,9 comp>+ hydraulics & electricity1 x mu/ be borne 9 m9d1 h[ev]1 t !re is really no su* ?+ z an 8electric fluid10 & t wat] 9 pipes has mass & weight1 :ile electricity has none4 ,x %\ld be not$1 h[ev]1 t electricity is conv5i5tly spok5 ( z hav+ weight 9 expla9+ "s ( ! ways 9 :i* x manife/s itself4 ,all electrical ma*9es & batt]ies are m]ely in/rum5ts = mov+ electricity f "o place to ano!r1 or = caus+ electricity1 :5 accumulat$ 9 "o place1 to d "w 9 return+ to its =m] level ( di/ribution4 ,! head or pressure 9 a /&pipe is :at causes wat] to move ?r\gh ! pipes :i* (f] resi/ance to ! fl[4 ,simil>ly1 ! conductors1 along :i* ! electric curr5t is said to fl[1 (f] m or less resi/ance to ! fl[1 dep5d+ on ! mat]ial4 ,copp] wire is g5]ally us$ z x (f]s little resi/ance4 ,! curr5t mu/ h pressure to ov]come ! resi/ance ( ! conductor & fl[ along its surface4 ,?is pressure is call$ voltage caus$ by :at is kn[n z diff]5ce ( pot5tial betwe5 ! s\rce & t]m9al4 ,illu/ration3 ,,fig4 #ce4--;,analogy ( ! fl[ ( wat] to ! electric curr5t4 ,! wat] 9 ! res]voirs ,a & ,b /&s at diff]5t heights4 ,z long z ?is diff]5ce ( level is ma9ta9$1 wat] f ,b w fl[ ?r\gh ! pipe ,r to ,a4 ,if by means ( a pump ,p ! level 9 ,b be kept con/ant1 fl[ ?r\gh ,r w also be ma9ta9$4 ,"h1 by means ( ! "w exp5d$ on ! pump1 ! level 9 ! res]voir is kept con/ant2 & 9 ! correspond+ case ( ! electric curr5t1 by ! conv]sion ( *emical en]gy a con/ant diff]5ce ( pot5tial is ma9ta9$4 ,! pressure "u :i* a curr5t fl[s is measur$ 9 volts & ! quantity t passes 9 amp]es4 ,! resi/ance ) :i* ! curr5t meets 9 fl[+ along a conductor is measur$ 9 ohms4 ,ques4 ,:at is a volt8 ,ans4 ,a volt is t electromotive =ce 7,e4 ,m4 ,f47 :i* produces a curr5t ( "o amp]e aga9/ a resi/ance ( "o ohm4 ,ques4 ,:at is an amp]e8 ,ans4 ,an amp]e is ! curr5t produc$ by an ,e4 ,m4 ,f4 ( "o volt 9 a circuit hav+ a resi/ance ( "o ohm4 ,x is t quantity ( electricity :i* w deposit 4#jjejhd gra9 ( copp] p] second4 ,ques4 ,:at is an ohm8 ,ans4 ,an ohm is equal to ! resi/ance (f]$ to an unv>y+ electric curr5t by a column ( m]cury at #cb ,fahr41 #ad4deba grams 9 mass1 ( a con/ant cross sectional area1 & ( ! l5g? ( #ajf4c c5timet]s4 ,ohm's ,law4--,9 a giv5 circuit1 ! am\nt ( curr5t 9 amp]es is equal to ! ,e4 ,m4 ,f4 9 volts divid$ by ! resi/ance 9 ohms2 t is3 curr5t pressure _/ resi/ance volts _/ ohms express$ z a =mula3 ,i ,e_/,r 7#a7 9 :i* ,i curr5t /r5g? 9 amp]es2 ,e electromotive =ce 9 volts2 ,r resi/ance 9 ohms4 ,f 7#a7 is d]iv$ ! foll[+3 ,e ,,ir 7#b7 ,r ,e_/,i 7#c7 ,f 7#a7 x is se5 t ! fl[ ( ! curr5t is proportional to ! voltage & inv]sely proportional to ! resi/ance2 ! latt] dep5ds ^u ! mat]ial1 l5g? & diamet] ( ! conductor4 ,s9ce ! curr5t w always fl[ along ! pa? ( lea/ resi/ance2 x mu/ be s gu>d$ t !re w be no leakage4 ,h5ce1 to prev5t leakage1 wires are insulat$1 t is1 cov]$ by wrapp+ !m ) cotton or silk ?read or o!r insulat+ mat]ial4 ,if ! insulation be n effective1 ! curr5t may leak1 & s return to ! s\rce )\t do+ its "w4 ,?is is kn[n z a %ort circuit4 ,! conductor :i* receives ! curr5t f ! s\rce is call$ ! lead1 & ! "o by :i* x fl[s back1 ! return4 ,:5 wires are us$ = bo? lead & return1 x is call$ a metallic circuit3 :5 ! gr\nd is us$ = ! return1 x is call$ a gr\nd circuit4 ,an electric curr5t is said to be3 #a4 ,direct1 :5 x is ( unv>y+ direction2 #b4 ,alt]nat+1 :5 x fl[s rapidly to & fro 9 opposite directions2 #c4 ,prim>y1 :5 x comes directly f ! s\rce2 #d4 ,second>y1 :5 ! voltage & amp]age ( a prim>y curr5t h be5 *ang$ by an induction coil2 #e4 ,l[ t5sion1 :5 its voltage is l[2 #f4 ,high t5sion1 :5 its voltage is high4 ,a high t5sion curr5t is capable ( =c+ its way aga9/ consid]able resi/ance1 :]eas1 a l[ t5sion curr5t mu/ h its pa? made easy4 ,production ( ! ,electric ,curr5t4--,to produce a /eady fl[ ( wat] 9 a pipe two conditions are necess>y4 ,!re mu/ fir/ be available a hydraulic pressure1 or1 z x is te*nically call$1 a 8head0 ( wat] produc$ by a pump1 or a diff]5ce ( level or o!rwise4 ,9 addition to ! pressure !re mu/ also be a suitable pa? or *annel provid$ = ! wat] to fl[ ?r\gh1 or !re w be no fl[1 h[ev] great ! 8head10 until some?+ breaks d[n "u ! /ra94 ,9 ! case j cit$1 al?\gh !re is full pressure 9 ! wat] 9 ! pipe1 !re is no curr5t ( wat] z long z ! tap rema9s clos$4 ,! op5+ ( ! tap completes ! necess>y pa? 7! great] "p ( :i* 0 already 9 exi/5ce7 & ! wat] fl[s4 ,illu/ration3 ,,fig4 #cf4--;,hydraulic analogy ( ! electric curr5t4 ,if1 say #aj gallons ( wat] fl[ 9 e second into a sy/em ( vessels & pipes ( any %ape1 :e!r simple or m complicat$ z %[n 9 ! figure1 & #aj gallons fl[ out aga9 p] second1 x is evid5t t ?r\gh e cross section ( any vessel or pipe ( ! sy/em #aj gallons ( wat] pass e second4 ,?is foll[s f ! fact t wat] is an uncompressible liquid & mu/ be practically ( ! same d5sity ?r\gh\t ! sy/em4 ,! wat] moves sl[ly :]e ! section is l>ge & quickly :]e x is small1 & ?us ! quantity ( wat] t fl[s ?r\gh any "p ( ! sy/em is indep5d5t ( ! cross section ( t "p4 ,! same condition holds good = ! electric curr5t2 if 9 a clos$ circuit a con/ant curr5t circulates1 ! same am\nt ( electricity w pass e cross section p] second4 ,h5ce ! foll[+ law3 ,! magnitude ( a con/ant curr5t 9 any circuit is equal 9 all p>ts ( ! circuit4 ,= ! production ( a /eady electric curr5t two v simil> conditions are necess>y4 ,!re mu/ be a /eadily ma9ta9$ electric pressure1 kn[n "u diff]5t aspects z 8electromotive =ce10 8pot5tial diff]5ce10 or 8voltage40 ,?is alone1 h[ev]1 is n suffici5t4 ,9 addition1 a suitable conduct+ pa? is necess>y4 ,any break 9 ?is pa? occupi$ by unsuitable mat]ial acts l ! clos$ tap 9 ! analog\s case above m5tion$1 & x is only :5 all su* breaks h be5 prop]ly bridg$ by suitable mat]ial1 t is1 by conductors1 t ! effects :i* d5ote ! fl[ ( ! curr5t w beg9 to be manife/$4 ,! necess>y electromotive =ce or voltage requir$ to cause ! curr5t to fl[ may be obta9$3 #a4 ,*emically2 #b4 ,me*anically2 #c4 ,!rmally4 ,9 ! fir/ me?od1 two dissimil> metals su* z copp] & z9c call$ elem5ts1 are imm]s$ 9 an excit+ fluid or electrolyte4 ,illu/ration3 ,,fig4 #cg4--,volta's 8,cr[n ( ,cups40 ,! metallic elem5ts ,c & ,z ea* consi/$ ( two metals1 ! plate ,c be+ ( copp] & ! plate ,z ( z9c4 ,!y 7 plac$1 z %[n1 9 ! glass vessels1 :i* conta9$ salt wat] & ord9>y wat] or lye4 ,into ea* vessel1 except ! two end ones1 ! copp] end ( "o arc & ! z9c end ( ! next 7 introduc$1 ! s]ies1 h[ev] long1 end+ ) copp] dipp+ into ! t]m9al vessel at "o end & z9c into t at ! o!r4 ,! arrangem5t is almo/ exactly t ( a mod]n "o-fluid prim>y batt]y4 ,:5 ! elem5ts are connect$ at _! t]m9als by a wire or conductor a *emical action takes place1 produc+ a curr5t :i* fl[s f ! copp] to ! z9c4 ,?is device is call$ a cell1 & ! comb9ation ( two or m ( !m connect$ s z to =m a unit is kn[n z a batt]y4 ,! ^w batt]y is frequ5tly us$ incorrectly = a s+le cell4 ,t t]m9al ( ! elem5t f :i* ! curr5t fl[s is call$ ! plus or positive pole1 & ! t]m9al ( ! o!r elem5t ! negative pole4 ,cells are said to be prim>y or second>y accord+ z !y g5]ate a curr5t ( !mselves1 or fir/ require to be *>g$ f an ext]nal s\rce1 /or+ up a curr5t supply :i* is aft]w>ds yield$ 9 ! rev]se direction to t ( ! *>g+ curr5t4 ,an electric curr5t is g5]at$ me*anically by a dynamo4 ,9 ei!r case no electricity is produc$1 b "p ( ! supply already exi/+ is simply set 9 motion by creat+ an electric pressure4 ,an electric curr5t1 accord+ to ! ?ird me?od1 is g5]at$ directly f heat en]gy1 z w be lat] expla9$2 ! curr5t ?us obta9$ is v feeble4 ,illu/ration3 ,,fig4 #ch4--;,hydro/atic analogy ( fall ( pot5tial 9 an electrical circuit4 ,illu/ration3 ,,fig4 #ci4--,%[+ me?od ( connect+ voltmet] to f9d pot5tial diff]5ce betwe5 any two po9ts z m & n on an electrical circuit4 ,/r5g? ( ,curr5t4--,x is important t ! read] h a cle> conception ( ?is t]m1 :i* is s (t5 us$4 ,! exact def9ition ( ! /r5g? ( a curr5t is z foll[s3 ,! /r5g? ( a curr5t is ! quantity ( electricity :i* fl[s pa/ any po9t ( ! circuit 9 "o second4 ,example4--,if1 dur+ #aj seconds1 #be c\lombs ( electricity fl[ ?r\gh a circuit1 !n ! av]age /r5g? ( ! curr5t dur+ t "t is #b-a_/b c\lombs p] second1 or #b-a_/b amp]es4 ,voltage ,drop 9 an ,electric ,circuit4--,a diff]5ce ( pot5tial exi/s betwe5 any two po9ts on a conductor ?r\gh :i* a curr5t is fl[+ on acc\nt ( ! resi/ance (f]$ to ! curr5t by ! conductor4 ,= in/ance1 9 ! electrical circuit %[n 9 fig4 #ci1 ! pot5tial at ! po9t a is high] ?an t at m1 t at m high] ?an t at n1 etc41 j z 9 ! wat] circuit1 %[n 9 fig4 #ch1 ! hydro/atic pressure at a is great] ?an t at m1 t at m great] ?an t at n1 etc4 ,! fall 9 ! wat] pressure betwe5 m & n 7fig4 #ch7 is measur$ by ! wat] head n's4 ,9 ord] to measure ! fall 9 electrical pot5tial betwe5 m & n1 7fig4 #ci71 ! t]m9als ( a volt met] are plac$ 9 contact ) ^! po9ts z %[n4 ,its read+ w give ! diff]5ce ( pot5tial betwe5 m & n1 9 volts1 provid$ t its own curr5t c>ry+ capacity is s small t x does n appreciably l[] ! pot5tial diff]5ce betwe5 ! po9ts m & n by be+ t\*$ across !m2 t is1 provid$ ! curr5t :i* fl[s ?r\gh x is negligible 9 comp>ison ) t :i* fl[s ?r\gh ! conductor :i* already jo9s ! po9ts m & n4 ,,*apt] ,,iv ,,prim>y ,,cells ,! ^w 8batt]y0 is a mu* abus$ ^w1 be+ (t5 us$ incorrectly = 8cell10 z 9 fig4 #dj4 ,h5ce1 c>eful di/9ction %\ld be made betwe5 ! two t]ms4 ,a batt]y consi/s ( two or m cells jo9$ toge!r s z to =m a s+le unit4 ,!re are num]\s =ms ( prim>y cell2 !y may be classifi$ z foll[s3 #a4 ,accord+ to ! s]vice = :i* !y are design$2 #b4 ,accord+ to ! *emical features4 ,) respect to ! fir/ me?od cells are classifi$ z3 #a4 ,op5 circuit cells2 ,us$ = int]mitt5t "w1 :]e ! cell is 9 s]vice = %ort p]iods ( "t1 su* z 9 electric bells1 signal+ "w1 & electric gas light+4 ,if kept 9 cont9u\s s]vice = any l5g? ( "t ! cell soon pol>izes or 8runs d[n10 b w recup]ate aft] rema9+ on op5 circuit = "s little "t4 #b4 ,clos$ circuit cells4 ,?is type ( cell is adapt$ to furni%+ curr5t cont9u\sly1 z 9 telegraphy1 etc4 ,) respect to ! second me?od1 cells are classifi$ z3 #a4 ,"o fluid2 #b4 ,two fluid2 ,ques4 ,describe a prim>y cell4 ,ans4 ,a prim>y cell consi/s ( a vessel conta9+ a liquid 9 :i* two dissimil> metal plates are imm]s$4 ,9 "o fluid cells bo? metal plates are imm]s$ 9 ! same solution4 ,9 two fluid cells ea* metal plate is imm]s$ 9 a sep>ate solution1 "o ( :i* is conta9$ 9 a por\s cup :i* is imm]s$ 9 ! o!r liquid4 ,ques4 ,:at "n is giv5 to ! metal plates8 ,ans4 ,!y are call$ elem5ts4 ,ques4 ,:at is ! fluid call$8 ,ans4 ,! electrolyte or excit+ fluid4 ,! t]m 8electropoion0 is a trade "n = ! electrolyte employ$ 9 ! ,full] cell4 ,action ( a ,prim>y ,cell4--,! fundam5tal fact on :i* ! electro-*emical g5]ation ( curr5t dep5ds is1 t if a plate ( metal be plac$ 9 a liquid !re is a diff]5ce ( electrical condition produc$ betwe5 !m ( su* sort t ! metal ei!r takes a l[] or high] electrical pot5tial ?an ! liquid1 accord+ to ! nature ( ! metal & ! liquid4 ,if two diff]5t metals be plac$ 9 "o electrolytic liquid1 !n !re is a diff]5ce ( /ate produc$ betwe5 !m1 s t1 if jo9$ by wire outside ! liquid1 a curr5t ( electricity w trav]se ! wire4 ,?is curr5t proce$s 9 ! liquid f ! metal :i* is mo/ act$ ^u *emically to t :i* is lea/ act$ ^u4 ,ref]r+ to fig4 #da1 ! con/ruction & action ( a simple prim>y cell may be briefly describ$ z foll[s3 ,place 9 a glass j> "s wat] hav+ a little sulphuric or o!r acid add$ to x4 ,place 9 x sep>ately two clean /rips1 "o ( z9c1 ,z1 & "o ( copp]1 ,c4 ,?is cell is capable ( supply+ a cont9u\s fl[ ( electricity ?r\gh a wire ^: ends are br\ght into connection ) ! two /rips4 ,:5 ! curr5t fl[s1 ! z9c /rip is obs]v$ to wa/e away1 its consumption 9 fact furni%+ ! en]gy or electromotive =ce requir$ to drive ! curr5t ?r\gh ! cell & ! connect+ wire4 ,! cell may !re=e be reg>d$ z a k9d ( *emical furnace 9 :i* ! fuel is ! z9c4 ,illu/ration3 ,,fig4 #dj4--,simple prim>y cell4 ,x consi/s ( two dissimil> metal plates 7su* z copp] & z9c :i* are call$ ! elem5ts71 imm]s$ 9 ! electrolyte or excit+ fluid conta9$ 9 ! glass j>4 ,ques4 ,h[ are ! positive & negative elem5ts ( a prim>y cell di/+ui%$8 ,ans4 ,! plate attack$ by ! electrolyte is ! negative elem5t1 & ! "o unattack$ ! positive elem5t4 ,*emical ,*anges2 ,pol>ization4--,! *emical *anges :i* take place 9 a simple cell1 consi/+ ( z9c & copp] elem5ts 9 an electrolyte ( dilute sulphuric acid1 may be briefly describ$ z foll[s3 ,:5 ! two elem5ts are connect$ & ! curr5t comm5ces to fl[1 ! sulphuric acid acts on ! surface ( ! z9c plate & =ms sulphate ( z9c4 ,! =mation ( ?is new sub/ance necessitates ! lib]ation ( "s ( ! hydrog5 conta9$ 9 ! sulphuric acid1 & x w be f\nd t bubbles ( free hydrog5 gas spe$ily appe> on ! surface ( ! negative elem5t1 t is1 on ! copp] plate4 ,:ile ! z9c is be+ dissolv$ to =m z9c sulphate1 hydrog5 gas is lib]at$ f ! sulphuric acid4 ,illu/ration3 ,,fig4 #da4--,simple prim>y cell ) circuit clos$1 %[+ direction ( ! curr5t4 ,"s bubbles ( ! gas rise to ! surface ( ! electrolyte & s escape into ! air1 b mu* ( x cl+s to ! surface ( ! copp] elem5t :i* ?us gradually becomes cov]$ ) a ?9 film ( hydrog54 ,p>tly on acc\nt ( ! decreas$ area ( copp] plate 9 contact ) ! electrolyte1 & p>tly because ! hydrog5 t5ds to produce a curr5t 9 ! opposite direction1 ! useful electrical output becomes consid]ably dim9i%$ & ! cell is said to be pol>iz$4 ,?is /ate ( affairs may be rectifi$ by /irr+ up ! electrolyte1 or by %ak+ ! cell1 s z to assi/ ! hydrog5 bubbles to deta* !mselves f ! surface ( ! copp] plate & make _! way to ! atmosph]e ?r\gh ! electrolyte4 ,?is1 h[ev]1 is only a tempor>y rem$y1 z ! pol>iz$ condition w soon be rea*$ aga91 & a fur!r agitation ( ! cell w be necess>y4 ,h5ce1 a simple cell ( ?is k9d is n desirable = practical "w1 & x mu/ be modifi$ to adapt x to con/ant use4 ,:5 ! sulphuric acid 9 a cell acts 9 ! z9c elem5t & produces sulphate ( z9c1 a c]ta9 am\nt ( "w is done :i* is manife/$ p>tly 9 ! =m ( useful electric en]gy1 & p>tly z heat :i* w>ms ! electrolyte & :i* is !reby lo/ = all practical purposes4 ,ques4 ,if ! z9c & copp] electrodes ( a simple cell be n connect$ ext]nally :at *anges take place )9 ! cell8 ,ans4 ,! z9c plate imm$iately becomes /rongly *>g$ ) negative electricity1 & ! copp] plate weakly s4 ,z long z ! plates rema9 unconnect$1 & ! z9c is pure1 no fur!r action takes place4 ,ques4 ,if ! electrodes be connect$ ext]nally :at happ5s8 ,ans4 ,if ! plates be connect$ by a wire outside ! electrolyte1 ! t5d5cy :i* dissimil> electrical *>ges h to neutralize "o ano!r causes a fl[ ( negative electricity ?r\gh ! wire f z9c to copp]1 & a positive fl[ 9 ! opposite direction4 ,! 8/atic0 *>ge be+ ?us dispos$ (1 a fre% *>ge is giv5 to ! plates by ! action ( ! acid1 :i* comm5ces to dissolve ! z9c4 ,z long z ! wire connects ! copp] & z9c plates1 ! acid w cont9ue its action on ! z9c until ei!r acid or z9c is exhau/$4 ,! read] may ask3 h[ c !re be a positive fl[ :5 bo? plates are negatively electrifi$8 ,an analogy is ! be/ way to make ?is po9t cle>3 ,imag9e two equal vessels1 f ea* ( :i* ! air has be5 p>tially exhau/$1 b f "o 7,a7 #aj times z mu* air has be5 tak5 z f ! o!r 7,b74 ,connect ,a & ,b by a tube4 ,n[1 al?\gh bo? vessels h less ?an ! atmosph]ic pressure1 t is1 bo? h 8negative0 pressures1 yet a curr5t ( air w fl[ f ,b to ,a until ! pressures 9 ea* are equaliz$2 t is1 until bo? h equal 8negative *>ges0 ( air4 ,!re is a second important effect ( ! acid solution or electrolyte 9 a cell4 ,if pure sulphuric acid 7 us$1 ! fir/ action or production ( an electrical *>ge on ! z9c plate w\ld be ! same1 b :5 ! plates 7 jo9$ by ! wire ! curr5t w\ld soon cease4 ,! reason = ?is lies 9 ! fact t ! sulphate ( z9c1 :i* is ! comp\nd produc$ by ! acid plus ! z9c1 be+ insoluble 9 pure undilut$ sulphuric acid1 rema9s on ! surface ( ! z9c plate4 ,! coat+ ( sulphate ( z9c ?us =m$ also op]ates z a protective ag5t1 & no fur!r electrical *>ge c be induc$ until x is remov$4 ,! addition ( wat] to ! acid has ! effect ( all[+ ! sulphate ( z9c to dissolve1 & ! z9c plate is left free = fur!r action4 ,ques4 ,:at gov]ns ! rate ( curr5t fl[ ( a prim>y cell8 ,ans4 ,! size ( ! elem5ts & _! proximity4 ,effects ( ,pol>ization4--,! film ( hydrog5 bubbles affects ! /r5g? ( ! curr5t ( ! cell 9 two ways3 #a4 ,x weak5s ! curr5t by ! increas$ resi/ance :i* x (f]s to ! fl[1 = bubbles ( gas are bad conductors2 #b4 ,x weak5s ! curr5t by sett+ up an oppos+ electromotive =ce4 ,hydrog5 is almo/ z oxidizable a sub/ance z z9c1 especially :5 fre%ly deposit$ 79 ! 8nasc5t0 /ate71 & is electro-positive2 h5ce1 ! hydrog5 itself produces a diff]5ce ( pot5tial1 :i* w\ld t5d to />t a curr5t 9 ! opposite direction to ! true z9c-to-copp] curr5t4 ,x is !re=e an important matt] to aboli% ?is pol>ization1 o!rwise ! curr5ts furni%$ by batt]ies w\ld n be con/ant4 ,me?ods ( ,depol>iz+4--,"o ( ! *ief aims 9 ! arrangem5t ( ! num]\s cells :i* h be5 devis$ is to avoid pol>ization4 ,! foll[+ are ! me?ods usually employ$3 #a4 ,*emical me?ods2 a4 ,oxidation ( ! hydrog5 by potassium bi*romate & by nitric acid4 b4 ,sub/itution ( ! hydrog5 by "s o!r sub/ance :i* does n give a c\nt] electromotive =ce ( pol>ization2 = in/ance1 9 ! ,daniell cell by replacem5t ( ! copp] 9 copp] sulphate by ! hydrog51 ! copp] be+ deposit$ on ! positive pole4 #b4 ,electro-*emical means2 ,x is possible by employ+ d\ble cells1 to secure su* action t "s solid metal1 su* z copp]1 %all be lib]at$ in/ead ( hydrog5 bubbles1 at ! po9t :]e ! curr5t leaves ! liquid4 ,?is electro-*emical ex*ange obviates pol>ization4 #c4 ,me*anical me?ods4 a4 ,agitation ( ! liquid or ( ! positive electrode1 9 ord] to prev5t ! accumulation ( hydrog5 !reon4 b4 ,corrugat+ or r\gh+ ! positive electrode1 z 9 ! ,smee cell4 ,?is causes ! hydrog5 gas to =m 9 l>ge bubbles :i* rise to ! surface m rapidly ?an ! small bubbles :i* =m on a smoo? electrode4 ,9 ! simple/ =m ( cell1 z z9c1 copp]1 & dilute sulphuric acid1 no attempt has be5 made to prev5t ! evil ( pol>ization1 h5ce1 x w quickly pol>ize :5 ! curr5t is clos$ = any l5g? ( "t1 & may be classifi$ z an op5 circuit cell4 ,:5 pol>ization is rem$i$ by *emical means1 ! *emical add$ is "o t has a /rong aff9ity = hydrog5 & w comb9e ) x1 ?us prev5t+ ! cov]+ ( ! negative plate ) ! hydrog5 gas4 ,illu/ration3 ,,figs4 #db & #dc4--;,c>bon cell & c>bon cyl9d]4 ,c>bon possesses a natural p[] to prev5t a limit$ am\nt ( pol>ization by absorb+ ! hydrog5 gas com+ f ! z9c rod2 h5ce x is us$ 9 v>i\s %apes = op5 circuit cells1 :i* gives rise to z _m diff]5t names1 su* z ,samson1 ,h]cules1 ,law1 ,national1 ,/&>d1 etc4 ,9 all ^! types ( cell1 sal-ammoniac & z9c are us$1 & by corrugat+ ! c>bon1 flut+ x1 or mak+ conc5tric cyl9d]s1 special m]its are obta9$ 9 ea* case4 ,! c>bon elem5t is usually made 9 ! =m ( a por\s cup1 fill$ ) oxide ( manganese to prev5t pol>ization1 & !n seal$4 ,! z9c rod is ins]t$ ?r\gh a porcela9 insulator4 ,ab\t #d to #f ounces ( sal-ammoniac are g5]ally us$ = cells ( ord9>y size4 ,! salt is plac$ 9 ! j>1 wat] p\r$ 9 until x is ab\t two-?irds full1 & !n /irr$ till all ! salt is dissolv$4 ,:5 ! c>bon cyl9d] is ins]t$1 ! solution %\ld be )9 #a-a_/b in*es ( ! top ( ! j>4 ,! electromotive =ce is f #a4j to #a4d volts = ! diff]5t =ms ( c>bon cell4 ,ques4 ,:at is a depol>iz]8 ,ans4 ,a sub/ance employ$ 9 "s types ( cell to comb9e ) ! hydrog5 :i* w\ld o!rwise be set free at ! positive electrode & cause pol>ization4 ,! *emical us$ = ?is purpose may be ei!r 9 a solid or liquid =m1 :i* gives rise to sev]al types ( cell1 su* z cells ) a s+le fluid1 conta9+ bo? ! acid & ! depol>iz]1 cells ) a s+le excit+ fluid & a solid depol>iz]1 & cells ) two sep>ate fluids4 ,9 ! two fluid cell1 ! z9c is imm]s$ 9 ! liquid 7frequ5tly dilute sulphuric acid7 to be decompos$ by ! action ^u x1 & ! negative plate is surr\nd$ by ! liquid depol>iz]1 :i* w be decompos$ by ! hydrog5 gas x arre/s1 !reby prev5t+ pol>ization4 ,9 op5 circuit cells pol>ization does n h mu* opportunity to occur1 s9ce ! circuit is clos$ = su* a %ort p]iod ( "t2 h5ce1 ^! cells are always ready to deliv] a /rong curr5t :5 us$ int]mitt5tly4 ,9 clos$ circuit cells pol>ization is prev5t$ by *emical action1 s t ! curr5t w be con/ant & /eady till ! en]gy ( ! *emicals is exp5d$4 ,ques4 ,:at is a depol>iz] bag8 ,ans4 ,a cyl9d] ( hemp or o!r fabric us$ 9 place ( a por\s pot 9 "s =ms ( ,leclan*e cell1 & also z a support = ! depol>iz+ mass 9 "s =ms ( dry cell :]e ! electrolyte is ( a ?9 gelat9\s nature4 ,volta's ,contact ,law4--,:5 metals diff]+ f ea* o!r are br\ght into contact1 diff]5t results are obta9$1 bo? z to ! k9d ( electrification z well z ! diff]5ce ( pot5tials4 ,volta f\nd t iron1 :5 9 contact ) z9c1 becomes negatively electrifi$2 ! same takes place1 b some:at weak]1 :5 iron is t\*$ ) lead or t94 ,:51 h[ev]1 iron is t\*$ by copp] or silv]1 x becomes positively electrifi$4 ,volta1 ,seebeck1 ,pfaff1 & o!rs h inve/igat$ ! behavior ( _m metals & alloys :5 9 contact ) ea* o!r4 ,! foll[+ li/s are s arrang$ t ^? metals fir/ 9 ea* li/ become positively electrifi$ :5 t\*$ by any tak+ rank aft] !m3 ,,contact ,,s]ies ,,( ,,metals ,accord+ to ,volta4 ,accord+ to ,pfaff4 z9c z9c lead cadmium t9 t9 iron lead copp] tung/5 silv] iron gold bismu? graphite antimony - manganese ore copp] silv] gold uranium tellurium plat9um - palladium ,volta laid d[n a law reg>d+ ! position ( ! metals 9 8 table :i* may be /at$ z foll[s3 ,! diff]5ce ( pot5tial betwe5 any two metals is equal to ! sum ( ! diff]5ces ( pot5tials ( all ! int]m$iate memb]s ( ! s]ies4 ,h5ce1 x is immat]ial = ! total effect :e!r ! fir/ & ! la/ are br\ght into contact directly1 or :e!r ! contact is br\ght ab\t by means ( all or any ( ! int]m$iate metals4 ,volta's law fur!r ass]ts t :5 any numb] ( metals are br\ght into contact ) ea* o!r1 b s t ! *a9 closes ) ! metal ) :i* x 0 begun1 ! total diff]5ce mu/ be z]o4 ,laws ( ,*emical ,action 9 ! ,cell4--,!re are two simple laws ( *emical action 9 ! cell3 #a4 ,! am\nt ( *emical action 9 a cell is proportional to ! quantity ( electricity t passes ?r\gh x4 ,"o c\lomb ( electricity 9 pass+ ?r\gh ! cell lib]ates 4#jjjjajceb ( a gramme ( hydrog51 & causes 4#jjjfccdd ( a gramme ( z9c to dissolve 9 ! acid4 #b4 ,! am\nt ( *emical action is equal 9 ea* cell ( a batt]y connect$ 9 s]ies4 ,requirem5ts ( a ,good ,cell4--,! sev]al conditions :i* %\ld be fulfill$ by a good cell are z foll[s3 #a4 ,its electromotive =ce %\ld be high & con/ant2 #b4 ,its int]nal resi/ance %\ld be small2 #c4 ,x %\ld be p]fectly quiesc5t :5 ! circuit is op52 #d4 ,x %\ld give a con/ant curr5t1 & !re=e mu/ be free f pol>ization1 & n liable to rapid exhau/ion2 #e4 ,x %\ld be easily c>$ =1 & if possible1 %\ld n emit corrosive fumes2 #f4 ,x %\ld be *eap & ( durable mat]ials4 ,s+le & ,two ,fluid ,cells4--,! di/9ction betwe5 a s+le & a two fluid cell has already be5 giv54 ,! s+le fluid cell ( ,volta ) its z9c & copp] plates repres5ts ! simple/ =m ( prim>y cell4 ,9 ! two fluid cell1 ! positive 7z9c7 plate is imm]s$ 9 ! excit+ liquid 7usually dilute sulphuric acid7 & is decompos$ by ! action ^u x1 :ile ! negative plate is plac$ 9 ! liquid depol>iz] :i* is decompos$ by ! hydrog5 arre/$ by x1 ?us prev5t+ pol>ization4 ,9 "s =ms ( cell1 ! two liquids are sep>at$ by a por\s p>tition ( unglaz$ e>!nw>e1 :i*1 :ile x prev5ts ! liquids mix+ except v sl[ly1 does n prev5t ! passage ( hydrog5 & electricity4 ,illu/ration3 ,,figs4 #dd & #de4--,leclan*e cell & por\s cup4 ,?is v common =m ( cell is an example ( ! s+le fluid type1 ) a solid depol>iz] surr\nd+ ! negative elem5t2 ! latt] is g5]ally c>bon1 ! positive elem5t be+ z9c4 ,! liquid us$ is a /rong solution ( ammonium *loride1 commonly kn[n z sal-ammoniac1 & :i* resembles table salt4 ,9 ! por\s cup type ( cell1 a c>bon slab is plac$ 9 ! por\s cup1 & is surr\nd$ by a mixture ( small pieces ( c>bon & manganese dioxide1 ! top be+ cov]$ by means ( pit*1 leav+ "o or two small holes = air & gas to pass ?r\gh4 ,! depol>iz] w take c>e ( a limit$ am\nt ( ! hydrog5 produc$ :5 ! cell is on clos$ circuit1 b if ! circuit be clos$ = any l5g? ( "t pol>ization occurs4 ,! cell is ?us ( ! op5 circuit class1 & w furni% a good curr5t :]e x is requir$ only int]mitt5tly4 ,z9c is dissolv$ only :5 ! cell is be+ us$4 ,?is type ( cell1 or its modification1 is us$ = gas light+ & bell "w4 ,! cell requires v little att5tion4 ,wat] mu/ be add$ z ! solution evaporates1 & ! z9c rod repl5i%$ :5 necess>y4 ,! electromotive =ce is ab\t #a4dh volts & ! int]nal resi/ance ab\t #d ohms4 ,complete depol>ization is usually obta9$ also 9 s+le fluid cells1 hav+ 9 addition a depol>iz+ solid body1 su* z oxide ( manganese1 oxide ( copp]1 or p]oxide ( lead1 9 contact ) ! c>bon pole4 ,su* cells really d n belong to ! s+le fluid cells1 & are consid]$ 9 ! two fluid class4 ,a few examples ( s+le & d\ble fluid prim>y cells w n[ be describ$4 ,! ,leclan*e ,cell4--,?is cell 0 inv5t$ by ,leclan*e1 a ,fr5* electrician1 & 0 ! fir/ cell 9 :i* sal-ammoniac 0 us$4 ,?is =m ( cell1 z %[n 9 fig4 #de1 is 9 g5]al use = electric bells1 its great recomm5dation be+ t1 once *>g$1 x reta9s its p[] )\t att5tion = consid]able "t4 ,two j>s are employ$ 9 its con/ruction2 ! out] "o is ( glass1 conta9s a z9c rod1 & is *>g$ ) a solution ( ammonium *loride1 call$ sal-ammoniac4 ,! inn] j> is ( por\s e>!nw>e1 conta9+ a c>bon plate1 & is fill$ ) a mixture ( manganese p]oxide & brok5 gas c>bon4 ,:5 ! c>bon plate & ! z9c rod are connect$1 a /eady curr5t ( electricity is set up1 ! *emical action :i* takes place be+ z foll[s3 ! z9c becomes oxidiz$ by ! oxyg5 f ! manganese p]oxide1 & is subsequ5tly conv]t$ into z9c *loride by ! action ( ! sal-ammoniac4 ,aft] ! batt]y has be5 9 cont9u\s use = "s h\rs1 ! manganese becomes exhau/$ ( oxyg51 & ! =ce ( ! electrical curr5t is greatly dim9i%$2 b if ! batt]y be all[$ to re/ = a %ort "t1 ! manganese obta9s a fre% supply ( oxyg5 f ! atmosph]e1 & is aga9 fit = use4 ,aft] ab\t #ah mon?s "w1 ! glass cell w probably require re*>g+ ) sal-ammoniac1 & ! z9c rod may also ne$ r5ew+2 b %\ld ! por\s cell get out ( ord]1 x is bett] to get a new "o ?an to attempt to re*>ge x4 ,! directions = sett+ up a ,leclan*e cell are z foll[s3 #a4 ,place 9 ! glass j> six ounces ( sal-ammoniac1 & p\r 9 wat] until ! j> is "o-?ird full1 !n /ir ?or\ghly4 #b4 ,place ! por\s cup 9 ! solution1 & if necess>y add wat] until x rises to )9 #a-a_/b in*es ( ! top ( ! por\s cup4 #c4 ,put ! z9c rod 9 place & set ! cell away 7n connect$ up71 = ab\t #ab h\rs1 s z to all[ ! liquid to ?or\ghly soak into ! por\s cup4 ,?is w l[] ! level ( ! liquid to ab\t "o-?ird ! height ( ! j>4 ,! cell w !n be ready = use4 ,z ! level ( ! liquid is l[]$ by evaporation1 x %\ld be ma9ta9$ at ! /at$ height by add+ wat]4 ,! ,leclan*e cell is adapt$ to op5 circuit "w1 be+ ext5sively us$ = r++ electric bells4 ,! objections to ! ,leclan*e cell are3 #a4 ,rapid pol>ization2 #b4 ,high int]nal resi/ance due to por\s pot2 #c4 ,re/rict$ space = electrolyte caus+ rapid l[]+ ( level ( liquid by evaporation2 #d4 ,eat+ away ( ! z9c rod at ! surface ( ! liquid1 r5d]+ ! rod useless be=e ! l[] "p is consum$4 ,full] ,bi*romate ,cell4--,9 ! bi*romate cells or ! *romic acid cells1 bi*romate ( soda1 or bi*romate ( potassium1 is us$ = ! depol>iz]1 wat] & sulphuric acid be+ add$ = attack+ ! z9c4 ,! ,full] cell is ( ! two fluid type4 ,a pyramidal block ( z9c at ! end ( a metallic rod cov]$ ) gutta-p]*a is plac$ 9 ! bottom ( a por\s cup conta9+ an ounce ( m]cury4 ,! cup is !n fill$ ) a v dilute solution ( sulphuric acid or wat] & plac$ 9 a j> ( glass or e>!nw>e conta9+ ! bi*romate solution & ! c>bon plate4 ,! diffusion ( ! acid ?r\gh ! por\s cup is suffici5tly rapid to attack ! z9c1 :i* be+ well amalgamat$1 prev5ts local action2 :ile ! hydrog5 passes ?r\gh ! por\s cup & comb9es ) ! oxyg5 9 ! bi*romate ( potassium4 ,?is type ( cell has an electromotive =ce ( #b4ad volts1 & is suit$ to op5 circuit1 or semi-clos$ circuit "w4 ,! directions = sett+ up a ,full] cell are z foll[s3 #a4 ,to make ! 