Circuits 24/08/2010. Question. Question. Practice Questions QV CV. Review Formula s RC R R R V IR ... Charging P IV I R ... E Pt.

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Gwendoline Nash
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1 4/08/00 eview Fomul s icuis cice s BL B A B I I I I E s n n hging Q Q 0 e... n... Q Q n 0 e Q I I0e Dischging Q U Q A wie mde of bss nd nohe wie mde of silve hve he sme lengh, bu he dimee of he bss wie is 4 imes he dimee of he silve wie. The esisiviy of bss is 5 imes gee hn he esisiviy of. ilve. If B denoes he esisnce of he bss wie nd denoes he esisnce of he silve wie, which of he following is ue? ) B =5/6 b) B =4/5 Le ρ c) B =5/4 s denoe he esisiviy of silve nd le A s denoe he coss-secionl e of he silve wie. d) B =5/ e) B =6/5 BL B A B Fo ohmic conduco, doubling he volge wihou chnging he esisnce will cuse he cuen o? ) Decese by fco of 4 b) Decese by fco of c) emin unchnged d) Incese by fco of e) Incese by fco of 4 I Theefoe doubling he volge, doubles he cuen. 5s L 4 A 5 6 s

4/08/00 If 60 w ligh bulb opees volge of 0, wh is he esisnce of he bulb? A bey whose emf is 40 hs n inenl esisnce of 5Ω. If his bey is connec o 5Ω esiso, wh will he volge dop coss be?

2 4/08/00 If 60 w ligh bulb opees volge of 0, wh is he esisnce of he bulb? A bey whose emf is 40 hs n inenl esisnce of 5Ω. If his bey is connec o 5Ω esiso, wh will he volge dop coss be? ) Ω b) 30Ω c) 40Ω d) 70Ω e) 700Ω W ) 0 b) 30 c) 40 d) 50 e) 70 I I 40 I A 5 5 I A5 30 Thee esisos e conneced o 0- bey s shown below. Wh is he cuen hough he.0 Ω esiso? ) 0.5A b) 0.50A c).0a d).0a e) 4.0A =0 ince ll esisos e in seies, he moun of cuen h psses hough ny one of hem is he sme. o we need o simply he cicui o deemine h cuen. 4.0Ω s... n Ω.0Ω I I 0 0 A s... n I Deemine he equivlen esisnce beween poins nd b? ) 0.67Ω b) 0.5 Ω c) Ω d).5 Ω e) Ω Ω 4Ω 3Ω 3Ω

3 4/08/00 Thee idenicl ligh bulbs e conneced o souce of emf, s shown in he digm bove. Wh will hppen if he middle bulb buns ou? ) All he bulbs will go ou b) The ligh inensiy of he ohe wo bulbs will decese (bu hey won go ou). c) The ligh inensiy of he ohe wo bulbs will incese. d) The ligh inensiy of he ohe wo bulbs will emin he sme. e) Moe cuen will be dwn fom he souce emf. If ech bulb hs esisnce of, hen ech individul bulb will dw /. This will be unchnged if ny individul bulb goes ou. (less cuen will be dwn fom he bey, bu he sme moun of cuen will pss hough ech bulb) An idel bey is hooked o ligh bulb wih wies. A second idenicl ligh bulb is conneced in pllel o he fis ligh bulb. Afe he second ligh bulb is conneced, he cuen fom he bey comped o when only one bulb ws conneced. ) Is Highe b) Is Lowe c) Is The me d) Don know Bulbs in pllel e like esisos in pllel. Theefoe since he ol esisnce of pllel esisos is lowe, nd he volge ins he sme, hen he cuen mus incese (double). An idel bey is hooked o ligh bulb wih wies. A second idenicl ligh bulb is conneced in seies wih he fis ligh bulb. Afe he second ligh bulb is conneced, he cuen fom he bey comped o when only one bulb ws conneced. An idel bey is hooked o ligh bulb wih wies. A second idenicl ligh bulb is conneced in pllel o he fis ligh bulb. Afe he second ligh bulb is conneced, he powe oupu fom he bey (comped o when only one bulb ws conneced) ) Is Highe b) Is Lowe c) Is The me d) Don know ince he ol esisnce goes up by wo, he cuen mus go down by wo. Theefoe lowe. ) Is fou imes highe b) Is wice s high c) Is he sme d) Is hlf s much e) Is one que s much f) Don know I I ince he cuen goes up by wo. Theefoe he owe goes up by wo 3

