Motors and Generators

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x Performa ifrs thandi nves itga itont oinvesitgatethemotoreffect ts e v n I igaiton :Bulidinga ismplemotor : m i A Toperformas implef rist-handi nvesitgaitont oi nvesitgatet hemoto reffec t :t n e m p i u q E -Smal lpermanen tba rmagnet( 2x5cm) -2l argepape rcilps -dowe/lmarker( 1.9cmdiameter) -connecitngwrie -sandpaper -packingf oam( 5x5cms quare ,2cmdeep) -D-el lbattery -24gaugei nsulatedwrie : d o h t e M / 1 Wrapt hewriearoundt hedowe l10-20 itme ,sl eaving5cmf reewriea teachend . e ri w f o g n ir p s a e v a h u o y t a h t o s l e w o d e v o m e R / 2 Squeezet hecolit ogethe randwraponeendt os ecurecoli: / 3 Windt hef reeendass hownbelow .Ensuret hel ead sarewell-cenrtedands rtaigh.t m c 5

/ 4 Sandonlyt hetophal fo feachl ead ,ensu irngt hepainti scompletelyr emovedf romt he fl a h p o t . / 5 Unfoldeachpapercilpandassembleass hownbelow: p il c r e p a P k c o l b m a o F t e n g a M f o l i o C e r i w r e p p o c c it s a l e / e p a T d n a b D ( y r e t t a B -c el)l w a r t s c it s a l P

/ 6 Whent hebattery i sconnectedandt hebarewrie soft hecoppe rcoi larei ncontac twtiht he . y l e e r f e t a t o r d l u o h s li o c e h t ,s p il c r e p a p / 7 Reverset hepolartiyoft hebatteryandr econnect .Yous houldobservethecolir otaitngi n . n o it c e ri d e ti s o p p o e h t ? g n i n e p p a h y ll a u t c a s i t a h W e u q r o t o n s e c n e ir e p x e l i o c e h T . li o c e h t n i d l e if c it e n g a m o n e r o f e r e h t ,t n e r r u c o N s w o lf t n e r r u c , e d a m s i t c a t n o c , h s u p a n e v i g s i li o c f I andt hecoi lact sa sanelecrtomagnet . d n a e l o p h tr o n e h t g n il l e p e r ,l i o c e h t f o e l o P h t u o S e h t s t c a rt t a t e n g a m e h t f o e l o P h tr o N e h T . n i p s o t li o c e h t g n i s u a c n o it c a rt t A betweenoppostiepole sandt hei neritakeep stir otaitngwhliecurren t lfow .s N I N S S S N I N S S I N S N N S e r i w ’ e r a B ‘ n o it a l u s n i e r i W p il c r e p a P ’ h s u r b ‘

e h T . f f o t n e r r u c e h t s n r u t n o it a l u s n i e h t , n r u t a ½ g n it e l p m o c n O ineritaoft hecoi lcariresi t e h t , n i a g a s w o lf t n e rr u c n e h W . n o it a l u s n i e h t t s a p n r u t r e h t o n a h g u o r h t torqueisi nt hesame n o it c e ri d sot hecoi lconitnuest or otatei nt hes amed rieciton. x Describequaltia itvelyandquanttia itvelyt hef orcebetweenl ongparalle lcurrent -: s r o t c u d n o c g n i y r r a c d I I k l F 1 2 e r d n A t s i c i s y h p , 0 2 8 1 n I -MaireAmperei nvesitgatedt hef orceexetredbetweent wol ong s i e c r o f e h t , n o it c e ri d e m a s e h t n i t n e r r u c y r r a c s e ri w e h t n e h w t a h t d n u o f e H . s e ri w l e ll a r a p .s e ri w e h t s l e p e r d e tr e x e e c r o f e h t ,s n o it c e ri d e ti s o p p o n i w o lf s t n e r r u c e h t f I . e v it c a rt t a if c it e n g a m e t a e r c s t n e r r u c l a c ir t c e l e t a h t s w o h s s i h T eld sandf orces ,whichi nterac twtihothe r .s t n e r r u c l a c ir t c e l e d n a s d l e if c it e n g a m s e ri w g n i y r r a c t n e r r u c l e ll a r a p o w t n e e w t e b e c r o f e h t f o n o it c e ri d e h T canbeexplainedusing . e l u r m l a p d n a h t h g ir e h t e h t ,s e ri w e h t n i t n e r r u c e h t f o t c u d o r p e h t n o s d n e p e d s e ri w o w t e h t n e e w t e b e c r o f e h T .s e ri w e h t f o h t g n e l e h t d n a s e ri w e h t n e e w t e b e c n a t s i d r a l u c i d n e p r e p n I creasingt hecurren tandt hel engthoft hewriesi ncreasest hef orce.I ncreasingt he . e c r o f e h t s e s a e r c e d s e ri w e h t f o n o it a r a p e s , y ll a c it a m e h t a M d I I k l F 1 2 _where = F Force,i nNewtons s e rt e m n i ,s r o t c u d n o c f o h t g n e l = L e m a s n i s t n e r r u C direc iton , c it e n g a m g n it l u s e r e h t o s e m a s e h t n i o s l a e r a s e x u lf s e r i w e h t , e c n e H . n o it c e r i d t c a r tt a . e ti s o p p o n i s t n e r r u C s n o it c e r i d , sot heresulitng n i e r a s e x u lf c it e n g a m e c n e H . s n o it c e r i d e ti s o p p o l e p e r s e r i w e h t .