8electropoion0 fluid1 mix toge!r "o gallon ( sulphuric acid & ?ree gallons ( wat]1 & 9 a sep>ate vessel1 dissolve six p\nds ( bi*romate ( pota% 9 two gallons ( boil+ wat]2 !n ?or\ghly mix toge!r ! two solutions4 #b4 ,imm]se ! z9c 9 a solution ( dilute sulphuric acid1 & !n 9 a ba? ( m]cury1 & rub x ) a bru% or clo? s z to rea* all p>ts ( ! surface4 #c4 ,p\r into ! por\s cell "o ounce 7a tablespoonful7 ( m]cury1 & fill ! por\s cell ) wat] up to )9 two in*es ( ! top4 #d4 ,place ! por\s cell & ! c>bon plate 9 ! glass j>1 z 9 fig4 #df1 & fill glass j> to )9 ab\t ?ree in*es ( ! top ) a mixture ( ?ree p>ts ( electropoion fluid to two p>ts ( wat]4 ,illu/ration3 ,,figs4 #df & #dg4--,! telephone /&>d & comp\nd =ms ( ! ,full] cell4 ,! type %[n 9 fig4 #df is especially adapt$ to long di/ance telephon+1 & t %[n 9 fig4 #dg to inc&esc5t lamps1 motors1 nickel & o!r electroplat+4 ,! ,full] cell is a d\ble fluid v>iety & has ! advantage ov] ! ,gr5et type1 9 t ! z9c is always kept well amalgamat$ & does n require removal f ! solution4 ,! ,full] cell is suitable = op5 & semi-clos$ circuit "w2 its electromotive =ce is ab\t #b4ad volts4 #e4 ,! z9c %\ld be lift$ out occasionally & ! sulphate wa%$ (f4 #f4 ,! supply ( m]cury 9 ! por\s cell %\ld be ma9ta9$1 s z to h ! z9c always well amalgamat$4 #g4 ,to r5ew1 clean all deposits f c>bon plate & z9c1 & set up ) fre% solution4 ,! ,edison ,cell4--,?is is a s+le fluid cell ) a solid depol>iz]1 z %[n 9 fig4 #dh1 & is well adapt$ = use on clos$ circuits4 ,illu/ration3 ,,fig4 #dh4--;,edison cell1 type ,r ,r4 ,! electrolyte us$ is cau/ic soda1 ! positive elem5t z9c1 & ! negative elem5t copp] oxide4 ,! ,edison cell is suitable = l>ge /ation>y gas eng9e ignition1 railroad cross+ signals1 electroplat+1 fire al>ms1 telephone circuits1 etc4 ,! positive elem5t is z9c1 & ! negative elem5t black oxide ( copp]4 ,! excit+ fluid is a solution ( cau/ic pota%4 ,! black oxide ( copp] plates are susp5d$ f ! cov] ( ! j> by a light framework ( copp]1 "o end ( :i* =ms ! positive pole ( ! batt]y4 ,a z9c plate is susp5d$ on ea* side ( ! copp] oxide elem5t & kept f com+ 9 contact ) ! latt] by means ( vulcanite buttons4 ,:5 ! cell is 9 action1 ! wat] is decompos$1 & ! oxyg5 ?us lib]at$ comb9es ) ! z9c & =ms oxide ( z9c1 :i* comb9es ) ! pota% to =m a d\ble salt ( z9c & pota%4 ,! la/ comb9ation dissolves z rapidly z x is =m$4 ,! hydrog5 lib]at$ by ! decomposition ( ! wat] r$uces ! copp] oxide to pure metallic copp]4 ,x is highly important t ! copp] oxide plates be completely subm]g$ 9 ! solution ( cau/ic pota%1 & t heavy p>aff9 oil be p\r$ on top ( ! solution to ! dep? ( ab\t #a_/d ( an in* to exclude ! air4 ,if oil be n us$1 ! =mation ( creep+ salts w r$uce ! life ( ! batt]y fully two-?irds4 ,! batt]y has a l[ electromotive =ce1 ab\t #j4g ( a volt1 b z ! int]nal resi/ance is also v l[1 q a l>ge curr5t c be drawn f ! cell4 ,! ,buns5 ,cell1 %[n 9 figs4 #di & #ej1 is a two fluid cell con/ruct$ ) z9c & c>bon electrodes4 ,! negative plate is c>bon1 ! positive plate amalgamat$ z9c4 ,! excitant is a dilute solution ( sulphuric acid4 ,! top "p ( ! c>bon is sometimes impregnat$ ) p>aff9 7to keep ! acid f creep+ up74 ,! =ce ( ! ,buns5 cell increases aft] sett+ up = ab\t an h\r1 & ! full effect is n atta9$ until ! acid soaks ?r\gh ! por\s cell4 ,c>bons are n affect$ & la/ any l5g? ( "t4 ,! z9c is sl[ly consum$ ?r\gh ! m]cury coat+4 ,gr5et ,bi*romate ,cell4--,9 ?is cell1 z %[n 9 figs4 #di & #ej1 ! positive elem5t is z9c & ! negative elem5t c>bon4 ,! electrolyte is a solution ( bi*romate ( pota% 9 a mixture ( sulphuric acid & wat]4 ,illu/ration3 ,,figs4 #di & #ej4--;,am]ican & ,fr5* =ms ( ,gr5et cell4 ,! elem5ts are z9c & c>bon4 ,9 ! ,gr5et cell1 a z9c plate is susp5d$ by a rod betwe5 two c>bon plates1 s t x does n t\* !m1 & :5 ! cell is n 9 use ! z9c is )drawn f ! solution by rais+ & fa/5+ ! rod by means ( a set screw1 z ! acid attacks ! z9c :5 ! cell is on op5 circuit4 ,?is cell has an electromotive =ce ( ov] #b volts at fir/1 & gives a /rong curr5t = a %ort "t1 b ! liquid soon becomes exhau/$1 z w be not$ by ! *ange 9 ! color ( ! solution f an orange to a d>k r$1 & mu/ be repl5i%$4 ,! z9c %\ld be kept well amalgamat$ & out ( ! solution except :5 9 use4 ,x is a good type ( cell = exp]im5tal "w4 ,to make ! electrolyte take #c ounces ( f9ely p[d]$ bi*romate ( pota% & #a p9t ( boil+ wat]2 /ir ) a glass rod & aft] x is cool1 add sl[ly1 /irr+ all ! "t1 #c ounces ( sulphuric acid4 ,! electrolyte may also be prep>$ z foll[s3 take #d ounces ( bi*romate ( soda1 #a-a_/d p9ts ( boil+ wat]1 & #c ounces ( sulphuric acid4 ,! cell consi/s ( a glass bottle conta9+ ! electrolyte & fitt$ ) a lid f :i* ! elem5ts are support$4 ,!re is a z9c plate 9 ! c5t] & a c>bon plate on ea* side4 ,! two c>bon plates are connect$ to ! same t]m9al1 ?us =m+ a l>ge negative surface1 & ! z9c plate to a t]m9al on ! top ( ! brass rod to :i* x is atta*$4 ,?is rod slides ?r\gh a hole 9 ! lid s t ! z9c plate c be lift$ out ( ! electrolyte :5 ! cell is n at "w1 ?us prev5t+ wa/eful consumption ( z9c & ( ! electrolyte4 ,bi*romate cells give a /rong curr5t1 ! electromotive =ce ( a s+le cell be+ #b volts4 ,illu/ration3 ,,fig4 #ea4--,! ,buns5 cell4 ,?is is a two fluid cell & has a b> ( c>bon imm]s$ 9 /rong nitric acid conta9$ 9 a por\s cup4 ,?is cup is !n plac$ 9 ano!r vessel1 conta9+ dilute sulphuric acid1 & imm]s$ 9 ! same liquid1 is a holl[ cyl9drical plate ( z9c1 :i* ne>ly surr\nds ! por\s cup4 ,! hydrog51 />t+ at ! z9c1 trav]ses by composition & recomposition1 ! sulphuric acid2 x !n passes ?r\gh ! por\s p>tition1 & ent]s into *emical action ) ! nitric acid1 s t none ( x rea*es ! c>bon4 ,wat] is produc$ by ?is action1 :i* 9 "t dilutes ! acid1 & orange color$ poison\s fumes ( nitric oxide rise f ! batt]y4 ,if ! nitric acid fir/ be saturat$ ) nitrate ( ammonia1 ! acid w la/ long] & ! fumes be prev5t$4 ,/rong sulphuric acid _c be us$ 9 any batt]y2 "o "p ( sulphuric acid is g5]ally add$ to #ab p>ts by weight1 or #bj by volume1 ( wat]4 ,grove us$ a /rip ( plat9um in/ead ( c>bon 9 8 cell4 ,a solution ( bi*romate ( potassium is frequ5tly sub/itut$ = ! nitric acid 9 ! por\s cup1 !reby avoid+ disagreeable fumes4 ,buns5's & ,grove's cells produce p[]ful & con/ant curr5ts1 & are well adapt$ = exp]im5ts1 b !y require frequ5t att5tion1 & are exp5sive1 s t !y are little us$ = "w ( long duration4 ,! electromotive =ce ( ^! cells is f #a4ge to #i4ea volts4 ,daniell ,cell4--,?is is "o ( ! be/ kn[n & mo/ widely us$ =ms ( prim>y cell4 ,x is a d\ble fluid cell1 compos$ ( an inn] por\s vessel conta9+ an electrolyte ( ei!r dilute sulphuric acid or dilute z9c sulphate solution1 & an out] vessel conta9+ a saturat$ solution ( copp] sulphate4 ,a z9c rod is plac$ 9 ! inn] electrolyte1 & a ?9 plate ( %eet copp] 9 ! out] electrolyte4 ,sometimes ?is arrangem5t ( ! elem5ts is modifi$1 ! out] vessel be+ made ( copp] & s]v+ z ! copp] plate4 ,?is w\ld !n conta9 ! copp] sulphate solution1 :ile ! z9c sulphate & ! z9c rod w\ld be conta9$ 9 ! por\s pot z be=e4 ,! *emical reactions :i* take place 9 a ,daniell cell are z foll[s3 ,! z9c dissolves 9 ! dilute acid1 ?us produc+ z9c sulphate1 & lib]at+ hydrog5 gas4 ,! free hydrog5 passes ?r\gh ! walls ( ! por\s pot1 b :5 x rea*es ! copp] sulphate solution x displaces "s ( ! copp] !refrom1 & comb9es ) ?is solution1 =m+ sulphuric acid4 ,! copp]1 :i* is ?us set free1 is deposit$ on ! surface ( ! copp] plate4 ,9 ?is way pol>ization is avoid$1 & a practically con/ant curr5t is obta9$4 ,:5 ! z9c sulphate solution is employ$ 9 place ( dilute acid1 a simil> s]ies ( *emical reactions occur1 except t ! z9c is lib]at$ in/ead ( hydrog54 ,daniell cells are us$ especially = electroplat+1 electrotyp+ & telegraphic "w4 ,! electromotive =ce ( a s+le cell is #a4jgi volts4 ,directions = ,mak+ a ,daniell ,cell4--,! simple ,daniell cell %[n 9 fig4 #eb may be easily made z foll[s3 ,! out] vessel ,a1 consi/s ( a glass j> 7an ord9>y glass jam j> w d7 conta9+ a solution ( sulphuric acid 7#a "p 9 #ab to #bj p>ts ( wat]71 & a z9c rod ,b4 ,inside ! j> is plac$ a por\s pot ,c conta9+ a /rip ( ?9 %eet copp] ,d1 & a saturat$ solution ( sulphate ( copp] 7also call$ 8blue /one0 & 8blue vitrol074 ,! z9c is pref]ably ( ! ,leclan*e =m1 :i* w be f\nd to be clean]1 m durable1 & *eap] ?an a z9c %eet4 ,! por\s pot %\ld be dipp$ 9 melt$ p>aff9 wax1 bo? top & bottom1 to prev5t ! solution m+l+ too freely & 8creep+40 ,a few cry/als ( copp] sulphate are plac$ 9 ! pot z %[n4 ,illu/ration3 ,,fig4 #eb4--,simple ,daniell cell = clos$ circuit "w4 ,to ma9ta9 a con/ant curr5t = an indef9ite "t1 x is only necess>y to ma9ta9 ! supply ( copp] cry/als & z9c4 ,! cell z %[n 9 ! figure is easily made by foll[+ ! direction giv5 9 ! accompany+ text4 ,9 mix+ ! sulphuric acid & wat]1 ! acid %\ld be add$ to ! wat]--nev] ! rev]se4 ,z9c sulphate is sometimes us$ in/ead1 z x r$uces ! wa/eful consumption ( ! z9c1 b x %\ld be pure4 ,) c>e ! cell w la/ = weeks4 ,:5 x weak5s or 8runs d[n10 an addition ( sulphuric acid to ! out] j> & a few m cry/als plac$ 9 ! por\s pot w put ! cell 9 good condition4 ,illu/ration3 ,,fig4 #ec4--;,daniell gravity cell1 8cr[foot0 patt]n4 ,?is is a two fluid cell 9 :i* gravity in/ead ( a por\s cup is dep5d$ ^u to keep ! liquids sep>ate4 ,! two solutions consi/ ( copp] sulphate & dilute sulphuric acid1 ! elem5ts be+ made ( z9c & copp]4 ,gravity ,cells4--,9 a two liquid cell1 in/ead ( employ+ a por\s cell to keep ! two liquids sep>ate1 x is possible1 :]e "o ( ! liquids is heavi] ?an ! o!r1 to arrange t ! heavi] liquid %all =m a /ratum at ! bottom ( ! cell1 ! light] float+ ^u x4 ,su* arrangem5ts are call$ gravity cells2 b ! sep>ation is nev] p]fect1 ! heavy liquid sl[ly diffus+ upw>ds4 ,daniell ,gravity ,cell4--,9 ?is cell1 %[n 9 fig4 #ec1 ! same elem5ts are us$ z 9 ! ord9>y ,daniell cell1 b ! por\s pot is disp5s$ )1 ! two solutions be+ sep>at$ by ! action ( gravity z expla9$ 9 ! prec$+ p>agraph4 ,illu/ration3 ,,fig4 #ed4--,p>tz acid gravity cell4 ,9 ?is =m ( cell1 ! electrolyte :i* surr\nds ! z9c is ei!r magnesium sulphate or common salt4 ,! depol>iz] is a bi*romate solution :i* surr\nds ! p]=at$ c>bon plate locat$ 9 ! bottom ( ! j>4 ,a v]tical c>bon rod fits snugly into ! tap]$ hole 9 ! c>bon plate1 & ext5ds ?r\gh ! cov] =m+ ! positive pole4 ,! depol>iz]1 be+ heavi] ?an ! electrolyte1 rema9s at ! bottom ( ! j>1 & ! two liquids are ?us kept sep>ate4 ,?is depol>iz] is plac$ on ! m>ket 9 ! =m ( cry/als1 kn[n z sulpho-*romic salt1 made by ! action ( sulphuric acid ^u *romic acid4 ,:5 dissolv$1 its action is simil> to t ( ! *romic acid solution4 ,aft] ! cell has be5 set up ) ev]y?+ else 9 place1 ! cry/als are introduc$ into ! solution1 ne> ! bottom ( ! j>1 ?r\gh ! v]tical glass tube %[n1 & sl[ly dissolve & diffuse ov] ! surface ( ! c>bon plate4 ,:5 ! cell curr5t weak5s a few tablespoonfuls ( ! salt introduc$ ?r\gh ! tube w re/ore ! curr5t to its normal value4 ,! cell %\ld rema9 undi/urb$ to prev5t ! solution f mix+4 ,its electromotive =ce is f #a4i to #b volts1 & ! #f 94 #h 94 size has an int]nal resi/ance ( ab\t 4#e ohm4 ,s9ce ! depol>iz] is q effective1 ! cell may be us$ on op5 or clos$ circuit "w4 ,! copp] sulphate solution1 be+ ! heavi] ( ! two1 re/s at ! bottom ( ! batt]y j>1 :ile ! dilute sulphuric acid rema9s at ! top4 ,to suit ?is arrangem5t ! copp] & z9c elem5ts are locat$ z %[n1 ! copp] elem5ts be+ at ! bottom1 & ! z9c elem5t1 %ap$ l a cr['s foot 7h5ce ! "n 8cr[foot cell07 is susp5d$ at ! top4 ,! abs5ce ( ! por\s pot decreases ! int]nal resi/ance1 b ! electromotive =ce is ! same z 9 ! ord9>y type ( ,daniell cell4 ,illu/ration3 ,,fig4 #ee4--,:eelock cell2 ! elem5ts are c>bon & z9c4 ,to set up1 place ! grid 9 ! bottom ( ! j> & fill its two tr\ghs ea* ab\t half full ( m]cury4 ,place ! por\s cell 9 position on ! grid s t x sits p]fectly upright1 re/+ 9 ! recess ( ! latt]4 ,! z9cs /& ) l[] ends re/+ 9 m]cury 9 ! tr\ghs ( ! grid4 ,into ! por\s cell1 to a height ( only two-?irds full1 p\r solution consi/+ ( equal p>ts wat] & sulphuric acid1 by measure4 ,add to ?is #a_/b p\nd nitrate soda1 #a ounce *romic acid4 ,?is solution may be made up 9 ! above proportion & kept 9 cov]$ receptacle 9 any desir$ quantity1 ready = use4 ,9 ! out] j> = #f #h size1 #b-a_/b p9ts ( wat]1 & #a_/b gill sulphuric acid1 #a "p sulphuric acid to #bj p>ts wat]1 or z mu* sulphuric acid z x w take )\t boil+4 ,:5 a *>ge becomes exhau/$ x may be r5ew$ by add+ sulphuric acid & salts 9 ! proportions giv5 above1 aft] draw+ out ) syr+e en\gh ( ! old solutions to make room = ! additions1 b ! be/ action is obta9$ ) entirely new solutions4 ,z9cs mu/ be kept ?or\ghly amalgamat$ by keep+ a good supply ( m]cury 9 ! tr\ghs4 ,:5 a curr5t is produc$ by a ,daniell cell3 #a4 ,copp] is deposit$ on ! copp] plate2 #b4 ,copp] sulphate is consum$2 #c4 ,! sulphuric acid rema9s un*ang$ 9 quantity2 #d4 ,z9c sulphate is =m$2 #e4 ,z9c is consum$4 ,if1 h[ev]1 ! copp] sulphate solution be too weak1 ! wat] is decompos$ in/ead ( ! copp] sulphate1 & hydrog5 is deposit$ on ! copp] plate4 ,?is deposit ( hydrog5 l[]s ! voltage1 h5ce c>e %\ld be tak5 to ma9ta9 an adequate supply ( copp] sulphate4 ,! voltage ( a ,daniell cell v>ies f ab\t #a4jg volt to #a4ad volt1 accord+ to ! d5sity ( ! copp] sulphate solution & ! am\nt ( z9c sulphate pres5t 9 ! dilute sulphuric acid4 8,dry0 ,cells4--,x is (t5 necess>y to use cells 9 places :]e !re is consid]able j>r+ or motion1 z = automobile or m>9e ignition4 ,! ord9>y cell is n well adapt$ to ?is s]vice on acc\nt ( ! liability ( spill+ ! electrolyte1 h5ce1 ! introduction ( ! s-call$ dry cell4 ,a dry cell is compos$ ( two elem5ts1 usually z9c & c>bon1 & a liquid electrolyte4 ,a z9c cup clos$ at ! bottom & op5 at ! top =ms ! negative electrode2 ?is is l9$ ) sev]al lay]s ( blott+ pap] or o!r absorb+ mat]ial4 ,! positive electrode consi/s ( a c>bon rod plac$ 9 ! c5t] ( ! cup2 ! space betwe5 is fill$ ) c>bon--gr\nd coke & dioxide ( manganese mix$ ) an absorb5t mat]ial4 ,?is fill+ is moi/5$ ) a liquid1 g5]ally sal-ammoniac4 ,! top ( ! cell is clos$ ) pit* to prev5t leakage & evaporation4 ,a b9d+ po/ = hold+ ! wire connections is atta*$ to ea* electrode & ea* cell is plac$ 9 a pap] box to protect ! z9cs ( adjac5t cells f com+ into contact ) ea* o!r :5 f9ally connect$ toge!r to =m a batt]y4 ,po9ts ,relat+ to ,dry ,cells4--,! foll[+ in/ructions on ! c>e & op]ation ( dry cells %\ld be c>efully not$ & foll[$ to get ! be/ results3 ,illu/ration3 ,,figs4 #ef & #eg4--,r\nd & rectangul> types ( ! s-call$ 8dry0 cell4 #a4 ,9 r5ew+ dry cells 7or any o!r k9d ( cell71 a great] numb] %\ld nev] be put 9 s]ies ?an 0 orig9ally requir$ to d ! "w1 because ! additional cells increase ! voltage beyond t requir$1 :i* causes m curr5t ?an is necess>y to fl[ ?r\gh ! coil4 ,?is increas$ curr5t fl[ %ort5s ! life ( ! batt]y4 #b4 ,9 connect+ dry cells 9 places :]e !re is vibration1 heavy copp] wire %\ld n be us$1 because vibration w cause x to break4 #c4 ,wat] %\ld n be all[$ to come 9 contact ) ! pap] cov]s ( ! cells because !y =m ! insulation1 h5ce1 :5 moi/1 curr5t w leak across f "o cell to ano!r1 result+ 9 runn+ d[n ! batt]y4 #d4 ,dry cells w det]iorate :5 n 9 use1 mak+ x necess>y to r5ew !m ab\t e sixty days4 ,! reason dry cells det]iorate is because ! moi/ure evaporates4 ,freez+1 exposure to heat1 & vibration :i* loos5s ! seal+1 causes ! evaporation4 #e4 ,weak cells c be /r5g!n$ some:at by remov+ ! pap] jacket1 pun*+ ! metal cup full ( small holes1 & !n plac+ 9 a weak solution ( sal-ammoniac1 all[+ ! cells to absorb all !y w take up4 ,?is is only to be recomm5d$ 9 cases ( em]g5cy :5 !y are h>d to get4 ,illu/ration3 ,,figs4 #eh to #fc4--,v>i\s z9cs2 fig4 #eh ,full]2 fig4 #ei ,daniell2 fig4 #fj ,leclan*e squ>e2 fig4 #fa ,leclan*e r\nd2 fig4 #fb ,sampson2 fig4 #fc1 bottle4 #f4 ,! av]age voltage ( a dry cell :5 new is "o & "o-half volts1 :ile ! amp]age ranges f ab\t tw5ty-five to fifty amp]es accord+ to size4 #g4 ,a dry cell :5 fre% %\ld %[ f #bj to #be amp]es :5 te/$2 ! date ( manufacture %\ld also be not$ z fre% cells are mo/ effici5t4 #h4 ,dry cells %\ld be te/$ ) an ammet]1 c>e be+ tak5 to d x quickly z ! ammet] be+ ( a v l[ resi/ance %ort circuits ! cell4 ,a volt met] is n us$ 9 te/+ because1 :ile ! cells are n giv+ out curr5t1 _! voltage rema9s practically ! same1 & a cell t is v weak w %[ ne>ly full voltage4 ,:5 no ammet] is at h&1 ! batt]y curr5t may be te/$ by disconnect+ ! end ( "o ( ! t]m9al wires & snapp+ x across ! b9d+ po/ ( ! o!r t]m9al2 ! int5sity ( ! sp>k produc$ w indicate ! condition ( ! batt]y4 ,po9ts ,relat+ to ! ,c>e ( ,cells4--,to get ! be/ results f prim>y cells1 !y %\ld receive prop] att5tion & be ma9ta9$ 9 good condition4 ,! in/ructions "h giv5 %\ld be c>efully foll[$4 ,illu/ration3 ,,figs4 #fd to #ff3 ,v>i\s c>bons2 fig4 #fa ,cyl9drical =m2 fig4 #fe ,call& />2 fig4 #ff1 :eel4 ,cleanl9ess4--,9 ! c>e ( batt]ies1 cleanl9ess is ess5tial 9 ord] to secure be/ results4 ,z9cs & copp]s %\ld be ?or\ghly clean$ e "t a cell is tak5 out ( use4 ,! z9c1 aft] be+ ?or\ghly clean$1 %\ld be rubb$ ) a little m]cury4 ,?is prev5ts local action4 ,por\s cups %\ld be soak$ 9 clean wat] f\r or five h\rs & !n wip$ dry4 ,! t]m9als ( ea* cell %\ld be ?or\ghly cleans$ & scrap$ bright s z to get good contact ( ! connect+ wires & ?us avoid extra resi/ance 9 ! circuit4 ,sep>at+ ! ,elem5ts4--,obvi\sly ! positive & negative elem5ts ( a cell mu/ n be 9 contact )9 ! excit+ fluid2 !y %\ld be sep>at$ by a space ( #c_/h to #a_/b in*4 ,9 ! case ( cells )\t por\s cups1 p]iodic att5tion mu/ be giv5 to ensure ?is condition be+ ma9ta9$4 ,illu/ration3 ,,figs4 #fg to #fi4--,v>i\s z9cs3 fig4 #fg ,cr[foot2 fig4 #fh ,lockwood2 fig4 #fi fire al>m4 ,creep+4--,z evaporation ( ! electrolyte takes place 9 a cell1 x increases 9 /r5g?1 & cry/als are left on ! sides ( ! j> previ\sly wett$ by ! solution1 ! action be+ v m>k$ :5 ! solution is a saturat$ "o4 ,! space betwe5 ^! cry/als & ! side ( ! j> acts z a numb] ( capill>y tubes1 & draws up m liquid1 :i* itself evaporates & deposits cry/als above ! =m] ones4 ,s t f9ally ! film ( cry/als passes ov] ! edge ( ! j> & =ms on ! outside1 ?us mak+ a k9d ( syphon :i* draws (f ! liquid4 ,?is action may1 to a great ext5t1 be prev5t$ by w>m+ ! edges ( ! glass1 or /onew>e1 j>s1 & ( ! por\s pots1 be=e ! cells are made up1 & dipp+ !m :ile w>m into "s p>aff9 wax melt$ 9 w>m oil1 a precaution t %\ld always be c>ri$ out :5 a d5se solution ( z9c sulphate is employ$ 9 ! cell4 ,amalgamat$ ,z9c4--,to 8amalgamate0 a piece ( z9c1 dip x into dilute sulphuric acid to clean its surface1 !n rub a little m]cury ov] x by means ( a piece ( rag ti$ on to ! end ( a /ick1 & la/ly1 leave ! z9c /&+ = a %ort "t 9 a di% to cat* ! surplus m]cury z x dra9s (f4 ,illu/ration3 ,,figs4 #gj & #ga4--,two =ms ( copp] elem5t3 fig4 #gj1 regul> =m = cr[foot cell2 fig4 #ga1 signal pan bottom copp]4 ,! action ( ! amalgamat$ z9c is n well und]/ood2 by "s x is consid]$ t amalgamat+ ! z9c prev5ts local curr5ts by ! amalgam me*anically cov]+ up ! impurities on ! surface ( ! z9c & prev5t+ _! com+ into contact ) ! liquid4 ,by o!rs x is ?\ght t amalgamat+ ! z9c protects x f local action by caus+ a film ( hydrog5 gas to adh]e to x4 ,?is !ory is bas$ on ! fact t :ile no action takes place :5 amalgamat$ z9c is plac$ 9 dilute sulphuric acid at ord9>y atmosph]ic pressure1 ! creation ( a vacuum above ! liquid causes a rapid evolution ( hydrog51 :i*1 h[ev]1 /ops on ! readmission ( ! air4 ,amalgamat+ a z9c causes x to act z a some:at m positive sub/ance ?an be=e1 !re=e ! voltage ( a cell conta9+ amalgamat$ z9c is slightly high] ?an t ( a cell con/ruct$ ) unamalgamat$ z9c4 ,illu/ration3 ,,fig4 #gb4--;,diagram ( a s]ies batt]y connection3 f\r cells are %[n connect$ by ?is me?od4 ,if ! cell voltage be "o & "o-half volts1 ! pressure betwe5 ! 77 & 7-7 t]m9als ( ! batt]y is equal to ! product ( ! voltage ( a s+le cell multipli$ by ! numb] ( cells4 ,= f\r cells x is equal to six volts4 ,! addition ( a v small am\nt ( z9c to m]cury causes ! m]cury to act z if x 7 z9c alone1 aris+ p]haps f ! amalgam hav+ ! effect ( br++ ! z9c to ! surface4 ,batt]y ,connections4--,!re are ?ree me?ods ( connect+ cells to =m a batt]y2 !y may be connect$3 #a4 ,9 s]ies2 #b4 ,9 p>allel2 #c4 ,9 s]ies multiple4 ,a s]ies connection consi/s 9 jo9+ ! positive pole ( "o cell to ! negative pole ( ! o!r1 z %[n 9 fig4 #gb2 ?is adds ! voltage ( ea* cell4 ,?us1 connect+ 9 s]ies f\r cells ( "o & "o-half volts ea* w give a total ( six volts4 ,fig4 #gc illu/rates a p>allel or multiple connection2 ?is is made by connect+ ! positive t]m9al ( "o cell ) ! positive t]m9al ( ano!r cell & ! negative t]m9al ( ! fir/ cell ) ! negative t]m9al ( ! second cell4 ,illu/ration3 ,,fig4 #gc4--;,diagram ( a multiple or p>allel connection4 ,:5 connect$ 9 ?is mann] ! voltage ( ! batt]y is ! same z t ( a s+le cell1 b ! curr5t is equal to ! amp]age ( a s+le cell multipli$ by ! numb] ( cells4 ,?us ) #a-a_/b volt #ae amp]e dry cells1 ! comb9ation or batt]y connect$ z %[n w\ld give #d #ae #fj amp]es at a pressure ( #a-a_/b volts4 ,illu/ration3 ,,fig4 #gd4--;,diagram ( a s]ies multiple connection4 ,two sets ( cells are connect$ 9 s]ies & ! two batt]ies ?us =m$1 connect$ 9 p>allel4 ,! pressure equals ! voltage ( "o cell1 multipli$ by ! numb] ( cells 9 "o batt]y1 & ! amp]age1 t ( "o cell multipli$ by ! numb] ( batt]ies4 ,?is =m ( connection is objectionable unless all ! cells be ( equal /r5g?4 ,if old cells be plac$ on "o side & new cells on ! o!r1 curr5t w fl[ 7z 9 fig4 #ge7 f ! /rong] ?r\gh ! weak] until ! pressure ( all ! cells ?us becomes equal4 ,?is process !re=e wa/es "s ( ! en]gy ( ! /rong cells4 ,a p>allel$ or multiple connection adds ! amp]age ( ea* cell2 t is1 ! amp]age ( ! batt]y w equal ! sum ( ! amp]age ( ea* cell4 ,= in/ance1 f\r cells ( tw5ty-five amp]es ea* w\ld give a total ( "o hundr$ amp]es :5 connect$ 9 p>allel4 ,a s]ies multiple connection1 fig4 #gd1 consi/s ( two s]ies sets ( cells connect$ 9 p>allel4 ,9 s]ies multiple connections ! voltage ( ea* set ( cells or batt]y mu/ be equal1 or ! batt]ies w be weak5$1 h5ce ea* batt]y ( a s]ies multiple connection %\ld conta9 ! same numb] ( cells4 ,! voltage ( a s]ies multiple connection is equal to ! voltage ( "o cell multipli$ by ! numb] ( cells 9 "o batt]y1 & ! amp]age is equal to ! amp]age ( "o cell multipli$ by ! numb] ( batt]ies4 ,illu/ration3 ,,fig4 #ge4--;,diagram to illu/rate incorrect wir+4 ,! curr5t pressure ( ! six cell batt]y be+ great] ?an t ( ! small] unit1 curr5t w fl[ f ! =m] ?r\gh ! latt] until ! pressure ( ! six cells is equal to t ( ! f\r cells4 ,fig4 #ge %[s an incorrect me?od ( wir+ 9 s]ies multiple connection4 ,if ! circuit be op51 ! six cells1 on acc\nt ( hav+ m electromotive =ce ?an ! f\r cells1 w ov]p[] !m & cause a curr5t to fl[ 9 ! direction indicat$ by ! arr[s until ! pressure ( ! six cells has dropp$ to t ( ! f\r4 ,?is w use up ! en]gy ( ! six cells1 b w n weak5 ! f\r cell batt]y4 ,?is action c be correct$ by plac+ a two-way swit* 9 ! circuit at ! junction ( ! two negative t]m9als s t only "o batt]y c be us$ at a "t4 ,,*apt] ,v ,,conductors ,,& ,,insulators ,bodies diff] f ea* o!r 9 a /rik+ mann] 9 ! fre$om ) :i* ! electric curr5t moves ^u !m4 ,if ! electric curr5t be imp>t$ to a c]ta9 portion ( ! surface ( glass or wax1 x w be conf9$ /rictly to t portion ( ! surface :i* orig9ally receives x1 by contact ) ! s\rce ( electricity2 b if x be 9 l mann] imp>t$ to a portion ( ! surface ( a metallic body1 x w in/antane\sly diffuse itself uni=mly ov] ! entire ext5t ( su* metallic surface1 exactly z wat] w\ld spread itself uni=mly ov] a level surface on :i* x is p\r$4#c ,bodies 9 :i* ! electric curr5t moves freely are call$ conductors1 & ^? 9 :i* x does n move freely are call$ insulators4 ,!re is1 h[ev]1 no sub/ance s good a conductor z to be devoid ( resi/ance1 & no sub/ance ( su* high resi/ance z to be a non-conductor4 ,m5tion %\ld be made "h ( ! misuse ( ! ^w non-conductor2 ! s-call$ 8non-conductors0 are prop]ly t]m$ insulators4 ,! bodies nam$ 9 ! foll[+ s]ies possess conduct+ p[] 9 diff]5t degrees 9 ! ord] 9 :i* !y /&1 ! mo/ effici5t conductor be+ fir/1 & ! mo/ effici5t insulator be+ la/ 9 ! li/4 ,,table ,,( ,,conductors ,,& ,,insulators ,silv] ,copp] ,alum9um ,z9c ,brass 7accord+ to composition7 ,plat9um ,iron ,good conductors#d ,nickel 7metals & alloys7 ,t9 ,lead ,g]man silv] 7copp] #b p>ts1 z9c #a1 nickel #a7 ,plat9oid 7,g]man silv] #di p>ts1 tung/5 #a "p7 ,antimony ,m]cury ,bismu?4 ,*>coal & coke ,c>bon ,plumbago ,acid solutions ,fair conductors ,sea wat] ,sal9e solutions ,metallic ores ,liv+ vegetable sub/ances ,moi/ e>?4 ,wat] ,! body ,flame ,l95 ,cotton ,p>tial conductors ,mahogany ,p9e ,dry woods ,rosewood ,lignum ,vit ,teak ,m>ble4 ,slate ,oils ,porcela9 ,dry lea!r ,dry pap] ,wool ,silk ,seal+ wax ,sulphur ,insulators1 or ,res9 s-call$ ,gutta-p]*a non-conductors4 ,%ellac ,ebonite ,mica ,jet ,amb] ,p>aff9 wax ,glass 7v>ies ) quality7 ,dry air4 ,illu/ration3 ,,figs4 #gf to #gh4--,v>i\s cov]$ wires4 fig4 #gf1 s+le2 fig4 #gg1 duplex2 fig4 #gh1 automobile high t5sion cable4 ,! e>? is a good conductor2 mu* difficulty is frequ5tly exp]i5c$ by ! wires mak+ contact ) "s sub/ance t w conduct ! electricity to ! e>?4 ,?is is call$ 8gr\nd+40 ,illu/ration3 ,,figs4 #gi to #ha4--,/&>d porcela9 insulators4 ,fig4 #gi1 tube type2 figs4 #hj & #ha1 groov$ insulators4 ,mode ( ,transmission4--,! exact nature ( electricity is n kn[n1 yet ! laws gov]n+ its action1 "u v>i\s conditions are well und]/ood1 j z ! laws ( gravitation are kn[n1 al?\gh ! con/itution ( gravity _c be def9$4 ,electricity1 ?\gh n a sub/ance1 c be associat$ ) matt]1 & its transmission requires en]gy4 ,:ile x is nei!r a gas nor a liquid1 its behavior sometimes is simil> to t ( a fluid s t x is said to 8fl[0 ?r\gh a conductor4 ,?is expression ( fl[+ does n really mean t !re is an actual movem5t 9 ! wire1 simil> to ! fl[ ( wat] 9 a pipe1 b is a conv5i5t expression = ! ph5om5a involv$4 ,effect ( ,heat4--,! conduct+ p[] ( bodies is affect$ 9 diff]5t ways by _! temp]ature4 ,9 ! metals x is dim9i%$ by elevation ( temp]ature2 b 9 all o!r bodies1 & especially 9 liquids1 x is augm5t$4 ,"s sub/ances :i* are insulators 9 ! solid /ate1 become conductors :5 fus$4 ,sir ,h4 ,davy f\nd t glass rais$ to a r$ heat became a conductor2 & t seal+ wax1 pit*1 amb]1 %ellac1 sulphur1 & wax1 became conductors :5 liquefi$ by heat4 ,heat+ ,effect ( ! ,curr5t4--,if a curr5t ( electricity pass ov] a conductor1 no *ange 9 ! heat condition ( ! conductor w be obs]v$ z long z its transv]se section is s consid]able z to leave suffici5t space = ! free passage ( ! curr5t4 ,b1 if ?is ?ickness be dim9i%$1 or ! quantity ( electricity pass+ ov] x be augm5t$1 or1 9 g5]al1 if ! ratio ( ! electricity to ! magnitude ( ! space af=d$ to x be increas$1 ! conductor w be f\nd to und]go an elevation ( temp]ature1 :i* w be great]1 ! great] ! quantity ( ! electricity & ! less ! space suppli$ = its passage4 ,illu/ration3 ,,fig4 #hb4--,/&>d two wire porcela9 cleat4 ,^! heat effects are manife/$ 9 diff]5t degrees 9 diff]5t metals1 accord+ to _! v>y+ conduct+ p[]s4 ,! poore/ conductors1 su* z plat9um & iron1 suff] mu* great] *anges ( temp]ature by ! same *>ge ?an ! be/ conductors1 su* z gold & copp]4 ,! *>ge ( electricity1 :i* only elevates ! temp]ature ( "o conductor a small am\nt1 w sometimes r5d] ano!r inc&esc5t1 & w vaporize a ?ird4 ,insulators4--,! t]m insulator is us$ 9 two ways3 #a1 z 9 insulat+ sub/ance or m$ium1 & #b1 z a specially =m$ piece ( "s insulat+ mat]ial1 su* z glass1 porcela91 etc4 ,no sub/ance has ! p[] ( absolutely prev5t+ ! passage ( electric curr5ts betwe5 conductors b _m h suffici5t insulat+ p[] = practical purposes4 ,! prop]ties to be desir$ 9 a good insulat+ mat]ial are3 #a4 ,p]man5ce2 #b4 ,high p[] ( resi/+ breakd[n2 #c4 ,me*anical /r5g?2 #d4 ,fairly high dielectric or insulation resi/ance2 #e4 ,special qualities = ! use to :i* ! mat]ial is to be put4 ,p]man5ce is ! mo/ important quality1 & is ! "o lea/ easily atta9$4 ,! p[] ( resi/+ breakd[n is a complex quality1 = x is n solely dep5d5t on m]e punctur+ pressure1 b also on me*anical goodness1 & to a c]ta9 ext5t on ! insulation resi/ance4 ,x _c be easily det]m9$ by a simple laboratory te/1 b mu/ be f\nd by exp]i5ce ( actual s]vice conditions4 ,impregnat+ ,comp\nds4--,^! are us$ = ! treatm5t ( fibr\s mat]ials4 ,!y increase ! insulat+ prop]ties ( ! fibr\s mat]ials1 r5d] !m moi/ure pro( & able to )/& ! effect ( heat ) less rapid det]ioration4 ,:5 wires or cables are to be us$ "u wat]1 !y mu/ be made imp]vi\s1 & great c>e mu/ be tak5 to prev5t ! wat] p5etrat+ & ?us injur+ ! insulation4 ,wat] z a ,conductor4--,wat]1 :e!r 9 ! liquid or vapor\s =m1 is a conductor1 ?