4 4/08/00 An idel bey is hooked o ligh bulb wih wies. A second idenicl ligh bulb is conneced in seies wih he fis ligh bulb. Afe he second ligh bulb is conneced, he ligh fom he fis bulb (comped o when only one bulb ws conneced) ) is fou imes s bigh b) is wice s bigh c) is he sme d) is hlf s bigh e) is one que s bigh ince he volge goes down by fco of wo, he powe goes down by 4. Theefoe dimme. I I Wh is he volge dop coss he ohm esiso in he poion of he cicui shown? ) 4 b) 36 c) 48 d) 7 e) 44 A 8Ω 4Ω 8Ω Ω I 4 ince he op bnch hs 4Ω of esisnce nd he boom bnch hs Ω of esisnce, heefoe 3 imes s much cuen will flow hough he 4Ω esiso hn he Ω esiso. This beks down he A ino 9A up nd 3A down. o fom =I we hve =(3A)(Ω)=36 Ω We could lso hve poduced T nd found 3Ω vlue, heefoe volge dop of (3Ω)(A)=36 on boh he uppe nd lowe bnch Wh is he cuen hough he 8Ω esiso in he cicui shown? How much enegy is dissiped s he in 0 seconds by 00 Ω esiso h cies cuen of 0.5A? ) 0.5A b).0a c).5a d).5a e) 3.0A Ω Ω Ω Ω Ω Ω Ω 8Ω 4 b Ω I ince poins nd b e gounded, hey e ll he sme poenil (cll i zeo). Tvelling fom b o coss he bey, he poenil inceses by 4, heefoe i mus decese by 4 coss he 8Ω esiso s we ech poin. Theefoe I=/ =(4)/(8Ω)=3A. ) 50 J b) 00 J c) 50 J d) 500 J e) 000J I 0.5A 00 5W J 5 s E J 5 0s s 500J E I 4

5 4/08/00 Wh is he ime consn fo he cicui shown? ) 0.0 s b) 0.05 s c) 0.04 s d) 0.05 s e) 0. s T F 0.05s A 00Ω,, nd 50Ω esiso e conneced o 9- bey s in he cicui shown below. Which of he hee esisos dissipes he mos powe? We cn lso nswe his quesion fse I I ) The 00Ω esiso by noicing h he volge dops coss b) The esiso he 00Ω nd hen coss he pllel c) The 50Ω esiso esisos. ince he 00Ω hs 3 highe d) Boh he nd he 50Ω vlue hn he pllel combinion, i will e) All dissipe he sme powe hve 5.4 lge volge 3.6dop hn he 3.6 combinion so vi =I, i dissipes he 00Ω mos powe. 0.9W 0.08W 0.086W 00 uf 50 00Ω 50Ω 9 50Ω Theefoe he 00Ω esiso dissipes he mos moun of powe. A.0 F cpcio is conneced o powe supply unil i is fully chged. The cpcio is hen disconneced fom he powe supply, nd hen is used o powe oy c. The vege dg foce on he c is N. bou how f will he c go? ) 36m b) 7m c) 44m d) 4m e) m Fis we find he enegy soed in he cpcio U.0 F 7J U W Fd This enegy is he Wok used in moving he c fixed disnce. W Fd 7J N d d 36m 9 Thee cpcios e conneced o 9 powe supply s shown. How much chge is soed by his sysem of cpcios? ) 3 u b) 30 u c).7 u d) 7 u e) 0 u =uf =4uF 3 =6uF implify he cicui o find equivlen cpcince. EQ F 4F 6F Q T 6F 6F 3F To deemine he chge, we use Q= T EQ Q 3F 9 7 n n 3 5