I1andI 2aret her especitvecurrentsi nt heconductor ,si namps k =magneitcf orceconstan t=2.0x10-7_TmA-1 t n e r r u c l e ll a r a p o w t n e e w t e b e c r o f e h t f o s m r e t n i d e n if e d s i , e r e p m a e h t ,t n e r r u c f o t i n u e h T s e ri w g n o l y l e ti n if n i o w t n e e w t e b s w o lf t n e r r u c f o e r e p m a e n o n e h W . s e ri w g n i y r r a c rt e m 1 f o e c n a t s i d e h t y b d e t a r a p e s ei navacuum,t heyexpeirenceaf orceo f2.0x10-7 .s n o t w e n x Solveproblem susing : d I I k l F 1 2 : s e l p m a x E ) 1 Calculatet hef orceperuntil engthbetweent wol ong ,para lle lwire scurrying n o it c e r i d e h t e t a t S . m c 0 0 . 1 y b d e t a r a p e s d n a A 7 . 2 1 d n a A 3 . 5 1 oft hef orce ,given .s n o it c e r i d e ti s o p p o n i e r a s t n e r r u c e h t t a h t s e ri w e h t g n il l e p e r m N 8 8 . 3 s i h t g n e l ti n u / e c r o f e h t s n o it c e ri d e ti s o p p o n i e r a s e ri w e h t n i s t n e r r u c e h t e c n i S ). f. s 3 ( m N 8 8 . 3 m N 0 1 2 6 8 8 . 3 1 0 . 0 A 1 3 . 4 9 1 0 1 x 0 . 2 d I I k l F A m T 0 1 x 0 . 2 k m 1 0 . 0 d A 1 3 . 4 9 1 7 . 2 1 3 . 5 1 I I 1 -1 -1 3 7 -2 1 1 7 -2 1 # u u u u    ) 2 Twol ong ,para lle lwire sarecarryingequa lcurrents .Thewire sare10.0cm 0 1 x 5 2 . 8 e b o t d n u o f s i m e h t n e e w t e b e c r o f e h T . t r a p a - m5N -1 ,a ttrac itngeach . s e r i w e h t n i s t n e r r u c e h t f o , n o it c e r i d e v it a l e r d n a , e d u ti n g a m e h t d n i F . r e h t o .r e h t o h c a e o t l e ll a r a p g n i w o lf e r a s t n e r r u c e h t ,s e ri w e h t s t c a rt t a e c r o f e h t e s u a c e B ). f. s 3 ( A 2 4 . 6 .. . 1 6 2 2 4 . 6 5 2 . 1 4 I y b n e v i g s i h c a e n i g n i w o lf t n e r r u c e h t , 1 I e c n i S 5 2 . 1 4 0 1 x 0 . 2 1 . 0 0 1 5 2 . 8 l k d F I I A m T 0 1 x 0 . 2 k m 1 . 0 d m N 0 1 5 2 . 8 l F I I 2 1 7 -5 2 1 1 7 -1 5 2 1 # u u u u u     ) 3 Twowire srunpara llelf oral engtho f1.48m .Thet otalf orceacitngbetween 0 1 x 4 4 . 6 s i h t g n e l s i h t r e v o m e h t -4Nwhent heyarecarryingcurrent so f8.90A ? y e h t e r a t r a p a r a f w o H . A 5 . 4 1 d n a l d n a I I t n a t s n o c r o f d 1 F d d n a I I t n a t s n o c r o f l F d d n a l t n a t s n o c r o f I I F 2 1 2 1 2 1 v v v

). f. s 3 ( m 0 1 6 5 . 3 0 1 1 6 5 . 3 5 0 . 9 2 1 0 1 4 4 . 6 8 4 . 1 0 1 x 0 . 2 I I F l k d d I I k l F A m T 0 1 x 0 . 2 k A 5 0 . 9 2 1 5 . 4 1 0 9 . 8 I I m 8 4 . 1 l N 0 1 4 4 . 6 F 6 6 4 7 -2 1 2 1 1 7 -2 1 4      u # u u u u ? u u u f o A 0 . 0 3 g n i y r r a c h t o b , s e l b a c r e w o p o w T currenti nt hes amedireciton ,ares eparated e h t s i t a h W . m 0 . 5 2 f o e c n a t s i d a r e v o l e ll a r a p n u r s e l b a c e h T . m c 0 0 . 8 f o e c n a t s i d a y b ? m e h t n e e w t e b g n it c a e c r o f l a t o t s e ri w e h t g n it c a rt t a ). f. s 3 ( 0 1 3 6 . 5 0 1 5 2 6 . 5 8 0 . 0 0 0 9 5 2 0 1 x 0 . 2 d I Il k F m 0 . 5 2 l m 8 0 . 0 d A 0 0 9 0 3 1 I 2 2 7 -2 1 2 2 1   _{# u} u u u x Identfiythatt hemotoreffecti sduet ot hef orceac itngonacurren tcarrying d l e if c it e n g a m a n i r o t c u d n o c t c e f f e s i h t ,r e v e w o H . k a e w y l e v it a l e r s i s r o t c u d n o c g n i y r r a c t n e r r u c o w t n e e w t e b e c r o f e h T a s e ri w f o r e b m u n g n i s a e r c n i y b l u f r e w o p e r o m h c u m e d a m e b n a c ndt hes rtengthoft he s i s i h T . r o t o m c ir t c e l e e h t f o s i s a b e h t s m r o f e c r o f e h t f o t c e f f e e h T . d e v l o v n i s d l e if c it e n g a m .t c e f f e r o t o m e h t d e ll a c t h g ir e h t e s u , d l e if c it e n g a m a n i e ri w a n o e c r o f e h t f o n o it c e ri d e h t e n i m r e t e d o T -handpalm : e l u r , t n e r r u C l a n o it n e v n o C I e g a p f o t u o e c r o F , d l e if c it e n g a M B

x Discussthee ffect ,ont hemagntiudeoft hef orceonacurrent-carryingconductor ,o f : n i s n o it a i r a v -thes trengthoft hemagneitc ifeldi nwhich tii sl ocated -themagntiudeoft hecurrenti nt heconductor - thelengthoft heconductori nt heexterna lmagneitc ifeld -Theanglebetweent hedirecitonoft heexterna lmagneitc ifeldandt hedirecitonoft he r o t c u d n o c e h t f o h t g n e l d l e if c it e n g a m l a n r e t x e n a n i r o t c u d n o c a r o f n o it a u q e e c r o f e h T si : d l e if c it e n g a m l a n r e t x e e h t d n a e ri w e h t n e e w t e b e l g n a e h t s e rt e m n i ,r o t c u d n o c f o h t g n e l l s p m a n i ,t n e r r u c I s a l s e t n i , h t g n e rt s x u lf c it e n g a m B s n o t w e n n i e c r o f F , e r e h w n i s lI B F T T d l e if c it e n g a M t n e r r u c o t e u d c it e n g a m l a n r e t x E d l e if o t n i t n e r r u C e g a p n o it c a r e t n i o t e u d e r i w n o e c r o F s d l e if c it e n g a m f o