\gh ( an ord] greatly inf]ior to ! metals4 ,?is fact is ( great importance 9 electrical ph5om5a4 ,! atmosph]e conta9s1 susp5d$ 9 x1 always m or less aque\s vapor1 ! pres5ce ( :i* impairs its insulat+ prop]ty4 ,! be/ insulators become less effici5t if _! surface be moi/1 ! electricity pass+ by ! conduct+ p[] ( ! moi/ure4 ,?is circum/ance also %[s :y x is necess>y to dry previ\sly ! bodies on :i* x is desir$ to develop electricity by friction4 ,,*apt] ,,vi ,,resi/ance ,,& ,,conductivity ,resi/ance is t prop]ty ( a sub/ance t opposes ! fl[ ( an electric curr5t ?r\gh x4 ,! practical electrician has to measure electrical resi/ance1 electromotive =ces1 & ! capacities ( cond5s]s4 ,ea* ( ^! sev]al quantities is measur$ by comp>ison ) asc]ta9$ /&>ds1 ! p>ticul> me?ods ( comp>ison v>y+1 h[ev]1 to meet ! circum/ances ( ! case4 ,ohm's law /ates t ! /r5g? ( a curr5t due to an electromotive =ce falls (f 9 proportion z ! resi/ance 9 ! circuit increases4 ,x is !re=e possible to comp>e two resi/ances ) "o ano!r by f9d+ out 9 :at proportion ea* w cause ! curr5t ( a con/ant batt]y to fall (f4#e ,silv] is tak5 z ! /&>d1 ) ! p]c5tage ( #ajj1 & ! conductivity ( all o!r metals is express$ 9 hundr$?s ( ! conductivity ( silv]4 ,conductivity ( ,metals & ,liquids4--,! metals 9 g5]al1 conduct well1 h5ce _! resi/ance is small1 b metal wires mu/ n be too ?9 or too long1 or !y w resi/ too mu*1 & p]mit only a feeble curr5t to pass ?r\gh !m4 ,! liquids 9 ! batt]y d n conduct ne>ly s well z ! metals1 & diff]5t liquids h diff]5t resi/ances4 ,pure wat] w h>dly conduct at all1 unless ! voltage be v high4 ,salt & saltpetre dissolv$ 9 wat] are good conductors1 & s are dilute acids1 ?\gh /rong sulphuric acid is a bad conductor4 ,gases are bad conductors4 ,effect ( ,heat4--,ano!r v important fact conc]n+ ! resi/ance ( conductors is t ! resi/ance 9 g5]al increases ) ! temp]ature4 ,:ile ?is fact is true reg>d+ metals1 x does n apply to non-metals4 ,! resi/ance ( diff]5t metals does n increase 9 ! same proportion4 ,iron at #ajj degrees ,c1 has lo/ #ci p] c5t4 ( ! conduct+ p[] x possess$ at z]o1 :ile silv] loses b #bc p] c5t4 ,laws ( ,electrical ,resi/ance4--,resi/ances 9 a circuit may be ( two k9ds3 #a4 ,resi/ance ( ! conductors2 #b4 ,resi/ance due to imp]fect contact4 ,! latt] k9d ( resi/ance is affect$ by pressure1 = :5 ! surfaces ( two conductors are br\ght into m intimate contact ! curr5t passes m freely f "o conductor to ! o!r4 ,! foll[+ are ! laws ( ! resi/ance ( conductors3 #a4 ,! resi/ance ( a conduct+ wire is proportional to its l5g?4 ,if ! resi/ance ( a mile ( telegraph wire be #ac ohms1 t ( fifty miles w be #ej #ac #fej ohms4 #b4 ,! resi/ance ( a conduct+ wire is inv]sely proportional to ! area ( its cross section1 & !re=e 9 ! usual r\nd wires is inv]sely proportional to ! squ>e ( its diamet]4 ,ord9>y telegraph wire is ab\t #a_/f? ( an in* ?ick2 a wire twice z ?ick w\ld conduct f\r times z well1 hav+ f\r times ! area ( cross section2 h5ce an equal l5g? ( x w\ld h only #a_/d? ! resi/ance4 #c4 ,! resi/ance ( a conduct+ wire ( giv5 l5g? & ?ickness dep5ds ^u ! mat]ial ( :i* x is made--t is1 ^u ! specific resi/ance ( ! mat]ial4 ,conductivity4--,?is is ! inv]se ( resi/ance4 ,! t]m expresses ! capability ( a sub/ance to conduct ! electric curr5t4 ,if ! symbol ,y repres5t ! conductivity ( a sub/ance1 & ,i ! curr5t !n3 ,i_/,y its resi/ance2 & if ,r repres5t ! resi/ance ( a sub/ance1 !n ,i_/,r its conductivity4 ,good conductors ( heat are also good conductors ( electricity4 ,specific ,conductivity4--,! figure :i* indicates ! relation betwe5 "o sub/ance & ano!r z to _! capacity to conduct electricity is call$ specific or relative conductivity4 ,tak+ ! specific conductivity ( silv] z #ajj1 t ( pure copp] is #if4 ,! specific resi/ance ( a sub/ance is ! rev]se ( its relative conductivity4 ,! specific resi/ance ( a metal is g5]ally express$ 9 million?s ( an ohm z ! resi/ance ( a c5timet] cube ( t metal betwe5 opposite sides4 ,! foll[+ table gives ! data = a few metals3 ,specific ,resi/ance ,specific ,sub/ance4 9 ,microhms4 ,conductivity4 ,silv] #a4fji #ajj4 ,copp] #a4fdb #if4 ,gold #b4aed #gd4 ,iron 7s(t7 #i4hbg #af4 ,lead #ai4hdg #h4 ,g]man ,silv] #ba4dgj #g4e ,m]cury 7liquid7 #if4adf #a4f ,! specific resi/ance ( copp] is !re=e3 #a4fdb _/ #a1jjj1jjj ohms1 or #a4fdb microhms4#f ,divid$ ,circuits4--,if a circuit be divid$1 z 9 fig4 #hc1 into two bran*es at ,a1 unit+ aga9 at ,b1 ! curr5t w also be divid$1 "p fl[+ ?r\gh "o bran* & "p ?r\gh ! o!r4 ,! relative /r5g? ( curr5t 9 ! two bran*es w be proportional to _! conductivities4 ,?is law w hold good = any numb] ( bran* resi/ances connect$ betwe5 ,a & ,b4 ,conductivity is1 z %[n be=e1 ! reciprocal ( resi/ance4 ,,example--,if1 9 fig #hc1 ! resi/ance ( ,r #aj ohms1 & ,r #bj ohms1 ! curr5t ?r\gh ,r w be to ! curr5t ?r\gh ,r z #a_/aj to #a_/bj2 or1 z #b3a1 or1 9 o!r words1 #b_/c ( ! total curr5t w pass ?r\gh ,r & #a_/c ?r\gh ,r4 ,! jo9t resi/ance ( ! two bran*es betwe5 ,a & ,b w be less ?an ! resi/ance ( ei!r bran* s+ly1 because ! curr5t has increas$ facilities = travel4 ,9 fact1 ! jo9t conductivity w be ! sum ( ! two sep>ate conductivities4 ,tak+ aga9 ! resi/ance ( ,r #aj ohms & ,r #bj ohms1 ! jo9t conductivity is #a_/aj #a_/bj #c_/bj & ! jo9t resi/ance is equal to ! reciprocal#g ( #c_/bj or #f-b_/c ,illu/ration3 ,,fig4 #hc4--;,divid$ circuit ) two conductors 9 p>allel4 ,9 mo/ cases ! resi/ance ( ! diff]5t bran*es w be alike4 ,?is simplifies ! calculations consid]ably4 ,take1 = in/ance1 two bran*es ( #ajj ohms resi/ance ea* & f9d ! jo9t resi/ance4 ,,solution3 #a_/ajj #a_/ajj #b_/ajj2 ! reciprocal is #ajj_/b #ej ohms1 or1 9 o!r words1 ! jo9t resi/ance is "o-half ( ! resi/ance ( a s+le bran*1 & ea* bran*1 ( c\rse1 w c>ry "o-half ( ! total curr5t 9 amp]es4 ,) ?ree bran*es ( equal resi/ance1 ! jo9t resi/ance w be #a_/c2 ) f\r bran*es #a_/d2 ) #ajj bran*es #a_/ajj ( ! resi/ance ( a s+le bran*4 ,illu/ration3 ,,fig4 #hd4--;,hydraulic analogy = divid$ circuits4 ,9 ! sy/em ( pipes %[n1 wat] fl[s f ,a ,b to ,c ,d ?r\gh ! six v]tical pipes #a to #f1 ! greate/ am\nt go+ ?r\gh ! "o :i* (f]s ! lea/ resi/ance4 ,if pipes #a to #f all h ! same dim5sions1 equal quantities ( wat] w fl[ ?r\gh !m4 ,x foll[s t ! resi/ance :i* ! wat] enc\nt]s dim9i%es ) ! increase 9 ! numb] ( pipes betwe5 ,a ,b & ,c ,d4 ,! electrical circuit pres5ts ! same conditions3 ! great] ! numb] ( p>allel connections 7correspond+ to ! pipes #a to #f7 ! less is ! resi/ance enc\nt]$ by ! curr5t4 ,if1 = in/ance1 ! resi/ance ( an inc&esc5t lamp hot be #ahj ohms1 ! jo9t resi/ance ( #ajj su* lamps connect$ 9 multiple is #ahj_/ajj #a4h ohms4 ,if ! electromotive =ce ( ! sy/em is to be1 say #aaj volts1 !n1 accord+ to ,ohm's law1 ! curr5t = #ajj lamps is3 #aaj_/a4h #fa4aa amp]es4 giv+ = ea* lamp a curr5t ( #aaj_/ahj 4#fa amp]e4 ,9 ! case ( two bran*es only1 ! foll[+ rule may be appli$ also3 ,multiply ! two resi/ances & divide ! product by _! sum4 ,writt5 z a =mula3 ,jo9t resi/ance 7,r ,r7_/7,r ,r7 ,aga91 assum+ t ,r #aj ohms & ,r #bj ohms3 ,jo9t resi/ance 7#aj #bj7_/7aj #bj7 #bjj_/cj #f-b_/c ohms4 ,?is rule _c be employ$ = m ?an two bran*es at a "t4 ,,example--,a curr5t ( #db amp]es fl[s ?r\gh ?ree conductors 9 p>allel ( #e1 #aj & #bj ohms resi/ance respectively4 ,f9d ! curr5t 9 ea* conductor4 ,,solution3 ,jo9t ,conductance #a_/e #a_/aj #a_/bj #g_/bj4 ,suppos+ ! curr5t to be divid$ into #g p>ts1 #d ( ^! p>ts w\ld fl[ 9 ! fir/ conductor #b 9 ! second & #a 9 ! ?ird4 ,! :ole curr5t is #db amp]es4 #d_/g ( #db #bd4 #b_/g ( #db #ab4 #a_/g ( #db #f4 ,curr5t 9 fir/ conductor #bd amp]es4 8 8 second 8 #ab 8 ,ans4 8 8 ?ird 8 #f 8 ,,*apt] ,,vii ,,electrical ,,& ,,me*anical ,,en]gy ,! production ( electricity is simply a trans=mation ( en]gy f "o =m into ano!r1 usually me*anical en]gy is *ang$ into electrical en]gy & a dynamo is simply a device = effect+ ! trans=mation4 ,pr(4 ,fess5d5 truly rem>ks !re are two indep5d5t prop]ties ( matt]--gravity & in]tia--& ^! give two ways ( def9+ =ce & en]gy4 ,x %\ld always be rememb]$ t electricity is some?+ real1 al?\gh n easily def9$4 ,& !n1 too1 :ile x is n matt] & n en]gy1 yet "u prop] conditions 7x hav+ ! p[] ( do+ "w7 x is conv5i5t to speak ( its p]=mances z electric en]gy4 ,! foll[+ que/ions & answ]s1 al?\gh few 9 numb]1 may pres5t ! subject ) cle>ness4 ,ques4 ,:at is en]gy8 ,ans4 ,en]gy is ! capacity = do+ "w4 ,/eam "u pressure is an example1 a spr+ b5t ready to be releas$ is ano!r =m1 aga91 wat] /or$ 9 an elevat$ tank has capacity = do+ "w4 ,^! examples illu/rate pot5tial en]gy1 z di/+ui%$ f k9etic en]gy4 ,pot5tial en]gy may be def9$ z en]gy due to position1 & k9etic en]gy1 z en]gy due to mom5tum4 ,ques4 ,:at is matt]8 ,ans4 ,matt] is any?+ occupy+ space1 & :i* prev5ts o!r matt] occupy+ ! same space at ! same "t4 ,ques4 ,:at "n is giv5 ! smalle/ quantity ( matt] :i* c exi/8 ,ans4 ,! atom4 ,an atom means t :i* _c be cut1 scrat*$1 or *ang$ 9 =m & t _c be affect$ by heat or cold or any kn[n =ce2 al?\gh inconceivably small1 atoms possess a def9ite size & mass4 ,ques4 ,:at is a molecule8 ,ans4 ,a molecule is compos$ ( two or m atoms4 ,ques4 ,:at is ! behavi\r ( ^! m9ute bodies8 ,ans4 ,!y are p]petually 9 motion1 vibrat+ ) incr$ible velocities4 ,ques4 ,:y at ?is po9t are def9itions ( en]gy & ( matt] mo/ useful8 ,ans4 ,because1 z /at$1 all electric action is an exhibition ( en]gy1 & en]gy mu/ act ?r\gh matt] z its m$ium4 ,ques4 ,:at is ! diff]5ce betwe5 electricity & magnetism8#h ,ans4 ,! ultimate nature ( nei!r is kn[n4 ,!re are1 h[ev]1 "s diff]5ces4 ,to su/a9 a curr5t ( electricity requires en]gy4 ,to su/a9 magnetism requires no en]gy4 ,a curr5t ( electricity is always accompani$ by a magnetic field ( peculi> =m4 ,magnetism alone _c produce electricity4 ,electricity c d "w2 b magnetism _c 9 ! same s5se--& alike ) electricity1 nei!r c x exi/ )\t contact ) matt]4 ,ques4 ,h[ is en]gy transmitt$ f "o "p ( a mat]ial sub/ance to ano!r8 ,ans4 ,gradually & successively4 ,x requires a m$ium & also "t4 ,ques4 ,:at is ! pr9cipal use or function 9 me*anics ( electricity8 ,ans4 ,x is purely t ( transmission4 ,x corresponds to ropes1 %afts & fluids z a m$ium ( convey+ & translat+ p[] or "w4 ,ques4 ,:at is "w8 ,ans4 ,"w is ! ov]com+ ( resi/ance ?r\gh a c]ta9 di/ance4 ,z a quantity ( wat] mov+ f a high] to a l[] level w d "w1 s also w a quantity ( electricity fall+ ?r\gh a diff]5ce ( pot5tial4 ,ques4 ,h[ is "w measur$8 ,ans4 ,9 foot p\nds4 ,ques4 ,:at is a foot p\nd8 ,ans4 ,! am\nt ( "w done 9 rais+ a weight ( "o p\nd "o foot or ! equival5t1 ov]com+ a pressure ( "o p\nd ?r\gh a di/ance ( "o foot4 ,ques4 ,:at is ! electrical unit ( "w8 ,ans4 ,! volt-c\lomb4 ,a volt-c\lomb ( "w is p]=m$ :5 "o amp]e ( curr5t fl[s = "o second 9 a circuit ^: resi/ance is "o ohm1 :5 ! pressure is "o volt4 ,! ,amp]e-,h\r4--,a gallon ( wat] may be drawn f a hydrant 9 a m9ute1 or 9 an h\r2 x is /ill "o gallon4 ,s 9 electricity1 a giv5 am\nt ( ! curr5t1 say "o c\lomb1 may be obta9$ 9 a second or 9 an h\r4 ,! amp]e is ! unit rate ( fl[4 ,:at is call$ ! electric curr5t is simply ! relation ( any quantity ( electricity pass$ to ! "t x is pass+2 t is quantity 9 c\lombs curr5t 9 amp]es "t 9 seconds1 or simply c\lomb amp]e second4 ,aga93 #aj c\lombs #b amp]es #e seconds #aj amp]es #a second #a amp]e #aj seconds1 etc4 ,"o amp]e-h\r is simply ano!r way ( say+ #c1fjj c\lombs4 ,( c\rse #c1fjj c\lombs ( electricity may be obta9$ 9 any desir$ "t4 ,x all dep5ds on ! rate ( fl[ or ! curr5t /r5g? 9 amp]es4 ,= in/ance1 #b amp]es 9 #a_/b h\r1 or #d amp]es 9 #a_/d h\r w also give "o amp]e-h\r ( #c1fjj c\lombs4 ,x is well to keep ! di/9ction betwe5 c\lombs & amp]es 9 m9d1 z ev5 9 text books v lately publi%$ ^! units are conf\nd$4 ,to illu/rate fur!r ! diff]5ce betwe5 c\lombs & amp]es1 ! foll[+ example is giv54 ,x is sometimes e/imat$ t ! quantity ( electricity 9 a fla% ( lightn+ is #a_/aj c\lomb1 & ! duration ( ! dis*>ge #a_/bjjjj "p ( a second4 ,:at is ! curr5t 9 amp]es8 ,n[ s9ce c\lombs amp]es seconds 7#a7 solv+ 7#a7 = ! curr5t1 amp]es c\lombs_/seconds 7#b7 sub/itut+ ! giv5 values 9 7#b71 amp]es 7#a_/aj7 _/ 7#a_/bjjjj7 #bjjj ,p[]4--,! t]m p[] means ! rate at :i* "w is done2 x is usually express$ z ! numb] ( foot p\nds done 9 "o m9ute1 t is p[] 7foot p\nds7 _/ m9utes ,p[] ex]t$ = a c]ta9 "t produces "w4 ,ques4 ,:at is ! me*anical unit ( p[]8 ,ans4 ,! horse p[]4 ,ques4 ,:at is "o horse p[]8 ,ans4 #cc1jjj foot p\nds p] m9ute4 ,! unit is due to ,james ,watt z be+ ! p[] ( a /rong ,london draught horse to d "w dur+ a %ort int]val & us$ by him to measure ! p[] ( 8 /eam eng9es4 ,"o horse p[] #cc1jjj ft4 lbs4 p] m9ute #eej ft4 lbs4 p] sec4 #a1ihj1jjj ft4 lbs4 p] h\r4 ,ques4 ,:at is "o horse p[] h\r8 ,ans4 ,"w done at ! rate ( "o horse p[] = "o h\r4 ,ques4 ,:at is ! electrical unit ( p[]8 ,ans4 ,! watt4 ,ques4 ,:at is a watt8 ,ans4 ,x is ! p[] due to a curr5t ( "o amp]e fl[+ at a pressure ( "o volt4 ,"o watt "o amp]e "o volt4 ,x is equal to "o j\le p] second4 ,ques4 ,:at is a kil[att8 ,ans4 #a1jjj watts4 ,! ,watt-,h\r4--,! elem5ts :i* may be measur$ are1 h[ev]1 n only ! volume ( curr5t1 ! unit ( :i* is ! amp]e1 & "t1 ! unit ( :i* is ! h\r1 b also ! pressure1 ! unit ( :i* is ! volt4 ,x is evid5t t a p]fect sy/em ( electrical measurem5t %\ld take acc\nt ( ! total am\nt ( en]gy consum$1 & %\ld dep5d n only ^u ! volume ( curr5t1 b also ^u ! pressure at :i* ! curr5t is appli$4 ,! basis ( su* a sy/em if provid$ 9 a unit :i* is ! product ( ! two units ( curr5t & pressure1 & :i* is t]m$ a volt-amp]e or watt4 ,! watt-h\r repres5ts ! am\nt ( "w done by an electric curr5t ( "o amp]e /r5g? fl[+ = "o h\r "u a pressure ( "o volt4 ,,example--,an inc&esc5t lamp tak+ "o-half an amp]e ( curr5t on a circuit hav+ a pressure ( #ajj volts1 or a lamp tak+ "o amp]e on a circuit hav+ a pressure ( #ej volts1 w\ld ea* be consum+ #ej watts ( en]gy1 & ?is multipli$ by ! numb] ( h\rs w\ld give ! total numb] ( watt-h\rs = any def9ite "t4 ,! watt1 !n1 is an accurate & complete unit ( measurem5t & is g5]ally applicable to all =ms ( electrical consumption4 ,illu/ration3 ,,fig4 #he4--,tyndall's exp]im5t illu/rat+ ! production ( heat by friction4 ,a brass tube ab\t #g in*es 9 l5g? & #c_/d ( an in* 9 diamet]1 is fix$ on a small :eel4 ,by means ( a cord pass+ r\nd a mu* l>g] :eel1 ?is tube c be rotat$ ) any desir$ velocity4 ,! tube is ?ree p>ts full ( wat]1 & is clos$ by a cork4 ,9 mak+ ! exp]im5t1 ! tube is press$ betwe5 a wood5 clamp1 :ile ! :eel is rotat$ ) "s rapidity4 ,! wat] rapidly becomes heat$ by ! friction1 & its temp]ature soon exce$s ! boil+ po9t4 ,! pressure caus$ by ! =mation ( /eam =ces out ! cork & projects x to a height ( sev]al y>ds4 ,a watt ( electrical en]gy corresponds to #a_/gdf ( a horse p[] ( me*anical en]gy2 h5ce1 if a lamp or motor require en]gy equival5t to #a_/gdf ( a horse p[] = "o h\r1 x might be said to take "o watt-h\r4 ,me*anical ,equival5t ( ,heat4--,! em95t ,engli% physici/1 ,james ,prescott ,j\le1 work$ = m ?an =ty ye>s 9 e/abli%+ ! relation betwe5 heat & me*anical "w2 he /at$ ! doctr9e ( ! cons]vation ( en]gy & discov]$ ! law1 kn[n z ,j\le's law1 = det]m9+ ! relation betwe5 ! heat1 curr5t pressure1 & "t 9 an electric circuit4 ,ques4 ,:at is heat8 ,ans4 ,a =m ( en]gy4 ,heat is produc$ 9 ! agitation ( ! molecules ( matt]--! en]gy exp5d$ 9 agitat+ ^! molecules is trans=m$ into heat4 ,illu/ration3 ,,fig4 #hf4--;,j\les' exp]im5t on ! me*anical equival5t ( heat1 9 :i* he caus$ paddle-:eels to rotate 9 a vessel ( wat] by means ( fall+ weights ,w4 ,! am\nt ( "w done by gravity ^u ! weights 9 caus+ !m to desc5d ?r\gh any di/ance d 0 equal to _! weight ,w times ! di/ance4 ,if ! weights desc5d$ sl[ly & uni=mly1 ?is "w 0 all exp5d$ 9 ov]com+ ! resi/ance ( ! wat] to ! motion ( ! paddle-:eels ?r\gh x2 t is1 x 0 wa/$ 9 eddy curr5ts 9 ! wat]4 ,j\le measur$ ! rise 9 ! temp]ature ( ! wat] & f\nd t ! mean ( 8 ?ree be/ trials gave #dbg gram met]s z ! am\nt ( "w requir$ to develop en\gh heat to raise a gram ( wat] "o degree4 ,he !n repeat$ ! exp]im5t1 sub/itut+ m]cury = wat]1 & obta9$ #dbe gram met]s z ! "w necess>y to produce a calorie ( heat4 ,! diff]5ce betwe5 ^! numb]s is less ?an 0 to h be5 expect$ f ! unavoidable errors 9 ! obs]vations4 ,he !n devis$ an arrangem5t 9 :i* ! heat 0 develop$ by ! friction ( iron on iron1 & aga9 obta9$ #dbe4 ,?is corresponds to #ggb foot p\nds1 b lat] exp]im5ts %[ t ! correct value is #ggh foot p\nds4 ,ques4 ,h[ is heat measur$8 ,ans4 ,9 ,briti% !rmal units 7,b4t4u474 ,ques4 ,:at is ! ,briti% !rmal unit8 ,ans4 ,! quantity ( heat requir$ to raise ! temp]ature ( #a lb4 ( pure wat] #a ,fahr41 at or ne> #ci4a ,f41 ! temp]ature ( maximum d5sity4 ,ques4 ,:at is ! me*anical equival5t ( heat8 ,ans4 ,! numb] ( foot p\nds ( me*anical en]gy equival5t to "o ,briti% !rmal unit4 ,j\le's exp]im5ts #ahdc-ej gave ! figure #ggb ft4 lbs4 :i* is kn[n z ,j\le's equival5t4 ,lat] exp]im5ts gave high] figures1 & ! pres5t accept$ value is #ggh ft4 lbs41 t is3 #a ,b4t4u4 #ggh ft4 lbs4 ,electrical ,horse ,p[]4--,x is desirable to e/abli% ! relation betwe5 watts & foot p\nds 9 ord] to det]m9e ! capacity ( an electric g5]ator or motor 9 t]ms ( horse p[]4 ,"o watt is equival5t to "o j\le p] second or #fj j\les p] m9ute4 ,"o j\le 9 turn1 is equival5t to 4#gcgd ft4 lbs41 h5ce #fj j\les equal3 #fj 4#gcgd #dd4bdd ft4 lbs4 ,s9ce "o horse p[] #ccjjj ft4 lbs4 p] m9ute1 ! electrical equival5t ( "o horse p[] is #ccjjj #dd4bdd #gdf watts4 or1 #gdf _/ #ajjj 4#gdf kil[atts 7,k4,w47 ,aga91 "o kil[att or #ajjj watts is equival5t to #ajjj #gdf #a4cd horse p[]4 ,! ,f>ad4--,! measure con/ruct$ to hold a gallon ( wat] may be call$ ! gallon measure4 ,! capacity ( a cond5s] :i* w\ld conta9 a *>ge ( "o c\lomb "u "o volt pressure is ! f>ad4 ,x may seem /range t !re is a unit ( quantity & ano!r ( capacity to hold t quantity1 :5 9 ! case ( wat] ! t]m 8gallon0 may suffice = ! measure & ! liquid x c hold4 ,electricity 9 ?is respect1 h[ev]1 corresponds to a compressible fluid or a gas4 ,a gallon measure may hold a gallon ( gas or t52 x dep5ds entirely ^u ! pressure4 ,s a cond5s] ( a c]ta9 size may hold any numb] ( c\lombs1 accord+ to ! electrical pressure4 ,! f>ad be+ inconv5i5tly l>ge = practical use1 "o-million? ( a f>ad1 call$ a micr(>ad1 is g5]ally adopt$4 ,,*apt] ,,viii ,,effects ,,( ,,! ,,curr5t ,! t]m 8electric curr5t10 9 ! pres5t /ate ( our k1 %\ld be reg>d$ z d5ot+ ! exi/5ce ( a /ate ( ?+s 9 :i* c]ta9 def9ite exp]im5tal effects are produc$1 = "s ( :i* !re c]ta9ly is no analogy exhibit$ 9 ord9>y hydraulic curr5ts4 ,! foll[+ are ! mo/ important ( ^! effects3 #a4 ,!rmal effect2 #b4 ,magnetic effect2 #c4 ,*emical effect4 ,x is r to ^! effects ?an to any imag9>y curr5t fl[ 9 ! conductor t ! m9d ( ! read] %\ld be direct$4 ,) ?is prelim9>y caution1 :i* %\ld nev] be lo/ sight (1 ! use ( famili> words & expressions connect$ ) ! fl[ ( wat] 9 pipes is ju/ifi$ 9 ord] to avoid r\ndab\t & cumbr\s phrases :i*1 ?\gh p]haps m ne>ly 9 accord ) pres5t k ( ! facts1 w\ld n t5d to cle>ness or concis5ess4 ,! ?ree mo/ important effects ( ! curr5t j m5tion$1 may be pres5t$ 9 m detail z foll[s3 #a4 ,! ,!rmal effect3-- ,! conductor along :i* ! curr5t fl[s becomes heat$4 ,! rise ( temp]ature may be small or great accord+ to circum/ances1 b "s heat is always produc$4 #b4 ,! ,magnetic effect2 ,! space bo? outside & inside ! sub/ance ( ! conductor1 b m especially ! =m]1 becomes a 8magnetic field0 9 :i* delicately pivot$ or susp5d$ magnetic ne$les w take up def9ite positions & magnetic mat]ials w become magnetiz$4 ,illu/ration3 ,,fig4 #hg4--,l5z's app>atus = measur+ ! heat giv5 (f by an electric curr5t4 ,x consi/$ ( a wide m\!d /opp]$ bottle fix$ upside d[n1 ) its /opp]1 b 9 a wood5 box2 ! /opp] 0 p]=at$ s z to give passage to two ?ick plat9um wires1 connect$ at "o end ) b9d+ screws1 s1 :ile _! free ends 7 provid$ ) plat9um cones by :i* ! wires "u inve/igation c\ld be readily affix$2 ! vessel conta9$ alcohol1 ! temp]ature ( :i* 0 indicat$ by a !rmomet] fitt$ 9 a cork ins]t$ 9 a hole made 9 ! bottom ( ! vessel4 ,! curr5t is pass$ ?r\gh ! plat9um wires1 & its /r5g? measur$ by means ( a galvanomet] int]pos$ 9 ! circuit4 ,by obs]v+ ! increase ( temp]ature 9 ! !rmomet] 9 a giv5 "t & kn[+ ! weight ( ! alcohol1 ! mass ( ! wire1 ! specific heat1 & ! calorimetric values ( ! vessel1 & ( ! !rmomet]1 comp>$ ) alcohol1 ! heat+ effect :i* is produc$ by ! curr5t 9 a giv5 "t c be calculat$4 #c4 ,! ,*emical effect2-- ,if ! conductor be a liquid :i* is a *emical comp\nd ( a c]ta9 class call$ electrolytes1 ! liquid w be decompos$ at ! places :]e ! curr5t ent]s & leaves x4 ,!rmal ,effect4--,if a quantity ( electricity 7 set fl[+ 9 a clos$ circuit & ! latt] (f]$ no resi/ance1 x w\ld fl[ =ev]1 j z a wagon set roll+ along a circul> railway w\ld nev] /op if !re 7 no friction4 ,illu/ration3 ,,fig4 #hh4--,! ,seebeck effect3 ,if 9 a complete metallic circuit hav+ junctions ( dissimil> metals1 ! junctions are at diff]5t temp]atures1 !n g5]ally a /eady curr5t w fl[ 9 ! circuit z long z ! diff]5ces ( ! temp]atures ( ! junction is ma9ta9$4 ,to demon/rate ?is1 a piece ( copp] ,k b5t 9 ! %ape se5 9 ! figure1 0 plac$ on a block ( bismu? ,a ,b1 c>ry+ a pivot$ magnetic ne$le ,n ,s2 z soon z ! equality ( temp]atures 0 alt]$ by ei!r heat+ or cool+ "o ( ! junctions ( ! two metals1 ! ne$le indicat$ a curr5t :i* cont9u$ to fl[ z long z ! diff]5ce ( temp]ature 0 ma9ta9$ at ! junctions4 ,! movem5t ( ! ne$le indicat$ ! direction 9 :i* ! curr5t fl[$4 ,if1 = in/ance1 ! nor? junction ,b 7 heat$1 ! ,n pole mov$ ea/w>ds1 %[+ t at ! heat$ junction ! curr5t fl[s f ! bismu? to ! copp]1 at ! cold junction f ! copp] to ! bismu?4 ,:5 matt] 9 motion is /opp$ by friction1 ! en]gy ( its motion is conv]t$ into heat by ! friction ?us caus+ ! matt] to come to re/4 ,simil>ly1 :5 electricity 9 motion1 t is1 an electric curr5t is /opp$ by resi/ance1 ! en]gy ( its fl[ is trans=m$ into heat by ! resi/ance ( ! circuit4 ,if ! t]m9als ( a batt]y be jo9$ by a %ort ?ick wire ( l[ resi/ance1 mo/ ( ! heat w be develop$ 9 ! batt]y1 :]eas1 if a ?9 wire ( high resi/ance be us$ x w become hot1 :ile ! batt]y itself w rema9 comp>atively cool4 ,to inve/igate ! developm5t ( heat by a curr5t1 ,j\le & ,l5z us$ in/rum5ts on ! pr9ciple ( fig4 #hg1 9 :i* a ?9 wire jo9$ to two /\t conductors is enclos$ )9 a glass vessel conta9+ alcohol1 into :i* is plac$ a !rmomet]4 ,! resi/ance ( ! wire be+ kn[n1 its relation to ! o!r resi/ances c be calculat$4 ,j\le f\nd t ! numb] ( heat units develop$ 9 a conductor is proportional to3 #a4 ,! resi/ance2 #b4 ,! squ>e ( ! curr5t /r5g?2 #c4 ,! "t t ! curr5t la/s4 ,j\les' law may be /at$ z foll[s3 ,! heat g5]at$ 9 a conductor by an electric curr5t is proportional to ! resi/ance ( ! conductor1 ! "t dur+ :i* ! curr5t fl[s1 & ! squ>e ( ! /r5g? ( ! curr5t4 ,! quantity ( heat 9 calories may be calculat$ by use ( ! equation1 calories p] second volts amp]es 4#bd4 7#a7 ,! total numb] ( calories ,h develop$ 9 t seconds w be giv5 by ,h ,p4,d4 ,c t 4#bd4 7#b7 ,,example--,if a curr5t ( #aj amp]es fl[s 9 a wire ^: t]m9als are at a pot5tial diff]5ce ( #ab volts1 h[ mu* heat w be develop$ 9 #e m9utes8 ,sub/itut+ 9 equation 7#b73 #aj #ab 7#fj #e7 4#bd #hfdj calories4 ,s9ce by ,ohm's ,law pot5tial diff]5ce ,i ,r sub/itut+ ,,ir = ,p4,d4 9 7#b7 ,h ,i#b ,r t 4#bd ,use ( ,heat f ,electric ,curr5t4--,9 ! transmission ( electricity f place to place1 x is v desirable t none ( ! en]gy be exp5d$ 9 heat+ ! conductor4 ,h5ce copp] wires ( ! prop] size mu/ be us$4 ,9 wir+ a build+ = electric lights1 ! insurance rules require t ! wires be ( a c]ta9 size & t !y be put up 9 a c]ta9 mann]4 ,o!rwise !y w n insure a build+ aga9/ fire4 ,x is (t5 desirable1 h[ev]1 to use ! electric curr5t = ! purpose ( produc+ heat4 ,! c>bons ( ! arc & inc&esc5t lamps are int5sely heat$ t !y may produce light4 ,coils ( ,g]man silv] wire or o!r high resi/ance wire are heat$ by ! passage ( a curr5t ?r\gh !m4 ,9 ?is mann] ! electric /ove is made4 ,sold]+ copp]s1 smoo?+ irons1 & bak+ ov5s are heat$ 9 a simil> mann]4 ,magnetic ,effect4--,an electric curr5t fl[+ 9 a wire causes x to be surr\nd$ by a magnetic field1 :i* consi/s ( l9es ( =ce encircl+ ! wire4 ,! field is /ronge/ ne> ! wire & dim9i%es gradually 9 /r5g? at increas+ di/ances !refrom4 ,! pres5ce ( ?is magnetic field is %[n by v>i\s exp]im5ts & ! subject is fully expla9$ 9 *apt] ,,ix on magnetism4 ,*emical ,effect4--,pats van ,tro/wyk 7#aghi7 po9t$ out t an electric dis*>ge 0 capable ( decompos+ wat]2 to %[ ?is he us$ gold wires1 :i* he all[$ to dip 9 wat]1 connect+ "o ( !m ) ! inn]1 & ano!r ) ! out] coat+ ( a ,leyd5 j>1 & pass+ ! dis*>ge ?r\gh ! wat]4 ,! gas bubbles collect$ prov$ to consi/ ( oxyg5 & hydrog5 gas4 ,ni*olson & ,c>lisle 7#ahjj7 dipp$ a copp] wire :i* 0 connect$ ) "o ( ! poles ( a voltaic pile into a drop ( wat]1 :i* happ5$ to be on ! plate connect$ ) ! o!r pole2 gas bubbles appe>$1 & ! drop ( wat] became small] & small]4 ,?is exp]im5t 0 repeat$ 9 a some:at diff]5t mann]1 ! brass wires f a pile be+ br\ght "u a tube fill$ ) wat] & clos$ at ! top4 ,gas bubbles 7 produc$ by ! wire 9 connection ) ! negative pole ( ! pile1 & ! wat] 0 obs]v$ to dim9i% gradually4 ,at ! positive wire1 on ! contr>y1 no gas came (f1 b ! metal lo/ its metallic lu/re1 became d>k1 & f9ally crumbl$ away4 ,! gas :i* _h collect$ 9 ! tube prov$ to be hydrog52 :ile on exam9+ ! black mass x 0 f\nd t ! con/itu5ts ( brass1 viz41 copp] & z9c1 _h become oxidiz$4 ,illu/ration3 ,,fig4 #hi4--;,an electrolytic cell4 ,! p>ts are3 ,a1 cell2 ,b1 electrolyte2 ,c1 positive electrode or ca?ode2 ,d1 negative electrode or ca?ode4#i ,electrolysis4--,electric analysis or m briefly electrolysis 0 ! t]m appli$ by ,f>aday to ! process ( decompos+ a liquid by ! passage ( a curr5t ( electricity ?r\gh x4 ,! vessel conta9+ ! liquid is kn[n z an electrolytic cell4 ,9 fig4 #hi1 ,a is ! cell1 :i* may be ( glass or ( any o!r suitable mat]ial1 & ,b is ! liquid :i* is to be electrolyz$4 ,curr5t ent]s by ! positive electrode ,c1 also kn[n z ! anode1 trav]ses ! liquid1 & leaves by ! negative electrode1 or ca?ode1 ,d4 ,illu/ration3 ,,fig4 #ij4--,mod]n app>atus = decompos+ wat] by electrolysis4 ,plat9um electrodes ,p & ,p are plac$ at ! bottom ( two upright tubes ,o & ,h1 & are connect$ to ! t]m9als ,t & ,t by plat9um wires1 :i* are fus$ ?r\gh ! glass ( ! tubes4 ,^! tubes h glass /op cocks ,s & ,s at _! upp] ends1 & at _! l[] ends are connect$ by a %ort glass tube1 f ! c5t] ( :i* rises ! l>ge c5tral tube :i* exp&s ) a bulb at its upp] end1 :i* is op5 at ! top4 ,! ?ree tubes c be fill$ ) acidulat$ wat] f ! c5tral tube1 ! previ\sly conta9$ air be+ all[$ to escape ?r\gh ! /op cocks1 :i* are aft]w>ds clos$4 ,if x be s fill$1 & ! t]m9al ,t be atta*$ to ! positive & ,t to ! negative pole ( a suitable batt]y1 bubbles ( gas w be obs]v$ to rise f ! plates ,p & ,p1 & f9d+ _! way to ! top ( ! respective tubes1 w displace ! liquid1 :i* w be driv5 into ! op5 c5tral tube4 ,! gas ris+ f ! anode ,p is oxyg5 7,o71 & t ris+ f ! ca?ode ,p is hydrog5 7,h74 ,if ! tubes are graduat$1 ! latt] w be f\nd to occupy ab\t twice ! volume ( ! =m]4 ,! proportion is !oretically #b to #a2 h[ev]1 on acc\nt ( ! diff]5t solubilities ( ! two gases 9 wat]1 oxyg5 be+ ! m soluble ( ! two1 is defici5t 9 quantity4 ,! passage ( curr5t ?r\gh ! wat] splits up its molecules into _! con/itu5t atoms ( oxyg5 & hydrog51 ! =m] be+ giv5 (f 9 bubbles at ! anode1 & ! latt] at ! ca?ode4 ,:5 curr5t is pass$ ?r\gh a solution ( copp] sulphate betwe5 plat9um electrodes1 ! liquid is decompos$1 atoms ( copp] be+ deposit$ at ! ca?ode1 bubbles ( oxyg5 be+ giv5 (f at ! anode1 & sulphuric acid be+ =m$ 9 ! liquid1 :i* latt] becomes m & m acid z ! copp] is )drawn4 ,illu/ration3 ,,fig4 #ia4--;,grot?uss' !ory ( electrolysis4 ,grot?uss 9 7#ahjf71 ann\nc$ 8 !ory t ! molecules 9 an electrolyte h _! individual electro-positive & electro-negative atoms *>g$ positively & negatively respectively4 ,9 an ord9>y liquid1 = in/ance 9 wat]1 ! molecules are arrang$ indiff]5tly1 l r[ #a1 ) _! positive & negative ends po9t+ 9 all directions4 ,:5 ! *>g$ plates ,a & ,b connect$ to ! & - poles ( a batt]y are ins]t$ 9 ! wat]1 ! molecules "u ! action ( ! laws ( electro/atic action turn z %[n 9 r[ #b1 s t all ! hydrog5 or %ad$ ends 77 are turn$ t[>ds ! 7-7 plate ,b & all ! oxyg5 or un%ad$ ends 7-7 t[>ds ! 