6 4/08/00 Wh is he esisnce of n idel mmee nd n idel volmee? Mesues cuen Mesues olge A ligh bulb is ed 00 W in nd, whee he sndd wll oule volge is 0. If his bulb ws plugged in in englnd, whee sndd wll oule volge is 40, which of he following would be ue? Idel Ammee ) zeo b) infinie c) zeo d) infinie e) Ω Idel olmee ) infinie b) zeo c) zeo d) infinie e) Ω An mmee is plced in seies wih ohe cicui componens. In ode fo he mmee no o iself esis cuen nd chnge he ol cuen in he cicui, you wn i o hve zeo esisnce. A volmee is plced in pllel wih ohe cicui componens. If i hd low esisnce, he cuen will flow hough i insed of he ohe cicui elemen. o you wn i o hve infinie esisnce o i won ffec he cicui elemen being mesued. ) The bulb would be ¼ s bigh. b) The bulb would be ½ s bigh. c) The bulb s bighness would he sme. d) The bulb would be ice s bigh. e) The bulb would be 4 imes s bigh I I You fis insinc is o sy h becuse bighness depends on powe, he bulb is excly s bigh. Bu h is no coec. The powe of he bulb cn chnge. The esisnce of ligh bulb is popey of he bulb iself, nd so will no chnge no me wh he bulb is hooked o. A cuen of 6.4A flows in segmen of coppe wie. The numbe of elecons cossing coss-secionl e of he wie evey second is bou? ) 6.4 b) 4 x 0 9 c) 4 x 0-9 d) 6.4 x 0 9 e) 6.4 x 0-9 q I ince ech elecon cies chge of.6 x 0-9. The we clcule h q I N A s 9 N 40 9 In house ile hee is 0 bey vilble fo use. A ose is designed o wok popely s 0, whee i is ed 00W, nd 0W blende which is only designed o wok popely 60. You look ound he ile nd find supply of 60Ω esisos ) Wh is he esisnce of he ose nd blende hei ed volges? b) Deemine he cuen h is chieved in he blende when i is woking popely. c) ee cicui h will mke boh devices wok simulneously. d) Wh powe mus he bey supply o un you cicui? 6

7 4/08/00 In house ile hee is 0 bey vilble fo use. A ose is designed o wok popely s 0, whee i is ed 00W, nd 0W blende which is only designed o wok popely 60. You look ound he ile nd find supply of 60Ω esisos ) Wh is he esisnce of he ose nd blende hei ed volges? ince we know he owe equiemens, le s us powe fomul: In house ile hee is 0 bey vilble fo use. A ose is designed o wok popely s 0, whee i is ed 00W, nd 0W blende which is only designed o wok popely 60. You look ound he ile nd find supply of 60Ω esisos b) Deemine he cuen h is chieved in he blende when i is woking popely. This is job fo Ohm s Lw: I ose Tose Tose 0 00W blende blende blende 60 0W 30 I A In house ile hee is 0 bey vilble fo use. A ose is designed o wok popely s 0, whee i is ed 00W, nd 0W blende which is only designed o wok popely 60. You look ound he ile nd find supply of 60Ω esisos c) ee cicui h will mke boh devices wok simulneously. In house ile hee is 0 bey vilble fo use. A ose is designed o wok popely s 0, whee i is ed 00W, nd 0W blende which is only designed o wok popely 60. You look ound he ile nd find supply of 60Ω esisos d) Wh powe mus he bey supply o un you cicui? =0 Tose 60Ω equied o give cuen of A fo blende 60Ω blende Fom Ohm s Lw, we cn deemine cuen in ose I I 0 0A ince he blende hd cuen of A, his gives he cicui ol cuen of A Using =I, we hve: I A0 440W 7

8 4/08/00 Given he following cicui Given he following cicui ) A wh e does he bey delive enegy o he cicui? =0 40Ω 0Ω 00Ω b ) A wh e does he bey delive enegy o he cicui? b) Deemine he cuen hough he 0 Ω esiso. c) i) Deemine he poenil diffeence beween poins nd b ii) A which of hese wo poins is he poenil highe? d) Deemine he enegy dissiped by he 00 Ω esiso in 0 s e) Given h he 00 Ω esiso is solid cylinde h s 4 cm long, composed of meil whose esisiviy is Ωm, deemine is dius. ecll: e is owe I We need o wie his s simple cicui wih T so h we cn deemine he cuen, I by using =I. T I A 60 T =0 40Ω I A0 40W 0Ω 00Ω Given he following cicui ecll: fom ) we hve A cuen The io of he esisnce of lef side o igh side is 40:0 o :3 b) Deemine he cuen hough he 0 Ω esiso. =0 A A 40Ω 0Ω 00Ω Theefoe ¼ of A goes hough he igh nd ¾ of A goes hough he lef. Thus (/4)(A)=0.5A psses hough he 0Ω esiso. We cn deemine he volge dop. 0- (A)()- (A)()- (A)() =60 Then we use =I o find ech individul cuen. Given he following cicui c) i) Deemine he poenil diffeence beween poins nd b ii) A which of hese wo poins is he poenil highe? i) I I b 0 00 =0 0.5A0 0.5A Ω b 0Ω 00Ω ii) oin is highe poenil. ince cuen flows fom high poenil o low poenil. O 8