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e h t m o r F forceequaiton: , e c n e H ani ncreaseo rdecreaseinthemagneitc ifelds rtength ,curren torl engthoft hewriei n e s a e r c n i ll i w d l e if e h t o rdecreasethef orceproporitonally. e l b a ir a v y l n o e h t s i , e l g n a e h t n e h w e c r o f f o e d u ti n g a m n o t c e ff E Fromabove ,wecans eet hatt hef orcei szerowhent hecurrenti sparallelt ot heexterna l . d l e if c it e n g a m Ast heangleincreases ,approaching90 ,°t hef orcei ncreasesinproporitont o . e l g n a e h t f o e n i s e h t Whent hecurrenti sperpendiculart ot he ifeld,t hef orcei samaximum F . e .i = IB l s r o t c u d n o c g n i y r r a c t n e r r u c n o e c r o f e h t t u o b a n o it a m r o f n i e s y l a n a d n a s m e l b o r p e v l o S : g n i s u s d l e if c it e n g a m n i

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: s e l p m a x E ) 1 ADCpower ilne250ml ongi sorientatedNE-SWi nt heEarth’ smagne itc ifeld s a h t a h t strengtho f1.5x10-5 _{Tint henorth-southdirec iton.I ft hecurren t} e d u ti n g a m e h t e t a l u c l a c E N e h t m o r f g n i w o lf A 0 5 1 s i e n il r e w o p e h t y b d e i r r a c e h t f o n o it c a r e t n i e h t o t e u d e n il r e w o p e h t n o d e t r e x e e c r o f e h t f o n o it c e r i d d n a . d l e if c it e n g a m e h t d n a e r i w g n i y r r a c t n e r r u c θ , e l g n A )( 0 ° 1 0 2 0 3 0 4 0 4 5 5 0 6 0 7 0 8 0 9 0 e c r o F (N) , .f .s 2 o t 0 0 .17 0 .34 0 .50 0 .64 0 .71 0 .77 0 .87 0 .94 0 .98 1 .0 l F I F B F v v v

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Thediagrams how showoneforcecancauseanobjecttor otate(clockwisei nt hi sexample): e t a t o r o t t c e j b o n a e s u a c n a c s e c r o f o w t w o h s w o h s m a r g a i d e h T (anitclockwisei nt hi s ) e l p m a x e : e c r o f a f o t c e f f e g n i n r u t e h t s a d e n if e d s i e u q r o T aroundanaxis ,pivo torf ulcrum .Wes ayt he . s i x a e h t d n u o r a e u q r o t a s tr e x e e c r o f Mathemaitcally, s e rt e m n i , ) d e v l o v n i e r a s e c r o f o w t fi ( s e c r o f o w t e h t r o e c r o f e h t o t n o it c a f o e n il e h t : m o r f e c n a t s i d r a l u c i d n e p r e p e h t d s n o t w e N n i , n o it a t o r f o s i x a e h t o t r a l u c i d n e p r e p e c r o f d e il p p a e h t F s e rt e m n o t w e N n i , e u q r o t e h t , e r e h w d F W W x Describethef orce sexperiencedbyacurrent-carryingl oopi namagneitc ifeldand e b i r c s e d thene tresul toft hef orces d e c r o F d =perpendiculardistancebetweenf orces r o t n i o p t o v i P s i x a e c r o F e c r o F

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x Describethemainf eature so faDC electricmotorandt heroleo feachf eature x Identfiythatt herequiredmagneitc ifeldsi nDCmotor scanbeproducedetiherby t n e r r u c -carryingcoli sorpermanen tmagnet s : o t n i d e d i v i d r e h tr u f e b n a c e s e h T . s r o t o m C D r o C A s a d e s s a l c e b n a c s r o t o m c ir t c e l E -DCCommutato rmotors -Inducitonmotors( DC) -Synchronou sACmotors e r u t a m r A s n o it a n i m a l l i o C s t c a t n o c r o t a t u m m o C s li o c r o t o R e l x A