77 plate ,a4 ,all along ! r[ ! electrical =ces are suppos$ to te> ! molecules asund]1 deposit+ ,h on ,b & ,o on ,a4 ,! atoms 9 ! middle ( ! liquid1 h[ev]1 recomb9e1 = ! hydrog5 atoms 9 _! j\rney t[>ds ,b meet ! oxyg5 atoms travell+ 9 ! opposite direction1 & we get ! /ate ( affairs repres5t$ 9 r[ #c4 ,! next /ep is to rotate once m ! atoms into ! positions %[n 9 r[ #b1 & s on4 ,9 ?is way ! !ory acc\nts = ! products only appe>+ at ! electrodes & n 9 ! body ( ! liquid4 ,if1 h[ev]1 ! anode be ( copp] in/ead ( plat9um1 no sulphuric acid w be =m$1 nei!r w oxyg5 be giv5 (f at ! anode4 ,z copp] is deposit$ at ! ca?ode1 an equal quantity w be dissolv$ at ! anode1 s t ! orig9al con/itution ( ! liquid is ma9ta9$4 ,! atoms sep>at$ f ea* o!r by ! electric curr5t 7 call$ ions by ,f>aday2 ^? go+ to ! anode be+ anions1 & ^? go+ to ! ca?ode be+ ka?ions4 ,anions are g5]ally reg>d$ z electro-negative1 because !y move z if attract$ to ! positive electrode1 :ile ka?ions are reg>d$ z electro-positive4 ,9 ord] to expla9 ! transf] ( electricity & ! transf] ( matt] ?r\gh ! electrolyte1 ,grot?uss put =w>d ! hypo!sis t :5 two metal plates at diff]5t pot5tials are plac$ 9 a cell1 ! effect produc$ 9 ! liquid is t ! molecules ( ! liquid arrange !mselves 9 innum]able *a9s1 z %[n 9 fig4 #ia1 9 :i* e molecule has its atoms po9t+ 9 a c]ta9 direction1 ! electro-positive atom be+ attract$ t[>ds ! ca?ode & ! electro-negative t[>ds ! anode4 ,an int]*ange !n takes place all along ! l9e1 ! free atoms appe>+ at ! electrodes1 & e atom dis*>g+ a m9ute *>ge ( electricity ^u ! electrode at :i* x is lib]at$4 ,electro-*emical ,s]ies4--,?is is an arrangem5t ( ! metals 9 a s]ies 9 su* a mann] t ! mo/ electro-positive is at "o end & ! mo/ electro-negative at ! o!r4 ,! ord] ( ! metals v>ies ) ! electrolyte 9 :i* ! metals are te/$4 ,! foll[+ table %[s su* s]ies = ! mo/ common metals1 9 ?ree diff]5t solutions3 ,sulphuric acid4 ,hydro*loric acid4 ,cau/ic pota%4 ,z9c ,z9c ,z9c ,cadmium ,cadmium ,t9 ,t9 ,t9 ,cadmium ,lead ,lead ,antimony ,iron ,iron ,lead ,nickel ,copp] ,bismu? ,bismu? ,bismu? ,iron ,antimony ,nickel ,copp] ,copp] ,silv] ,nickel ,silv] ,antimony ,silv] ,gold ,plat9um ,f>aday /at$ sev]al laws ( electrolysis1 z foll[s3 #a4 ,! quantity ( an ion lib]at$ 9 a giv5 "t is proportional to ! quantity ( electricity t has pass$ ?r\gh ! voltamet]#aj 9 t "t4 #b4 ,! quantity ( an ion lib]at$ 9 a voltamet] is proportional to ! electro-*emical equival5t ( ! ion4 #c4 ,! quantity ( an ion lib]at$ is equal to ! electro-*emical equival5t ( ! ion multipli$ by ! total quantity ( electricity t has pass$4 ,electric ,osmose4--,porret obs]v$ t if a /rong curr5t be l$ into c]ta9 liquids z if to electrolyze !m1 a por\s p>tition be+ plac$ betwe5 ! electrodes1 ! curr5t me*anically c>ries "p ( ! liquid ?r\gh ! por\s diaphragm1 s t ! liquid is =c$ to a high] level on "o side ?an on ! o!r4 ,?is ph5om5on is kn[n z electric osmose4 ,electric ,di/illation4--,closely connect$ ) ! prec$+ ph5om5on is t ( ! electric di/illation ( liquids4 ,x 0 notic$ by ,becc>ia t an electrifi$ liquid evaporates m rapidly ?an "o n electrifi$4 ,g]nez has rec5tly %[n t 9 a b5t clos$ tube1 conta9+ two portions ( liquid1 "o ( :i* is made highly & ! o!r highly -1 ! liquid passes ov] f to -4 ,?is app>5t di/illation is n due to diff]5ce ( temp]ature1 nor does x dep5d on ! ext5t ( surface expos$1 b is effect$ by a sl[ creep+ ( ! liquid along ! int]ior surface ( ! glass tubes4 ,bad conductors1 su* z turp5t9e1 d n ?us pass ov]4 ,illu/ration3 ,,fig4 #ib4--;,effect ( ! electric curr5t on a frog's legs2 discov]$ 9 #afgh by ,galvani4 ,muscul> ,contractions4--,x 0 discov]$ 9 #afgh t :5 a portion ( muscle ( a frog's leg1 hang+ by a ?read ( n]ve b\nd ) a silv] wire1 0 held ov] a copp] support s t bo? n]ve & wire t\*$ ! copp]1 ! muscle imm$iately contract$4 ,m ?an a c5tury lat] ,galvani's att5tion 0 drawn to ! subject by 8 obs]vation ( spasmodic contractions 9 ! legs ( fre%ly kill$ frogs "u ! influ5ce ( ! 8return %ock0 exp]i5c$ e "t a neighbor+ electric ma*9e 0 dis*>g$4 ,! limbs ( ! frog1 prep>$ z direct$ by ,galvani1 are %[n 9 fig4 #ib4 ,aft] ! animal has be5 kill$ ! h9d limbs are deta*$ & sk9n$2 ! crural n]ves & _! atta*m5ts to ! lumb> v]tebrae rema9+4 ,= "s h\rs aft] dea? ! limbs reta9 _! contractile p[]4 ,! frog's limbs ?us prep>$ =m an excessively delicate galvanoscope4 ,electroplat+4--,?is is ! process ( deposit+ a lay] or coat+ ( a r>] metal ^u ! surface ( a bas]1 or ( a metal ^u any conduct+ surface1 by electrolysis4 ,! electric curr5t us$ may be obta9$ f a batt]y or o!r s\rce4 ,! batt]y has its positive plate connect$ to a rod ext5d+ across a tr\gh or tank conta9+ ! plat+ ba?4 ,susp5d$ f ! rod are anodes ( gold1 silv]1 or copp] or :atev] metal f :i* a deposit is desir$4 ,! o!r plates ( ! batt]y or ! negative elem5ts1 are connect$ ) ano!r rod across ! tr\gh1 to :i* are susp5d$ ! articles to be plat$4 ,electrotyp+4--,?is is ! process by :i*1 type1 wood cuts1 etc41 are reproduc$ 9 copp] by ! process ( electroplat+4 ,a m\ld is fir/ made ( ! set type 9 wax2 ?is m\ld is next coat$ ) black lead to give x a metallic surface1 z ! wax is an insulator2 ! m\ld is !n subject$ to ! process ( electro deposition1 result+ 9 ! =mation ( a film ( copp] on ! prep>$ surface4 ,! copp] %ell is remov$ f ! m\ld by apply+ hot wat]2 ! %ell is !n back$ up ) electrotype metal to r5d] x /rong en\gh = use4 ,almo/ all ! illu/rations 9 ?is book1 = example1 are pr9t$ f electrotype copies1 & n f ! orig9al wood blocks1 :i* w\ld n we> s well4 ,,*apt] ,,ix ,,magnetism ,magnetism4--,! anci5ts appli$ ! ^w 8magnet10 magnes lapes1 to c]ta9 h>d black /ones :i* possess ! prop]ty ( attract+ small pieces ( iron1 & z discov]$ lat]1 to h ! /ill m rem>kable prop]ty ( po9t+ nor? & s\? :5 hung up by a /r+4 ,at ?is "t ! magnet receiv$ ! "n ( lode/one or 8lead+ /one40 ,x is commonly1 ?\gh incorrectly1 spell$ load/one4 ,illu/ration3 ,,fig4 #ic4--,simple compass4 ,x consi/s ( a magnetic ne$le re/+ on a /eel pivot1 protect$ by a brass case cov]$ ) glass1 & a graduat$ circle m>k$ ) ! lett]s ,n1 ,e1 ,s1 ,w1 to indicate ! c>d9al po9ts2 a b is a lev] :i* arre/s ! ne$le by pu%+ x aga9/ ! glass :5 ! button d is press$4 ,ques4 ,describe two k9ds ( magnetism4 ,ans4 ,magnets h two opposite k9ds ( magnetism or magnetic poles1 :i* attract or repel ea* o!r 9 mu* ! same way z w\ld two opposite k9ds ( electrification4 ,ques4 ,:at is ! nature ( ea* k9d ( magnetism8 ,ans4 ,"o has a t5d5cy to move t[>d ! nor? & ! o!r t[>d ! s\?4 ,illu/ration3 ,,figs4 #id to #if4--,simple b> magnet & horse %oe magnet ) keep]4 ,^! are kn[n z p]man5t magnets 9 di/9ction f electromagnets4 ,! horse %oe magnet w attract m ?an ! b> magnet because bo? poles act toge!r4 ,a piece ( s(t iron1 or keep] is plac$ across ! ends ( a horse %oe magnet to assi/ 9 prev5t+ ! loss ( magnetism4 ,illu/ration3 ,,figs4 #ig & #ih4--;,horizontal magnetic ne$le1 & magnetic 8dip0 ne$le4 ,a magnetic ne$le consi/s ( a small b> magnet1 support$ ^u a pivot or susp5d$ s t x is free to turn 9 a horizontal or v]tical plane4 ,! =m ( magnetic ne$le illu/rat$ 9 fig4 #ig is arrang$ to %[ ! magnetic m]idian2 ! ne$le moves ^u a p]p5dicul> axis or pivot ab4 ,9 fig4 #ih1 ! ne$le sn turns ^u a horizontal axis ab4 ,?is ne$le indicates ! dip or incl9ation1 t is1 ! angle :i* x makes ) ! horizontal plane1 due to ! fact t 9 mo/ places ! l9es ( =ce are n horizontal4 ,9 ! nor!rn hemisph]e ! ,n pole ( ! ne$le is depress$1 9 ! s\!rn hemisph]e ! ,s pole is simil>ly affect$4 ,:5 us$1 ! dip ne$le mu/ be set s t ! plane 9 :i* ! ne$le sw+s conta9s ! magnetic m]idian1 z indicat$ by ! horizontal ne$le4 ,ques4 ,:]e is ! magnetism ! /ronge/8 ,ans4 ,9 two regions call$ ! poles4 ,ques4 ,describe ! di/ribution ( magnetism 9 a long %ap$ magnet4 ,ans4 ,! /ronge/ magnetism resides 9 ! ends1 :ile all ar\nd ! magnet half way betwe5 ! poles !re is no attraction at all4 ,illu/ration3 ,,fig4 #ii4--,magnetic poles4 ,if a b> magnet be plung$ into iron fil+s & !n lift$1 z illu/rat$ 9 ! figure1 a mass ( fil+s w cl+ to ! ends ( ! magnet b n to ! middle4 ,! ends are call$ ! poles ( ! magnet4 ,ques4 ,h[ are ! poles designat$8 ,ans4 ,!y are call$ ! nor? pole & ! s\? pole4 ,ques4 ,:at is ! di/+ui%+ feature ( ea*8 ,ans4 ,! nor? pole po9ts approximately to ! e>?'s geographical nor?1 :ile ! s\? pole ( a magnet po9ts approximately to ! e>?'s geographical s\?4 ,! nor? pole is ! positive 77 pole & ! s\? pole is ! negative4 ,! nor? & s\? poles 7 =m]ly call$ 9 ,france1 ! au/ral & boreal poles respectively4 ,magnetic ,field4--,:5 a /raight b> magnet is held "u a piece ( c>d bo>d ^u :i* iron fil+s are spr9kl$1 ! fil+s w arrange !mselves 9 curv$ l9es radiat+ f ! poles4 ,if a horse %oe magnet be held at "r angles to ! plane ( ! c>d bo>d1 ! fil+s w arrange !mselves 9 curv$ l9es1 z %[n 9 fig4 #ajh4 ,^! l9es are call$ magnetic l9es ( =ce or simply l9es ( =ce2 !y %[ t ! m$ium surr\nd+ a magnet is 9 a /ate ( /ress1 ! space s affect$ be+ call$ ! magnetic field4 ,illu/ration3 ,,fig4 #ajj4--;,badly magnetiz$ b>4 ,prop]ly magnetiz$ magnets h only two poles2 x is possible1 h[ev]1 by special or c>eless magnetization1 to produce magnets ) m ?an two poles1 b no process w produce a magnet ) a s+le pole4 ,if an abnormal magnet ) m ?an two poles be dipp$ into iron fil+s1 ! latt] w adh]e at places o!r ?an ! two ends1 z %[n 9 ! illu/ration4 ,! pol>ities are alt]nately ,n & ,s2 t is1 ! regions ,n1 ,b1 ,n1 h nor? pol>ity1 :ile ,a & ,c h s\? pol>ity4 ,^! are kn[n z consequ5t poles4 ,illu/ration3 ,,figs4 #aja to #ajg4--;,effect ( break+ a magnet into sev]al p>ts4 ,if a magnetiz$ ne$le be brok51 ea* "p w be f\nd to be a complete magnet hav+ a ,n & ,s pole4 ,! sub-division may be cont9u$ indef9itely1 b always ) ! same result z indicat$ 9 ! figure4 ,?is is evid5ce ( ! correctness ( ! molecul> !ory ( magnetism1 :i* /ates t ! molecules ( a magnet are !mselves m9ute magnets arrang$ 9 r[s ) _! opposite poles 9 contact4 ,ques4 ,:at is ! ext5t & "* ( ! magnetic field8 ,ans4 ,! influ5ce ( a magnet is suppos$ to ext5d 9 all directions indef9itely1 h[ev]1 ! effect is v slight beyond a comp>atively limit$ area4 ,illu/ration3 ,,fig4 #ajh4--,! region ab\t a magnet 9 :i* its magnetic =ces c be detect$ is call$ ! magnetic field4 ,?is c be repres5t$ graphically by plac+ a piece ( c>dbo>d ov] ! magnet & spr9kl+ iron fil+s on ! pap]1 g5tly tapp+ at ! same "t4 ,ea* fil+ becomes a tempor>y magnet by induction1 & sets itself1 l ! compass ne$le1 9 ! direction ( ! l9e ( =ce ( ! magnetic field4 ,illu/ration3 ,,fig4 #aji4--,trac+ l9es ( =ce ) a susp5d$ magnet4 ,if a small magnetic ne$le1 susp5d$ by a ?read1 be held ne> a magnet1 x w po9t 9 "s fix$ direction dep5d+ on ! proximity ( ! poles ( ! magnet4 ,! direction tak5 by ! magnet is call$ ! direction ( ! =ce at ! po9t1 & if ! susp5d$ ne$le be mov$ =w>d 9 ! direction ( ! pole1 x w trace out a curv$ l9e :i* w be f\nd to />t f "o ( ! poles1 & end at ! o!r4 ,any numb] ( su* l9es c be trac$2 ! space fill$ by ^! l9es ( =ce is call$ ! magnetic field4 ,illu/ration3 ,,fig4 #aaj4--,magnetic action3 ,unlike poles ( magnets attract ea* o!r4 ,illu/ration3 ,,fig4 #aaa4--,magnetic action3 ,l poles ( magnets repel ea* o!r4 ,magnetic ,=ce4--,?is is ! =ce ) :i* a magnet attracts or repels ano!r magnet or any piece ( iron or /eel4 ,! =ce v>ies ) ! di/ance1 be+ great] :5 ! magnet is ne>] & less :5 ! magnet is f>!r (f4 ,! foll[+ are ! laws relat+ to magnetic =ce3 #a4 ,l magnetic poles repel "o ano!r2 unlike magnetic poles attract "o ano!r4 #b4 ,! =ce ex]t$ betwe5 two magnetic poles v>ies inv]sely z ! squ>e ( ! di/ance betwe5 !m4 ,magnetic ,circuit4--,! pa? tak5 by magnetic l9es ( =ce is call$ a magnetic circuit2 ! great] "p ( su* a circuit is usually 9 magnetic mat]ial1 b !re are (t5 "o or m air gaps includ$4 ,! total numb] ( l9es ( =ce 9 ! circuit is kn[n z ! magnetic flux4 ,ques4 ,h[ is magnetic flux measur$8 ,ans4 ,by a unit call$ ! maxwell4 ,nam$ aft] ,james ,cl]k ,maxwell ! ,scotti% physici/4 ,ques4 ,:at is ! maxwell8 ,ans4 ,! am\nt ( magnetism pass+ ?r\gh e squ>e c5timetre ( a field ( unit d5sity4 ,ques4 ,:at is ! unit ( field /r5g?8 ,ans4 ,! gauss4 ,ques4 ,:at is a gauss8 ,ans4 ,! int5sity ( field :i* acts on a unit pole ) a =ce ( "o dyne4 ,x is equal to "o l9e ( =ce p] squ>e c5timetre4 ,nam$ aft] ,k>l ,fri$ri* ,gauss1 ! ,g]man ma!matician4 ,! ,magnetic ,effect ( ! ,curr5t4--,hans ,*ri/ian ,o]/ead1 ! ,dani% sci5ti/1 discov]$ 9 #ahai t a magnet t5ds to set itself at "r angles to a wire c>ry+ an electric curr5t4 ,he also f\nd t ! way 9 :i* ! ne$le turns1 :e!r to ! "r or left ( its usual position1 dep5ds3 #a1 ^u ! position ( ! wire t c>ries ! curr5t1 :e!r x be above or bel[ ! ne$le1 & #b1 on ! direction 9 :i* ! curr5t fl[s ?r\gh ! wire4 ,illu/ration3 ,,fig4 #aab4--;,illu/rat+ ,maxwell's 8corkscrew rule0 = relative directions ( curr5t & l9es ( =ce4 ,accord+ to ! rule3 ! direction ( ! curr5t & t ( ! result+ magnetic =ce are 9 ! same relation to ea* o!r z is ! =w>d travel & rotation ( an ord9>y corkscrew1 ,?us1 9 ! figure1 if a curr5t fl[ ?r\gh ! wire ab 9 ! direction f a to b1 ! magnetic l9es w encircle ! wire 9 ! direction ( ! curv$ arr[ ro :i* %[s ! direction 9 :i* ! corkscrew mu/ be turn$ to advance 9 ! direction ( ! arr[ n4 ,to keep ^! movem5ts 9 m9d num]\s rules h be5 sugge/$1 ( :i* ! foll[+ w be f\nd conv5i5t3 ,corkscrew ,rule4--,if ! direction ( travel ( a "r h&$ corkscrew repres5t ! direction ( ! curr5t 9 a /raight conductor1 ! direction ( rotation ( ! corkscrew w repres5t ! direction ( ! magnetic l9es ( =ce4 ,illu/ration3 ,,fig4 #aac4--;,exp]im5t %[+ direction ( l9es ( =ce 9 ! magnetic field surr\nd+ a conductor c>ry+ an electric curr5t4 ,a piece ( copp] wire is pi]c$ ?r\gh ! c5t] ( a %eet ( c>dbo>d1 & c>ri$ v]tically = two or ?ree feet !n b5t ar\nd to ! t]m9als ( a batt]y or o!r s\rce ( curr5t4 ,if iron fil+s be spr9kl$ ov] ! c>d :ile ! curr5t is pass+1 !y w arrange !mselves 9 circles ar\nd ! wire1 ?us indicat+ ! =m ( ! magnetic field surr\nd+ ! conductor4 ,compass ne$les may also be us$ to %[ ! direction ( ! l9es ( =ce at any po9t4 ,illu/ration3 ,,fig4 #aad4--,"r h& rule to det]m9e ! direction ( magnetic field ar\nd a conductor c>ry+ a curr5t4 ,! ?umb ( ! "r h& is plac$ along ! conductor1 po9t+ 9 ! direction 9 :i* ! curr5t is fl[+1 !n1 if ! f+]s be p>tly clos$1 z %[n 9 ! illu/ration1 ! f+] tips w po9t 9 ! direction ( ! magnetic :irls4 ,ques4 ,:at is ! effect ( a curr5t fl[+ 9 a loop ( wire8 ,ans4 ,if1 9 figs4 #aaf & #aag1 ! curr5t fl[ 9 ! direction indicat$ by ! arr[1 ! l9es = magnetic =ce are f\nd to surr\nd ! loop z %[n2 all ! l9es leave on "o side ( ! loop & return on ! o!r2 accord+ly1 a nor? pole is =m$ on "o side1 & a s\? pole on ! o!r4 ,illu/ration3 ,,fig4 #aae4--,"r h& palm rule to det]m9e ! direction ( ! magnetic field ar\nd a conductor c>ry+ a curr5t3 ,place ! palm ( ! out/ret*$ "r h& above & to ! "r side ( ! wire ) ! f+]s po9t+ 9 ! direction ( ! curr5t1 & ! ?umb ext5d$ at "r angles1 t is1 po9t+ d[nw>d4 ,! direction 9 :i* ! ?umb po9ts w indicate ! direction ( ! magnetic :irls4 ,illu/ration3 ,,fig4 #aaf4--,l9es ( =ce ( a circul> loop4 ,if a curr5t fl[ ?r\gh ! loop 9 ! direction indicat$1 ! l9es ( =ce bo? inside & outside ! loop1 w cross ! plane ( ! loop at "r angles1 & all ^? :i* cross ! loop on ! inside w pass ?r\gh ! plane 9 "o direction 7d[nw>ds 9 ! figure71 :ile all on ! outside w return ?r\gh ! plane 9 ! opposite direction4 ,sol5oids4--,a sol5oid consi/s ( a spiral ( conduct+ wire w\nd cyl9drically s t1 :5 an electric curr5t passes ?r\gh x1 its turns are ne>ly equival5t to a succession ( p>allel circul> circuits1 & x acquires magnetic prop]ties simil> to ^? ( a b> magnet4 ,illu/ration3 ,,fig4 #aag4--,l9es ( =ce ( a circul> loop4 ,if ! loop pass ?r\gh a piece ( c>dbo>d at "r angles to its plane1 & ! curr5t fl[ z indicat$1 ! dott$ l9es on ! c>dbo>d w repres5t ! direction ( ! l9es ( =ce 9 ! plane ( ! c>dbo>d4 ,! /ud5t %\ld v]ify ! l9es ( =ce z "h giv5 by apply+ ! corkscrew rule4 ,ques4 ,:at is ! "* ( ! l9es ( =ce ( a sol5oid 9 :i* a curr5t is fl[+8 ,ans4 ,! l9es ( =ce mu/ be ?\ght ( z clos$ loops l9k$ ) ! curr5t4 ,! conductor convey+ ! curr5t passes ?r\gh all ! loops ( =ce1 & ^! are1 s to speak1 ?read$ or slung on ! curr5t-l9e ( fl[1 z 9 fig4 #aaf4 ,ques4 ,:at is ! di/ribution ( ! l9es ( =ce8 ,ans4 ,! l9es ( =ce =m cont9u\s clos$ curves runn+ ?r\gh ! int]ior ( ! coil2 !y issue f "o end & ent] into ! o!r end ( ! coil1 z %[n 9 fig4 #aag4 ,ques4 ,:at are ! prop]ties ( a sol5oid8 ,ans4 ,a sol5oid has nor? & s\? poles1 & 9 fact possesses all ! prop]ties ( an ord9>y p]man5t magnet1 ) ! important diff]5ce t ! magnetism is entirely "u control4 ,s9ce a sol5oid c>ry+ a curr5t attracts & repels by its extremities ! poles ( a magnet1 two su* sol5oids w attract & repel ea* o!r4 ,illu/ration3 ,,fig4 #aah4--,magnetic field ( a sol5oid4 ,?is is be/ obs]v$ by cutt+ a piece ( c>dbo>d & fitt+ x ar\nd ! sol5oid1 z %[n4 ,if iron fil+s be spr9kl$ on ! c>dbo>d & a curr5t pass$ ?r\gh ! sol5oid1 ! "* ( ! field is indicat$4 ,) ! curr5t 9 ! direction %[n1 x w be f\nd t :]ev] small compass ne$les are plac$1 ! direction 9 :i* _! nor? poles turn is along arr[s m>k$ on ! c>d4 ,! c>d only exhibits ! field 9 "o ( ! sectional planes ( ! coil1 b x is obvi\s t ! field is ! same = all sectional planes4 ,ques4 ,h[ does ! magnetic /r5g? ( a sol5oid v>y8 ,ans4 ,x is proportional to ! /r5g? ( ! electric curr5t pass+ ?r\gh x4 ,ques4 ,on :at1 besides ! curr5t /r5g?1 does ! magnetiz+ p[] ( a sol5oid dep5d8 ,ans4 ,! magnetic effect or ! magnetiz+ p[] is proportional to ! numb] ( turns ( wire compos+ ! coil4 ,ques4 ,h[ may ! magnetiz+ p[] ( a sol5oid be increas$8 ,ans4 ,by ins]t+ 9 ! sol5oid an iron core or r\nd b> ( s(t iron4 ,illu/ration3 ,,fig4 #aai4--,"r h& rule = pol>ity ( a sol5oid3 ,if ! sol5oid be grasp$ 9 ! "r h&1 s t ! f+]s po9t 9 ! direction 9 :i* ! curr5t is fl[+ 9 ! wires1 ! ?umb ext5d$ w po9t 9 ! direction ( ! nor? pole4 ,ques4 ,describe ! action ( an iron core4 ,ans4 ,at fir/1 ! pres5ce ( an iron core greatly increases ! /r5g? ( ! field2 aft] a "t1 h[ev]1 z ! /r5g? ( ! curr5t fl[+ 9 ! excit+ coils is increas$1 ! conductibility ( ! iron = ! l9es ( =ce appe>s to decrease1 until a po9t is ev5tually rea*$ :5 ! pres5ce ( ! iron core appe>s to h no effect 9 increas+ ! /r5g? ( ! field4 ,p]meability4--,p]meability is a measure ( ! ease ) :i* magnetism passes ?r\gh any sub/ance4 ,x is def9$ z3 ! ratio betwe5 ! numb] ( l9es ( =ce p] unit area pass+ ?r\gh a magnetizable sub/ance1 & ! magnetiz+ =ce :i* produces !m4 ,illu/ration3 ,,figs4 #abj & #aba4--;,illu/rat+ ! effect ( introduc+ an iron core into a sol5oid4 ,9 ! upp] figure1 ! air space or 8air core0 surr\nd$ by ! sol5oid (f]s consid]able resi/ance to ! passage ( magnetic l9es1 all[+ only a small numb] to pass ?r\gh4 ,if a piece ( iron be introduc$1 z 9 ! l[] figure1 ! numb] ( l9es w be greatly increas$4 ,! numb] ( l9es ,b pass+ ?r\gh a unit cross section ( ! iron core divid$ by ! numb] ( l9es ,h1 pass+ ?r\gh a unit cross section ( ! air core is call$ ! p]meability & designat$ by ! ,greek lett] 4 ,9 o!r words1 x is ! ratio ( flux d5sity to magnetiz+ =ce4 ,p]meability is a measure ( ! ease ) :i* magnetism passes ?r\gh any sub/ance4 ,! p]meability ( good s(t wr\ght iron is sometimes #cjjj times t ( air1 v>y+ ) ! quality ( ! iron4 ,ques4 ,:at is ! effect ( increas+ ! magnetization8 ,ans4 ,! magnetic p]meability decreases z ! magnetization increases4 ,ques4 ,:at is magnetic saturation8 ,ans4 ,! /ate ( a magnet :i* has rea*$ ! highe/ degree ( magnetization4 ,illu/ration3 ,,fig4 #abb4--;,action ( curr5ts on sol5oids4 ,to demon/rate ?is fact exp]im5tally1 a sol5oid is con/ruct$ z %[n1 s t x c be susp5d$ by two pivots 9 ! cups a & c4 ,! sol5oid is !n movable ab\t a v]tical axis1 & if a rectil9e> curr5t ,,qp be pass$ b5ea? x1 :i* at ! same "t trav]ses ! wires ( ! sol5oid1 ! latt] is se5 to turn & set at "r angles to ! l[] curr5t2 t is1 9 su* a position t its circuits are p>allel to ! fix$ curr5t2 moreov]1 ! curr5t 9 ! l[] "p ( ea* ( ! circuits is 9 ! same direction z 9 ! rectil9e> wire4 ,if1 in/ead ( pass+ a rectil9e> curr5t bel[ ! sol5oid1 x be pass$ v]tically on ! side1 an attraction or repulsion w take place1 accord+ z ! two curr5ts 9 ! v]tical wire1 & 9 ! ne>e/ "p ( ! sol5oid1 are 9 ! same or 9 contr>y directions4 ,a magnet1 j aft] be+ magnetiz$1 w appe> to h a high] degree ( magnetism ?an x is able to reta9 p]man5tly2 t is1 x w appe> to be sup]-saturat$1 s9ce x w support a great] weight imm$iately aft] be+ magnetiz$ ?an x w aft] its armature has be5 once remov$4 ,= all practical purposes1 magnetic saturation may be def9$ z3 ,t po9t ( magnetization :]e a v l>ge increase 9 ! magnetiz+ =ce does n produce any p]ceptible increase 9 ! magnetization4 ,f te/s x has be5 %[n t p]meability increases ) ! flux d5sity up to a c]ta9 po9t & !n decreases1 indicat+ t ! iron is approa*+ a /ate ( saturation4 ,magnetomotive ,=ce4--,?is is a =ce simil> to electromotive =ce1 t is1 magnetic pressure4 ,:5 a coil passes ar\nd a core sev]al times1 its magnetiz+ p[]1 or magnetomotive =ce1 7m4m4f47 is proportional bo? to ! /r5g? ( ! curr5t & to ! numb] ( turns 9 ! coil4 ,! product ( ! curr5t pass+ ?r\gh ! coil multipli$ by ! numb] ( turns compos+ ! coil is call$ ! amp]e turns4 ,x is kn[n by exp]im5t t "o amp]e turn produces #a4beff units ( magnetic pressure1 h5ce3 magnetic pressure #a4beff turns amp]es t is1 magnetomotive =ce 7m4m4f47 #a4beff n ,i4 ,! unit ( magnetic pressure is ! gilb]t 7nam$ aft] ,william ,gilb]t1 ! ,engli% physici/7 & is equal to #a #a4beff amp]e turn 4#gieh amp]e turn4 ,reluctance4--,! magnetic pressure 7magnetomotive =ce7 act+ 9 a magnetic circuit enc\nt]s a c]ta9 opposition to ! production ( a magnetic field1 j z electromotive =ce 9 an electric circuit enc\nt]s opposition to ! production ( a curr5t4 ,9 ! magnetic circuit ?is opposition is call$ ! reluctance2 x is simply magnetic resi/ance & may be def9$ z3 ! resi/ance (f]$ to ! magnetic flux by ! sub/ance magnetiz$1 be+ ! ratio ( ! magnetomotive =ce to ! magnetic flux4 ,! unit ( reluctance or magnetic resi/ance is ! o]/$ 7nam$ aft] ,hans ,*ri/ian ,o]/$1 ! ,dani% physici/7 & is def9$ z3 ! reluctance (f]$ by a cubic c5timetre ( vacuum4 ,illu/ration3 ,,fig4 #abc4--,mutual action ( sol5oids4 ,:5 two sol5oids trav]s$ by a curr5t are all[$ to act on ea* o!r1 "o ( !m be+ held 9 ! h& & ! o!r be+ movable ab\t a v]tical axis1 z %[n 9 ! figure1 attraction & repulsion w take place j z 9 ! case ( two magnets 7see figs4 #aaj & #aaa74 ,analogy ,betwe5 ,electric & ,magnetic ,circuits4--,! total numb] ( magnetic l9es ( =ce1 or magnetic flux1 produc$ 9 any magnetic circuit w dep5d on ! magnetic pressure 7m4m4f47 act+ on ! circuit & ! total reluctance ( ! circuit1 j z ! curr5t 9 ! electrical circuit dep5ds ^u ! electrical pressure & ! resi/ance ( ! circuit4 ,to make ?is pla91 ,ohm's law /ates t electric curr5t electromotive =ce _/ resi/ance or ,i ,e_/,r express$ 9 units amp]es volts _/ ohms ,! resi/ance1 z already expla9$1 dep5ds on ! mat]ials ( :i* ! circuit is compos$1 & _! geometrical %ape & size4 ,simil>ly1 9 ! magnetic circuit1 ! total numb] ( magnetic l9es produc$ by a giv5 magnetiz+ sol5oid dep5ds on ! magnetic pressure1 ! mat]ial compos+ ! circuit1 & its %ape & size4 ,t is1 magnetic flux magnetomotive =ce _/ reluctance express$ 9 units1 ! equation becomes3 maxwells gilb]ts _/ o]/$s ,! gilb]t is ! unit ( magnetomotive =ce1 equival5t to ! magnetomotive =ce ( 4#gieh amp]e turn4 ,x %\ld be not$ t 9 ! electric circuit resi/ance causes heat to be g5]at$ & !re=e en]gy to be wa/$1 b 9 ! magnetic circuit reluctance does n involve any simil> wa/e ( en]gy4 ,ques4 ,^u :at does ! reluctance ( a magnetic circuit dep5d8 ,ans4 ,! reluctance is directly proportional to ! l5g? ( ! circuit1 & inv]sely proportional to its cross sectional area4 ,! reluctance ( a magnetic circuit is calculat$ accord+ to ! foll[+ equation3 reluctance l5g? 9 c5timetres _/ 7p]meability cross section 9 squ>e c5timetres7 ,hy/]esis4--,! t]m hy/]esis has be5 giv5 by ,ew+ to ! subject ( lag ( magnetic effects beh9d _! causes4 ,hy/]esis means to 8lag beh9d10 h5ce its application to d5ote ! lagg+ ( magnetism1 9 a magnetic metal1 beh9d ! magnetiz+ flux :i* produces x4 ,ques4 ,:at is ! cause ( hy/]esis8 ,ans4 ,x is due to ! friction betwe5 ! molecules ( iron or o!r magnetic sub/ance :i* requires an exp5diture ( en]gy to *ange _! positions4 ,illu/ration3 ,,figs4 #abd & #abe4--;,exp]im5t illu/rat+ ! molecul> !ory ( magnetism4 ,co>se /eel fil+s are plac$ inside a small glass tube & ! cont5ts magnetiz$4 ,x w be f\nd t fil+s :i* at fir/ _h no def9ite arrangem5t w re>range !mselves "u ! influ5ce ( magnetic =ce1 & assume symmetrical positions1 ea* "o ly+ 9 l9e )1 or p>allel to its neighbor1 z %[n 9 ! l[] figure4 ,ques4 ,:5 d ! molecules *ange _! positions8 ,ans4 ,bo? 9 ! process ( magnetization & demagnetization4 ,ques4 ,:at becomes ( ! loss ( en]gy due to hy/]esis8 ,ans4 ,x is conv]t$ into heat 9 *ang+ ! positions ( ! molecules dur+ magnetization & demagnetization4 ,ew+ gives ! value = ! en]gy 9 ergs dissipat$ p] cubic c5timetre1 = a complete cycle ( d\bly rev]s$ /rong magnetization = a numb] ( sub/ances z foll[s3 ,sub/ance ,en]gy dissipat$ 7ergs7 ,v s(t anneal$ iron #i1cjj ,less 8 8 8 #af1cjj ,h>d drawn /eel wire #fj1jjj ,anneal$ 8 8 #gj1jjj ,same /eel glass h>d #gf1jjj ,piano /eel wire anneal$ #id1jjj 8 8 8 normal temp] #aaf1jjj 8 8 8 glass h>d #aag1jjj ,approximately #bh foot p\nds ( en]gy are conv]t$ into heat 9 mak+ a d\ble rev]sal ( /rong magnetization 9 a cubic foot ( iron4 ,residual ,magnetism4--,:5 a mass ( iron has once be5 magnetiz$1 x becomes a difficult matt] to entirely remove all traces :5 ! magnetiz+ ag5t has be5 remov$1 &1 z a g5]al rule1 a small am\nt ( magnetism is p]man5tly reta9$ by ! iron4 ,?is is kn[n z residual magnetism1 & x v>ies 9 am\nt ) ! quality ( ! iron4 ,well anneal$1 pure wr\ght iron1 z a rule1 possesses v little residual magnetism1 :ile1 on ! o!r h&1 wr\ght iron1 :i* conta9s a l>ge p]c5tage ( impurities1 or :i* has be5 subject$ to "s h>d5+ process1 su* z hamm]+1 roll+1 /amp+1 etc41 & ca/ iron1 possess a v l>ge am\nt ( residual magnetism4 ,residual magnetism 9 iron is ( great importance 9 ! work+ ( ! self-excit+ dynamo1 & is1 inde$1 ! ess5tial pr9ciple ( ?is class ( ma*9e4 ,t is1 )\t residual magnetism 9 ! field magnet core1 ! dynamo :5 />t$ w\ld n g5]ate any curr5t unless x receiv$ an initial excitation f an ext]nal s\rce4 ,,*apt] ,x ,,electromagnetic ,,induction ,! ^w induction1 introduc$ by ,f>aday1 has v>i\s mean+s s f> z x relates to electricity4 ,x signifies1 9 g5]al1 ph5om5a produc$ 9 bodies by ! influ5ce ( o!r bodies1 hav+ no necess>y mat]ial connection ) !m4 ,a body *>g$ ) electricity causes or 8induces0 *>ges on neighbor+ bodies4 ,! process 9 ?is case is call$ electro/atic induction4 ,a magnet induces magnetism 9 neighbor+ masses ( iron or o!r magnetic mat]ials by ! process ( magnetic induction4 ,aga91 a mov+ magnet induces electric curr5ts 9 neighbor+ conductors by ! process ( electromagnetic induction4 ,f>aday's ,discov]y4--,all dynamos ( :atev] =m1 are bas$ ^u ! discov]y made by ,f>aday#aa 9 #ahca1 :i* may be /at$ z foll[s3 ,electric curr5ts are g5]at$ 9 conductors by mov+ !m 9 a magnetic field1 s z to cut magnetic l9es ( =ce4 ,ques4 ,:at does ! expression 8cut l9es ( =ce0 mean8 ,ans4 ,a conductor1 =m+ "p ( an electric circuit1 cuts l9es ( =ce :5 x moves across a magnetic field 9 su* mann] z to alt] ! numb] ( magnetic l9es ( =ce :i* are embrac$ by ! circuit4 ,x is important to cle>ly und]/& ! mean+ ( ?is expression1 :i* w be lat] expla9$ 9 m detail4 ,illu/ration3 ,,fig4 #abf4--;,f>aday's dynamo :i* embodies 8 discov]y 9 #ahca ( electromagnetic induction1 ! pr9ciple ^u :i* all dynamos "w1 z well z induction coils1 trans=m]s1 & o!r electrical app>atus4 ,f>aday's ,ma*9e4--,aft] v>i\s exp]im5ts1 ,f>aday made 8 8new electrical ma*9e0 z %[n 9 fig4 #abf4 ,?is piece ( app>atus is pres]v$ & 0 %[n 9 p]fect action by ,pr(4 ,s4 ,p4 ,?ompson 9 a lecture deliv]$ ,april #aa?1 #ahia1 aft] an int]val ( sixty ye>s4 ,x consi/s ( a horse %oe magnet & a copp] disc atta*$ to a %aft & support$ s z to turn freely4 ,! magnet is s plac$ t its int]-pol> l9es ( =ce trav]se ! disc f side to side4 ,!re are two copp] bru%es1 "o be>s aga9/ ! %aft1 & ! o!r aga9/ ! circumf]5ce ( ! disc4 ,a h&le s]ves to rotate ! disc 9 ! magnetic field4 ,n[1 if ! nor? pole ( ! magnet be ne>e/ ! obs]v] & ! disc be rotat$ clockwise1 ! curr5t induc$ 9 ! circuit w fl[ out at ! bru% :i* t\*es ! circumf]5ce1 & return ?r\gh ! bru% at ! %aft4 ,f>aday's ,pr9ciple4--,! pr9ciple d$uc$ f ,f>aday's exp]im5t may be /at$ z foll[s3 ,:5 a conduct+ circuit is mov$ 9 a magnetic field s z to alt] ! numb] ( l9es ( =ce pass+ ?r\gh x1 a curr5t is induc$ !re91 9 a direction at "r angles to ! direction ( ! motion1 & at "r angles also to ! direction ( ! l9es ( =ce1 & to ! "r ( ! l9es ( =ce1 z view$ f ! po9t f :i* ! motion orig9at$4 ,f>aday's pr9ciple may be ext5d$ z foll[s to cov] all cases ( electromagnetic induction3 ,:5 a conduct+ circuit is mov$ 9 a magnetic field1 s z to alt] ! numb] ( l9es ( =ce pass+ ?r\gh x1 or :5 ! /r5g? ( ! field is v>i$ s z to ei!r increase or decrease ! numb] ( l9es ( =ce pass+ ?r\gh ! circuit1 a curr5t is induc$ !re9 :i* la/s only dur+ ! int]val ( *ange 9 ! numb] ( l9es ( =ce embrac$ by ! circuit4 ,ques4 ,expla9 j :at happ5s :5 a curr5t is induc$ by electromagnetic induction4 ,ans4 ,9 ord] to induce an electromotive =ce by mov+ a conductor across a uni=m magnetic field1 x is necess>y t ! conductor1 9 its