9 4/08/00 Given he following cicui d) Deemine he enegy dissiped by he 00 Ω esiso in 0 s ecll: Enegy equls owe muliplied by Time E I =0 40Ω E I 0.5A 000s 50J b 0Ω 00Ω Given he following cicui e) Given h he 00 Ω esiso is solid cylinde h s 4 cm long, composed of meil whose esisiviy is Ωm, deemine is dius. BL B A AB 40Ω =0 BL B BL 0.45m0.04m B m b 0Ω 00Ω Given he following cicui wih he swich uned o poin ime =0. Expess ll nswes in ems of,,,, nd consns. ) Deemine he cuen hough ime =0. b) ompue he ime equied fo he chge on he cpcio o ech one-hlf is finl vlue. c) When he cpcio is fully chged, which ple is posiive? d) Deemine he elecic poenil enegy soed in he cpcio when he cuen is zeo. When he cuen hough is zeo, he swich is moved o b [=0]. e) Deemine he cuen hough s funcion of ime. f) Find he powe dissiped in s funcion of ime. b Given he following cicui wih he swich uned o poin ime =0. Expess ll nswes in ems of,,,, nd consns. ) Deemine he cuen hough ime =0. I b I 0 9

10 4/08/00 Given he following cicui wih he swich uned o poin ime =0. Expess ll nswes in ems of,,,, nd consns. b) ompue he ime equied fo he chge on he cpcio o ech one-hlf is finl vlue. Q Q i e Theefoe we need 0 e 0 e ln 0 0 ln b Given he following cicui wih he swich uned o poin ime =0. Expess ll nswes in ems of,,,, nd consns. c) When he cpcio is fully chged, which ple is posiive? + b Becuse he op ple is conneced o he posiive end of he bey, he op is posiive. Given he following cicui wih he swich uned o poin ime =0. Expess ll nswes in ems of,,,, nd consns. d) Deemine he elecic poenil enegy soed in he cpcio when he cuen is zeo. U b Given he following cicui wih he swich uned o poin ime =0. Expess ll nswes in ems of,,,, nd consns. When he cuen hough is zeo, he swich is moved o b [=0]. e) Deemine he cuen hough s funcion of ime. I I0e b When he cuen hough is zeo, he cpcio is fully chged, wih volge coss he ples mching he emf of he bey. U The cuen esblished by he dischging cpcio deceses exponenilly. I I0e e 0

11 4/08/00 Given he following cicui wih he swich uned o poin ime =0. Expess ll nswes in ems of,,,, nd consns. 00Ω When he cuen hough is zeo, he swich is moved o b [=0]. f) Find he powe dissiped in s funcion of ime. I I I0e b I e e = 9 ) implify he bove cicui so h i consiss of one equivlen esiso nd he bey. b) Wh is he ol cuen hough his cicui? c) Find he volge coss ech esiso. d) Find he cuen hough ech esiso. e) The esiso is now emoved fom he cicui. e whehe he cuen hough he 00Ω esiso would incese, decese, o emin he sme. 00Ω 00Ω = 9 EQ = 9 EQ =34.Ω ) implify he bove cicui so h i consiss of one equivlen esiso nd he bey EQ EQ b) Wh is he ol cuen hough his cicui? I I A

12 4/08/00 00Ω 00Ω c) Find he volge coss ech esiso. d) Find he cuen hough ech esiso. Le s use I ch = 9 e) The esiso is now emoved fom he cicui. e whehe he cuen hough he 00Ω esiso would incese, decese, o emin he sme. = 9 00Ω I Ω Tol A 34.Ω A 0.005A 0.046A 0.07A I 0.063A By emoving esiso fom pllel se, we cully incese he esisnce of he ol cicui. Theefoe by Ohm s lw if he volge emins he sme nd he esisnce inceses, he ol cuen mus decese Now hough he 00Ω se, he ol esisnce emins he sme, ye he cuen deceses, heefoe he volge coss ech esise deceses s well s he cuen.

PHYSICS 102. Intro PHYSICS-ELECTROMAGNETISM

PHYSICS 102. Intro PHYSICS-ELECTROMAGNETISM PHYS 0 Suen Nme: Suen Numbe: FAUTY OF SIENE Viul Miem EXAMINATION PHYSIS 0 Ino PHYSIS-EETROMAGNETISM Emines: D. Yoichi Miyh INSTRUTIONS: Aemp ll 4 quesions. All quesions hve equl weighs 0 poins ech. Answes