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t r a P Descrip iton R ole g n i w o ll o f e h t f o e n o ) r o t a t S ( s t e n g a m l a n r e t x e e h t r o F arrangementsi sused: ) a apai ro fpermanen t s t e n g a m ( ifeld e l p m i s a n i ) s t e n g a m r o t o m n o s t e n g a m t n e n a m r e p o w T . r o t o m e h t f o s e d i s e ti s o p p o d n u o r r u s o t d e v r u c e r a y e h T . e r u t a m r a e h t e h t y l p p u s s t e n g a m e h T magneitc d l e if thati nteract swtiht hecurren t e c u d o r p o t li o c e h t n i torque .The s t e n g a m e h t f o e p a h s d e v r u c a s e c u d o r p radia lmagneitc ifeld l e ll a r a p s y a w l a s i li o c e h t t a h t h c u s . n o it a t o r t u o h g u o r h t d l e if e h t o t Thi s a t a s y a t s e u q r o t s n a e m constan t m u m i x a m ,providings mooth . n o it o m ) b pai ro felectromagneitc s li o c inmorecomplex s r o t o m li o c c it a t s h c a E i swound e r o c n o ri t f o s a d n u o r a e h t o t d e h c a tt a moto rcasing. a e c u d o r p s li o c r o t a t s e h T magneitc l e if d simliart opermanen tmagnet s s e l o p h t u o S d n a h tr o N h ti w . e .i . r e h t o h c a e g n i c a f Howeve,rt he y lt a e r g e r o c n o ri e h t d n a s li o c e s a e r c n i thes rtengthoft he d l e if c it e n g a m e r u t a m r A Alaminateds o tf rioncyilnder n a n o d e t n u o m axle . d e t a n i m a L conductor s (elecrtomagnets) arei mbedded e r o c l a t e m e h t o t n i s t o l s n i to n e e w t e b p a g r i a e h t e c u d e r . r o t a t s d n a s r o t c u d n o c . s li o c r o t o r e h t s d l o h e r u t a m r a e h T e h T rioncoreconcenrtatest he e h t g n i s a e r c n i , d l e if c it e n g a m e c u d e r s n o it a n i m a l e h T . e u q r o t s t c e f f e g n it a e h duet oeddycurrents. s li o c r o t o R Thecoli so fcoppe rwriet ha t . e r u t a m r a e h t d n u o r a p a r w e v a h y l n o l li w s r o t o m e l p m i S s r o t o m x e l p m o c e r o m t u b e n o . s li o c r o t o r l a r e v e s e v a h y a m r a e l c a h ti w d e t a l u s n i e r a y e h T r e u q c a l andareconnectedby r o t a t u m m o c e h t o t s d n e r i e h t e h t s a e u q r o t e h t e d i v o r p s li o c e h T m e h t h g u o r h t g n i s s a p t n e r r u c c it e n g a m l a n r e t x e e h t h ti w s t c a r e t n i e h t o t e u q r o t r e f s n a rt y e h T . d l e if . e l x a e h t y b e r e h t d n a e r u t a m r a ti l p S -ringcommutator Abroad irngo fmeta lmounted , e l x a e h t f o d n e e n o n o f o r e b m u n a o t n i d e t a r a p e s n e v e secitons ,dependingon h c a E . s li o c r o t o r f o r e b m u n e h t s t c e n n o c s li o c f o t e s g n i s o p p o .r o t o r e n o o t o c l a c ir t c e l e s e d i v o r P nneciton e h t d n a s li o c r o t o r e h t n e e w t e b t I .t i u c ri c l a n r e t x e reverses the e h t f o y ti r a l o p currenteveryhal f e h t t a h t g n ir u s n e , n o it a t o r torque . n o it c e ri d e m a s e h t n i s n i a m e r N S a r o f r o t a t u m m o C t o m orwtih2rotor s s li o c

s e h s u r B Thin , lfexiblecoppe rbrushes d e s s e r p m o c r o carbonblocks , e h t o t d e t c e n n o c externa l ti u c ri c .Theyaremountedon d l e h e r a d n a s e d i s e ti s o p p o n i a t n i a m o t s g n ir p s y b r o t a t u m m o c e h t h ti w t c a t n o c n i a t n i a m s e h s u r b e h T e h t n e e w t e b t c a t n o c l a c ir t c e l e l a n r e t x e d n a r o t a t u m m o c e h T . s e t a t o r ti s a t i u c ri c e c u d e r s g n ir p s sparking. e l x A Acyilnd irca lba ro fhardened l e e t s passingt hrought he e r u t a m r a e h t f o e rt n e c n o it a t o r f o e rt n e c a s e d i v o r P . s t n e n o p m o c r e h t o e h t r o f e b o t k r o w l u f e s u s w o ll A g n i s u r o t o m e h t m o r f n e k a t s r a e g r o s y e ll u p DC moto rAdvantages -larges taritngtorquei sablet omovel oad squickly -constantt orqueeven fil oadvaire s.ie.s efl-regulaitng( backAMFdecrease swhenl oadi s ) d e il p p a -ablet oconrto lmotors peedbyconrtolilngelecrtomagnets rtength -ablet or everser otaitonbyr eversing ifeldcurrentdrieciton r o t o M C D s e g a t n a v d A Disadvantages e u q r o t g n it r a t s e g r a l i sablet omovel oad s y l k c i u q Sdapnagrkeirnogusa tcommutatori spotenitally e u q r o t t n a t s n o c even fil oadvaire s.ie.s efl s i d a o l n e h w s e s a e r c e d F M A k c a b ( g n it a l u g e r ) d e il p p a e s i o N duet ocontac to fbrushe swtih r o t a t u m m o c o t e l b a con rto lmotors peedbycon rtolilng h t g n e rt s t e n g a m o rt c e l e R‘beuqrunirineg soaust’taritngr esistortopreven t -ablet oreverser otaitonbyr eversing ifeld n o it c e ri d t n e r r u c n o m m o c t s o m e r a s r o t o m C D lyusedi nindustira lappilcaitons ,especiallywherevairable s l o o t r e w o p . g . e d e d e e n e r a s d e e p s n o it a t o r x Identfiydatas ources ,gatherandprocessi nforma itontoqualtia itvelydescribethe : n i t c e ff e r o t o m e h t f o n o it a c il p p a -thegalvanometer -thel oudspeaker r e t e m o n a v l a G e h T f o s i s a b e h t s m r o f r e t e m o n a v l a g e h T ammetersandvotlmeters . tIi sdesignedmainlyt odetec t t n e r r u c rathert hanmeasure .ti I tconsist so facoi lo f ifnewir ewrappedaroundan rioncore h c i h w iss uspendedi napermanen tU-shapedmagnet .Acolieds p irngi sattachedt ot hecoli g n ir p s e h T . r e t n i o p a o t d e h c a tt a s i h c i h w servestob irngt hepointe rbackt ot hezeroposiiton. n e h W CD curren tpassest hroughi tcoi,li texpeirencesmagneitcde lfecitngt orque .Ast he a t o r li o c te ,ss odoest hepointe runtlit hemagneitct orquei sbalancedbyt her esto irngt orque g n ir p s e h t f o .Thes calei sdesignedt omeasurecurrenti nbothdrieciton sandt heconcave