motion1 %\ld s cut ! magnetic l9es z to alt] ! numb] ( l9es ( =ce t pass ?r\gh ! circuit ( :i* ! mov+ conductor =ms a "p4 ,ques4 ,:at is ! prop] "n = a 8conductor0 :i* moves across ! magnetic field8 ,ans4 ,an inductor1 because x is t "p ( ! electric circuit 9 :i* induction takes place4 ,9 ! case ( a dynamo1 an inductor may be ei!r a copp] wire or copp] b>4 ,ques4 ,h[ may a conduct+ circuit be mov$ across a magnetic field )\t hav+ a curr5t induc$ !re98 ,ans4 ,if a conduct+ circuit--a wire r+ or s+le coil1 = example--be mov$ 9 a uni=m magnetic field1 z %[n 9 fig4 #abg1 s t only ! same numb] ( l9es ( =ce pass ?r\gh x1 no curr5t w be g5]at$1 = s9ce ! coil is mov$ by a motion ( translation to ano!r "p ( ! field1 z _m l9es ( =ce w be left beh9d z are ga9$ 9 advanc+ f its fir/ to its second position4 ,illu/ration3 ,,fig4 #abg4--;,electromagnetic induction3 ,9 ord] to induce a curr5t by electromagnetic induction1 a conductor mu/ be s mov$ ?r\gh a magnetic field t ! numb] ( l9es ( =ce pass+ ?r\gh x 7t is1 embrac$7 are alt]$4 ,if a coil be giv5 a simple motion ( translation 9 a uni=m magnetic field z indicat$ 9 ! figure1 no curr5t w be induc$ because ! numb] ( l9es ( =ce pass+ ?r\gh x are n *ang$1 t is1 dur+ ! movem5t z _m l9es are lo/ z are ga9$4 ,ques4 ,describe ano!r movem5t by :i* no curr5t w be induc$4 ,ans4 ,if ! coil be m]ely rotat$ on itself ar\nd a c5tral axis1 t is1 l a fly :eel rotat+ ar\nd a %aft1 ! numb] ( l9es ( =ce pass+ ?r\gh ! coil w n be alt]$1 h5ce no curr5t w be g5]at$4 ,ques4 ,/ate ! ess5tial condition = curr5t induction 9 a uni=m field4 ,ans4 ,! coil 9 :i* a curr5t is to be induc$1 mu/ be tilt$ 9 its motion across ! uni=m field1 or rotat$ ar\nd any axis 9 its plane z 9 fig4 #abh1 s z to alt] ! numb] ( l9es ( =ce :i* pass ?r\gh x4 ,illu/ration3 ,,fig4 #abh4--;,electromagnetic induction3 ,if a coil be giv5 a motion ( rotation f any po9t )9 its own plane s t x passes ?r\gh a uni=m magnetic field1 a curr5t w be induc$ 9 ! coil because ! numb] ( l9es ( =ce pass+ ?r\gh x is alt]$4 ,ques4 ,9 :at direction w ! curr5t fl[ 9 ! coil1 fig4 #abh8 ,ans4 ,! curr5t induc$ 9 ! coil w fl[ ar\nd x 9 a clockwise direction 7z obs]v$ by look+ along ! magnetic field 9 ! direction 9 :i* ! magnetic l9es run7 if ! effect ( ! movem5t be to dim9i% ! numb] ( l9es ( =ce t pass ?r\gh ! coil4 ,! curr5t w fl[ 9 ! opposite direction1 7c\nt]-clockwise7 if ! movem5t be su* z to increase ! numb] ( int]cept$ l9es ( =ce4 ,ques4 ,if ! magnetic field be n uni=m1 z 9 fig4 #abi1 :at w be ! result8 ,ans4 ,! effect ( mov+ ! coil by a simple motion ( translation f a d5se region ( ! field to "o less d5se1 or vice v]sa1 w be to induce a curr5t because 9 ei!r case1 ! numb] ( l9es ( =ce pass+ ?r\gh ! coil is alt]$4#ab ,laws ( ,electromagnetic ,induction4--,!re are c]ta9 laws ( electromagnetic induction :i*1 on acc\nt ( ! importance ( ! subject1 x is well to c>efully consid]4 ,! facts pres5t$ 9 ! prec$+ p>agraphs are embodi$ 9 ! foll[+ fundam5tal laws3 ,illu/ration3 ,,fig4 #abi4--;,electromagnetic induction3 ,if a coil be giv5 a simple motion ( translation 9 a non-uni=m or v>iable magnetic field1 a curr5t w be induc$ 9 ! coil1 :e!r ! motion be f ! d5se to ! less d5se region ( ! field or ! rev]se1 because ! numb] ( l9es ( =ce pass+ ?r\gh ! coil is alt]$4 #a4 ,to induce a curr5t 9 a circuit1 !re mu/ be a relative motion betwe5 ! circuit & a magnetic field1 ( su* a k9d z to alt] ! numb] ( magnetic l9es embrac$ 9 ! circuit4 #b4 ,! electromotive =ce induc$ 9 a circuit is proportional to ! rate ( increase or decrease 9 ! numb] ( magnetic l9es embrac$ by ! circuit4 ,= in/ance1 if n equal ! numb] ( magnetic l9es embrac$ by ! circuit at ! beg9n+ ( ! movem5t1 & n ! numb] embrac$ aft] a v %ort int]val ( "t t1 !n ! av]age induc$ electromotive =ce 7n - n7_/t ,x w\ld require ! cutt+ ( #ajj1jjj1jjj l9es p] second to produce an electromotive =ce equal to t ( "o ,daniell cell4 ,! unit ( electromotive =ce1 call$ ! volt1 is ! electric pressure produc$ by cutt+ #ajj1jjj1jjj l9es p] second1 usually express$ #ajh4 ,illu/ration3 ,,fig4 #acj4--;,exp]im5t illu/rat+ ,l5z's law :i* /ates t 9 all cases ( electromagnetic induction1 ! direction ( ! induc$ curr5t is su* z to t5d to /op ! motion produc+ x4 ,9 ! exp]im5t1 9 ord] to produce ! induc$ curr5t1 en]gy mu/ be exp5d$ 9 br++ ! magnet to ! coil & 9 tak+ x away1 :i* is 9 accordance ) ! law ( cons]vation ( en]gy4 #c4 ,by jo9+ 9 s]ies a numb] ( conductors or coils mov+ 9 a magnetic field1 ! electromotive =ces 9 ! sep>ate p>ts are add$ toge!r4 ,! reason = ?is is app>5t by consid]+ a coil ( wire hav+ sev]al turns & mov+ 9 a magnetic field s z to cut magnetic l9es4 ,dur+ ! movem5t1 ! l9es cut by ! fir/ turn are successively cut by all ! o!r turns ( ! coil1 h5ce1 ! total numb] ( l9es cut is equal to ! numb] cut by a s+le turn multipli$ by ! numb] ( turns4 ,! electromotive =ces !re=e ( ! sep>ate turns are add$4 ,,example--,if a coil ( wire ( #ej turns cut #ajj1jjj l9es 9 #a_/ajj ( a second1 :at w be ! induc$ voltage8 ,! numb] ( l9es cut p] second p] turn ( ! coil is #ajj1jjj #ajj #aj1jjj1jjj4 ,! total numb] ( l9es cut by ! coil ( #ej turns is #aj1jjj1jjj #ej #ejj1jjj1jjj4 :i* w induce a pressure ( #ejj1jjj1jjj #ajh #e volts4 ,illu/ration3 ,,fig4 #aca4--;,exp]im5t illu/rat+ ,l5z's law4 ,if a copp] r+ be held 9 front ( an ord9>y electromagnet1 & ! curr5t circulat+ ?r\gh ! coil ( ! magnet be 9 su* a direction z to magnetize ! core z indicat$ by ! lett]s ,s ,n1 !n z ! curr5t increases 9 ! coil m & m ( ! l9es ( =ce proce$+ f ,n pass ?r\gh ! r+ ,o ,o f left to "r4 ,:ile ! field is ?us increas+ curr5ts w be induc$ 9 ! copp] r+ 9 ! direction indicat$ by ! arr[s1 su* curr5ts t5d+ to set up a field t w\ld pass ?r\gh ! r+ f "r to left1 & w\ld !re=e ret>d ! gr[? ( ! field due to ! electromagnet ,m4 #d4 ,a decrease 9 ! numb] ( magnetic l9es :i* pass ?r\gh a circuit induces a curr5t ar\nd ! circuit 9 ! positive direction4 ,! t]m positive direction is und]/ood to be ! direction along :i* a free ,n pole w\ld t5d to move4 #e4 ,an increase 9 ! numb] ( magnetic l9es :i* pass ?r\gh a circuit induces a curr5t 9 ! negative direction ar\nd ! circuit4 ,! reason = ! *ange ( direction ( ! curr5t = decrease or increase 9 ! numb] ( l9es cut1 z /at$ 9 ! f\r? & fif? laws1 w be se5 by aid ( ! =mula giv5 "u ! second law1 viz3 electromotive =ce 7n - n7_/t 7#a7 b by ,ohm's law curr5t electromotive =ce _/ resi/ance or1 ,i ,e_/,r 7#b7 ,sub/itut+ 7#a7 9 7#b7 curr5t 77n - n7_/t7_/,r or 7n - n7_/7,rt7 7#c7 ,illu/ration3 ,,fig4 #acb4--;,flem+'s rule = direction ( induc$ curr5t4 ,ext5d ! ?umb1 =ef+] & middle f+] ( ! "r h& s t ea* w be at "r angles to ! o!r two4 ,place ! h& 9 su* position t ! ?umb w po9t 9 ! direction 9 :i* ! conductor moves1 ! =ef+] 9 ! direction ( ! l9es ( =ce 7,n to ,s71 !n w ! middle f+] po9t 9 ! direction 9 :i* ! induc$ curr5t fl[s4 ,n[ 9 equation 7#c7 if !re be a decrease 9 ! numb] ( l9es cut n w be less ?an n h5ce ! curr5t w be positive 772 aga91 if ! l9es increase n w be great] ?an n1 :i* w give a m9us value1 t is1 ! curr5t w be negative or 9 a rev]se direction4 #f4 ,! approa* & recession ( a conductor f a magnet pole w yield curr5ts alt]nat+ 9 direction4 ,s9ce ! /r5g? ( ! field dep5ds on ! proximity to ! pole1 ! approa* & recession ( a conductor involve an increase & decrease 9 ! rate ( cutt+ ( magnetic l9es1 h5ce a rev]sal ( curr5t4 #g4 ,! m rapid ! motion1 ! high] w be ! induc$ electromotive =ce4 ,9 o!r words1 ! great] ! numb] ( l9es cut p] unit ( "t1 ! high] w be ! voltage4 ,illu/ration3 ,,fig4 #acc4--;,a rule = direction ( induc$ curr5t :i*1 9 "s cases1 is m conv5i5tly appli$ ?an ,flem+'s rule3 ,hold ! ?umb1 =ef+] & rema9+ f+]s ( ! "r h& at "r angles to ea* o!r2 place ! h& 9 su* position t ! =ef+] po9ts 9 ! direction ( motion ( ! conductor1 ! ?ree f+]s 9 ! direction ( ! l9es ( =ce1 !n w ! ?umb po9t 9 ! direction ( ! induc$ curr5t4 #h4 ,l5z's law4 ,! direction ( ! induc$ curr5t is always su* t its magnetic field opposes ! motion :i* produces x4 ,?is is illu/rat$ 9 figs4 #acj & #aca4 ,rules = ,direction ( ,induc$ ,curr5t4--,!re are a numb] ( rules to quickly det]m9e ! direction ( an induc$ curr5t1 :5 ! direction ( ! l9es ( =ce1 & motion ( ! conductor are kn[n4 ,! fir/ rule "h giv5 0 devis$ by ,flem+ & is v useful4 ,x is sometimes call$ ! 8dynamo rule40 ,flem+'s ,rule4--,if ! =ef+] ( ! "r h& be po9t$ 9 ! direction ( ! magnetic l9es1 & ! ?umb 7at "r angles to ! =ef+]7 be turn$ 9 ! direction ( ! motion ( ! conductor1 !n w ! middle f+]1 b5t at "r angles to bo? ?umb & =ef+]1 %[ ! direction ( ! induc$ curr5t4 ,! application ( ?is rule is %[n 9 fig4 #acb4 ,"h ! "r h& is s plac$ at ! nor? pole ( a magnet1 t ! =ef+] po9ts 9 ! direction ( ! magnetic l9es2 ! ?umb 9 ! direction ( motion ( ! conductor2 ! middle f+] po9t$ at "r angles to ! ?umb & =ef+] indicates ! direction ( ! curr5t induc$ 9 ! conductor4 ,illu/ration3 ,,fig4 #acd4--,! palm rule = direction ( induc$ curr5t3 ,if ! palm ( ! "r h& be held aga9/ ! direction ( ! l9es ( =ce1 ! ?umb 9 ! direction ( ! motion1 !n ! f+]s w po9t 9 ! direction ( ! induc$ curr5t4 ,amp]e's ,rule4--,if a man c\ld swim 9 a conductor ) ! curr5t1 !n ! nor? seek+ 77 pole ( a magnetic ne$le plac$ directly ahead ( him1 w be deflect$ to ! left1 :ile ! s\? seek+ 7-7 pole w be urg$ to ! "r4 ,= c]ta9 p>ticul> cases 9 :i* a fix$ magnet pole acts on a movable circuit1 ! foll[+ conv]se to ,amp]e's rule w be f\nd useful3 ,if a man swim 9 ! wire ) ! curr5t1 & turn s z to look along ! direction ( ! l9es ( =ce ( ! pole 7t is1 z ! l9es ( =ce run1 f ! pole if x be nor? seek+1 t[>d ! pole if x be s\? seek+71 !n he & ! conduct+ wire ) him w be urg$ t[>d 8 left4 ,! palm rule4--,if ! palm ( ! "r h& be held fac+ or aga9/ ! l9es ( =ce1 & ! ?umb 9 ! direction ( ! motion1 !n w ! f+]s po9t 9 ! direction ( ! induc$ curr5t4 ,self-induction4--,?is t]m signifies ! prop]ty ( an electric curr5t by virtue ( :i* x t5ds to resi/ any *ange ( value4 ,self-induction is sometimes spok5 ( z electromagnetic in]tia1 & is analog\s to ! me*anical in]tia ( matt]4 ,x is on acc\nt ( self-induction ( ! induc$ curr5ts 9 ! armature w9d+ ( a dynamo1 t sp>ks appe> at ! bru%es :5 ! latt] are n prop]ly adju/$1 h5ce ! importance ( cle>ly und]/&+ ! nature ( ?is peculi> prop]ty ( ! curr5t4 ,self-induction is fully expla9$ 9 ! *apt] foll[+4 ,,*apt] ,,xi ,,induction ,,coils ,! induction coil has always be5 a popul> piece ( app>atus ) ^? int]e/$ 9 electrical sci5ce2 ! exp]im5ts :i* c be p]=m$ ) its aid are v num]\s4 ,x is ( consid]able importance1 especially 9 its application to su* useful purposes z ,x ray "w1 wireless telegraphy & ignition = gas eng9es4 ,! latt] has caus$ manufactur]s to give mu* att5tion to ! developm5t ( ! induction coil1 result+ 9 _m ref9em5ts ( design & con/ruction4 ,induction coils may be divid$ into two g5]al classes3 #a4 ,prim>y coils2 #b4 ,second>y coils4 ,! subject ( electromagnetic induction has be5 fully expla9$ 9 *apt] ,x1 b x may be said1 ) special ref]5ce to induction coils1 t ! op]ation ( ! two classes j m5tion$ is respectively due to3 #a4 ,self-induction2 #b4 ,mutual induction4 ,self-induction4--,?is is ! prop]ty ( an electric curr5t by virtue ( :i* x t5ds to resi/ any *ange 9 its rate ( fl[4 ,x is sometimes spok5 ( z electromagnetic in]tia & is analog\s to ! me*anical in]tia ( matt]4 ,self-induction is due to ! action ( ! curr5t ^u itself dur+ v>iations 9 /r5g?4 ,x becomes especially m>k$ 9 a coil ( wire1 9 :i* ! adjac5t turns act inductively ^u ea* o!r ^u ! pr9ciple ( mutual induction aris+ betwe5 two sep>ate adjac5t circuits4 ,self-induction manife/s itself by giv+ 8mom5tum0 to ! curr5t s t x _c be in/antly /opp$ :5 ! circuit is brok51 ! result be+ a bright sp>k at ! mom5t ( break+ ! circuit4 ,on acc\nt ( ?is sp>k a prim>y induction coil is us$ 9 l[ t5sion or 8make & break0 ignition sy/ems4 ,illu/ration3 ,,fig4 #ace4--;,diagram illu/rat+ ! action ( mutual induction betwe5 two circuits2 ! "o includ+ a s\rce ( electrical en]gy & a swit*2 ! o!r includ+ a galvanomet]1 b hav+ no cell or o!r electrical s\rce4 ,dur+ ! increase or decrease 9 ! /r5g? ( ! curr5t z on clos+ or op5+ ! key a curr5t is induc$ 9 ! second>y circuit 9 a direction opposite to t ( ! prim>y curr5t z indicat$ by ! arr[s4 ,9 a s+le circuit1 consi/+ ( a /raight wire & a p>allel return wire !re is little or no self-induction4 ,:5 a circuit conta9+ a prim>y induction coil & a batt]y is clos$ !re is no sp>k because at ! in/ant ( clos+ ! circuit ! curr5t is at re/ & on acc\nt ( self-induction ! curr5t _c at once rise to its full value4 ,mutual ,induction4--,?is is a p>ticul> case ( electromagnetic induction 9 :i* ! magnetic field produc+ an electromotive =ce 9 a circuit is due to ! curr5t 9 a neighbor+ circuit4 ,! effect ( mutual induction may be expla9$ ) ! aid ( fig4 #ace4 ,if1 z illu/rat$1 a circuit includ+ a batt]y & a swit*1 be plac$ ne> ano!r circuit1 =m$ by connect+ ! two t]m9als ( a galvanomet] by a wire1 x w be f\nd t :5ev] ! fir/ circuit1 #a1 is clos$ by ! swit*1 all[+ a curr5t to pass 9 a giv5 direction1 a mom5t>y curr5t w be induc$ 9 ! second circuit1 #b1 z %[n by ! galvanomet]4 ,a simil> result w foll[ on ! op5+ ( ! batt]y circuit1 ! diff]5ce be+ t ! mom5t>y induc$ curr5t occurr+ at closure moves 9 a direction opposite to t 9 ! batt]y circuit1 :ile ! mom5t>y curr5t at op5+ moves 9 ! same direction4 ,curr5ts1 besides be+ induc$ 9 circuit #b at make or break ( circuit #a1 are also induc$ :5 ! curr5t 9 #a is fluctuat+ 9 int5sity4 ,! mo/ m>k$ results are obs]v$ :5 ! make or break is sudd51 ! action be+ /ronge/ at ! break ( ! curr5t 9 #a4 ,! inductive effect ( ! curr5t 9 ! arrangem5t %[n 9 fig4 #ace is v weak4 ,ques4 ,:at "n is giv5 to circuit #a8 ,ans4 ,! prim>y circuit4 ,ques4 ,:at "n is giv5 to circuit #b8 ,ans4 ,! second>y circuit4 ,ques4 ,:at names are giv5 respectively to ! curr5ts 9 circuits #a & #b8 ,ans4 ,! prim>y & second>y or induc$ curr5ts4 ,prim>y ,induction ,coils4--,^! repres5t ! simple/ =m ( coil1 & are us$ *iefly 9 l[ t5sion ignition to int5sify ! sp>k :5 a batt]y =ms ! curr5t s\rce4 ,a prim>y coil consi/s ( a long iron core w\nd ) a consid]able l5g? ( l[ resi/ance insulat$ copp] wire1 ! l5g? ( ! core & ! numb] ( turns ( ! insulat$ wire w9d+ det]m9+ ! effici5cy4 ,! effect ( ! iron core is to increase ! self-induction4 ,illu/ration3 ,,fig4 #acf4--,prim>y induction coil z us$ = l[ t5sion ignition4 ,coils ( ?is type are made 9 a great v>iety ( =m & size4 ,ord9>ily ! w9d+ consi/s ( ab\t six convolutions ( ,no4 #ad copp] wire4 ,! w9d+ is usually cov]$ & ! ends capp$ ) ebonite heads s t ! core wires are n expos$4 ,! sp>k produc$1 z previ\sly expla9$1 is due to self-induction1 & x %\ld be rememb]$ t 9 ! op]ation ( ! coil1 ! sp>k occurs at ! in/ant ( break+ ! circuit1 n at ! in/ant ( mak+4 ,second>y ,induction ,coils4--,! arrangem5t %[n 9 fig4 #acg1 may be consid]$ z a v simple or rudim5t>y =m ( second>y induction coil4 ,9 ! actual coil1 ! prim>y & second>y circuits 7correspond+ to #a & #b 9 fig4 #ace7 are made up ( coils ( insulat$ wire1 z %[n 9 fig4 #adc1 ! prim>y coil ,p1 be+ w\nd ov] a core ,c & ! second>y coil ,s be+ w\nd ov] ! prim>y4 ,! "o prop]ty ( su* an arrangem5t t makes x ( great value = mo/ purposes is t ! voltage ( ! induc$ curr5ts may be increas$ or dim9i%$ to any ext5t dep5d+ on ! relation betwe5 ! numb] ( turns 9 ! prim>y & second>y w9d+4 ,?is relation may be express$ 9 ! foll[+ rule3 ,! voltage ( ! second>y curr5t is 7approximately7 to ! voltage ( ! prim>y curr5t z ! numb] ( turns ( ! second>y w9d+ is to ! numb] ( turns ( ! prim>y w9d+4 ,illu/ration3 ,,fig4 #acg4--,production ( sp>k ) pla9 coil4 ,connect ! ends or leads ( ! second>y w9d+ to fix$ insulators & b5d ! ends s !y are f "o-sixte5? to "o-eigh? in* ap>t4 ,connect "o end ( ! prim>y w9d+ to an electric batt]y1 & ) ! o!r lead ( ! prim>y w9d+ bru% aga9/ ! o!r t]m9al ( ! batt]y1 z indicat$4 ,:5 ! contact is brok5 !re w be a sp>k bo? at ! po9t ( rupture 9 ! prim>y circuit & at ! gap4 ,an electric impulse is also induc$ 9 ! second>y circuit :5 ! prim>y circuit is clos$ & ! curr5t fl[+ 9 x gradually rises to its maximum value1 b ?is impulse is too feeble to cause a sp>k to jump across ! gap4 ,only ! impulse induc$ 9 ! second>y dur+ ! dy+ out ( ! curr5t 9 ! prim>y is utiliz$4 ,= in/ance1 if ! voltage ( ! prim>y curr5t be #e volts1 ! prim>y w9d+ h #aj turns & ! second>y #ajj turns1 !n ,second>y voltage3 #e 33 #ajj 3 #aj f :i* ,second>y voltage #ej volts 7approximately7 ,! watts 9 ea* circuit are approximately ! same2 h5ce3 if1 = in/ance1 ! curr5t /r5g? 9 ! prim>y circuit be #e amp]es1 ! watts 9 prim>y circuit are #e #e #be4 ,accord+ly1 = ! second>y circuit ! curr5t /r5g? is3 #be watts _/ #ej volts #a_/b amp]e 7approximately7 ,f ?is1 x is se5 t :]e ! voltage is rais$ 9 ! second>y circuit1 ! curr5t fl[ is small z comp>$ to t 9 ! prim>y circuit2 !re=e1 heavy wire is us$ 9 ! prim>y w9d+ & f9e wire 9 ! second>y1 z indicat$ 9 figs4 #acg & #adc4 ,= mo/ purposes a v mu* high] second>y voltage is requir$ ?an 9 ! example j giv54 ,illu/ration3 ,,fig4 #ach4--;,diagram ( batt]y & coil connections = jump sp>k ignition z appli$ to a motor cycle4 ,coils are usually pla9ly label$ ) ! abbreviations3 8,bat410 8,pri410 8,sec410 indicat+ t ! wires are to be connect$ to ! batt]y1 ! prim>y circuit or contact mak]1 & ! sp>k plug4 ,! batt]y & prim>y wires be+ = ! l[ t5sion circuit are easily di/+ui%$ f ! second>y wire by ! small am\nt ( insulation surr\nd+ !m4 ,second>y induction coils may be divid$ into ?ree g5]al classes3 #a4 ,pla9 coils2 #b4 ,vibrator coils2 #c4 ,cond5s] coils4 ,! pla9 coil gives b "o sp>k :5 ! prim>y circuit is made & brok51 :ile ! vibrator coil gives a s]ies ( sp>ks foll[+ ea* o!r 9 rapid succession4 ,pla9 ,second>y ,induction ,coils4--,coils ( ?is class are v simple & consi/ (3 #a4 ,core2 #b4 ,prim>y w9d+2 #c4 ,second>y w9d+4 ,! con/ruction ( a pla9 coil1 su* z w\ld be suitable = ignition s]vice1 is ab\t z foll[s3 ,! core is made ( s(t anneal$ iron wires 7,no4 #bj ,b & ,s gauge7 f "o-half to ?ree-qu>t]s ( an in* 9 diamet] & ab\t six in*es long4 ,ov] ?is core is slipp$ a spool ( insulat+ mat]ial 7h>d rubb] or composition71 on :i* is w\nd fir/ ! prim>y w9d+ ( ! coil1 :i* consi/s ( sev]al lay]s ( ab\t ,no4 #ah ,b & ,s gauge silk insulat$ magnet wire4 ,aft] ! prim>y w9d+ has be5 w\nd ov] ! insulat$ core1 & ! ends h be5 prop]ly br\ght out ?r\gh ! heads ( ! spool to be connect$ to b9d+ po/s !reon1 a lay] ( insulat+ mat]ial is appli$ ov] ! prim>y wire1 & ! second>y w9d+ is !n w\nd on4 ,! wire = ! second>y w9d+ consi/s ( ab\t ,no4 #cf ,b & ,s gauge silk cov]$ magnet wire1 ! am\nt us$ v>y+ consid]ably1 dep5d+ on ! desir$ voltage ( ! second>y curr5t4 ,:5 all ! wire has be5 w\nd on1 ! ends are br\ght out to ! b9d+ po/s1 ! coil is soak$ 9 %ellac dissolv$ 9 alcohol & bak$1 or 9 melt$ p>aff9 or a p>aff9 comp\nd1 & all[$ to cool4 ,x is !n plac$ 9 ei!r a cyl9drical h>d rubb] %ell or 9 a h>d wood box4 ,! proportions ( su* coils v>y greatly2 = motor cycle use !y are made long & ( small diamet] 7#ajb-a_/b in*es = in/ance71 :ile = "s o!r purposes %ort & ?ick coils are f\nd m conv5i5t4 ,ques4 ,h[ may ! coil j describ$ be connect$ = demon/rat+ purposes8 ,ans4 ,connect ! ends ( ! second>y w9d+ to fix$ insulators & b5d ! ends s !y are ab\t #a_/h in* or less ap>t4 ,connect "o end ( ! prim>y w9d+ to a batt]y & bru% ! o!r end ( ! prim>y w9d+ aga9/ ! o!r t]m9al ( ! batt]y z indicat$ 9 fig4 #acg4 ,ques4 ,:at happ5s :5 ! prim>y circuit is made8 ,ans4 ,an electric pressure is induc$ 9 ! second>y circuit1 b ( n en\gh int5sity to cause a sp>k to jump across ! air gap4 ,illu/ration3 ,,fig4 #aci4--;,a ,m$ical coil ) armature & atta*m5ts consi/+ ( electrodes1 foot place1 sponge1 induction coil etc4 ,a curr5t ( any degree ( int5sity may be obta9$4 ,! curr5ts furni%$ are3 #a1 prim>y1 #b1 second>y2 & #c1 prim>y & second>y comb9$4 ,ques4 ,:at happ5s :5 ! prim>y circuit is sudd5ly brok58 ,ans4 ,a sp>k is produc$ bo? at ! po9t ( break 9 ! prim>y circuit & at ! air gap 9 ! second>y circuit4 ,ques4 ,:y is a sp>k produc$ at ! air gap at break & n at make ( ! prim>y curr5t8 ,ans4 ,because :5 ! curr5t is fl[+ x _c be /opp$ in/antly on acc\nt ( self-induction1 t is1 x acts z ?\gh x possess$ weight4 ,if ! read] has *>ge ( a gas eng9e ) a make & break ignition sy/em1 he w (t5 avoid vexati\s delays 9 locat+ ignition tr\bles1 if he rememb] t "o ( ! mo/ important conditions = obta9+ a good sp>k is t ! break take place ) great rapidity4 ,?is1 ( c\rse1 involves t ! ignition spr+ be adju/$ to ! prop] t5sion4 ,illu/ration3 ,,fig4 #adj4--,rhumkorff induction coil4 ,a second>y coil ) vibrator & cond5s]2 a type g5]ally us$ 9 ! laboratory4 ,! "n ,rhumkorff 0 =m]ly v widely appli$ to induction coils = ! reason t "s ( ! e>lie/ coils 7 con/ruct$ by ,rhumkorff4 ,second>y ,induction ,coils ) ,vibrator & ,cond5s]4--,a pla9 second>y coil1 su* z j describ$1 w only give feeble sp>ks = its size = ! foll[+ reasons3 ,! inductive effect ( ! prim>y w9d+ 9 ! second>y dep5ds z previ\sly expla9$ on ! rate at :i* ! curr5t 9 ! prim>y w9d+ decreases or dies out4 ,if a /rong inductive effect is to be produc$ 9 ! second>y1 ! curr5t 9 ! prim>y mu/ /op sudd5ly4 ,?is is prev5t$ by self-induction 9 ! prim>y w9d+1 :i* opposes any *ange 9 ! curr5t /r5g?4 ,! direct result is t1 z ! prim>y circuit is brok51 a sp>k appe>s at ! break1 :i* means t ! curr5t cont9ues to fl[ aft] ! break has occurr$1 dy+ d[n comp>atively sl[ly1 h5ce1 ! inductive effect on ! second>y w9d+ is small4 ,illu/ration3 ,,fig4 #ada4--;,conv5tional diagram ( a cond5s]4 ,a cond5s] is a device design$ to absorb or hold an electric *>ge 9 ab\t ! same mann] z a vessel w hold a liquid4 ,e conductor ( electricity =ms a cond5s] & its capacity = hold+ a *>ge dep5ds ^u ! ext5t ( its surface4 ,a cond5s] is !re=e made ( conductive mat]ial =m$ into su* %ape z to pres5t ! maximum surface = a giv5 am\nt ( mat]ial4 ,! sp>k at ! break 9 ! prim>y circuit is ev5 l>g] ?an t 9 ! second>y circuit1 & z ?is prim>y sp>k s]ves no useful purpose1 b1 on ! contr>y1 quickly burns away ! contact po9ts1 su* an arrangem5t is obvi\sly defective4 ,! vibrator-cond5s] coil is design$ to ov]come ?is tr\ble & also to give a s]ies ( sp>ks foll[+ 9 rapid succession in/ead ( "o4 ,x %\ld be not$ t a s]ies ( sp>ks foll[+ ea* o!r ) consid]able rapidity may be obta9$ ) a pla9 coil by plac+ a me*anical vibrator 9 ! prim>y circuit1 z us$ on "s motor cycle ignition circuits4 ,! object ( ! vibrator1 ( a vibrator-cond5s] coil1 is to rapidly make & break ! prim>y circuit dur+ ! "t ! prim>y circuit is clos$ ext]nally4 ,x consi/s ( a flat /eel spr+ secur$ at "o end1 ) ! o!r free to vibrate4 ,at a po9t ab\t midway betwe5 its ends1 contact is made ) ! po9t ( an adju/+ screw1 f :i* x spr+s away & returns 9 vibrat+4 ,! po9ts ( contact ( blade & screw are tipp$ ) plat9um4 ,"o wire ( ! prim>y circuit is connect$ to ! blade & ! o!r to ! screw1 h5ce1 ! circuit is made :5 ! blade is 9 contact ) ! screw & brok5 :5 x spr+s away4 ,illu/ration3 ,,fig4 #adb4--;,con/ruction ( cond5s] = an induction coil4 ,! conduct+ mat]ial us$ is t9foil1 ( :i* a l>ge numb] ( %eets are prep>$1 all cut to ! same size4 ,^! are plac$1 "o on top ( ! o!r1 l ! pages ( a book1 ) a ?9 lay] ( insulat+ mat]ial betwe51 usually two %eets ( p>aff9$ pap]4 ,numb]+ ! successive %eets ( t9foil s]ially1 all %eets ( ev5 numb] are connect$ toge!r & all %eets ( odd numb] are connect$ toge!r1 ^! connections =m+ ! t]m9als ( ! cond5s]4 ,! cond5s] is !n connect$ across ! break 9 ! prim>y circuit4 ,a cond5s] is us$ to absorb ! self-induc$ curr5t ( ! prim>y w9d+ & ?us prev5t x oppos+ ! rapid fall ( ! prim>y curr5t4 ,e conductor ( electricity =ms a cond5s] & its capacity = absorb+ a *>ge dep5ds ^u ! ext5t ( its surface4 ,h5ce1 a cond5s] is con/ruct$ ( conductive mat]ial s arrang$ z to pres5t ! greate/ surface = a giv5 am\nt ( mat]ial4 ,! usual =m ( cond5s] = induction coils z %[n 9 figs4 #ada & #adb is compos$ ( a numb] ( lay]s ( t9 foil sep>at$ by p>aff9 pap]1 ea* alt]nate lay] be+ connect$ at ! ends4 ,fig4 #adc is a diagram ( a vibrator coil4 ,,cc repres5ts ! core compos$ ( s(t iron wires4 ,,pp is ! prim>y w9d+ & ,,ss ! second>y4 ,!re is no connection betwe5 ^! w9d+s & !y are c>efully insulat$4 ,y is ! vibrator or trembl] & ,d ! c5t] ab\t :i* x vibrates4 ,w is a swit* us$ = op5+ & clos+ ! prim>y circuit2 ,b1 a batt]y ( five cells4 ,! po9t ( adju/+ screw ,a re/s aga9/ a plat9um po9t ,r sold]$ ^u ! vibrator4 ,illu/ration3 ,,fig4 #adc4--;,diagram ( a vibrator coil4 ,! p>ts are z foll[s3 ,a1 contact screw2 ,b batt]y2 ,c1 core2 ,d1 vibrator t]m9al2 ,g1 cond5s]2 ,p1 prim>y w9d+2 ,s1 second>y w9d+2 ,w1 swit*2 ,y1 vibrator4 ,:5 ! swit* is clos$1 ! foll[+ cycle ( actions take place3 #a1 ! prim>y curr5t fl[s & magnetizes core2 #b1 magnetiz$ core attracts ! vibrator & breaks prim>y circuit2 #c1 ! magnetism vani%es1 includ+ a mom5t>y high t5sion curr5t 9 ! second>y w9d+2 #d1 magnetic attraction ( ! core hav+ ceas$1 vibrator spr+ r5ews contact2 #e1 prim>y circuit is aga9 complet$ & ! cycle beg9s anew4 ,if ! swit* ,w be clos$1 ! electric curr5t g5]at$ by ! batt]y ,b w fl[ ?r\gh ! prim>y w9d+4 ,?is w cause ! core ,,cc to become magnetiz$1 & ! vibrator ,y w at once be drawn t[>d x4 ,?is w break ! connection at ,r4 ,! core1 be+ made ( s(t iron1 imm$iately ^u ! int]ruption ( ! curr5t1 w aga9 lose its magnetism1 & ! vibrator w return to its orig9al position4 ,?is aga9 closes ! circuit1 aft] :i* ! op]ation ( op5+ & clos+ x is repeat$ ) great rapidity s long z ! swit* ,w rema9s clos$4 ,illu/ration3 ,,fig4 #add4--;,circuit diagram ( a ma/] vibrator coil4 ,b1 is ! batt]y2 ,c1 ! unit coils2 ,c#a1 ,c#b1 etc41 ! cond5s]s2 ,p1 ! prim>y w9d+s & ,s1 ! second>y w9d+s2 ,h#a1 ,h#b1 etc41 ! sp>k plugs2 ,t1 ! tim]2 ,,mp1 ! ma/] prim>y2 ,v1 ! vibrator2 ,w1 ! common prim>y connection2 #a1 #b1 etc41 ! /ation>y contacts ( ! tim]4 ,! cycle ( actions may be briefly /at$ z foll[s3 #a4 ,a prim>y curr5t fl[s & magnetizes ! core2 #b4 ,! magnetiz$ core attracts ! vibrator :i* breaks ! prim>y circuit2 #c4 ,! core loses its magnetism & ! vibrator spr+s back to its orig9al position2 #d4 ,! vibrator1 by return+ to its orig9al position1 closes ! prim>y circuit & ! cycle beg9s aga94 ,illu/ration3 ,,fig4 #ade4--,! ,splitdorf ma/] vibrator coil4 ,z %[n 9 ! illu/ration ! sev]al unit coils are indicat$ by ! figures #a1 #b1 #c1 & #d4 ,a fif? unit ,v at ! left conta9s ! ma/] vibrator4 ,! prim>y wires ,p connect ) ! tim] & ! second>y wires ,s ) ! plugs4 ,b ,b %[s ! batt]y connections4 ,magnetic ,vibrators4--,_m types ( vibrator are us$ on induction coils1 ! mo/ important requirem5t be+ t ! break occur ) great rapidity4 ,9 ord] to r5d] ! break z sudd5 z possible1 diff]5t exp$i5ts h be5 resort$ to1 all t5d+ to make ! me*anism m complicat$1 yet hav+ suffici5t m]it 9 "s cases to w>rant _! adoption4 ,9 ! pla9 vibrator1 ! circuit is brok5 at ! in/ant ! spr+ beg9s to move1 h5ce1 ! op]ation mu/ be comp>atively sl[4 ,9 ord] to r5d] ! break m abrupt "s vibrators h two mov+ p>ts1 "o ( :i* is attract$ by ! magnetic core ( ! coil & mov$ a c]ta9 di/ance be=e ! break is effect$4 ,a vibrator ( ?is type is %[n 9 fig4 #adf & describ$ "u ! illu/ration4 ,illu/ration3 ,,fig4 #adf4--;,a hamm] vibrator4 ,:5 at re/1 ! upw>d t5sion ( ! spr+1 :i* c>ries ! armature ,a1 holds ! plat9um po9ts 9 contact & causes ! upp] spr+ ,c1 to leave %\ld] ( adju/+ screw ,d1 & re/ aga9/ ! heavy brass plate above x4 ,:5 ! iron core ,b1 attracts ! armature ,a1 ! d[nw>d t5sion on ! upp] spr+1 ,c1 causes ! latt] to foll[ ! armature d[n1 hold+ ! plat9um po9t 9 contact1 until ! end ( ! upp] spr+ ,c1 /rikes ! l[] %\ld] ( ! adju/+ screw1 ,d1 :i* gives x a 8hamm] break40 ,! adju/+ screw is held firmly 9 position by a bronze spiral spr+ "u %\ld] ,d4 ,vibrator ,adju/m5t4--,:5 a vibrator coil is us$1 ! quality ( ! sp>k dep5ds l>gely ^u ! prop] adju/m5t ( ! vibrator4 ,! foll[+ g5]al in/ructions = adju/+ a pla9 vibrator %\ld be c>efully not$3 #a4 ,remove entirely ! contact adju/+ screw4 #b4 ,see t ! surfaces ( ! contact po9ts are flat1 clean & bright4 #c4 ,adju/ ! vibrator spr+ s t ! hamm] or piece ( iron on ! end ( ! vibrator spr+ /&s normally ab\t "o-sixte5? ( an in* f ! end ( ! coil4 #d4 ,adju/ ! contact screw until x j t\*es ! plat9um contact on ! vibrator spr+--be sure t x t\*es1 b v lightly4 ,n[ />t ! eng9e2 if x miss at all1 tight5 up1 or screw 9 ! contact screw a trifle fur!r--j a trifle at a "t1 until ! eng9e w run )\t miss+ explosions4 ,,table ,,( ,,induction ,,coil ,,dim5sions4 ,l5g? ( sp>k #c_/h in* #a_/b in* #a in* #b in*es ---------------------------------------- -------------------------------- ,size ( bobb9 #b-a_/h #b-a_/b #c #c_/h #d #b-c_/d ends #a-a_/d #e_/af #c_/h ---------------------------------------- -------------------------------- ,l5g? ( bobb9 #d #e-a_/b #f-a_/b #f-a_/b ---------------------------------------- -------------------------------- ,l5g? & #d-a_/d #f #e_/h #f-a_/b #c_/d ---- diamet] ( core #g_/af ---------------------------------------- -------------------------------- ,size ( base #g-a_/d #i #e #b #ad-a_/b #ab #g-a_/b #c-a_/d #f #c-a_/d #a-a_/b #a-c_/d ---------------------------------------- -------------------------------- ,size ( t9foil #d #b #e-a_/b #f #d #f #f %eets #c-a_/d ---------------------------------------- -------------------------------- ,numb] ( t9foil #cf #dj #dj #fj %eets ---------------------------------------- -------------------------------- ,size ( pap] #e #c #f-a_/b #i #e ---- %eets #d-a_/d ---------------------------------------- -------------------------------- ,prim>y coil ,no4 #ah ,no4 #ah #b lay]s ,no4 #b lay]s #ad #af1 silk ,b4 ,w4 ,g4 silk cov]$4 cov]$4 ---------------------------------------- -------------------------------- ,second>y coil #c_/d lb4 #a lb4 #a-a_/d lbs4 #b-a_/b lbs4 ,no4 #dj ,no4 #dj ,no4 #ch ,no4 #cf ---------------------------------------- -------------------------------- ,,table ,,( ,,sp>k+ ,,di/ances ,,9 ,,air4#ac ,di/ance4 ,volts4 7,in*es47 ------------------------- #ejjj 4#bbe #ajjjj 4#dg #bjjjj #a4jj #cjjjj #a4fbe #cejjj #b4jj #dejjj #b4ie #fjjjj #d4fe #gjjjj #d4he #hjjjj #g4a #ajjjjj #i4f #acjjjj #ab4ie #aejjjj #ae4jj ,po9ts ,relat+ to ,ignition ,coils4--#a4 ,mo/ ignition induction coils or 8sp>k coils0 z !y are call$1 h t]m9als m>k$ 8batt]y10 8gr\nd10 etc41 & to %ort circuit ! tim] = ! purpose ( te/+ ! vibrator1 x is only necess>y to bridge ) a screw driv] f ! 8batt]y0 b9d+ po/ to ! 8gr\nd0 b9d+ po/4 #b4 ,9 adju/+ ! vibrator ( an ignition coil1 ! latt] %\ld n require ov] "o-half amp]e ( curr5t4 ,illu/ration3 ,,fig4 #adg to #afa4--,wir+ diagrams %[+ connections ( "s /&>d sp>k coils4 ,key3 ,b1 to batt]y2 ,c1 to commutator or tim]2 ,g1 to gr\nd 7eng9e frame72 ,p1 to plugs2 ,s1 to swit*4 #a1 #f t]m9al /&>d non-vibrator coil2 #b1 #c t]m9al /&>d vibrator coil2 #c & #d1 t]m9al /&>d vibrator coil2 #e1 /&>d d\ble vibrator coil2 #f1 /&>d triple vibrator coil2 #g1 /&>d quadruple vibrator coil2 #h1 s+le da% coil2 #i1 s+le da% coil ) swit*2 #aj1 d\ble da% coil2 #aa1 d\ble da% coil ) swit*2 #ab1 triple da% coil2 #ac1 triple da% coil ) swit*2 #ad1 quadruple da% coil2 #ae1 sextuple da% coil4 #c4 ,a half turn ( ! adju/+ screw on a coil w (t5 increase ! /r5g? ( ! curr5t f\r or five times ! orig9al am\nt1 h5ce1 ! necessity ( c>efully adju/+ ! vibrator4 ,:5 ! adju/m5t is n prop]ly made x causes1 #a1 %ort life ( ! batt]y1 #b1 burn$ contact po9ts1 & #c1 poor runn+ ( ! eng9e4 #d4 ,9 adju/+ a multi-unit coil1 if any misfir+ be notic$1 hold d[n "o vibrator aft] ano!r until ! faulty "o is locat$1 !n screw 9 its contact screw v slightly4 #e4 ,! numb] ( cells 9 ! circuit %\ld be proportion$ to ! design ( ! coil4 ,if ! coil be describ$ by ! mak] z a #d volt coil1 x %\ld be work$ by two cells ( a /orage batt]y or f\r dry cells4 ,! voltage ( ! latt] w be some:at high]1 b s9ce _! int]nal resi/ance is also great]1 ! curr5t deliv]y w be ab\t ! same4 ,mo/ coils are made to op]ate on f #d to #f volts4 #f4 ,x is a mi/ake to use a high] voltage ?an t = :i* ! coil is design$1 because x does n improve ! sp>k & ! contact po9ts ( ! vibrator w be burn$ m rapidly1 moreov]1 ! life ( ! batt]y w be %ort5$4 ,,*apt] ,,xii ,,! ,,dynamo ,! dynamo is a ma*9e :i* conv]ts me*anical en]gy into electrical en]gy by electromagnetic induction4 ,! ^w dynamo is us$ to designate a ma*9e :i* produces direct curr5t z di/+ui%$ f ! alt]nator or ma*9e g5]at+ an alt]nat+ curr5t4 ,9 a broad] s5se1 ! ^w g5]ator is us$ to d5ote any ma*9e g5]at+ electric curr5t by electromagnetic induction2 ! t]m !re=e includes bo? dynamos & alt]nators4 ,op]ation ( a ,dynamo4--,a dynamo does n create electricity1 b g5]ates or produces an induc$ electromotive =ce :i* causes a curr5t ( electricity to fl[ ?r\gh a circuit ( conductors 9 mu* ! same way z a =ce pump causes a curr5t ( wat] to fl[ 9 pipes4 ,! electromotive =ce g5]at$ 9 ! dynamo causes ! curr5t ( electricity to pass f a l[] to a high] pot5tial 9 ! ma*9e1 & f ! high] back to ! l[] pot5tial 9 ! ext]nal circuit2 t is1 ! dynamo g5]ates electrical pressure :i* ov]comes ! resi/ance or opposition to ! curr5t fl[ 9 ! circuit4 ,! pump produces a me*anical pressure :i*1 = in/ance1 may be us$ to =ce wat] into an elevat$ res]voir aga9/ ! back pressure due to its weight4 ,illu/ration3 ,,fig4 #afb4--;,holz] ,cabot type 8,m0 dynamo4 ,! design ( ! base is su* t x all[s ! field r+ or frame to drop d[n1 l[]+ ! c5t] ( gravity1 :i* gives increas$ /ability4 ,! p$e/als are bolt$ directly to ! base4 ,bo? front & re> p$e/als are removable1 s t ! armature may be tak5 out f ei!r end )\t di/urb+ ! bru%es or connections4 ,! j\rnals are provid$ ) oil r+s :i* keep ! oil 9 cont9ual circulation ar\nd ! %aft by means ( oil grooves 9 ! j\rnal4 ,! pole pieces are cyl9drical 9 %ape & are fitt$ ) %oes :i* reta9 ! field coils 9 place & assi/ commutation4 ,! field coils are =m] w\nd1 ! insulation be+ re9=c$ ) mica4 ,!y are soak$ 9 v>ni% & bak$ = #bd h\rs at #bbe ,fahr4 ,! armature is w\nd z desir$1 s]ies1 %unt or comp\nd4 ,! armature core is ( ! drum type & is lam9at$1 ! discs be+ held by end plates lock$ )\t ?r\gh bolts4 ,! armature coils are =m$ ( r\nd1 ribbon or b> copp]1 & are )\t jo9t except at ! commutator2 !y lie 9 tr\ghs ( insulat+ mat]ial1 ! upp] lay]s be+ insulat$ f ! l[] lay]s2 !y are reta9$ 9 place by maple w$ges secur$ by b9d+ wires1 sold]$ ?r\gh\t _! l5g?4 ,! commutator segm5ts are drop =g$ 9 ! small]1 & h>d drawn 9 ! l>g] sizes4 ,radial bru%es are us$4 ,! effici5cy ( ?is type ma*9e is /at$ by ! mak] at f #hj to #ij1 accord+ to size4 ,! po9t to be emphasiz$ is t ! dynamo does n create electricity 7nor ! pump wat]7 b sets into motion some?+ already exi/+ by g5]at+ suffici5t pressure to ov]come ! opposition to its movem5t4 ,illu/ration3 ,,fig4 #afc4--;,g5]al ,electric #af ,,kw multi-pol> dynamo design$ to op]ate at mod]ate & sl[ spe$s4 ,! out] /ructure ( ! ma*9e consi/s ( a magnet frame hav+ feet 9 "o ca/+4 ,adju/m5t is provid$ = mov+ ! ma*9e on its b$ plate to tight5 ! belt4 ,! field coils are =m] w\nd & ! s]ies w9d+s p]mit ( any degree ( comp\nd+ up to #aj by ! use ( suitable ,g]man silv] %unts connect$ across ! s]ies field4 ,ess5tial ,p>ts ( a ,dynamo4--,! dynamo 9 its simple/ =m consi/s ( two pr9cipal p>ts3 #a4 ,! field magnet2 #b4 ,! armature4 ,illu/ration3 ,,fig4 #afd4--;,g5]al ,electric dynamo ) end %ield & armature remov$ %[+ con/ruction4 ,! core ( ! armature consi/s ( lam9ations key$ to spid] ) space blocks ins]t$ at int]vals to provide v5tilat+ ducts = cool+ ! core & w9d+s4 ,! armature is =m] w\nd--t is1 ! inductors are b5t to ! prop] %ape on a =m2 !y are1 !re=e1 int]*angeable4 ,ques4 ,:at is ! object ( ! field magnet8 ,ans4 ,to provide a field ( magnetic l9es or l9es ( =ce to be cut by ! armature inductors z !y revolve 9 ! field4 ,ques4 ,:at is an armature8 ,ans4 ,a collection ( inductors m\nt$ on a %aft & arrang$ to rotate 9 a magnetic field ) provision = collect+ ! curr5ts induc$ 9 ! inductors4 ,a simple loop or turn or wire may be consid]$ z ! simple/ =m ( armature4 ,ques4 ,h[ d armatures & field magnets diff] 9 dynamos & alt]nators8 ,ans4 ,a *>act]i/ic feature is t 9 ! dynamo ! field magnet is ! /ation>y "p & ! armature ! rotat+ "p1 :ile 9 ! alt]nator ! rev]se conditions usually obta94 ,ques4 ,) respect to ?is feature1 :at names are sometimes giv5 to ! armature & field magnet8 ,ans4 ,! /ator & ! rotor dep5d+ on :i* moves4 ,ques4 ,:at is ! real di/9ction betwe5 an armature & a field magnet8 ,ans4 ,! "n field magnet is prop]ly giv5 to t "p :i*1 :e!r /ation>y or revolv+1 ma9ta9s its magnetism /eady dur+ op]ation2 ! "n armature is prop]ly giv5 to t "p :i*1 :e!r revolv+ or fix$1 has its magnetism *ang$ 9 a regul>ly repeat$ fa%ion :5 ! ma*9e is 9 motion4 ,con/ruction ( ,dynamos4--,9 ! make up ( a dynamo1 z actually con/ruct$1 !re are five pr9cipal p>ts1 z foll[s3 #a4 ,b$ plate2 #b4 ,field magnets2 #c4 ,armature2 #d4 ,commutator2 #e4 ,bru%es4 ,,*apt] ,,xiii ,,! ,,dynamo3 ,,basic ,,pr9ciples ,a dynamo is a ma*9e = conv]t+ me*anical en]gy into electrical en]gy1 by means ( electromagnetic induction1 ! am\nt ( electric en]gy ?us obta9$ dep5d+ ^u ! me*anical en]gy orig9ally suppli$4 ,! ^w dynamo is prop]ly appli$ to a ma*9e :i* g5]ates#ad direct curr5t1 z di/+ui%$ f ! alt]nator1 :i* g5]ates alt]nat+ curr5t4 ,ques4 ,def9e a dynamo ) respect to its pr9ciple ( op]ation4 ,ans4 ,a dynamo is a ma*9e = fill+ & empty+ conduct+ loops ) magnetic flux1 & utiliz+ ! electromotive =ce ?us induc$ 9 !m = ! production ( curr5t 9 ! ext]nal circuit4 ,! fitness ( ?is def9ition is app>5t1 hav+ 9 m9d ! pr9ciples ( electromagnetic induction4 ,ques4 ,:at are ! ?ree ess5tial p>ts ( a dynamo8 ,ans4 ,! field magnet1 armature1 & commutator4 ,ques4 ,:at is ! object ( ! field magnet8 ,ans4 ,to provide a magnetic field1 ?r\gh :i* ! conduct+ loops arrang$ on a c5tral hub & =m+ ! armature are c>ri$1 or ! flux c>ri$ ?r\gh !m1 s t !y are successively fill$ & empti$ ( magnetic l9es4 ,ques4 ,:at is a commutator8 ,ans4 ,a device = caus+ ! alt]nat+ curr5ts g5]at$ 9 ! armature to fl[ 9 ! same direction 9 ! ext]nal circuit4 ,ques4 ,^u :at does ! voltage dep5d8 ,ans4 ,^u ! rate at :i* ea* conduct+ loop is fill$ & empti$ ( l9es ( =ce & ! numb] ( su* loops ) _! gr\p+ or connection4 ,ques4 ,h[ is ! op]ation ( a dynamo be/ expla9$8 ,ans4 ,by consid]+ fir/ ! action ( ! simple/ =m ( curr5t g5]ator1 or elem5t>y alt]nator4 ,ques4 ,describe an elem5t>y alt]nator4 ,ans4 ,x consi/s1 z %[n 9 fig4 #afe1 ( a s+le rectangul> loop ( wire ,a ,b ,c ,d1 "o end be+ atta*$ to a r+ ,f & ! o!r to ! %aft ,g1 & arrang$ s z to revolve ar\nd ! axis ,x ,x1 :i* is locat$ midway betwe5 ! two poles ( ! magnet4 ,two metallic /rips or bru%es ,m & ,s connect$ ) ! ext]nal circuit1 be> on ! r+ ,f & %aft ,g1 respectively1 9 ord] to 8collect0 ! curr5t g5]at$ 9 ! armature :5 ! ma*9e is 9 op]ation4 ,! long1 /raight1 horizontal arr[s jo9+ ! two poles ( ! magnet1 repres5t ! l9es ( =ce :i* make up ! magnetic field betwe5 ! poles4 ,! field is "h assum$ to be uni=m1 z indicat$ by ! equal spac+ ( ! arr[s4 ,ques4 ,:at happ5s :5 ! loop is rotat$8 ,ans4 ,accord+ to ! law ( electromagnetic induction1 :5 ! loop is rotat$ ar\nd its horizontal axis 9 ! direction indicat$ by ! curv$ arr[1 an electromotive =ce w be induc$ 9 ! loop1 ! magnitude ( :i* dep5ds on ! rate ( *ange ( ! numb] ( l9es ( =ce ?read+ ?r\gh1 or embrac$ by ! loop4 ,illu/ration3 ,,fig4 #afe4--,simple elem5t>y alt]nator4 ,its p>ts are a s+le conduct+ loop1 ,a ,b ,c ,d1 plac$ betwe5 ! poles ( a p]man5t magnet1 & hav+ its ends connect$ ) a r+1 ,f1 & %aft1 ,g1 ^u :i* be> bru%es ,m & ,s1 connect$ ) ! ext]nal circuit4 ,:5 ! loop is rotat$ clockwise ! induc$ curr5t w fl[ 9 ! direction indicat$ by ! arr[s dur+ ! fir/ half ( ! revolution4 ,t is1 if ! numb] ( l9es embrac$ by ! loop be increas$ f1 say1 #j to #ajjj1 or decreas$ f #ajjj to #j1 9 "o second1 ! electromotive =ce g5]at$ w be two times z great z if ! increase or decrease 7 only #ejj l9es p] second4 ,ques4 ,^u :at does ! direction ( ! induc$ curr5t dep5d8 ,ans4 ,^u ! direction ( ! l9es ( =ce & direction ( rotation ( ! loop4 ,ques4 ,h[ is ,flem+'s rule appli$ to det]m9e ! direction ( curr5t8 ,ans4 ,9 apply+ ?is rule1 ! horizontal portion ( ! loop1 su* z ,a ,b or ,c ,d 7fig4 #afe71 is to be consid]$ z mov+ up or d[n2 t is1 ! compon5t ( its motion at "r angles to ! l9es ( =ce is tak5 z ! direction ( motion4 ,:5 ! loop is 9 ! position ,a ,b ,c ,d1 su* t its plane is v]tical or p]p5dicul> to ! l9es ( =ce1 ! maximum numb] ( magnetic l9es ?read ?r\gh x1 b :5 x is 9 a horizontal position1 ,a ,b ,c ,d1 s t its plane is p>allel to ! l9es ( =ce1 no l9es pass ?r\gh ! loop4 ,dur+ ! rotation f position ,a ,b ,c ,d to ,a ,b ,c ,d1 ! numb] ( l9es pass+ ?r\gh ! loop is r$uc$ f ! maximum to z]o1 ! r$uction tak+ place ) increas+ rapidity z ! loop approa*es ! horizontal position1 ! electromotive =ce ?us induc$ increas+ 9 l proportion4 ,cont9u+ ! rotation f ! horizontal position ,a ,b ,c ,d to ! inv]t$ v]tical position ,a ,b ,c ,d 7fig4 #aff71 ! numb] ( l9es pass+ ?r\gh ! loop is increas$ f z]o to ! maximum1 ! increase tak+ place ) decreas+ rapidity z ! loop approa*es ! inv]t$ v]tical position1 ! electromotive =ce ?us induc$ decreas+ 9 l proportion4 ,ques4 ,h[ does ! curr5t fl[ dur+ ! fir/ half ( ! revolution ( ! loop8 ,ans4 ,x fl[s 9 ! direction ,a ,b ,c ,d 7fig4 #afe71 z is easily asc]ta9$ by aid ( ,flem+'s rule4 ,illu/ration3 ,,fig4 #aff4--,simple elem5t>y alt]nator1 %[+ rev]sal ( curr5t :5 ! loop has made "o half revolution f ! position ( fig4 #afe4 ,x %\ld be not$ t ,a ,b1 = in/ance1 :i* has be5 mov+ d[nw>d dur+ ! fir/ half ( ! revolution 7fig4 #afe71 moves upw>d dur+ ! second half 7fig4 #aff72 h5ce1 ! curr5t dur+ ! latt] int]val fl[s 9 ! opposite direction4 ,ques4 ,:at is ! pa? ( ! curr5t to ! ext]nal circuit8 ,ans4 ,x fl[s out ?r\gh bru% ,m 7fig4 #afe7 & returns ?r\gh bru% ,s1 ?us mak+ ,m positive & ,s negative4 ,ques4 ,:at occurs dur+ ! second half ( ! revolution8 ,ans4 ,! wire ,a ,b 7fig4 #aff71 :i* be=e 0 mov+ 9 a d[nw>d direction1 moves 9 an upw>d direction2 h5ce1 ! curr5t is rev]s$ & fl[s ar\nd ! loop 9 ! direction ,a ,d ,c ,b 7fig4 #aff71 go+ out ?r\gh bru% ,s & return+ ?r\gh bru% ,m4 ,?is makes ,m negative & ,s positive4 ,illu/ration3 ,,fig4 #afg4--;,illu/rat+ ! increase & decrease 9 ! rate magnetic l9es are cut by a revolv+ loop4 ,! initial position ( ! loop is tak5 at "r angles to ! direction ( ! l9es ( =ce4 ,s9ce ! loop rotates at a con/ant spe$1 x is evid5t t x does n cut ! magnetic l9es at uni=m rate1 because ! int]cept$ arcs #j-a1 #a-b1 etc41 are unequal4 ,^! arcs1 rectifi$ at ! "r by ! horizontal l9es #j-a1 #a-b1 etc41 %[ m cle>ly ! increase & decrease 9 ! rate at :i* ! magnetic l9es are cut4 ,ques4 ,:at may be said ( ! electromotive =ce dur+ ! second half ( ! revolution8 ,ans4 ,x v>ies 9 a simil> mann] z 9 ! fir/ half ( ! revolution2 t is1 ! magnetic l9es are cut ) increas+ rapidity dur+ ! ?ird qu>t]1 & ) decreas+ rapidity dur+ ! f\r? qu>t] ( ! revolution1 :i* causes ! electromotive =ce to increase & decrease dur+ ^! int]vals4 ,! cycle ( ev5ts j describ$ may be summ$ up z foll[s3 ,dur+ ! revolution ( ! loop3 #a4 ,f #j to #ij1 ! electromotive =ce increases f #j to maximum2 #b4 ,f #ij to #ahj1 ! electromotive =ce decreases f maximum to z]o2 #c4 ,f #ahj to #bgj1 curr5t rev]ses & ! electromotive =ce increases f z]o to maximum2 #d4 ,f #bgj to #cfj1 ! electromotive =ce decreases f maximum to z]o4 ,x 0 /at$ t1 dur+ ! revolution ( ! loop1 ! magnetic l9es 7 cut 8) increas+ or decreas+ rapidity10 caus+ ! electromotive =ce to rise or fall4 ,! reason = ?is is illu/rat$ 9 fig4 #afg4 ,! loop is "h %[n 9 a horizontal position at "r angles to ! direction ( ! magnetic field2 ! latt]1 z indicat$ by ! ev5 spac+ ( ! v]tical arr[s repres5t+ ! magnetic l9es1 is assum$ to be uni=m4 ,! wire ,c ,d ( ! loop1 z x rotates at con/ant spe$1 cuts ! magnetic l9es at ! po9ts #j1 #a1 #b1 #c1 etc41 b ! di/ances #j-a1 #a-b1 #b-c1 etc41 betwe5 ^! po9ts1 are unequal2 t is1 ! wire ,c ,d travels f>!r 9 cutt+ ! l9es #j & #a1 ?an x does 9 cutt+ #a & #b1 & /ill less 9 cutt+ ! l9es #b & #c4 ,aft] cutt+ ! l9e #d1 :i* passes ?r\gh ! axis ( revolution1 ! opposite conditions obta94 ,if ! arcs #j-a1 #a-b1 etc41 ( ! dott$ circle1 :i* are int]cept$ by ! magnetic l9es & pass$ ?r\gh by ! wire1 be rectifi$ & laid d[n "u ea* o!r1 z l9es #j-a1 #a-b1 etc41 ! "t ( passage ( ! wire betwe5 successive magnetic l9es w v>y z ! l5g?1 s9ce ! spe$ is uni=m4 ,?us ! wire 9 pass+ f l9e #j to l9e #a1 takes mu* m "t ?an 9 pass+ f #a to #b1 z indicat$ at ! left ( ! figure by #j-a & #a-b1 & /ill less 9 pass+ f #b to #c2 t is1 ! rate ( cutt+ ! l9es increases z ,c ,d rotates f #j to #d & decreases f #d to #h4 ,s9ce simil> conditions prevail ) respect to ,a ,b1 = its correspond+ movem5t1 x is evid5t t ! numb] ( l9es :i* ?read ?r\gh ! loop are decreas$ ) increas+ rapidity z ! loop rotates ?r\gh ! fir/ qu>t] ( a revolution1 & increas$ ) decreas+ rapidity dur+ ! second qu>t] ( ! revolution4 ,moreov]1 x mu/ be evid5t t ! rev]se conditions obta9 = ! ?ird & f\r? qu>t]s ( ! revolution4 ,! ,s9e ,curve4--,9 ! prec$+ p>agraph x 0 %[n t an alt]nat+ curr5t is induc$ 9 ! armature ( ei!r an alt]nator or dynamo2 t is1 ! curr5t3 #a1 beg9s ) z]o electromotive =ce1 #b1 rises to a maximum1 #c1 decreases aga9 to z]o1 #d1 increases to a maximum 9 ! opposite direction1 & #e1 decreases to z]o4 ,illu/ration3 ,,fig4 #afh4--;,application & con/ruction ( ! s9e curve4 ,! s9e curve is a wave-l curve us$ to repres5t ! *anges 9 /r5g? & direction ( an alt]nat+ curr5t4 ,an elem5t>y alt]nator is %[n at ! left to illu/rate ! application ( ! s9e curve to ! alt]nat+ curr5t cycle4 ,x consi/s ( a loop ( wire ,a ,b ,c ,d1 ^: ends are atta*$ to ! r+ ,f & %aft ,g1 be+ arrang$ to revolve 9 a uni=m magnetic field indicat$ by ! v]tical arr[s :i* repres5t magnetic l9es at equidi/ances4 ,! alt]nat+ curr5t induc$ 9 ! loop is c>ri$ to ! ext]nal circuit ?r\gh ! bru%es ,m & ,s4 ,n[1 z ! loop rotates1 ! induc$ electromotive =ce w v>y 9 su* a mann] t its int5sity at any po9t ( ! rotation is proportional to ! s9e ( ! angle correspond+ to t po9t1 ?is is repres5t$ by ! wave-l curve4 ,! mean value ( ! s9e curve1 or av]age electromotive =ce develop$ dur+ ! revolution1 or p]iod1 is equal to #b 1 or 4#fcg ( t ( ! maximum ord9ate1 t is1 av]age electromotive =ce 4#fcg amplitude4 ,! s9e curve lies above ! horizontal axis dur+ ! fir/ half ( ! revolution & bel[ x dur+ ! second half1 :i* indicates t ! curr5t fl[s 9 "o direction = a half revolution & 9 ! opposite direction dur+ ! rema9d] ( ! revolution4 ,a wave-l curve1 z %[n 9 fig4 #afh1 is us$ to repres5t ^! sev]al *anges1 9 :i* ! horizontal di/ances repres5t "t1 & ! v]tical di/ances1 ! v>y+ values ( ! electromotive =ce4 ,x is call$ ! s9e curve because a p]p5dicul> at any po9t to its axis is proportional to ! s9e ( ! angle correspond+ to t po9t4 ,ques4 ,describe ! con/ruction & application ( ! s9e curve4 ,ans4 ,9 fig4 #afh1 at ! left1 is %[n an elem5t>y armature 9 ! horizontal position1 b at "r angles to ! magnetic field4 ,! dott$ circle indicates ! circul> pa? describ$ by ,a ,b or ,c ,d dur+ ! revolution ( ! loop4 ,n[1 z ! loop rotates1 ! induc$ electromotive =ce w v>y 9 su* a mann] t its int5sity at any po9t ( ! rotation is proportional to ! s9e ( ! angle correspond+ to t po9t4 ,h5ce1 on ! horizontal l9e :i* passes ?r\gh ! c5t] ( ! dott$ circle1 take any l5g?1 z #jh1 & divide x into any numb] ( p>ts repres5t+ fractions ( a revolution1 z #j1 #ij1 #ahj1 etc4 ,erect p]p5dicul>s at ^! po9ts1 & f ! correspond+ po9ts on ! dott$ circle project l9es p>allel to #jh2 ! int]sections ) ! p]p5dicul>s give po9ts on ! s9e curve4 ,?us ! loop passes ?r\gh #b at ! #ij po9t ( its revolution1 h5ce1 project+ ov] to ! correspond+ p]p5dicul> gives #b #b1 a po9t ^: elevation f ! axis is proportional to ! electromotive =ce at t po9t4 ,9 l mann] o!r po9ts are obta9$1 & ! curv$ l9e ?r\gh !m w repres5t ! v>iation 9 ! electromotive =ce = all po9ts ( ! revolution4 ,at #ij1 ! electromotive =ce is at a maximum2 h5ce1 by us+ a pressure scale su* t ! l5g? ( ! p]p5dicul> #b #b = #ij w measure ! maximum voltage ! l5g? ( ! p]p5dicul> at any o!r po9t w repres5t ! actual pressure at t po9t4 ,! curve lies above ! horizontal axis dur+ ! fir/ half ( ! revolution1 & bel[ x dur+ ! second half1 :i* indicates t ! curr5t fl[s 9 "o direction = a half revolution & 9 ! opposite direction dur+ ! rema9d] ( ! revolution4 ,! application ( ! s9e curve to repres5t ! alt]nat+ cycle1 is fur!r illu/rat$ 9 figs4 #afi to #agc1 :i* %[ ! position ( ! armature at ea* qu>t] ( ! revolution4 ,illu/ration3 ,,figs4 #afi to #agc4--,! s9e curve ) view ( armature = ea* #ij ( ! revolution1 %[+ progressively ! application ( ! s9e curve to ! alt]nat+ curr5t cycle4 ,9 fig4 #agi1 ! loop ,a ,b ,c ,d is 9 ! v]tical position at ! beg9n+ ( ! revolution4 ,at ?is in/ant ! electromotive =ce is z]o1 h5ce ! s9e curve z %[n beg9s at ,e1 ! z]o po9t--t is1 on ! axis or l9e ( no pressure4 ,z soon z ! loop rotates out ( ! v]tical plane1 ! electromotive =ce rises & ! curr5t beg9s to fl[ 9 ! direction indicat$ by ! arr[s1 go+ out to ! ext]nal circuit ?r\gh bru% ,m1 & return+ ?r\gh bru% ,s4 ,cont9u+ ! rotation1 ! electromotive =ce increases 9 proportion to ! s9e ( ! angle made by ! plane ( ! loop ) ! horizontal1 until ! loop comes into ! horizontal position illu/rat$ 9 fig4 #agj4 ,?is increase is indicat$ by ! gradual rise ( ! s9e curve f ,e to ,f4 ,! loop has n[ made "o qu>t] ( a revolution & ! electromotive =ce rea*$ its maximum value4 ,z ! loop rotates pa/ ! horizontal position ( fig4 #agj1 ! electromotive =ce gradually decreases 9 int5sity1 rea*+ ! z]o po9t at ! end ( ! second qu>t]--t is1 :5 ! loop has turn$ "o half revolution4 ,?is is indicat$ by ! gradual fall ( ! curve f ,f to ,g4 ,:5 ! loop turns out ( ! v]tical position %[n 9 fig4 #aga ! curr5t rev]ses1 because ! movem5t ( ,a ,b & ,c ,d is rev]s$2 at ?is in/ant ! bru% ,m becomes negative1 & ,s positive4 ,?is rev]sal ( curr5t is indicat$ by ! curve fall+ bel[ ! axis f ,g to ,i4 ,dur+ ! second half ( ! revolution1 figs4 #aga to #agc1 ! *anges t occur are ! same z 9 ! fir/ half1 ) ! exception t ! curr5t is 9 ! rev]se direction2 ^! *anges are z %[n by ! curve f ,g to ,i4 ,,*apt] ,,xiv ,,! ,,dynamo3 ,,curr5t ,,commutation ,h[ ! ,dynamo ,produces ,direct ,curr5t3 ,! ,commutator4--,! ess5tial diff]5ce betwe5 an alt]nator & a dynamo is t ! alt]nator deliv]s alt]nat+ curr5t to ! ext]nal circuit :ile ! dynamo deliv]s direct curr5t4 ,9 bo? ma*9es1 z be=e /at$1 alt]nat+ curr5ts are induc$ 9 ! armature1 b ! k9d ( curr5t deliv]$ to ! ext]nal circuit dep5ds on ! mann] 9 :i* ! armature curr5ts are collect$4 ,9 ! case ( an alt]nator1 ! me?od is q simple4 ,z previ\sly expla9$1 ea* end ( ! loop is connect$ ) an insulat$ collector r+ c>ri$ by ! %aft1 ! curr5t be+ collect$ by means ( bru%es :i* be> aga9/ ! r+s4 ,?is pr9ciple1 r ?an ! actual con/ruction1 is %[n 9 ! prec$+ illu/rations4 ,its important po9t1 z di/+ui%$ f o!r me?ods ( collect+ ! curr5t1 is t ea* end ( ! loop is always 9 connection ) ! same bru%4 ,ques4 ,h[ is direct curr5t obta9$ 9 a dynamo8 ,ans4 ,a =m ( swit* call$ ! commutator is plac$ betwe5 ! armature & ! ext]nal circuit & s arrang$ t x w rev]se ! connections ) ! ext]nal circuit at ! in/ant ( ea* rev]sal ( curr5t 9 ! armature4 ,ques4 ,h[ is a commutator con/ruct$8 ,ans4 ,x consi/s ( a s]ies ( copp] b>s or segm5ts arrang$ side by side =m+ a cyl9d]1 & insulat$ f ea* o!r by %eets ( mica or o!r insulat+ mat]ial4 ,illu/ration3 ,,figs4 #agd to #agh4--;,commutation ( ! curr5t4 ,^! figures %[ h[ a dynamo trans=ms alt]nat+ into ! s-call$ direct curr5t4 ,dur+ ! fir/ half ( ! revolution ! curr5t fl[s 9 ! direction ,a ,b1 out ?r\gh segm5t ,f ( ! commutator & bru% ,m1 return+ ?r\gh bru% ,s & segm5t ,g1 figs4 #agd & #age4 ,at ! beg9n+ ( ! second half ( ! revolution1 fig4 #agf1 ! curr5t 9 ! armature rev]ses & fl[s ar\nd ! loop 9 ! direction ,b ,a4 ,at ?is in/ant ! bru%es ,m & ,s pass ! gaps betwe5 ! commutator segm5ts1 ?us rev]s+ contact ) ! segm5ts1 & caus+ ! curr5t 9 ! ext]nal circuit to rema9 9 ! same direction4 ,ques4 ,:]e is ! commutator plac$8 ,ans4 ,x is atta*$ to ! %aft at ! front end ( ! armature4 ,ques4 ,:at are inductors8 ,ans4 ,! insulat$ wires w\nd on ! armature core1 & 9 :i* ! electric curr5t is induc$4 ,ques4 ,h[ are ! inductors connect$ to ! commutator8 ,ans4 ,! ends ( ea* conduct+ loop or coil mu/ be connect$ ) ! commutator segm5ts 9 a c]ta9 ord] to correspond ) ! type ( w9d+4 ,ques4 ,expla9 9 detail h[ direct curr5t is obta9$ 9 a dynamo4 ,illu/ration3 ,,figs4 #agi to #aha4--;,elem5t>y dynamo armatures4 ,fig4 #a1 s+le turn loop2 fig4 #b1 coil ( two turns 9 s]ies2 fig4 #c1 coil ( two turns 9 p>allel4 ,9 op]ation ! amplitude or maximum pressure induc$ ) ! two turn coil1 fig4 #ahj1 is d\ble t ( a s+le turn loop1 fig4 #agi4 ,9 fig4 #ahj1 ! pressure is d\ble t induc$ 9 fig4 #aha1 :ile ! am\nt ( curr5t g5]at$ ) s]ies turns1 fig4 #ahj1 is only half t g5]at$ ) turns 9 p>allel fig4 #aha4 ,ans4 ,x w be easily se5 by ! aid ( a s]ies ( illu/rations j h[ ! alt]nat+ armature curr5ts are trans=m$ into direct curr5t4 ,figs4 #agd to #agh %[1 9 sev]al positions1 a s+le loop ( wire ) its ends jo9$ to a commutator2 ! latt] has only two segm5ts1 "o = ea* end ( ! loop4 ,9 fig4 #agd ! loop is %[n 9 ! v]tical position1 & x %\ld be not$ t ! division betwe5 ! two segm5ts =m+ ! commutator is 9 ! same plane z ! loop4 ,:5 ! loop is 9 ! v]tical position1 z %[n 9 fig4 #agd1 bru% ,m is 9 contact ) segm5t ,f1 & ,s ) ,g4 ,z ! armature rotates1 ! curr5t fl[s = "o half revolution 9 ! direction ,a ,b1 ?r\gh segm5t ,f & out to ! ext]nal circuit ?r\gh bru% ,m z %[n 9 figs4 #agd & #age1 return+ ?r\gh bru% ,s & segm5t ,g4 ,at ! beg9n+ ( ! second half ( ! revolution1 fig4 #agf1 ! curr5t 9 ! loop rev]ses & fl[s 9 ! opposite direction ,b ,a z indicat$ by ! arr[s4 ,at ?is in/ant1 h[ev]1 ! bru%es ,m & ,s pass out ( contact ) segm5ts ,f & ,g1 & come into contact ) ,g & ,f respectively2 t is1 ,m leaves ,f & contacts ) ,g1 :ile ,s leaves ,g & contacts ) ,f4 ,! effect ( ?is is to rev]se ! connections ) ! ext]nal circuit at ! in/ant ! alt]nation or rev]sal ( curr5t 9 ! armature takes place1 ?us keep+ ! curr5t 9 ! ext]nal circuit 9 ! same direction4 ,illu/ration3 ,,fig4 #ahb4--;,gramme r+ armature ) "o coil1 & *>act]i/ic s9e curve bel[4 ,) "o coil z %[n1 !re are two pulsations ( ! curr5t p] revolution ( ! armature4 ,ques4 ,h[ is ?is indicat$ by ! s9e curve8 ,ans4 ,! s9e curve1 in/ead ( fall+ bel[ ! axis1 z 9 figs4 #afi to #agc1 aga9 rises z 9 ! fir/ half ( ! p]iod1 t is ,g,h,i is id5tical ) ,e,f,g4 ,ques4 ,is ! direct curr5t indicat$ by ! s9e curve 9 figs4 #agd to #agh cont9u\s8 ,ans4 ,no2 x is prop]ly describ$ z a pulsat+ curr5t1 or "o1 con/ant 9 direction1 b p]iodically v>y+ 9 int5sity s z to progress 9 a s]ies ( ?robb+s or pulsations in/ead ( ) uni=m /r5g?4 ,ques4 ,:at is g5]ally und]/ood by ! ^w 8cont9u\s0 z appli$ to ! curr5t obta9$ f a dynamo8 ,ans4 ,x is usually accept$ z mean+ a /eady or non-pulsat+ direct curr5t2 "o t has a uni=m pressure & con/ant direction ( fl[ z oppos$ to an alt]nat+ curr5t4 ,ques4 ,is a cont9u\s curr5t ev] obta9$ ) a dynamo8 ,ans4 ,no4 ,illu/ration3 ,,fig4 #ahc4--;,gramme r+ armature ) two coils plac$ #ahj ap>t4 ,?is arrangem5t gives d\ble ! pressure ( ! "o coil armature1 fig4 #ahb4 ,x %\ld be cle>ly und]/ood at ! outset t x is impossible to obta9 a cont9u\s curr5t ) a dynamo4 ,! s-call$ cont9u\s curr5t :i* x is said to produce is 9 reality a pulsat+ curr5t1 b ) pulsations s m9ute & foll[+ ea* o!r ) su* rapidity t ! curr5t is practically cont9u\s1 & z su* is g5]ally call$ cont9u\s4 ,ques4 ,h[ is ! s-call$ cont9u\s curr5t produc$ by a dynamo8 ,ans4 ,9 ord] to obta9 a l>ge numb] ( small pulsations p] revolution ( ! armature in/ead ( two l>ge pulsations1 z ) ! s+le loop armature1 ! latt] mu/ be replac$ by "o hav+ a great numb] ( loops prop]ly connect$ to commutator segm5ts & s arrang$ t ! successive loops beg9 ! cycle progressively4 99 99 99 99 99 ,! difficulties enc\nt]$ 9 connect+ up num]\s loops 7 ov]come by ,gramme1 :o1 9 #ahga inv5t$ a 8r+0 armature4 ,8 me?od consi/s 9 w9d+ a r+ ) a cont9u\s coil ( wire1 connections be+ made at suitable int]vals ) ! commutator4 ,illu/ration3 ,,fig4 #ahd4--;,f\r sep>ate coils w\nd on r+ to illu/rate ! action ( a ,gramme r+ armature4 ,if ! r+ be rotat$ ! electromotive =ces induc$ 9 adjac5t coils w be equal & t5d to produce curr5ts 9 opposite directions2 h5ce1 if ! inn] ends be jo9$1 ! junctions w\ld be at a high] pot5tial 7 or -7 ?an ! loose ends4 ,) prop] connections curr5t may be collect$ at ! junctions4 ,9 ord] to und]/& ! action ( su* an arrangem5t1 x w be well to fir/ consid] f\r sep>ate coils w\nd on a r+ z %[n 9 fig4 #ahd4 ,^! coils are all simil>1 b at ! mom5t occupy diff]5t magnetic positions on ! r+4 ,! rotation be+ clockwise1 #a is ab\t to ent] ! field adjac5t to ! nor? pole1 :ile #b is em]g+ f ! field 9 ! region ( ! s\? pole4 ,aga91 #c is approa*+ ! s\? pole & #d rec$+ f ! nor? pole4 ,ques4 ,describe 9 detail ! action ( ! f\r coils w\nd ar\nd ! r+ z 9 fig4 #ahd4 ,ans4 ,accord+ to ! laws ( electromagnetic induction1 pressures are set up at ! ends ( ! coils su* z t5d to produce curr5ts 9 ! directions