e h t f o e c a f r u s magne tpole sproduce sar adia lmagneitc ifeldwhichensure sconstantt orque. .t n e r r u c e h t f o e d u ti n g a m e h t o t l a n o it r o p o r p s i r e t n i o p e h t f o n o it c e lf e d r a l u g n a e h t , e c n e H .t n e r r u c r o e g a tl o v r e h ti e d a e r o t d e t a r b il a c e b n a c e l a c s e h T a f o n o it c u r ts n o C movingcoi lgalvanometer: r e k a e p s d u o l e h T a d n u o r a d e p p a r w l i o c a f o s t s i s n o c r e k a e p s d u o l e h T cenrta lpolepiece .Thecenrta lpole e h t f o t r a p s m r o f e c e i p permanentmagnet ,whichi ss haped ilkeanall-roundhorseshoe t e n g a m .Thecenrta lpolei ss urroundedbyacricula rNo trhPole .Thecenrta lcorei sattached a n e h W . c it s a l p r o r e p a p f fi t s f o e n o c a o t natlernaitngcurrenti spassedt hrought hecoi,li t e t a r b i v o t e n o c e h t g n i s u a c , t e n g a m t n e n a m r e p e h t h ti w s t c a r e t n i backandf o trhaccordingt o l a n g i s d e t a l u d o m e h t . Ast heconevibrate ,si tampilifest hedesrieds oundvias oundwave .s l i o c g n i v o m a f o n o it c u r ts n o C loudspeaker: e r o c n o r I r e t n i o P n e e s li o c c it e n g a M d n e - no g n i r p s d e li o C

N

S

e l a c S e n o c g n it a r b i V e l o p l a r t n e C e c e i p li o C

N

N

S

2

.

T

h

e

G

e

n

e

r

a

t

o

r

x OutilneMichae lFaraday’ sdiscoveryoft hegenera itono fanelectriccurren tbya t e n g a m g n i v o m , 1 3 8 1 n I Faradaydemonsrtatedthatr elaitvemoitonbetweenamagneitc ifeldandaconducto r n o it c u d n i c it e n g a m o rt c e l e s a n w o n k s i s i h T . r o t c u d n o c e h t n i t n e r r u c a e c u d n i ll i w andf orm s . y t e i c o s n r e d o m n i n o it a r e n e g r e w o p l a c ir t c e l e r o f s i s a b e h t h c u s e n O apparatu sconsistedoft wowrie selectircallyconnectedt oacoppe rdiscviacoppe r e h t n e h W . t e n g a m e o h s e s r o h a f o s e l o p e h t n e e w t e b n i d e c a l p s a w c s i d r e p p o c e h T . s e h s u r b r o t c u d n o c e h t h ti w n o it o m e v it a l e r e h t , d e t a t o r s a w c s i d inducedanelectircalcurren tint he s a w h c i h w e ri w detectedb yagalvanomete rwhichwa sconnectedt ot hewiirng. : n o it c u d n i c it e n g a m o r t c e l e r o f s u t a r a p p a s ’ y a d a r a F x Performani nvesitga itont omodelthegenera itono fanelectriccurren tbymovinga t e n g a m a r a e n l i o c a r o l i o c a n i t e n g a m t n e r r u c c ir t c e l e n a g n it a r e n e G : n o it a g it s e v n I : m i A Toperformani nvesitgaitont ogenerateanelectirccurren tbyt her elaitvemoitono fa t e n g a m a r a e n l i o c :t n e m p i u q E -digtia lmulitmeter -1ml engthofs ingles rtandcoppe rwrie - cardboardt ube -alilgato rcilps - Aba rmagnet : d o h t e M / 1 Maket hewriei ntoa itgh tcoi lbywrappingaroundt hecardboardt ube .Tapet heend soft he . e b u t e h t o t li o c Dono tovelrapt hecoli .sThi scoi lwli lac ta sas olenoid N c s i d n r u t o t e l d n a H s e h s u r b r e p p o C t e n g a m e o h s e s r o H c s i d r e p p o C Galvanometer

s p il c r o t a g il l a g n i s u r e t e m it l u m o t s e ri w t c e n n o C / 2 / 3 Sett hemulitmetert or eadmicroamps( μA) . :t e n g a m e h t n e h w s n e p p a h t a h w e v r e s b O / 4 -i spushedt ot hecen rteoft hes olenoid -I sheldstaitonary ni thes olenoid - sI removed -I shelds taitonaryandt hesolenoidi smoved : s tl u s e R n o it o M o fmagnet Observa iton d i o n e l o s f o e rt n e c o t d e h s u p Curren tdetectedonmulitmeter d i o n e l o s n i y r e n o it a t S Nocurren tdetected d i o n e l o s m o r f d e v o m e R Curren tdetectedi noppostiedrieciton d e v o m s i li o c d n a y r e n o it a t s t p e K Currenti sdetectedonmulitmeter : n o i s u l c n o C Anelectirca lcurrenti sproducedwhent herei sr elaitvemoitonbetweena .l i o c a d n a t e n g a m x Plan ,chooseequipmen tandresourcesf or ,andperforma ifrst-handi nvesitga itont o : n e h w t n e r r u c d e t a r e n e g a f o t c e f f e e h t y fi r e v d n a t c i d e r p -thedistancebetweent hecoi landt hemagneti svaried -thes trengthoft hemagneti svaried -therela itvemo itonbetweent hecoi landmagneti svaried t n e r r u c d e c u d n i n a f o h t g n e r ts e h t g n it c e ff a s r o t c a F : n o it a g it s e v n I : m i A Toverfiyt hef actor saffecitngt hes rtengthoft hecurrenti nducedbyt her elaitvemoiton t e n g a m a d n a l i o c a n e e w t e b : y r o e h T Anelect irca lcurrenti sgeneratedbyt her elaitvemoitonbetweenacoi landa : e r a t n e r r u c e h t f o e z i s e h t g n it c e f f a s r o t c a f e h T . t e n g a m -Distancebetweent hecoi landt hemagnet -Srtengthoft hemagnet