indicat$ by ! arr[s4 ,n[1 assum+ ! electromotive =ces 9 coils #a & #b to be equal1 if ! adjac5t ends be jo9$1 no fl[ ( curr5t w take place1 b ! junction w be at a high] pressure ?an ! loose ends ( ! coils & if a wire be atta*$ to ?is junction1 & ! necess>y circuits complet$1 a curr5t w fl[ along ! wire outw>d f ! junction4 ,simil>ly1 if ! adjac5t ends ( coils #c & #d be jo9$1 !re w be no fl[ ( curr5t1 b ! junction w be at a l[] pressure ?an ! loose ends1 & if a wire be atta*$ to ! junction & ! necess>y circuits complet$1 curr5t w fl[ f ! junction ar\nd ! coils4 ,illu/ration3 ,,fig4 #ahe4--;,gramme r+ armature ) f\r coils4 ,! electromotive =ce induc$ 9 coils ,a1 ,a rea*es ! z]o po9t at ! in/ant t ( coils ,b1 ,b is at a maximum2 h5ce1 s9e curve ,no4 #a1 beg9n+ at z]o1 & ,no4 #b1 at ! maximum1 %[ ! pressure *anges = ,a1 ,a & ,b1 ,b1 respectively4 ,! summation ( ^! curves gives ! resultant curve ,no4 #c1 %[+ *anges 9 pressure ( curr5t deliv]$ to ! ext]nal circuit4 ,ques4 ,:at may be said ) respect to ! f\r coil ,gramme r+ armature %[n 9 fig4 #ahe8 ,ans4 ,accord+ to ! laws ( electromagnetic induction1 ) ! nor? pole ( ! field at ! left & clockwise rotation1 ! induc$ curr5ts fl[ upw>d on bo? sides ( ! r+1 h5ce1 ! electromotive =ces oppose ea* o!r at only two ( ! junctions1 namely3 at ! "o connect$ to bru% ,m :]e ! pressures on ei!r side are bo? direct$ t[>d ! junction & ! o!r at ! junction connect$ to bru% ,s1 at :i* ! pressures are bo? direct$ f ! junction4 ,illu/ration3 ,,fig4 #ahf4--;,gramme r+ armature ) six coils4 ,! s9e curves #a1 #b & #c1 repres5t ! conditions due to coils ,,aa1 ,,bb & ,,cc1 respectively1 & #d1 ! resultant pulsations4 ,x is evid5t1 !n1 t ! pressure at ,m is high] ?an at ,s2 t is1 ,m is positive & ,s negative2 consequ5tly1 ! curr5t fl[s f ,m to ! ext]nal circuit & returns ?r\gh ,s4 ,ques4 ,9 :at o!r way may ! f\r coils ( ! armature 9 fig4 #ahe be reg>d$8 ,ans4 ,!y may be consid]$ z two pairs ,a ,a & ,b ,b1 ! action ( ei!r pair be+ id5tical ) ! two coil armature %[n 9 fig4 #ahc2 ?is1 9 turn1 produces ! same effect z ! "o coil armature ( fig4 #ahb1 ) ! exception t ! amplitude ( ! curr5t g5]at$ ) two coils is twice z great z t ) "o coil ( ! same numb] ( turns4 ,aga9 consid]+ ! action ( ! f\r r+ coil %[n 9 fig4 #ahe1 & />t+ at ! beg9n+ ( ! revolution1 ! v>iation ( electromotive =ce induc$ 9 coils ,,aa is indicat$ by ! dott$ s9e curve #a1 & ( ,,bb by dott$ curve #b4 ,x w be se5 t #a beg9s at ! axis or l9e ( no pressure1 & #b at maximum pressure4 ,illu/ration3 ,,fig4 #ahg4--,! resultant curves ( figs4 #ahc1 #ahe & #ahf are "h %[n = comp>ison to illu/rate ! approa* to uni=m pressure z ! numb] ( coils are increas$4 ,x %\ld be not$ t ! numb] ( pulsations p] cycle dep5ds on ! numb] ( coils1 & t z ! pulsations increase 9 numb]1 ! v>iation 9 pressure decreases4 ,! two curves ov]lap ea* o!r1 & 9 ord] to det]m9e ! effect ( ?is x is necess>y to trace ! resultant curve1 #c4 ,?is is easily done1 z ! resultant electromotive =ce induc$ at any po9t 9 ! revolution ( ! armature is equal to ! sum ( ! pressures induc$ 9 ,,aa & ,,bb4 ,?us1 at ! beg9n+ ( ! revolution ! pressure induc$ 9 ,,aa is at z]o po9t1 & 9 ,,bb at its maximum ,j1 h5ce1 ! resultant curve beg9s at ! po9t ,j4 ,aga91 = any po9t 9 ! revolution1 z ,n1 ! height ( ! resultant curve is equal to ,,np ,,nt ,,nv4 ,= #de or #a_/h revolution1 ! resultant curve rea*es its amplitude1 :i* is equal to #b ,,rz ,,rw1 & at #ij x aga9 rea*es its m9imum1 ,,xy4 ,ques4 ,/ate ! conditions ^u :i* ! /ead9ess ( ! curr5t dep5ds4 ,ans4 ,x dep5ds on ! numb] ( coils & ! mann] 9 :i* !y are connect$4 ,comp>+ curves #a & #c1 9 fig4 #ahe1 x w be not$ t ) f\r coils ! v>iation ( pressure or amplitude ( ! pulsations is less ?an half t obta9$ ) two2 moreov]1 ) f\r coils ! numb] ( pulsations p] cycle is d\bl$4 ,9 ord] to fur!r obs]ve ! approa* to cont9u\s curr5t obta9$ by increas+ ! numb] ( coils1 ! effect ( a six coil armature is %[n 9 fig4 #ahf1 ! resultant curve be+ obta9$ 9 ! same mann] z j expla9$4 ,= comp>ison1 ! curves = ! ?ree cases ( two1 f\r1 & six coils are reproduc$ "u ea* o!r 9 fig4 #ahg4 ,z ! numb] ( coils is fur!r increas$1 ! amplitude ( ! pulsations decreases s t ! resultant curve approa*es ne>] ! =m ( a /raight l9e4 ,9 ! actual dynamo !re are a great _m coils1 h5ce ! amplitude ( ! pulsations is exce$+ly small2 accord+ly1 x is cu/om>y to speak ( ! curr5t z 8cont9u\s10 al?\gh z previ\sly m5tion$ su* is n ! case4 ,,*apt] ,,xv ,,classes ,,( ,,dynamo ,9 ord] to adapt ! dynamo to ! v>i$ conditions ( s]vice1 its design is modifi$ 9 num]\s ways1 giv+ rise to ! diff]5t 8types40 ,^! may be classifi$ ) respect to3 #a4 ,field magnets2 #b4 ,field excitation2 #c4 ,field w9d+4 ,! fir/ division relates to ! numb] ( magnetic poles1 z unipol>1 bipol>1 & multi-pol> dynamos2 also int]-pol> dynamos4 ,"u ! second division are includ$ ! foll[+3 #a4 ,self-excit+ ma*9es ( :i* ! magneto is ! simple/4 ,its magnetic field is obta9$ f p]man5t magnets1 h5ce ! electromotive =ce g5]at$ is comp>atively small4 ,! m important type ( self-excit+ ma*9e is provid$ ) electromagnets 9 :i* ! field ( =ce is 8built up0 f ! residual magnetism ( ! s(t iron or /eel cores ( ! field magnets ( ! dynamo itself4 ,ne>ly all comm]cial types ( dynamo are ( ?is class4 #b4 ,sep>ately excit$ ma*9es 9 :i* ! field magnets are magnetiz$ :5 ! ma*9e is 9 op]ation by curr5t suppli$ f a sep>ate s\rce su* z a batt]y or magneto g5]ator4 ,) respect to ! ?ird division1 bas$ on ! field w9d+1 dynamos are class$ z3 #a4 ,s]ies w\nd2 #b4 ,%unt w\nd2 #c4 ,comp\nd w\nd4 ,9 addition to ! =ego+ !re are fur!r di/9ctions ) respect to ! me*anical features4 ,mo/ dynamos h a revolv+ armature & /ation>y field magnets2 h[ev]1 9 "s cases1 bo? ! armature & field magnets are /ation>y1 a revolv+ iron inductor be+ provid$ to int]cept ! magnetic l9es int]mitt5tly :i* produces ! same effect z is obta9$ 9 cutt+ ! magnetic l9es by a revolv+ armature4 ,ques4 ,:at may be said ( bipol> & multi-pol> dynamos8 ,ans4 ,dynamos ) bipol> field magnets 7 univ]sally us$ prior to #ahij1 b s9ce t "t ma*9es ( ?is type are only made 9 v small sizes2 ! multi-pol> dynamo is ! type n[ 9 g5]al use4 ,ques4 ,/ate "s ( ! features ( ! multi-pol> dynamo4 ,ans4 ,9 ?is class ( ma*9e1 ! armature & field magnets are surr\nd$ by a circul> frame1 or r+ yoke to :i* ! field magnets are atta*$4 ,?is r+ arrangem5t has ! advantages ( /r5g?1 simplicity1 symmetrical appe>ance1 & m9imum magnetic leakage1 s9ce ! pole pieces h ! lea/ possible surface & ! pa? ( ! magnetic flux is %ort]4 ,ques4 ,:at important advantage is ga9$ by ! use ( multi-pole field magnets8 ,ans4 ,comm]cial voltages are obta9$ at mod]ate armature spe$4 ,! difficulty exp]i5c$ ) bipol> ma*9es is t1 ) a dynamo ( l>ge output1 ! spe$ at :i* its armature w\ld h to rotate to g5]ate comm]cial voltages w\ld be excessive4 ,illu/ration3 ,,figs4 #ahh & #ahi4--;,circuit diagrams to illu/rate ! diff]5ce betwe5 a dynamo & a magneto4 ,! =m] has its field magnets ,f ,f magnetiz$ by means ( a small curr5t fl[+ ar\nd a %unt circuit4 ,9 a magneto ! field magnets are p]man5tly magnetiz$4 ,! /r5g? ( ! magnet field ( a magneto is con/ant :ile t ( a dynamo v>ies ) ! output4 ,x is evid5t t ) two or m magnetic fields1 secur$ by increas+ ! numb] ( poles1 ! armature inductors revolv+ betwe5 !m cut m magnetic l9es 9 "o revolution ?an ) a s+le field1 h5ce1 a giv5 voltage is obta9$ ) less spe$ ( ! armature ?an 9 ! bipol> ma*9e4 ,= in/ance1 if a bipol> dynamo be requir$ to run at say #ijj revolutions p] m9ute to g5]ate #abe volts1 a f\r pole ma*9e ( equal output w require only #dej revolutions1 & "o ( eight poles only #bbe revolutions p] m9ute4 ,ques4 ,:at is a self-excit+ dynamo8 ,ans4 ,a ma*9e 9 :i* ! initial excitation ( ! field is due to ! residual magnetism reta9$ by ! cores4 ,ques4 ,:at may be said ( ! field due to ?is residual magnetism8 ,ans4 ,x pres5ts a v weak field1 & ! voltage t c\ld be g5]at$ by ! armature revolv+ 9 su* a field w\ld be only ab\t two to t5 volts4 ,illu/ration3 ,,fig4 #aij4--,s]ies w\nd dynamo1 us$ = s]ies arc light+1 & z a boo/] = increas+ ! pressure on a fe$] c>ry+ curr5t furni%$ by "s o!r g5]ator4 ,! coils ( ! field magnet are 9 s]ies ) ^? ( ! armature & ext]nal circuit1 & consi/s ( a few turns ( heavy wire4 ,! *>act]i/ic ( ! s]ies dynamo is to furni% curr5t ) increas+ voltage z ! load increases4 ,if ov]load$1 ! voltage w drop4 ,ques4 ,h[ !n c comm]cial voltages su* z #ajj or m volts be obta9$ ) a self-excit+ dynamo8 ,ans4 ,"p or all ( ! curr5t induc$ 9 ! armature is pass$ ?r\gh ! w9d+s ( ! field magnets1 ?us /r5g!n+ ! field4 ,! voltage1 !re=e1 w 8build up10 increas+ until ! maximum has be5 rea*$4 ,! maximum voltage w dep5d ^u ! capacity ( ! field magnets z det]m9$ by ! con/ruction1 & ^u ! /r5g? ( curr5t us$ to excite !m4 ,ques4 ,h[ long does ! process ( 8build+ up0 require8 ,ans4 ,! "t requir$ to fully excite ! field magnets is f t5 to tw5ty seconds1 ! rise 9 field /r5g? be+ indicat$ on ! voltmet] or by ! gradual increase 9 ! brilliancy ( ! pilot lamp4 ,ques4 ,"n ?ree important classes ( dynamo4 ,ans4 ,s]ies w\nd1 %unt w\nd1 & comp\nd w\nd4 ,ques4 ,describe ! w9d+ ( a s]ies dynamo4 ,ans4 ,9 ?is ma*9e1 ! field magnets are w\nd ) a few turns ( ?ick wire jo9$ 9 s]ies ) ! armature bru%es z %[n 9 fig4 #aij4 ,ques4 ,:at is ! effect ( ?is arrangem5t8 ,ans4 ,all ( ! curr5t g5]at$ by ! ma*9e passes ?r\gh ! coils ( ! field magnets to ! ext]nal circuit4 ,! curr5t 9 pass+ ?r\gh ! field magnets1 en]gizes !m & /r5g!ns ! weak field due to ! residual magnetism ( ! magnet cores1 result+ 9 ! gradual build+ up ( ! field4 ,ques4 ,= :at s]vice is ! s]ies dynamo adapt$8 ,ans4 ,x may be us$ = s]ies arc light+1 s]ies inc&esc5t light+1 & z a boo/] = increas+ ! pressure on a fe$] c>ry+ curr5t furni%$ by "s o!r g5]ator4 ,ques4 ,:at is ! effect ( ! s]ies w9d+ 9 ! op]ation ( ! ma*9e8 ,ans4 ,its *>act]i/ic is to furni% curr5t at an increas$ voltage z ! load increases4 ,if suffici5t curr5t be drawn to ov]load ! ma*9e1 ! voltage w drop4 ,s9ce ! armature coils1 field magnets & ext]nal circuits are 9 s]ies1 any increase 9 ! resi/ance ( ! ext]nal circuit less5s ! p[] ( ! ma*9e to supply curr5t1 because x dim9i%es ! curr5t 9 ! coils ( ! field magnets & !re=e dim9i%es ! effective magnetism4 ,aga91 a decrease 9 ! resi/ance ( ! ext]nal circuit w increase ! voltage because m curr5t w fl[ ?r\gh ! field magnets4 ,accord+ly1 :5 ! ext]nal circuit has lamps 9 s]ies 7z is common 9 an arc light circuit7 ! swit*+ on ( an additional lamp bo? adds to ! resi/ance ( ! circuit & dim9i%es ! p[] ( ! ma*9e to supply curr5t4 ,:5 ! lamps are 9 p>allel1 ! swit*+ on ( additional lamps n only dim9i%es ! resi/ance ( ! circuit1 b causes ! field magnets to be fur!r excit$ by ! increas$ curr5t1 s t ! great] ! numb] ( lamps put on1 ! great] becomes ! risk ( induc+ too mu* curr5t4 ,! s]ies dynamo has also ! disadvantage ( n />t+ action until a c]ta9 spe$ has be5 atta9$1 or unless ! resi/ance ( ! ext]nal circuit be bel[ a c]ta9 limit4 ,regulation ( ,s]ies ,dynamos4--,! s]ies dynamo is ord9>ily us$ = op]at+ arc lamps connect$ 9 s]ies4 ,! curr5t g5]ally consum$ is ab\t #aj amp]es1 & x is necess>y t x %\ld rema9 at ?is /r5g? to keep ! lights burn+ /eadily4 ,if x increase1 ! lights w be too bright1 & if x decrease1 !y w be too dim or flick]4 ,) all ! lamps connect$ 9 s]ies x is evid5t t ! resi/ance ( ! circuit w v>y widely z !y are turn$ on or (f1 ! resi/ance increas+ z ! lamps are turn$ on1 & decreas+ z !y are turn$ (f4 ,x is necess>y1 !re=e1 t "s means ( regulation be provid$ to enable ! dynamo to increase or decrease ! voltage 9 proportion to ! load4 ,!re are sev]al me?ods ( regulation1 z by3 #a4 ,v>iation ( armature spe$2 #b4 ,v>iation ( position ( bru%es2 #c4 ,v>iation ( field /r5g?4 ,:atev] me?od be us$ ! necess>y regulation %\ld be accompli%$ by automatic devices1 z x w\ld n be practical to /ation a man 9 con/ant att5dance to regulate ! voltage e "t "o or m lamps 7 ?r[n on or (f4 ,ques4 ,:5 is ! fir/ me?od ( regulation us$8 ,ans4 ,x is only us$ 9 special cases1 z = con/ant load2 if ! voltage be n j "r to give ! requir$ curr5t1 x may be adju/$ by *ang+ ! spe$ ( ! eng9e4 ,ques4 ,:at may be said ( ! second me?od8 ,ans4 ,9 bo? ! 8r+0 & 8drum0 types ( armature1 rotat+ 9 a bipol> field1 !re are two po9ts situat$ at opposite extremities ( a diamet] ( ! commutator1 at "o ( :i* ! pot5tial is a maximum & at ! o!r a m9imum1 & x is at ^! po9ts t ! bru%es mu/ be plac$ 9 ord] to obta9 ! greate/ diff]5ce ( pressure1 ! diff]5ce be+ less at o!r po9ts4 ,h5ce1 by rock+ ! bru%es ar\nd ! commutator ! pressure at ! t]m9als ( ! ma*9e may be v>i$ & regulat$ z requir$4 ,ques4 ,:at difficulty is exp]i5c$ 9 rock+ ! bru%es to regulate ! voltage8 ,ans4 ,sp>k+ takes place at ! bru%es :5 !y are mov$ any consid]able di/ance f ! neutral position4 ,special dynamos h be5 design$ to ov]come ?is objectionable feature1 /ill ?is me?od ( regulation is n ext5sively us$4 ,ques4 ,:at may be said ( ! ?ird me?od ( regulation8 ,ans4 ,! ?ird me?od1 t ( v>iation ( field /r5g?1 is ! "o 9 g5]al use4 ,ques4 ,h[ is ! field /r5g? v>i$8 ,ans4 ,?is may be done by ! two pa? me?od1 or by ! v>iable field coil me?od4 ,ques4 ,describe ! two pa? me?od ( field regulation4 ,ans4 ,an adju/able resi/ance or rheo/at is connect$ 9 p>allel ) ! field w9d+ z %[n 9 fig4 #aia4 ,?is %unts m or less ( ! curr5t f ! field w9d+ accord+ to ! am\nt ( resi/ance made active by ! lev]1 ,l4 ,?us1 if ! curr5t 9 ! armature & ma9 circuit be #aj amp]es & ! resi/ance ( ! field w9d+ #aj ohms1 a resi/ance ( #dj ohms 9 p>allel ) ! w9d+ w\ld cause ! curr5t to split 9 ! ratio ( #dj to #aj1 or #d to #a2 #b amp]es w\ld pass ?r\gh ! resi/ance & #h amp]es ?r\gh ! field4 ,illu/ration3 ,,fig4 #aia4--,! two pa? me?od ( regulat+ a s]ies dynamo4 ,! ends ( ! s]ies w9d+ are connect$ by a %unt conta9+ a rheo/at4 ,! curr5t induc$ 9 ! armature1 divides & fl[s ?r\gh ! two pa?s ?us (f]$1 ! am\nt fl[+ ?r\gh ! %unt be+ regulat$ by ! rheo/at4 ,9 ?is way ! field /r5g? is easily regulat$4 ,illu/ration3 ,,fig4 #aib4--,regulation ( s]ies dynamo by v>iable field4 ,a multipo9t swit* is provid$ ) connections to ! field w9d+ at v>i\s sections1 ?us p]mitt+ m or less ( ! field w9d+ to be cut out to regulate its /r5g?4 ,ques4 ,describe ! v>iable field coil me?od ( field regulation4 ,ans4 ,?is consi/s 9 divid+ ! field w9d+ into a numb] ( sections & ?r[+ ! sections 9 & out ( circuit z %[n 9 fig4 #aib4 ,s9ce ! /r5g? ( any magnet dep5ds on ! numb] ( amp]e turns 9 its field w9d+1 r$uc+ or increas+ ! numb] ( turns w respectively r$uce or increase ! field /r5g?1 ! curr5t be+ kept con/ant4 ,ques4 ,:at is ! objection to ?is me?od8 ,ans4 ,?is arrangem5t is undesirable = magnets ( l>ge size1 because ( ! t5d5cy to fla%+ at ! contacts ( ! regulat+ swit*4 ,illu/ration3 ,,fig4 #aic4--,%unt w\nd dynamo = p>allel circuit inc&esc5t light+1 & = mill & factory p[]4 ,! coils ( ! field magnet =m a %unt to ! ma9 circuit2 !y consi/ ( _m turns ( f9e wire & consequ5tly absorb only a small fraction ( ! curr5t induc$ 9 ! armature4 ,! *>act]i/ic ( ! %unt dynamo is t x gives practically con/ant voltage = all loads )9 its range4 ,if ov]load$ ! pressure w drop & ! ma*9e cease to g5]ate curr5t4 ,! ,%unt ,dynamo4--,! %unt w\nd dynamo diff]s f ! s]ies w\nd ma*9e1 9 t an indep5d5t circuit is us$ = excit+ its field magnet4 ,?is circuit is compos$ ( a l>ge numb] ( turns ( f9e insulat$ copp] wire1 :i* is w\nd r\nd ! field magnets & connect$ to ! bru%es1 s z to =m a %unt or 8by pass0 to ! bru%es & ext]nal circuit1 z %[n 9 fig4 #aic4 ,two pa?s are ?us pres5t$ to ! curr5t z x leaves ! armature1 betwe5 :i* x divides 9 ! inv]se ratio ( ! resi/ance4 ,"o "p ( ! curr5t fl[s ?r\gh ! magnetiz+ coils1 & ! o!r portion ?r\gh ! ext]nal circuit4 ,9 all well design$ %unt dynamos1 ! resi/ance ( ! %unt circuit is always v great1 z comp>$ ) ! resi/ance ( ! armature & ext]nal circuit1 ! /r5g? ( ! curr5t fl[+ 9 ! %unt coils be+ v small ev5 9 ! l>ge/ ma*9es4 ,ques4 ,= :at s]vice is ! %unt dynamo adapt$8 ,ans4 ,x is us$ = con/ant voltage circuits1 z 9 inc&esc5t light+4 ,ques4 ,9 ! op]ation ( a %unt dynamo :at is its *>act]i/ic feature8 ,ans4 ,! voltage at ! dynamo rema9s practically un*ang$1 & ! curr5t v>ies accord+ to ! load4 ,ques4 ,does ! voltage rema9 con/ant = all loads8 ,ans4 ,!re is a c]ta9 maximum load curr5t t ! %unt dynamo is capable ( supply+ at con/ant voltage2 beyond ?is1 ! voltage w decrease1 ! ma*9e f9ally demagnetiz+ itself1 & ceas+ to g5]ate curr5t4 ,ques4 ,:y does ! voltage n rema9 con/ant = all loads8 ,ans4 ,because !re is a drop 9 ! voltage 9 =c+ ! curr5t ?r\gh ! armature w9d+s :i* increases ) ! load4 ,ques4 ,:at is ! usual me?od ( regulation = %unt dynamos8 ,ans4 ,! me?od ( v>y+ ! curr5t ?r\gh ! field coils by means ( a rheo/at ins]t$ 9 s]ies ) ! field w9d+ z %[n 9 fig4 #aid4 ,mov+ ! lev] ,l ( ! rheo/at to ! "r increases ! resi/ance 9 s]ies ) ! field w9d+1 & ?is r$uces ! am\nt ( curr5t 9 t w9d+1 ?us r$uc+ ! /r5g? ( ! magnet & consequ5tly ! voltage at ! bru%es4 ,! contr>y movem5t ( ! lev]1 by cutt+ out ! resi/ance1 produces ! opposite effect4 ,! ,comp\nd ,dynamo4--,?is class ( g5]ator is design$ to automatically give a bett] regulation ( voltage on con/ant pressure circuits ?an is possible ) a %unt ma*9e4 ,x possesses ! *>act]i/ics ( bo? ! s]ies & %unt ma*9es1 ( :i* x is 9 fact a comb9ation4 ,illu/ration3 ,,fig4 #aid4--,regulation ( %unt dynamo by me?od ( v>y+ ! field /r5g?4 ,a rheo/at is plac$ 9 s]ies ) ! field coils1 & by v>y+ ! resi/ance1 m or less curr5t w fl[ ?r\gh ! coils1 ?us regulat+ ! field /r5g?4 ,! field magnets ( ! comp\nd dynamo1 z %[n 9 fig4 #aie1 are w\nd ) two sets ( coils1 "o set be+ connect$ 9 s]ies1 & ! o!r set 9 p>allel1 ) ! armature & ext]nal circuit4 ,! purpose ( ! s]ies w9d+ is to /r5g!n ! magnets by ! curr5t suppli$ f ! armature to ! circuit1 & ?us automatically su/a9 ! pressure4 ,if ! s]ies w9d+ 7 n pres5t1 ! pressure at ! t]m9als w\ld fall z ! load increas$4 ,?is fall ( pressure is c\nt]act$ by ! excitation ( ! s]ies w9d+1 :i* increases ) ! load & causes ! pressure to rise4 ,! numb] ( turns & relative curr5t /r5g?s ( ! s]ies & %unt w9d+s are s adju/$ t ! pressure at ! t]m9als is ma9ta9$ practically con/ant "u v>y+ loads4 ,) respect to ! ratio betwe5 ! numb] ( turns ( ! two field w9d+s1 ! dynamo is spok5 ( z3 #a4 ,comp\nd2 #b4 ,ov] comp\nd$4 ,ques4 ,:at is ! diff]5ce betwe5 a comp\nd & an ov] comp\nd$ dynamo8 ,ans4 ,9 ! fir/ in/ance1 !re are j en\gh turns 9 ! s]ies w9d+ to ma9ta9 ! voltage con/ant at ! bru%es = v>iable load4 ,if a great] numb] ( turns be us$ 9 ! s]ies w9d+ ?an is requir$ = con/ant voltage at ! bru%es = all loads1 ! voltage w rise z ! load is increas$1 & ?us make up = ! loss or drop 9 ! transmission l9es1 s t a con/ant voltage w be ma9ta9$ at "s di/ant po9t f ! g5]ator4 ,! ma*9e is !n said to be ov] comp\nd$4 ,ques4 ,= :at s]vice is ov] comp\nd+ desirable8 ,ans4 ,= inc&esc5t light+ :]e !re is consid]able l5g? ( transmission l9es4 ,ques4 ,:at is ! usual degree ( ov] comp\nd+8 ,ans4 ,g5]ally = a rise ( voltage ( f five to t5 p] c5t4 ,9 con/ruction1 ! field coils are w\nd ) a great] numb] ( turns ?an actually requir$1 ! ma*9e be+ accurately adju/$ by a runn+ load te/ aft] completion4 ,ques4 ,h[ is ! degree ( ov] comp\nd+ v>i$8 ,ans4 ,a rheo/at is plac$ 9 %unt ) ! s]ies w9d+ s t ! curr5t pass+ ?r\gh ! w9d+ may be regulat$ to control ! voltage ( ! ma*9e4 ,illu/ration3 ,,fig4 #aie4--;,comp\nd w\nd dynamo1 us$ :5 bett] automatic regulation ( voltage on con/ant pressure circuits is desir$ ?an is possible ) ! %unt ma*9e4 ,! comp\nd dynamo is a comb9ation ( ! s]ies & %unt types1 t is1 ! field magnet is excit$ by bo? s]ies & %unt w9d+s4 ,) a prop] selection ( ! numb] ( turns 9 ! s]ies coils1 ! voltage may be kept automatically con/ant = wide fluctuations 9 ! load4 ,:5 ! ma*9e is ov] comp\nd$ its *>act]i/ic is to slightly increase ! voltage ) increase ( load1 a desirable feature = long transmission l9es 9 ord] to comp5sate = ! l9e drop4 ,ques4 ,h[ are ! ends ( ! %unt w9d+ ( a comp\nd dynamo connect$8 ,ans4 ,!re are two me?ods ( connection1 be+ kn[n z ! %ort %unt & ! long %unt4 ,ques4 ,describe ! %ort %unt4 ,ans4 ,9 ! %ort %unt1 ! ends ( ! %unt w9d+ are connect$ directly to ! bru%es z 9 fig4 #aif4 ,ques4 ,describe ! long %unt4 ,ans4 ,9 ! long %unt1 "o end ( ! %unt w9d+ is connect$ to "o ( ! bru%es & ! o!r end to ! t]m9al connect+ ! s]ies w9d+ ) ! ext]nal circuit z 9 fig4 #aig4 ,ques4 ,:i* is ! m desirable8 ,ans4 ,!oretically1 ! long %unt is pref]able z be+ ! m effici5t2 h[ev]1 9 practice1 ! ga9 is n v appreciable & ! %ort %unt is g5]ally us$4 ,illu/ration3 ,,figs4 #aif & #aig4--,%ort & long %unt types ( comp\nd w\nd dynamos4 ,! di/9ction betwe5 ! two is t ! ends ( ! %ort %unt connect direct ) ! bru% t]m9als1 :ile 9 ! long %unt type1 fig4 #aig1 "o end ( ! %unt connects ) "o bru% t]m9al & ! o!r ) ! t]m9al connect+ ! s]ies w9d+ ) ! ext]nal circuit4 ,r is ! %unt field rheo/at = regulat+ ! curr5t ?r\gh ! %unt4 ,ques4 ,:at may be said reg>d+ ! voltage 9 %ort1 & long %unt ma*9es8 ,ans4 ,9 a %ort %unt ma*9e1 ! %unt w9d+ is subject$ to a high] voltage ?an ) a long %unt4 ,! pressure appli$ ?r\gh a %unt w9d+ ) a long %unt1 = any p>ticul> load1 is equal to ! voltage at ! bru%es plus ! drop 9 ! s]ies w9d+4 ,ques4 ,= :at o!r s]vice besides inc&esc5t light+ are comp\nd dynamos adapt$8 ,ans4 ,!y are employ$ 9 electric railway p[] /ations :]e ! load is v fluctuat+4 ,ques4 ,:at is ! effect ( a %ort circuit on a comp\nd dynamo8 ,ans4 ,x ov]loads ! ma*9e1 s9ce ! excessive curr5t fl[+ ?r\gh ! s]ies field t5ds to keep ! voltage at its normal value4 ,unless ! l9e be automatically op5$ "u su* a condition ei!r by a fuse or circuit break]1 ! ma*9e & its driv+ eng9e may be damag$4 ,to avoid ?is dang] fuses or automatic circuit break]s are employ$4 ,ques4 ,m5tion ano!r s]vice = :i* ! comp\nd dynamo is us$4 ,ans4 ,9 "s isolat$ plants1 z small c\ntry resid5ces :]e x is frequ5tly necess>y to h a dynamo capable ( *>g+ a /orage batt]y dur+ ! day1 & ( furni%+ curr5t = light+ dur+ a c]ta9 portion ( ! ev5+4 ,"u su* conditions ! comp\nd ma*9e ) slight modification is us$1 ! ord9>y %unt dynamo n be+ capable ( ma9ta9+ ! necess>y consi/5cy ( voltage1 )\t att5tion to ! %unt regulator 9 driv+ ! lamps direct1 ! ord9>y comp\nd dynamo on ! o!r h&1 be+ unsatisfactory = *>g+ /orage batt]ies4 ,ques4 ,h[ is ! comp\nd dynamo modifi$ to adapt x to ! dual s]vice ( light+ & batt]y *>g+8 ,ans4 ,x is furni%$ ) alt]native comp\nd w9d+1 9 :i* ! s]ies w9d+ is provid$ ) a swit*1 :i* may be fix$ ei!r ^u ! ma*9e itself or ^u ! swit*bo>d4 ,?is swit* p]mits ! s]ies coils to be ei!r %ort circuit$ 9 "p or cut out ( ! circuit entirely :ile ! ma*9e is *>g+ ! /orage batt]y1 be+ aga9 cut into circuit :5 ! ma*9e is requir$ to furni% curr5t = ! lamps4 ,illu/ration3 ,,fig4 #aih4--,sep>ately excit$ dynamo4 ,curr5t = field excitation is suppli$ by a second & small] g5]ator4 ,sep>ately ,excit$ ,dynamos4--,9 ?is class ( ma*9e ! curr5t requir$ to excite ! field magnets is obta9$ f "s indep5d5t ext]nal s\rce4 ,?\gh us$ by ,f>aday1 ! sep>ately excit$ dynamo did n come into favor until1 9 #ahff1 ,wilde employ$ a small auxili>y magneto ma*9e to furni% curr5ts to excite ! field magnets ( a l>g] dynamo4 ,a sep>ately excit$ dynamo is %[n 9 fig4 #aih4 ,?is me?od ( field excitation is seldom us$ except = alt]nators2 x is1 h[ev]1 to be f\nd occasionally 9 /reet railway p[] h\ses1 ! %unt fields ( all ! dynamos be+ sep>ately excit$ by "o dynamo4 ,9 common ) ! magneto1 ! sep>ately excit$ ma*9e possesses ! prop]ty t1 ) ! exception ( armature reactions1 ! magnetism 9 its field & !re=e ! total voltage ( ! ma*9e is indep5d5t ( v>iations 9 ! load4 ,illu/ration3 ,,fig4 #aii4--;,diagram %[+ pr9ciple ( ,dobr[olski ?ree wire dynamo4 ,?is type ( ma*9e is %[n 9 m detail 9 fig4 #gie on page #gjh4 ,dobr[olski ,?ree ,wire ,dynamo4--,?is type ( dynamo 0 design$ to op]ate a ?ree wire sy/em ( di/ribution )\t a balanc]4 ,! armature is provid$ ) insulat$ slip r+s connect$ to suitable po9ts 9 ! armature w9d+ & 7by means ( bru%es7 ) *ok+ coils meet+ at a common po9t1 to :i* ! neutral wire ( ! sy/em is connect$1 ! ma9 t]m9als be+ connect$ ) ! outside wires4 ,! ma*9e is capable ( fe$+ unbalanc$ loads )\t s]i\s di/urbance ( ! pressure on ei!r side ( ! sy/em4 ,! pr9ciple ( ! ,dobr[olski ?ree wire dynamo is illu/rat$ 9 fig4 #aii4 ,! armature ,a is tapp$ at two po9ts1 ,b & ,b1 & connect$ to slip r+s ,c ,c4 ,a comp5sator or reactance coil ,d1 betwe5 ! two halves ( :i* !re is m9imum magnetic leakage1 is connect$ to ,c & ,c by bru%es1 & has its middle po9t tapp$ & connect$ to ! neutral wire ,e4 ,illu/ration3 ,,fig4 #bjj4--;,armature ( ,we/+h\se ?ree wire dynamo4 ,collector r+s are m\nt$ at "o end ( ! armature z %[n1 & ! leads to !m ) ! armature w9d+ are simil> to ^? employ$ on ! alt]nat+ curr5t side ( a rot>y conv]t] armature4 ,! connections f ! armature to collector r+s may be ei!r s+le phase1 two phase1 or ?ree phase4 ,! two phase connection ) f\r collector r+s & two balance coils is us$ 9 ! ,we/+h\se ?ree wire dynamo4 ,x is cle>1 f ! symmetry ( ! arrangem5t1 t ! c5t] po9t ( ! coil mu/ always be approximately midway 9 pressure betwe5 t ( ! bru%es1 & h5ce any unbalanc$ curr5t w return into ! armature1 divid+ equally betwe5 ! two halves ( ! coil4 ,! arrangem5t =ms a *eap & effective sub/itute = a balanc] set1 b lacks ! adju/able prop]ties ( ! latt]4 ,!re are v>i\s modifications ( ! arrangem5t4 ,?us m ?an two slip r+s may be us$4 ,! comp5sator w9d+s1 h[ev]1 %\ld always be arrang$ s t ! magnetiz+ effect ( ! neutral curr5t is self-neutraliz$ 9 ! w9d+s1 z o!rwise saturation occurs caus+ a v heavy alt]nat+ magnetiz+ compon5t4 ,,*apt] ,,xvi ,,field ,,magnets ,! object ( ! field magnet is to produce an int5se magnetic field )9 :i* ! armature revolves4 ,x is con/ruct$ 9 v>i\s =ms1 due 9 a l>ge measure to consid]ations ( economy1 & also to ! special conditions "u :i* ! ma*9e is requir$ to "w4 ,electromagnets are g5]ally us$ 9 place ( p]man5t magnets on acc\nt (3 #a1 ! great] magnetic effect obta9$1 & #b1 ! ability to regulate ! /r5g? ( ! magnetic field by suitably adju/+ ! /r5g? ( ! magnetiz+ curr5t fl[+ ?r\gh ! magnet coils4 ,! field magnet1 9 addition to furni%+ ! magnetic field1 has to d duty z a framework :i* (t5 involves consid]ations o!r ?an ^? respect+ maximum economy4 ,! ,make ,up ( a ,field ,magnet4--,9 con/ruction1 ! electromagnet1 us$ = creat+ a field 9 :i* ! armature ( a dynamo revolves1 consi/s ( f\r p>ts3 #a4 ,yoke2 #b4 ,cores2 #c4 ,pole pieces2 #d4 ,coils4 ,^! are %[n assembl$ 9 figs4 #bja to #bjd4 ,ques4 ,:at is ! object ( ! yoke8 ,ans4 ,! yoke s]ves to connect ! two 8limbs10 t is1 ! cores & pole pieces1 & ?us provide a cont9u\s metallic circuit up to ! faces ( ! pole pieces4 ,ques4 ,h[ is ! yoke con/ruct$8 ,ans4 ,x usually =ms ! frame ( ! dynamo z %[n 9 figs4 #bje & #bjf4 ,illu/ration3 ,,fig4 #bja4--,sali5t pole1 bipol> field magnet ) s+le coil w\nd ar\nd ! yoke4 ,ques4 ,:at may be said ( ! cores8 ,ans4 ,! cores1 :i* are usually ( circul> =m1 c>ry ! coils ( insulat$ wire us$ to excite ! magnets4 ,classes ( ,field ,magnet4--,al?\gh num]\s =ms ( field magnet h be5 devis$1 !y c be class$ into two gr\ps accord+ to ! type ( pole1 z3 #a4 ,sali5t pole2 #b4 ,consequ5t pole4 ,! di/9ction betwe5 ^! two types ( pole is %[n 9 figs4 #bja to #bjc4 ,by inspection ( ! figures1 x w be se5 t ! t]m sali5t applies to poles produc$ :5 ! pole pieces =m ! ends ( ! magnet1 z di/+ui%$ f consequ5t poles1 or ^? =m$ by coils w\nd on a cont9u\s metal r+ or equival5t4 ,9 ! sali5t pole bipol> magnet1 ! w9d+ may be ei!r ^u ! limbs1 ,m ,m fig4 #bjb1 or ^u ! yoke1 ,y z %[n 9 fig4 #bja4 ,! magnetic circuit ( sali5t & consequ5t poles is indicat$ 9 ! figures by ! dott$ l9es4 ,illu/ration3 ,,fig4 #bjb4--,sali5t pole1 bipol> field magnet ) two coils w\nd ar\nd ! cores4 ,illu/ration3 ,,fig4 #bjc4--;,consequ5t pole1 bipol> field magnet ) two coils on ! cores4 ,?is is kn[n z ! 