N

S

-Relaitvemoitonoft hecoi landmagnet :t n e m p i u q E -Solenoidf rompreviou sexpeirment -Alilgato rcilps -Ba rmagnet -mulitmeter : d o h t e M / 1 Connectt hes olenoidt ot hemulitmete rusingalilgato rcilps .Se tmulitmetert or eadmicro .s p m a h t e v o M . p u g n i c a f e l o P h tr o N e h t h ti w d n e s ti n o t e n g a m e h t e c a l P / 2 ecoi lovert hemagne t s n e p p a h t a h w e t o n d n a y l w o l s e r o m l i o c e h t e v o M . t n e r r u c e h t f o n o it c e ri d e h t g n it o n , y l d i p a r . g n i d a e r e h t o t .t n e r r u c e h t f o n o it c e ri d e h t f o e t o n e k a T n o it c e ri d e ti s o p p o e h t n i y l d i p a r li o c e h t e v o M / 3 4 /Keept heco lis tli landmovet hemagneti nandou toft hecoi la tdfiferents peedswtiht he li o c e h t o t n i g n i v o m e l o P h tr o N .Notewha thappenst ot her eading. 5 /Tapet woba rmagnetstogethers ot heno trhpole saret ogethe randr epeats tep4. h tr o f d n a k c a b t e n g a m e h t e v o M / 7 a taconstants peedt owardst hecoi,ls toppinga tadistance e h t m o r f m c 5 f o e c n a t s i d a o t h tr o f d n a k c a b t e n g a m e h t e v o m , n e h T . li o c e h t m o r f m c 1 f o . d e e p s e m a s e h t t a l i o c s tl u s e R : s / e l b a i r a V Observa iton . p u s e c a f e l o p h tr o N d n a y r e n o it a t s s i t e n g a M o C i lmovedr apidlyands lowly. Tmhoevecu srurpenan tcdhadnogwen s .dThrieecf itaosntearst ht heeccuorrie ln t . d e t c e t e d t n e rr u c e h t r e g r a l e h t ,s e v o m y r a n o it a t s s i li o C andmagne tmoves Acurrenti sdetected t e n g a m r e g n o rt S Large rcurren tdetected o r f y a w a r e h tr u f d n a r e s o l c d e v o m t e n g a M m li o c Tcuhrerecnlo tsdeertet hcteecdoi landmagne,tt hel argert he -Thedriecitonoft hecurrenti sdependan tont hepolartiyoft hemagneitc ifeldwtihr espectt o . li o c e h t -Thefaster therelaitvemoitonoft hecoi landt hemagne,tt helargert hecurrentgenerated -Thes rtongert hemagnet,t hel argert hei nducedcurrent -Theclosert hemagne tandt hecoi lmove,t hel argert hecurrent : n o i s u l c n o C Thes izeoft hei nducedcurren tproducedwhent herei srelati vemoitonbetween n e h w s e s a e r c n i t e n g a m a d n a l i o c a : thedistancedecrease sandi ncreases ;thes peedoft he d e s a e r c n i s i n o it o m ;as rtonge rmagneti sused.

x Deifnemagne itc ifelds trengthB a smagneitc lfuxdenstiy x Describetheconcep to fmagneitc lfuxi nt erm so fmagneitc lfuxdenstiyands urface a e r a e h T numbe ro fmagneitc ilnesemergingf romani maginarys urfacei namagneitc ifeldi s . e .i s e n il e s e h t f o y ti s n e d e h T . x u lf c it e n g a m e h t d e ll a c themagneitc lfuxpe rarea B( )i sa s n e t n i e r o m e h t , y ti s n e d x u lf e h t r e t a e r g e h T . d l e if c it e n g a m e h t f o y ti s n e t n i e h t f o e r u s a e m e a e r a n e v i g a n i h ti w d l e if c it e n g a m e h t . e h t s i t n e m e r u s a e m f o t i n u e h t d n a B s i x u lf c it e n g a m e n if e d o t s n o it a u q e n i d e s u l o b m y s e h T . a l s e t Mathemaitcally, x u lf c it e n g a m e h t o t r a l u c i d n e p r e p a e r a e h t A n i , x u lf c it e n g a m e h t s a l s e t n i , y ti s n e d x u lf c it e n g a m B , e r e h w A B I I

x Describegeneratedpoten ita ldi fferenceast herateo fchangeo fmagneitc lfux ti u c r i c a h g u o r h t s i e r e h t n e h W relaitvemoitonbetweenaconducto randamagneitc ifeld ,avotlage ro s i F M E d e c u d n i e h t t a h t s e t a t s w a l s ’ y a d a r a F . d e c u d o r p s i ) F M E ( e c r o f e v it o m o rt c e l e e h t o t l a n o it r o p o r p rateo fchangeo f lfuxthrought hecricui.t ? F M E d e c u d n i e h t s e s u a c t a h W o t s e v o m e ri w e h T . e g a p e h t o t n i g n i w o lf t n e r r u c e h t h ti w e ri w a r e d i s n o C the irgh tanglest o y l n o t u b i e l c u n e v it a g e n d n a e v it i s o p f o s r e b m u n l a u q e s n i a t n o c e ri w e h T . B , d l e if c it e n g a m a e l u r n a l p d n a h t h g ir e h t g n i s U . e v o m n a c s n o rt c e l e e h t (fo rnegaitvecharges),i tcanbes hown a e l s i h T . e g a p e h t o t n i e c r o f a e c n e ir e p x e y e h t ve sadeifciencyo felecrton sa toneend .ie .a l a it n e t o p dfiferenceo rEMFi sproduced .Thecharge sconitnuet os eparateuntlit heelectirc . e c r o f c it e n g a m e h t s e c n a l a b s e g r a h c e k il n e e w t e b n o i s l u p e r f o e c r o f