8,man*e/]0 type 9 :i* ! cores are connect$ at ! ends by two yokes--s nam$ f its orig9al place ( manufacture at ,man*e/]1 ,engl&4 ,multi-,pol> ,field ,magnets4--,9 ! multi-pol> ma*9e1 ! subdivision ( ! magnetic flux r$uces ! am\nt ( mat]ial ( bo? magnet & armature4 ,moreov]1 !re is less heat+ on acc\nt ( ! great] capability ( dissipat+ ! heat1 (f]$ by ! increas$ area ( surface p] unit ( volume 9 ea* magnet pole & w9d+4 ,illu/ration3 ,,fig4 #bjd4--,mod]n dynamo ) f\r consequ5t pole field magnets4 ,9 ?is con/ruction ! r+ %ap$ yoke also s]ves z a frame2 ! circul> =m ( yoke gives ! lea/ *ance = magnetic leakage4 ,!re may be f\r1 six1 eight1 or m poles1 arrang$ 9 alt]nate ord] ar\nd ! armature4 ,fig4 #bjd %[s a f\r pole field magnet hav+ a common yoke or iron r+1 ) f\r pole pieces project+ inw>dly1 & ov] :i* ! excit+ coils are slipp$4 ,9 ! l>g] ma*9es ! yoke is made 9 two p>ts bolt$ toge!r z %[n 9 fig4 #bjf1 s t ! upp] portion may be lift$ (f = exam9ation ( ! armature4 ,ques4 ,c ! numb] ( poles 9 a multi-pol> ma*9e be advantage\sly increas$ to #af1 #cb1 or m8 ,ans4 ,a l>ge numb] ( poles is n advisable except 9 v l>ge ma*9es1 s9ce x involves an increase 9 ! exp5se ( ma*9e "w1 fitt+s1 etc41 some:at out ( proportion to ! r$uction 9 co/ ( mat]ial & increase 9 effici5cy4 ,ques4 ,:at mat]ials are g5]ally us$ = field magnets8 ,ans4 ,wr\ght iron1 /eel & copp]4 ,!re are a numb] ( consid]ations :i* gov]n ! selection ( ! mat]ials to be us$ 9 a p>ticul> ma*9e1 su* z initial co/1 weight1 effici5cy1 etc4 ,illu/ration3 ,,figs4 #bje & #bjf4--,solid & split con/ruction ( yoke = multi-pol> dynamos4 ,9 ! latt] type ! yoke is 9 two halves jo9$ along a horizontal diamet]2 :ile ! upp] half may be conv5i5tly remov$ to give access to ! armature1 x has ! disadvantage ( ! jo9t1 :i*1 no matt] h[ well made1 w add to ! reluctance ( ! magnetic circuit4 ,! figures also illu/rate ! circul> & segm5tal =ms ( yoke con/ruction4 ,ques4 ,9 ! con/ruction ( field magnets1 :at gov]ns ! *oice ( mat]ials8 ,ans4 ,= cores1 wr\ght iron is mo/ desirable1 z requir+ ! smalle/ am\nt ( mat]ial = a giv5 flux4 ,!re is a sav+ 9 copp] due to us+ wr\ght iron = ! core s9ce1 on acc\nt ( its small size1 ! l5g? ( ea* turn ( ! magnetiz+ coil is r$uc$4 ,= heavy yokes1 :]e lightness is n ess5tial1 b v (t5 ! rev]se1 ca/ iron is us$1 z its cross section c be made l>g] ?an t ( ! cores1 ?is increase 9 area s]v+ to give /r5g? & rigidity to ! ma*9e4 ,ca/ /eel occupies a place int]m$iate betwe5 ca/ iron & wr\ght iron bo? 9 co/ & magnetic prop]ties4 ,illu/ration3 ,,figs4 #bjg to #bji4--,v>i\s sections ( ca/ iron yoke4 ,9 =m1 ^! yokes may be ei!r circul> or segm5tal z %[n 9 figs4 #bje & #bjf4 ,illu/ration3 ,,figs4 #baj to #bab4--,v>i\s sections ( ca/ /eel yoke4 ,! ribs %[n 9 figs4 #baj & #baa are provid$ to secure /iffness4 ,ques4 ,"n two =ms ( yoke 9 g5]al use4 ,ans4 ,! solid1 & divid$ types z %[n 9 figs4 #bje & #bjf4 ,ques4 ,:at is ! object ( divid+ a yoke8 ,ans4 ,to p]mit access to ! armature1 :]e ! con/ruction does n admit ( removal ( ! latt] f ! side4 ,ques4 ,h[ is ! yoke usually divid$8 ,ans4 ,across its horizontal diamet] into an upp] & l[] half1 z %[n 9 fig4 #bjf1 ! l[] half be+ seat$ on1 or m frequ5tly ca/ 9 "o piece ) ! b$ plate4 ,ques4 ,:at is ! objection to divid+ a yoke8 ,ans4 ,! jo9ts introduc$1 ev5 if c>efully fac$ & well bolt$ toge!r1 add a little reluctance to ! magnetic circuit4 ,illu/ration3 ,,figs4 #bac to #bae4--,"s me?ods ( atta*+ deta*able cores4 ,! core seat is ma*9$ to receive ! core1 x be+ necess>y to secure good contact 9 ord] to avoid a l>ge increase 9 ! reluctance ( ! magnetic circuit4 ,ques4 ,h[ does ?is affect ! poles adjac5t to ! po9ts1 & :at provision is made8 ,ans4 ,x weak5s !m1 & 9 ord] to ov]come ?is1 ! coils ( ^! poles are giv5 a few extra turns4 ,ques4 ,h[ is ! reluctance ( a yoke jo9t r$uc$8 ,ans4 ,by enl>g+ ! area ( contact2 ! flange = ! bolts furni%es ! necess>y increase4 ,ques4 ,:at det]m9es *iefly ! co/ ( field magnets8 ,ans4 ,! mat]ial us$ 9 mak+ ! cores & _! %ape4 ,ques4 ,h[ does ?is affect ! co/8 ,ans4 ,s9ce consid]able cross sectional area ( core is requir$1 ! problem confront+ ! design] is to design ! core by judici\s selection ( mat]ial & %ape1 t ! requir$ numb] ( turns 9 ! magnetiz+ coil is obta9$ ) ! %orte/ l5g? ( wire4 ,illu/ration3 ,,figs4 #baf to #bba4--;,comp>ison ( field magnet core sections4 ,! %ort] ! p]imet] or outside b\nd>y ( ! core = a giv5 cross sectional area1 ! less w be ! am\nt ( copp] requir$ = ! magnetiz+ coils4 ,all ! above sections are ( equal area1 & ! figures m>k$ on ea* repres5t relative values = ! p]imet]s1 ! circle = conv5i5ce be+ tak5 at #ajj4 ,ques4 ,:at is ! pr9cipal objection to ! use ( ca/ iron = core con/ruction8 ,ans4 ,s9ce its sectional area mu/ be consid]ably m ?an wr\ght iron1 a mu* great] quantity ( copp] is requir$ = ! magnetiz+ coils4 ,copp] is exp5sive1 :ile ca/ iron cores are less exp5sive ?an equival5t ones ( wr\ght iron2 9 ?is connection1 x is int]e/+ to obs]ve h[ diff]5t design]s aim at true economy 9 con/ruction4 ,/eel is sometimes us$ 9 place ( wr\ght iron1 & ?\gh less effici5t magnetically1 x c be ca/ into ! desir$ %ape1 ?us avoid+ ! some:at exp5sive processes ( =g+ & ma*9+1 :i* are necess>y 9 ! case ( wr\ght iron4 ,ques4 ,:at =m ( core requires ! lea/ am\nt ( copp] = ! magnetiz+ coils1 & :y8 ,ans4 ,! cyl9drical core1 because x has ! %orte/ p]iph]y or b\nd>y = a giv5 area enclos$4 ,illu/ration3 ,,figs4 #bbb to #bbe4--,sev]al =ms ( pole piece4 ,:]e ! extremities project z 9 figs4 #bbb & #bbc1 !y are call$ horns4 ,! object ( ^! is to r$uce ! reluctance ( ! air gap4 ,! wid? ( 8fr+e0 ( ! magnetic field is influ5c$ by ! %ape ( ! pole piece2 ! m>g9 ( fr+e %\ld be su* t ! flux d5sity w v>y f z]o to a high value :]e ! inductors ent]4 ,figs4 #baf to #bba1 %[ a s]ies ( cross sections1 all ( ! same area4 ,! numb] m>k$ on ea* section indicates ! l5g? ( ! b\nd>y l9e1 t ( ! circle be+ tak5 = conv5i5ce z #ajj4 ,ques4 ,:at are ! pole pieces8 ,ans4 ,^! are ! end portions ( ! field magnets1 jo9$ to1 or ca/ toge!r ) ! core & plac$ adjac5t to ! armature4 ,! faces ( ! pole pieces are ( circul> %ape1 ?us =m+ ! sides ( ! s-call$ armature *amb] )9 :i* ! armature rotates4 ,illu/ration3 ,,fig4 #bbf4--,unsymmetrical pole piece introduc$ by ,gravi] to conc5trate ! magnetic field4 ,:5 ! dynamo is work+ at small loads1 ! flux 9 ! gap is ne>ly uni=m1 b at heavy loads1 ! di/ortion due to ! armature curr5t =ces ! flux =w>d & saturates ! =w>d horn1 ?us prev5t+ mu* *ange 9 its flux d5sity1 on acc\nt ( ! saturation1 & ! dim9i%+ area4 ,lundell comb9$ ! unsymmetrical & slott$ =ms ( pole piece z %[n 9 fig4 #bcg4 ,ques4 ,:y are ! pole faces made l>g] ?an ! coils8 ,ans4 ,9 ord] to r$uce ! reluctance ( ! air gap betwe5 ! face & ! armature1 ?us enabl+ few] magnetiz+ coils to be us$4 ,illu/ration3 ,,fig4 #bbg4--,pole piece ) oblique slots2 a modification ( ,lundell's =m ( pole piece z sugge/$ by ,?ompson4 ,9 op]ation1 ! neck ( ! ca/+ becomes saturat$ & (f]s consid]able reluctance1 :i* t5ds to prev5t di/ortion ( ! magnetic field4 ,x is important t ! field %\ld be magnetically rigid1 t is1 n easily di/ort$4 ,?is /iffness ( field c be p>tially secur$ by judici\s %ap+ ( ! pole pieces4 ,a few =ms ( pole piece are %[n 9 figs4 #bbb to #bca4 ,if ! project+ tips ( ! pole pieces1 or horns z !y are call$1 be widely sep>at$1 z 9 fig4 #bbb1 !y are n always good1 ev5 ?\gh ?94 ,x is bett] t !y %\ld be ext5d$ z 9 fig4 #bbc s t !y may be saturat$ by ! leakage field or else cut (f z 9 fig4 #bbd4 ,an extreme design1 sugge/$ by ,dobr[olski1 z %[n 9 fig4 #bbe1 surr\nds ! armature ) iron4 ,illu/ration3 ,,fig4 #bbh4--,non-conc5tric pole faces2 "o me?od ( secur+ suitable magnetic 8fr+e0 ) fair magnetic rigidity ( field4 ,illu/ration3 ,,figs4 #bbi to #bca4--,v>i\s %apes ( pole piece = secur+ a gradual entrance ( ! armature inductors into ! magnetic field4 ,ano!r s*eme1 propos$ by ,gravi]1 employ$ ! unsymmetrical =m %[n 9 fig4 #bbf4 ,9 ?is pole piece ! =w>d horn is elongat$4 ,! action due to ?is arrangem5t is su* t :5 ! ma*9e is work+ at small loads1 ! field 9 ! gap is ne>ly uni=m1 b at heavy loads ) di/ort+ reactions :i* h a t5d5cy to drive ! flux into ! =w>d horn1 ! small section ( ! latt] causes x to become saturat$1 ?us r$uc+ ! di/ortion to a m9imum4 ,eddy ,curr5ts2 ,lam9at$ ,fields4--,! field magnet cores & pole pieces1 z well z ! armature ( a dynamo are subject to eddy curr5ts1 t is1 induc$ electric curr5ts occurr+ :5 a solid metallic mass is rotat$ 9 a magnetic field4 ,^! curr5ts consume a l>ge am\nt ( en]gy & (t5 occasion h>mful rise 9 temp]ature4 ,?is loss may be almo/ entirely avoid$ by lam9at+ ! pole piece1 or bo? pole piece & core2 9 ! latt] case1 bo? =m "o "p )\t any jo9t4 ,illu/ration3 ,,fig4 #bcb4--;,illu/rat+ ! alt]ation ( magnetic field due to movem5t ( mass ( iron 9 ! armature4 ,if ! masses ( iron 9 ! armature are s dispos$ t z x rotates1 ! di/ribution ( ! l9es ( =ce 9 ! n>r[ field betwe5 ! armature & ! pole piece is be+ cont9ually alt]$1 !n1 ev5 ?\gh ! total am\nt ( magnetism ( ! field magnet rema9 un*ang$1 eddy curr5ts w be set up 9 ! pole piece & w heat x4 ,?is is %[n 9 ! above figures1 :i* repres5t ! effect ( a project+ too?1 su* z t ( a ,pac9otti r+1 9 *ang+ ! di/ribution ( magnetism 9 ! pole piece4 ,illu/ration3 ,,fig4 #bcc4--;,eddy curr5ts induc$ 9 pole pieces by movem5t ( masses ( iron4 ,^! diagrams1 :i* correspond to ^? ( fig4 #bcb1 %[ ! eddy curr5ts gr\p$ 9 pairs ( vortices4 ,! /ronge/ curr5t fl[s betwe5 ! vortices & is situat$ j bel[ ! project+ too?1 :]e ! magnetism is mo/ int5se2 x moves onw>d foll[+ ! too?4 ,at ,c is %[n :at occurs dur+ ! f9al retreat ( ! too? f ! pole piece4 ,^! eddy curr5ts p5etrate into ! int]ior ( ! iron1 al?\gh to no great dep?4 ,cle>ly ! greate/ am\nt ( su* eddy curr5ts w be g5]at$ at t "p ( ! pole piece :]e ! magnetic p]turbations are greate/ & mo/ sudd54 ,a glance at ! figures %[s t ?is %\ld be at ! =w>d horn ( ! pole piece4 ,h[ev]1 :5 a dynamo1 ) horn$ pole pieces1 has be5 runn+ = "s "t z a motor ! =w>d horns are cool & ! h9dw>d horns hot4 ,illu/ration3 ,,fig4 #bcd4--;,=t ,wayne lam9at$ pole piece be=e be+ ca/ weld$ into frame4 ,9 ! faces ( solid pole pieces !re exi/ m9ute electric curr5ts call$ eddy curr5ts :i* cause heat+ ( ! iron & increase ! en]gy requir$ to ma9ta9 a magnetic circuit 9 mu* ! same mann] z does reluctance4 ,?is loss is r$uc$ by divid+ ! magnetic circuit 9 ! l9e ( flux into num]\s p>allel pa?s sep>at$ by "s mat]ial ( relatively high resi/ance4 ,9 con/ruction1 ! above core & pole piece is made up ( %eets ( anneal$ /eel ( two diff]5t wid?s assembl$ toge!r to =m prop] size & %ape4 ,! m9ute spac+ betwe5 ^! lam9ations & ! slight oxidiz+ on ea* surface is suffici5t to r$uce consid]ably ! eddy curr5ts4 ,by ca/ weld+ ! pole piece into ! frame1 a l[ reluctance is secur$4 ,ques4 ,:at is a lam9at$ pole8 ,ans4 ,"o built up ( lay]s ( iron %eets1 /amp$ f %eet metal & insulat$1 z %[n 9 fig4 #bcd4 ,ques4 ,:at may be said ( ?is con/ruction8 ,ans4 ,x is a mo/ approv$ me?od1 & "o frequ5tly employ$ 9 ! con/ruction ( cores & pole pieces4 ,fig4 #bcd %[s a comb9$ core & pole piece made entirely ( %eet iron pun*+s assembl$ & rivet$ toge!r1 & fig4 #bce1 a core to be us$ ) sep>ate pole piece4 ,x %\ld be not$ t 9 bo? cases !re is a longitud9al slot ext5d+ f ! end into ! core4 ,?is 0 fir/ sugge/$ by ,lundell1 ! object be+ to prev5t1 z f> z possible1 ! di/ortion ( ! magnetic field due to armature reaction especially on heavy ov]loads4 ,illu/ration3 ,,fig4 #bce4--;,=t ,wayne lam9at$ core )\t pole piece1 z us$ on l>ge dynamos4 ,x is con/ruct$ ( pun*+s f %eet iron1 & rivet$ "u pressure4 ,! alt]nate end projections & groov$ base insure good me*anical union ( metal 9 ca/ weld+ to magnet frame4 ,reluctance betwe5 core & yoke is r$uc$ to a m9imum by ca/ weld+4 ,! core is slott$ p>allel ) ! %aft to prev5t1 z f> z possible1 ! di/ortion ( ! magnetic field1 especially on heavy ov]loads4 ,ques4 ,:at mode ( con/ruction is adopt$ to r$uce ! reluctance ( ! magnetic circuit :5 lam9at$ poles are us$8 ,ans4 ,!y are ca/ weld$ into ! frame4 ,illu/ration3 ,,fig4 #bcf4--;,=t ,wayne "o piece frame ) ca/ weld$ comb9$ cores & pole pieces4 ,9 any electrical app>atus a magnetic circuit ( l[ reluctance requires less en]gy to ma9ta9 a giv5 flux ?an "o hav+ a comp>atively high reluctance4 ,to r$uce ?is to a m9imum ! pole pieces & cores are comb9$ into "o "p & !n ca/ weld$ into ! yoke or frame4 ,?us ! cont9uity ( ! magnetic circuit is practically unbrok5 save = ! air gap4 ,! frame end ( ! core z %[n 9 ! illu/rations has irregul>ities 9 ! heights ( ! diff]5t %eets1 z well z groov$ und]cut surfaces1 9 ord] to enable ! molt5 metal ( ! frame to key well into ! lam9ations ( ! core1 mak+ a good jo9t1 bo? me*anically & electrically4 ,by ?is con/ruction1 ! cont9uity ( ! magnetic circuit is practically unbrok5 save = ! air gap betwe5 ! pole piece & armature4 ,fig4 #bcf %[s a "o piece frame ( a six pole dynamo hav+ ca/ weld$ into x1 comb9$ cores & pole pieces4 ,ques4 ,:at is ! disadvantage ( lam9at+ a core8 ,ans4 ,x necessitates a ne>ly squ>e or rectangul> section1 :i* requires m copp] = ! w9d+ ?an ! cyl9drical =m4 ,illu/ration3 ,,fig4 #bcg4--,lundell type ( comb9$ core & pole piece2 a comb9ation ( ,gravi]'s unsymmetrical horns & longitud9al slot design$ to prev5t di/ortion ( field4 ,! ,magnetiz+ ,coils4--,! object ( ! magnetiz+ coils1 is to provide1 "u ! v>i\s conditions ( op]ation1 ! numb] ( amp]e turns ( excitation requir$ to give ! prop] flux ?r\gh ! armature to produce ! desir$ electromotive =ce4 ,) respect to ! mann] 9 :i* magnetiz+ coils are w\nd !y are said to be3 #a4 ,spool w\nd2 #b4 ,=m] w\nd4 ,ques4 ,describe ! me?ods ( con/ruct+ spool w\nd coils4 ,ans4 ,! spool is made 9 v>i\s ways1 sometimes entirely ( brass1 or ( %eet iron ) brass flanges1 or ( v ?9 ca/ iron4 ,"s build]s use %eet metal ) a flange ( h>dwood1 su* z teak4 ,if a spool be simply put ^u a la! to be w\nd1 ! inn] end ( ! wire1 :i* mu/ be prop]ly secur$1 %\ld be br\ght out 9 su* a way t x _c possibly make a %ort circuit ) any ( ! wires 9 ! upp] lay]s4 ,to avoid ?is difficulty1 ! wire is sometimes w\nd on ! spool 9 two sep>ate halves1 ! two inn] ends ( :i* are unit$1 s t bo? ! work+ ends ( ! coil come to ! outside z %[n 9 fig4 #bch4 ,illu/ration3 ,,fig4 #bch4--,me?od ( w9d+ magnet spool s t ! two ends ( ! coil w come to ! outside4 ,?is me?od has also be5 us$ = induction coils1 :]e x is desirable to keep ! ends ( ! wire away f ! core & prim>y coil4 ,ques4 ,describe ! con/ruction ( =m] w\nd coils4 ,ans4 ,=m] w\nd coils are w\nd ^u a block ( wood hav+ tempor>y flanges to hold ! wire toge!r dur+ ! w9d+4 ,su* coils h pieces ( /rong tape ins]t$ betwe5 ! lay]s & lapp$ at int]vals ov] ! w9d+s to b9d !m toge!r4 ,coils are usually soak$ ) insulat+ v>ni% & /ove dri$4 ,ques4 ,:at may be said ) respect to ! coil ends8 ,ans4 ,sev]al me?ods ( br++ out ! ends ( coils are %[n 9 figs4 #bch to #bda4 ,9 fig4 #bci copp] /rip1 laid 9 beh9d an end %eet ( insulat+ mat]ial1 makes connection to ! inn] end1 z %[n 9 ! "r side ( ! figure1 :ile ano!r /rip1 %[n on ! left side simil>ly inlaid1 s]ves z a me*anical & electrical atta*m5t = ! out] end ( ! w9d+4 ,illu/ration3 ,,fig4 #bci4--;,core & edge /rip w9d+ = %unt field coils ( l>ge multi-pol> dynamo4 ,! w9d+ consi/s ( a copp] /rap ,s c>efully insulat$ & plac$ edgewise on ! core ,c 9 a s+le lay] ( w9d+4 ,) ?is arrangem5t1 ! space occupi$ by insulation is r$uc$ to a m9imum1 &1 al?\gh ! cool+ surface is small1 ea* turn ( ! w9d+ has "o edge on ! out] surface1 be+ ample = adequate cool+4 ,two o!r me?ods are %[n 9 figs4 #bdj & #bda4 ,a simple device = secur+ ! out] end is to fa%ion a t]m9al piece s t x c be laid ^u ! w9d+1 ! la/ ?ree or f\r turns ( :i* are w\nd ov] its base1 & aft] w9d+1 are b>$ at ! place & securely sold]$4 ,ques4 ,h[ are ! coils insulat$8 ,ans4 ,! spools ^u :i* ! coils are w\nd are usually insulat$ ) sev]al lay]s ( pap] prep>ations2 a ?ickness ( "o-t5? ( an in* made up ( sev]al sup]pos$ lay]s is g5]ally suffici5t4 ,v>ni%$ canvas is useful z an und]lay1 & vulcaniz$ fibre = l9+ ! flanges4 ,x is important to protect ! jo9t betwe5 ! cyl9drical "p & ! flanges4 ,a core pap] may be laid ^u e f\r lay]s ( w9d+4 ,betwe5 s]ies & %unt coils1 9 comp\nd w\nd ma*9es !re %\ld be an insulation z effici5t z t on ! cores4 ,:5 ! w9d+ is complet$1 two lay]s ( press$ bo>d or equival5t are laid ov] & b\nd ) an ext]nal w9d+ ( h>d rope or tape4 ,?is protective ext]nal lagg+ cov]+ ! out] surface ( ! complet$ coils is n altoge!r a b5efit = x t5ds to prev5t dissipation ( heat4 ,illu/ration3 ,,fig4 #bdj4--,"o mode ( br++ out ! coil ends1 9 :i* copp] /rip is laid 9 beh9d an end %eet ( insulat+ mat]ial4 ,illu/ration3 ,,fig4 #bda4--;,ano!r mode ( br++ out ! coil ends4 ,a n>r[ insulat$ /rip ( ?9 copp] ,g1 lead+ to t]m9al ,h1 is connect$ ) ! end e ( ! coil be=e w9d+4 ,illu/ration3 ,,figs4 #bdb & #bdc4--,squ>e & hexagonal ord] ( 8b$d+40 ,! t]m b$d+ is an expression us$ to indicate ! relation betwe5 ! cross sectional area ( ! w9d+ :5 w\nd squ>e1 z 9 fig4 #bdb1 & :]e w\nd 9 "s o!r way1 z 9 fig4 #bdc4 ,9 ! squ>e ord] ( b$d+1 ! degree ( b$d+ equals z]o4 ,illu/ration3 ,,fig4 #bdd4--,me?od ( secur+ coils 9 position :5 ! pole pieces are simply ext5sions ( ! core )\t enl>gem5t4 ,ques4 ,h[ are ! coils atta*$8 ,ans4 ,:]e ! pole pieces are simply ext5sions ( ! cores )\t enl>gem5t1 ! coils c be slipp$ ov] ! ends1 b "s k9d ( clamp+ device is necess>y to hold !m 9 place1 z = in/ance1 ! me?od %[n 9 fig4 #bdd4 ,9 case ! pole piece be made l>g] ?an ! core & sep>ate !refrom1 x is put into position aft] ! coils are 9 place1 ?us s]v+ ! d\ble purpose ( pole piece & clamp4 ,ques4 ,describe ! coil connections4 ,ans4 ,coils are g5]ally unit$ 9 s]ies s t ! same magnetiz+ curr5t may fl[ ?r\gh all ( !m4 ,! coils %\ld be s connect$ t !y produce alt]nate nor? & s\? poles4 ,if all ! coils be simil>ly w\nd ) respect to ! t]m9als1 & simil>ly plac$2 t is1 s plac$ t ! w9d+1 consid]$ f ! coil t]m9al ne>e/ ! pole face1 />ts 9 all ! coils 9 ! same direction1 !n ! connections w come at ! nor? end & at ! s\? end ( ! spools4 ,illu/ration3 ,,fig4 #bde4--,we/]n ,electric set ( =m] w\nd field coils = f\r pole dynamo4 ,^! coils are w\nd ar\nd a =m] or template1 & are !n slipp$ ov] ! cores be=e ! latt] are bolt$ to ! yokes or frame4 ,heat+4--,! heat g5]at$ 9 ! magnetiz+ coils is dissipat$ 9 ?ree ways2 by3 #a4 ,induction2 #b4 ,radiation2 #c4 ,convection4 ,9 ! fir/ in/ance1 x passes ?r\gh ! copp] & ! insulation1 ei!r to ! ext]nal surface1 :5ce x passes (f by radiation & convection into ! air1 or to ! magnet core & yoke1 :i* 9 turn conduct x away4 ,9 l>ge multi-pol> ma*9es ! masses ( metal 9 ! pole cores & frame are m effici5t 9 dissipat+ heat ?an ! ext]nal surface ( ! coil4 ,illu/ration3 ,,fig4 #bdf4--;,=t ,wayne comp\nd w\nd rectangul> v5tilat$ spool field coil4 ,! s]ies & %unt coils are w\nd side by side1 v5tilat+ passages be+ provid$ l5g?wise ?r\gh ea* coil & betwe5 ! %unt & s]ies coils z %[n4 ,v5tilation4--,sometimes provision is made = v5tilation ( ! field magnet coils z %[n 9 fig4 #bdf4 ,"h ! s]ies & %unt coils are w\nd side by side1 ample v5tilation be+ provid$ l5g?wise ?r\gh & betwe5 ! coils4 ,,hawk9s ,,practical ,,libr>y ,,( ,,electricity ,,9 ,,h&y ,,pocket ,,=m ,,price #a ,,ea* ,!y are n only ! be/1 b ! *eape/ "w publi%$ on ,electricity4 ,ea* numb] be+ complete 9 itself4 ,sep>ate numb]s s5t po/paid to any address on receipt ( price4 ,!y are gu>ante$ 9 e way or y\r money w be return$4 ,complete catalog ( s]ies w be mail$ free on reque/4 ,,electrical ,,guide1 ,,no4 #a ,conta9+ ! pr9ciples ( ,elem5t>y ,electricity1 ,magnetism1 ,induction1 ,exp]im5ts1 ,dynamos1 ,electric ,ma*9]y4 ,,electrical ,,guide1 ,,no4 #b ,! con/ruction ( ,dynamos1 ,motors1 ,armatures1 ,armature ,w9d+s1 ,in/all+ ( ,dynamos4 ,,electrical ,,guide1 ,,no4 #c ,electrical ,in/rum5ts1 ,te/+1 ,practical ,managem5t ( ,dynamos & ,motors4 ,,electrical ,,guide1 ,,no4 #d ,di/ribution ,sy/ems1 ,wir+1 ,wir+ ,diagrams1 ,sign ,fla%]s1 ,/orage ,batt]ies4 ,,electrical ,,guide1 ,,no4 #e ,pr9ciples ( ,alt]nat+ ,curr5ts & ,alt]nators4 ,,electrical ,,guide1 ,,no4 #f ,alt]nat+ ,curr5t ,motors1 ,trans=m]s1 ,conv]t]s1 ,rectifi]s4 ,,electrical ,,guide1 ,,no4 #g ,alt]nat+ ,curr5t ,sy/ems1 ,circuit ,break]s1 ,measur+ ,in/rum5ts4 ,,electrical ,,guide1 ,,no4 #h ,alt]nat+ ,curr5t ,swit* ,bo>ds1 ,wir+1 ,p[] ,/ations1 ,in/allation & ,op]ation4 ,,electrical ,,guide1 ,,no4 #i ,telephone1 ,telegraph1 ,wireless1 ,bells1 ,light+1 ,railways4 ,,electrical ,,guide1 ,,no4 #aj ,mod]n ,practical ,applications ( ,electricity & ,ready ,ref]5ce ,index ( ! #aj ,numb]s4 ,!o4 ,audel ,co41 ,publi%]s #gb ,,fif? ,,av5ue1 ,,new ,,york ,,footnotes3 #a ,,note4--,9 #agdi1 ,b5jam9 ,frankl91 obs]v+ lightn+ to possess almo/ all ! prop]ties obs]vable 9 electric sp>ks1 sugge/$ t ! electric action ( po9ts1 :i* 0 discov]$ by him1 might be tri$ on ?und]cl\ds1 & s draw f !m a *>ge ( electricity4 ,he propos$1 !re=e1 to fix a po9t$ iron rod to a high t[]1 b %ortly aft] succe$$ 9 ano!r way4 ,he s5t up a kite dur+ ! pass+ ( a /orm1 & f\nd ! wett$ /r+ to conduct ! electricity to ! e>?1 & to yield abundance ( sp>ks4 ,^! he drew f a key ti$ to ! /r+1 a silk ribbon be+ int]pos$ betwe5 8 h& & ! key = safety4 ,leyd5 j>s c\ld be *>g$1 & all o!r electrical effects produc$1 by ! sp>ks furni%$ f ! cl\ds4 ,! pro( ( ! id5tity 0 complete4 ,! kite exp]im5t 0 repeat$ by ,romas1 :o drew f a metallic /r+ sp>ks #i feet long4 ,9 #agec1 ,ri*mann1 ( ,/4 ,pet]sburg1 :o 0 exp]im5t+ ) a simil> app>atus1 0 /ruck by a sudd5 dis*>ge & kill$4 #b ,,note4--,suppose t ! conditions are z 9 ! fig4 #cd1 t is1 ! segm5t ,a#a is positive & ! segm5t ,b#a negative4 ,n[1 z ,a#a moves to ! left & ,b#a to ! "r1 _! pot5tials w rise on acc\nt ( ! "w done 9 sep>at+ !m aga9/ attraction4 ,:5 ,a#a comes opposite ! segm5t ,b#b ( ! ,b plate1 :i* is n[ 9 contact ) ! bru% ,y1 x w be at a high positive pot5tial1 & w !re=e cause a displacem5t ( electricity along ! conductor betwe5 ,y & ,y#a1 br++ a l>ge negative *>ge on ,b#b & s5d+ a positive *>ge to ! segm5t t\*+ ,y#a4 ,z ,a#a moves on1 x passes ne> ! bru% ,z & is p>tially dis*>g$ into ! ext]nal circuit4 ,x !n passes on until1 on t\*+ ! bru% ,x1 x is put 9 connection ) ,x1 & has a new *>ge1 ?is "t negative1 driv5 into x by induction f ,b#b4 ,positive electricity1 !n1 be+ c>ri$ by ! conduct+ pat*es f "r to left on ! upp] half ( ! ,a plate1 & negative f left to "r on its l[] half4 ,a simil> process is tak+ place on ! ,b plate1 b 9 ?is case ! negative electricity is go+ f left to "r above1 & ! positive f "r to left bel[4 ,on ! :ole1 !re=e1 positive electricity is be+ suppli$ to ! left h& ma9 conductor ,z by bo? upp] & l[] plates1 & negative to ,z#a4 #c ,,note4--,! discov]y ( ?is prop]ty ( matt] is due to ,/eph5 ,gray1 :o1 9 #agbi1 f\nd t a cork1 ins]t$ into ! end ( a rubb$ glass tube1 & ev5 a rod ( wood /uck into ! cork1 possess$ ! p[] ( attract+ light bodies4 ,he f\nd1 simil>ly1 t metallic wire & pack ?read conduct$ electricity1 :ile silk did n4 ,gray ev5 succe$$ 9 transmitt+ a *>ge ( electricity ?r\gh a hemp5 ?read ov] #gjj feet long1 susp5d$ on silk5 loops4 ,a little lat]1 ,du ,fay succe$$ 9 s5d+ electricity to no less a di/ance ?an #a1bef feet ?r\gh a moi/5$ ?read1 ?us prov+ ! conduct+ p[] ( moi/ure4 ,f t "t ! classification ( bodies into conductors & insulators has be5 obs]v$4 #d ,,note4--,copp] is pre-em95tly ! metal us$ = electric conduction1 be+ among ! be/ conductors1 x is excell$ by "o or m ( ! o!r metals1 b no o!r approa*es x 9 ! av]age ( all qualities4 #e ,,note4--,a curr5t ( electricity always fl[s 9 a conduct+ circuit :5 its ends are kept at diff]5t pot5tials1 9 ! same way t a curr5t ( wat] fl[s 9 a pipe :5 a c]ta9 pressure is suppli$4 ,! same electrical pressure does n1 h[ev]1 always produce a curr5t ( electricity ( ! same /r5g?1 nor does a c]ta9 pressure ( wat] always produce a curr5t ( wat] ( ! same volume or quantity4 ,9 bo? cases ! /r5g? or volume ( ! curr5ts is dep5d5t n only ^u ! pressure appli$1 b also ^u ! resi/ance :i* ! conduct+ circuit (f]s to ! fl[ 9 ! case ( electricity1 & on ! friction 7:i* may be express$ z resi/ance7 :i* ! pipe (f]s to ! fl[ 9 ! case ( wat]4 #f ,,note4--,! prefixes 8meg0 & 8micro0 d5ote million & million?4 ,= example1 a megohm equals #a1jjj1jjj ohms1 a microhm equals #a_/a1jjj1jjj ( an ohm4 #g ,,note4--,! reciprocal ( a numb] is equal to #a ! numb]2 = in/ance1 ! reciprocal ( #c_/bj #a #c_/bj #bj_/c #f-b_/c #h ,,note4--,a writ] 9 ! ,new ,sci5ce ,review und]takes to answ] ! "q3 8,:at is electricity80 ,9 ord] to lead ! read] up to ! ma9 "q1 he fir/ consid]s ! natural =ces1 gravitation & heat4 ,examples are giv5 ( h[ ^! =ces are manife/$ & h[ en]gy is *ang$ f "o =m to ano!r4 ,e =m ( =ce1 ! au?or says1 %\ld be reg>d$ z a diff]5t me?od 9 :i* en]gy makes itself kn[n to ! s5ses4 ,he calls p>ticul> att5tion to ! important fact t ! 8resi/ance ( "o k9d or ano!r is always ! ag5t t acts to alt] en]gy f "o =m to ano!r10 & sugge/s t electricity is simply a =m or manife/ation t en]gy may assume "u giv5 conditions1 & g5]ally is a m]e transitory /age betwe5 ! me*anical =m & ! heat =m4 8,9 mo/ op]ations10 he cont9ues1 8me*anical =ce passes to ! heat =m )\t pass+ ?r\gh ! electric =m2 b :5ev] magnetism is br\ght into play z a resi/ance t mu/ be ov]come1 !n me*anical p[] appli$ to ov]come ?is resi/ance always becomes electricity1 if only mom5t>ily 9 its passage f ! me*anical to ! heat =m40 ,9 conclusion1 he asks if ! "q3 8,:at is electricity80 _c be answ]$ 9 a fairly satisfactory way by say+ t x is simply a =m t en]gy may assume :ile und]go+ trans=mation f ! me*anical or ! *emical =m to ! heat =m or ! rev]se4 #i ,,note4--,! ca?ode is ! conductor by :i* curr5t fl[s away z di/+ui%$ f ! anode or conductor ?r\gh :i* ! curr5t ent]s4 ,! t]ms usually apply to conductors lead+ ! curr5t ?r\gh a liquid or gas1 z an electrolytic cell1 or vacuum tube4 #aj ,,note4--,! "n voltamet] 0 giv5 by ,f>aday to an electrolytic cell employ$ z a means ( measur+ an electric curr5t by ! am\nt ( *emical decomposition ! curr5t effects 9 pass+ ?r\gh ! cell4 #aa ,,note4--,f>aday's own description ( 8 discov]y is z foll[s3 8,two hundr$ & ?ree feet ( copp] wire 9 "o l5g? 7 coil$ r\nd a l>ge block ( wood2 ano!r two hundr$ & ?ree feet ( simil> wire 7 intropos$ z a spiral betwe5 ! turns ( ! fir/ coil1 & metallic contact ev]y:]e prev5t$ by tw9e4 ,"o ( ^! helices 0 connect$ ) a galvanomet]1 & ! o!r ) a batt]y ( "o hundr$ pairs ( plates1 f\r in*es squ>e1 ) d\ble copp]s1 & well *>g$4 ,:5 ! contact 0 made !re 0 a sudd5 & v slight effect at ! galvanomet]1 & !re 0 also a simil> slight effect :5 ! contact ) ! batt]y 0 brok540 #ab ,,note4--,9 reality x w\ld be impossible to h a magnetic field exactly l fig4 #abi1 = 9 ! less d5se "p1 ! magnetic l9es w\ld be ( curv$ complex =m4 #ac ,,note4--,^! values are correct = effective s9usoidal voltages4 #ad ,,note4--,x %\ld be und]/ood t a dynamo does n g5]ate electricity1 = if x 7 only ! quantity ( electricity t is desir$1 x w\ld be ( no use1 z ! e>? may be reg>d$ z a va/ res]voir ( electricity4 ,h[ev]1 electricity )\t pressure is incapable ( do+ "w1 h5ce a dynamo1 or s-call$ 8g5]ator10 is necess>y to create an electromotive =ce by electromagnetic induction 9 ord] to cause ! curr5t to fl[ aga9/ ! resi/ance ( ! circuit & d useful "w4 99 99 99 99 99 ,,transcrib]',s ,,am5dm5ts ,transcrib]'s ,note3 ,blank pages h be5 delet$4 ,"s illu/rations may h be5 mov$4 ,notes at ! bottom ( pages 9 ! text 7 conv]t$ to footnotes & footnote tags 7 add$ to ! text itself4 ,! footnotes are n[ locat$ prior to ?is section4 ,:5 ! au?or's pref]5ce c be det]m9$1 we h r5d]$ consi/5t on a p]-^w-pair basis ! hyph5ation or spac+ ( su* pairs :5 repeat$ 9 ! same grammatical context4 ,! publi%]'s inadv]t5t omissions ( important punctuation h be5 correct$4 ,duplicative front matt] has be5 remov$4 ,! foll[+ li/ indicates any additional *anges4 ,! page numb] repres5ts t ( ! orig9al publication & applies 9 ?is etext except = footnotes & illu/rations s9ce !y may h be5 mov$4 ,,toc ,table ( ,cont5ts ,,toc ,add$ ,,introductory ,,*apt] & ,,signs ,,& ,,symbols ,,toc betwe5 electric & neticmagnetic circuits ,,toc action ( ,toepl]-,holz,holtz ma*9e #d species inhabit+ ! ,m$it]anean,m$it]ranean #ad w\ld fly f x )\t any elecricalelectrical #af pi? balls on /rips ( pap] ,c1 ,d1 ,e1 z %[n4 #bh betwe5 ! s\rce & r]m9alt]m9al4 #ci a c]ta9 an\ntam\nt ( "w #dc ,:5 metals diff]e+diff]+ f ea* o!r #fa ,v>i\s z9cs2 fig4 #eh ,full]2 fig4 #ei ,daniel,daniell #fb ,v>i\s c>bons2 fig4 #fa ,cyl9drical f=m1 #fc fig4 #fh ,lockwood2 fig4 #fi fire alramal>m4 #ff ,a p>all$p>allel$ or multiple connection #gj b no o!r aproa*esapproa*esx #ic ,) ?is prelim>yprelim9>y caution1 #if ,if a curr5t ( #aj amp]es fl[fl[s 9 a wire #ih z an electrotylicelectrolytic cell1 #ii ris+ f ! ka?odeca?ode ,p is hydrog5 #ajj hydrog5 atoms 9 _! j\rney t[>ds b,b meet #ajj at ! electrodueselectrodes & n #acc ,,vi4#f4 ,! approa* & recession ( a conductor #adb #cb4 ,vibrator coils2 #adb #bc4 ,cond5s] coils4 #adc soak$ 9 %ellac dissolv$ 9 al*oolalcohol #aea ! hamm] or piece ( (#bnd #8(' del iron #agj ,,fig4,,figs4 #afi to #agc4-- ,! s9e curve #bji ,an extreme design1 sugge/$ by ,dobr[olsky,dobr[olski1 99 99 99 99 99