A

B

x AccountforLenz’ sLawi nt erm soft heconserva itono fenergy h tr o N e h T . w o l e b n o it a u ti s e h t r e d i s n o C Poleo faba rmagneti smovedt oward sacoi l c it e n g a m a s e t a e r c n o it o m e v it a l e r s i h t o t e u d l i o c e h t n i d e c u d n i t n e r r u c e h T . t n e r r u c g n i y r r a c e b n a c t i , e l u r p ir g d n a h t h g ir e h t g n i s U . F M E s i h t d e c u d o r p t a h t e g n a h c e h t g n i s o p p o d l e if o it c e ri d e h t t a h t n w o h s noft hemagneitc lfuxproducedbyt hecoi lopposest he lfuxf romt he . t e n g a m Thu ,st hei nducedcurrenti ss implyar esul toft heworkdonet oovercomet he . n o i s l u p e r c it e n g a m : n o it o m e h t s e s o p p o t n e r r u c d e c u d n i e h T . li o c s d r a w o t d e v o m s i e l o P h tr o N e h t f o l a w a r d h ti w e h t s e s o p p o t n e r r u c d e c u d n i e h t ,l i o c e h t m o r f d e v o m e r s i t e n g a m e h t n e h W e l o P h tr o N .ie .energyi sr equriedt or emovet hemagnet .Becauset hedriecitonoft hecurrent . x u lf c it e n g a m e h t s e o d o s ,s e t a n r e tl a d l e if c it e n g a m d e c u d n i e h t , e c n e h d n a t n e r r u c d e c u d n i e h T . li o c m o r f d e v o m e r e l o P h tr o N : n o it o m e h t e s o p p o o t n o it c e r i d s e g n a h c

+

_

N

S

t e n g a m f o t n e m e v o M B f o w o l F o t n i s n o r t c e l e e g a p f o t n e m e v o M e r i w g n is o p p O e r i w n o e c r o f

B

o t s e v o m e r i W t h g i r e h t

N

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t e n g a m f o t n e m e v o M

t n e r r u c d e c u d n i n a f o d l e if c it e n g a m e h t t a h t s e t a t s w a l s ’ z n e L opposesthechanget ha t . ti d e s u a c Lenz’sl awi ssimplyaconsequenceoft hel awo fconservaitono fenergy.I ft he , t e n g a m e h t f o n o it o m e h t d e d i a t n e r r u c d e c u d n i kineitcenergy wouldbeproduced . d e t a e r c e b d l u o w y g r e n e d n a y l e ti n if e d n i x RelateLenz’sl awt ot hegenera itono fbackemfi nmotors Aworkingmotorhast het wot hingsr equriedt ogenerateanEMF :amovingcolianda d l e if c it e n g a m .TheappiledEMFinduce sanothe rEMFi nt hecoli ,whosedriecitonopposes e h t s e s o p p o n o it o m s i h t e s u a c e B . ) w a l s ’ z n e L m o r f ( li o c e h t f o n o it o m e h t app iledEMF tii s e h t d e ll a c backEMF. x Explainthati nelectricmotors ,backem fopposest hes upplyemf . d e c u d o r p s i F M E k c a b a , g n i k r o w s i r o t o m a n e h W Thi silmtist hecurrenti nt hecoi land .r o t o m e h t f o d e e p s e h t s ti m il e c n e h o t r o t o m e h t e s u a c o t e g a tl o v a s e c u d o r p F M E d e il p p a n a , g n i k r o w s n i g e b r o t o m a n e h W .s e s a e r c n i r o t o m e h t f o d e e p s d n a t n e r r u c e h t ,s e s a e r c n i F M E d e il p p a e h t s A . e t a t o r Hence , F M E d e il p p a = F M E t e n : t a h t h c u s s e s a e r c n i o s l a F M E k c a b e h t – backEMF .Eventually,t he d e e p s y d a e t s a s e h c a e r r o t o m whenappiledEMFequal sbackEMF. . r o t o m e h t t u o n r u b y a m t n e r r u c e h t o s d n a l l a m s s i F M E k c a b e h t , d e tr a t s s i r o t o m a n e h W e r p o T ventt his ,astaritngr esistancei splacedi nt hecoli .Ast hemotors peed sup,t heback . d e v o m e r e b n a c e c n a t s i s e r g n it r a t s e h t d n a s e s a e r c n i F M E x Explaintheproducitono feddycurrentsi nt erm so fLenz’sl aw c it e n g a m g n i g n a h c f o n o i g e r a n i d e c a l p s i ti r e v e n e h w r o t c u d n o c a n i d e c u d n i s i F M E n A . x u lf Int hecaseo fas oildconducto ,rt hebackEMFinduces ti sowncurrent swhich rtaveli n . ’ s t n e r r u c y d d e ‘ e m a n e h t e c n e h , s e c it r o v t n e t s i s r e p Eddycurrent scanr esutlf rommovinga . x u lf c it e n g a m g n i g n a h c a n i h ti w r o t c u d n o c e h t g n i v a h r o d l e if c it e n g a m a n i h ti w r o t c u d n o c 1 # n o it a u ti S : Conducto rmovingwtihinamagneitc ifeld: D C B A e t a l p l a t e m r a l u g n a t c e r a r e d i s n o C movingt ot he ir ghtduet oanappiledf orce, : e g a p e h t o t n i d e t c e ri d d l e if c it e n g a m a o t r a l u c i d n e p r e p B C D A

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t , w a l s ’ z n e L m o r F heinducedcurrenti nsidet hemagneitc ifeldmus tproduceamagneitc ifeld e h t s e s o p p o h c i h w appiledf orce .Applyingt he irght-handpalmr ule,t hei nducedcurren t e h T . B o t C m o r f e g a p e h t p u w o lf t s u m d l e if c it e n g a m e h t n i h ti w C B e d i s e h t n i g n i w o lf i t e y t o n e t a l p e h t f o t r a p e h t n i g n i w o lf t n e r r u c nt he ifeld rtavelsi nt heoppostiedrieciton . d e c u d n i s i e s i w k c o l c it n a g n i w o lf t n e r r u c y d d e r a l u c ri c a t a h t h c u s Usingt he irgh thand-girp l a it i n i e h t s e s o p p o t n e r r u c y d d e e h t y b d e c u d o r p d l e if c it e n g a m e h t t a h t m ri f n o c n a c e w , e l u r e h d n a , d l e if c it e n g a m ncet hef orceproducedbyt heeddycurren topposest heappiledf orce. e h T . d l e if e h t n i t e y t o n e t a l p e h t f o t r a p e h t r o f C o t B m o r f e g a p e h t n w o d s w o lf t n e r r u c e h T . e s i w k c o l c it n a g n i w o lf t n e r r u c y d d e r a l u c ri c a s i tl u s e r i w y l e ri t n e s i e t a l p e h t n e h W thint hemagneitc ifeld ,noeddycurrent sarei nduced .Whent he . e g n a h c s i h t t s i s e r o t e s i w k c o l c w o lf t n e r r u c y d d e e h t , d l e if e h t s e v a e l e t a l p : 2 # n o it a u ti S Conductori nt hepresenceo fchangingmagneitc lfux d e c a l p e t a l p g n it c u d n o c a r e d i s n o C perpendicular ,inaunfiormmagneitc ifeld . if e h t f I elds rtengthi si ncreased,t hent hei nducedcurrenti nt heplatewli lbes ucht hati t . e g a p e h t f o t u o d e t c e ri d d l e if c it e n g a m a s e c u d o r p Applyingt he irght-handg irpr ule,t hi scan . n o it o m e s i w k c o l c it n a r a l u c ri c a n i s l e v a rt t n e r r u c e h t n e h w r u c c o y l n o x Gather ,analyseandpresentinforma itont oexplainhowi nducitoni susedincook s e g n a r c i r t c e l e n i s p o t s s a l g a r e d n u d e c a l p ) s t e n g a m o rt c e l e ( e ri w r e p p o c f o s li o c e s u s p o t e v o t s n o it c u d n I -ceramic s e c u d o r p h c i h w l i o c e h t h g u o r h t d e s s a p s i t n e r r u c C A . g n i k o o c r o f t a e h e t a r e n e g o t p o t k o o c c it e n g a m o r r e f a n e h W . s d l e if c it e n g a m g n it a ll i c s o -basedmeta lpani splacedont heheaitng s t n e r r u c y d d e e h T . n a p e h t n i s t n e r r u c y d d e e c u d n i s d l e if c it e n g a m g n it a ll i c s o e h t , e t a l p I ( g n it a e h e l u o j e c u d o r p 2R )duet ot her esisitvtiyoft hemetal .Theheatedmeta lcookst he .t o p e h t f o s t n e t n o c

s e g a t n a v d A Disadvantages 3 8 -90%efifciency( comparedt o40%f o r ) s a g Onlyf unciton swtihf erromagneitcpans ri a g n i d n u o r r u s t a e h t o n s e o D Expensivet oi nstall t n a t s n i t s o m l a s i g n it a e H c i m a r e C -glas scookt opi seasyt oclean p o t e v o t s n o d n a h g n i n r u b f o k s ir o N x Gathersecondaryi nforma itont oidentfiyhoweddycurrent shavebeenu itilsedi n g n i k a r b c it e n g a m o r t c e l e a r e d i s n o C soildaluminiumo rcoppe rdisks pinningon ti saxle .Arrangingmagnet s e h T . c s i d e h t n i s t n e r r u c y d d e s e t a e r c k s i d g n i n n i p s e h t o t r a l u c i d n e p r e p magneitc ifeld s .t s e r o t ti g n i g n ir b y l k c i u q , c s i d e h t f o n o it o m e h t e s o p p o s t n e rr u c y d d e e h t y b d e c u d o r p Eddy y b d e s il it u n e e b s a h g n i k a e r b t n e r r u c indusrtyand rtanspo traiton. g n ir u D . s n i a rt ’ t e ll u b ‘ e s e n a p a J e m o s n i g n i k a r b c it e n g a m o rt c e l e r o f d e s u e r a s t n e r r u c y d d E , g n i k a e r b elecrtomagnetsinduceeddycurrentsi nt hemetalr aiilngsort hemovingmeta l s l e e h w oft he rtain .Theeddycurrentsi nducedi nt her ali so rwheel sopposethef orward f o d e e p s e h t o t l a n o it r o p o r p s i s t n e r r u c y d d e e h t f o h t g n e rt s e h t e s u a c e B . n i a rt e h t f o n o it o m a n i g n it l u s e r ,s e s a e r c e d n i a rt e h t f o d e e p s e h t s a s e s a e r c e d t c e f f e g n i k a r b e h t , n i a rt e h t . p o t s h t o o m s t n e r r u c y d d E elecrtomagneitcbrakingi salsousedins omeamusemen tpark irdes .Thereare r e g n e s s a p e h t o t s e t a l p r e p p o c g n i c a l p s e v l o v n i t s ri f e h T . d e s u y l n o m m o c s t n e m e g n a r r a o w t r e p p o c e h t s A . e d ir e h t f o m o tt o b e h t r a e n s t e n g a m d e x if , g n o rt s h g u o r h t s e s s a p h c i h w t a e s g a m e h t h g u o r h t s e s s a p e t a l p neitc ifelds ,eddycu rrent sarei nduced .Becauset hes izeoft he d e c u d e r y ll a u d a r g s i e c r o f g n i k a r b e h t , e d ir e h t f o d e e p s e h t o t l a n o it r o p o r p s i s t n e r r u c y d d e ’ s r e g n e s s a p e h t n i s t e n g a m e h t e c a l p o t s i h c a o r p p a r e h t o e h T . y l h t o o m s s p o t s e s ir e h t d n a s t a e s .Ast hepassengers eatf all sdu irngt hel as thal foft hedescen,tt heypas sbetweencoppe r s t e e h s .Eddycurrent sarei nduced ,b irngingt he irdet oas mooths top. c s i d f o n o it o M

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