1

Induction_P1

1.[1mark]

Twoidenticalcircularcoilsareplacedonebelowtheothersothattheirplanesarebothhorizontal.The

topcoilisconnectedtoacellandaswitch.

Theswitchisclosedandthenopened.Whatistheforcebetweenthecoilswhentheswitchisclosing

andwhentheswitchisopening?

2

2.[1mark]

ThegraphshowsthevariationwithtimetofthecurrentIintheprimarycoilofanidealtransformer.

Thenumberofturnsintheprimarycoilis100andthenumberofturnsinthesecondarycoilis200.

Whichgraphshowsthevariationwithtimeofthecurrentinthesecondarycoil?

3

3.[1mark]

Thediagramshowsadiodebridgerectificationcircuitandaloadresistor.

Theinputisasinusoidalsignal.Whichofthefollowingcircuitswillproducethemostsmoothedoutput

signal?

4

4.[1mark]

Aparallelplatecapacitorisconnectedtoacellofnegligibleinternalresistance.

Theenergystoredinthecapacitoris4Jandtheelectricfieldinbetweentheplatesis100NC–1.The

distancebetweentheplatesofthecapacitorisdoubled.Whataretheenergystoredandtheelectric

fieldstrength?

5

5.[1mark]

ThecurrentIflowinginloopAinaclockwisedirectionisincreasingsoastoinduceacurrentbothin

loopsBandC.Allthreeloopsareonthesameplane.

WhatisthedirectionoftheinducedcurrentsinloopBandloopC?

6

6.[1mark]

Arectangularflatcoilmovesatconstantspeedthroughauniformmagneticfield.Thedirectionofthe

fieldisintotheplaneofthepaper.

Whichgraphshowsthevariationwithtimet,oftheinducedemfεinthecoilasitmovesfromPtoQ?

7

7.[1mark]

Thegraphshowsthepowerdissipatedinaresistorof100Ωwhenconnectedtoanalternatingcurrent

(ac)powersupplyofrootmeansquarevoltage(Vrms)60V.

Whatarethefrequencyoftheacpowersupplyandtheaveragepowerdissipatedintheresistor?

8

8.[1mark]

Threecapacitors,eachonewithacapacitanceC,areconnectedsuchthattheircombinedcapacitanceis

1.5C.Howaretheyconnected?

9.[1mark]

TheplaneofacoilispositionedatrightanglestoamagneticfieldoffluxdensityB.ThecoilhasNturns,

eachofareaA.Thecoilisrotatedthrough180˚intimet.

Whatisthemagnitudeoftheinducedemf?

A.

B.

C.

D.

9

10.[1mark]

Theratio foratransformeris2.5.

Theprimarycoilofthetransformerdrawsacurrentof0.25Afroma200Valternatingcurrent

(ac)supply.Thecurrentinthesecondarycoilis0.5A.Whatistheefficiencyofthetransformer?

A.20%

B.50%

C.80%

D.100%

11.[1mark]

Analternatingcurrent(ac)generatorproducesapeakemfE0andperiodictimeT.Whatarethepeak

emfandperiodictimewhenthefrequencyofrotationisdoubled?

10

12.[1mark]

Sixidenticalcapacitors,eachofvalueC,areconnectedasshown.

Whatisthetotalcapacitance?

A.

B.

C.

D.6C

11

13.[1mark]

AcapacitorofcapacitanceCdischargesthrougharesistorofresistanceR.Thegraphshows

thevariationwithtimetofthevoltageVacrossthecapacitor.

Thecapacitorischangedtooneofvalue2Candtheresistorischangedtooneofvalue2R.Whichgraph

showsthevariationwithtofVwhenthenewcombinationisdischarged?

12

14.[1mark]

Adirectcurrent(dc)of5AdissipatesapowerPinaresistor.Whichpeakvalueofthealternating

current(ac)willdissipateanaveragepowerPinthesameresistor?

A.5A

B.

C.

D.

15.[1mark]

Whataretheunitsofmagneticfluxandmagneticfieldstrength?

16.[1mark]

AbatteryisusedtochargeacapacitorfullythrougharesistorofresistanceR.Theenergysuppliedby

thebatteryisEb.TheenergystoredbythecapacitorisEc.

WhatistherelationshipbetweenEbandEc?

A.Eb<Ec

B.Eb=Ec

C.Eb>Ec

D.TherelationshipdependsonR.

13

17.[1mark]

Acapacitorischargedbyaconstantcurrentof2.5μAfor100s.Asaresultthepotentialdifference

acrossthecapacitorincreasesby5.0V.

Whatisthecapacitanceofthecapacitor?

A.20μF

B.50μF

C.20mF

D.50mF

18.[1mark]

Aconductingsquarecoilisplacedinaregionwherethereisauniformmagneticfield.Themagnetic

fieldisdirectedintothepage.Thereisaclockwisecurrentinthecoil.

Whatisacorrectforcethatactsonasideofthecoil?

14

19.[1mark]

Thediagramshowsabarmagnetnearanaluminiumring.

Theringissupportedsothatitisfreetomove.Theringisinitiallyatrest.Inexperiment1themagnetis

movedtowardsthering.Inexperiment2themagnetismovedawayfromthering.Foreachexperiment

whatistheinitialdirectionofmotionofthering?

15

20.[1mark]

Threeconductingloops,X,YandZ,aremovingwiththesamespeedfromaregionofzeromagnetic

fieldtoaregionofuniformnon-zeromagneticfield.

Whichloop(s)has/havethelargestinducedelectromotiveforce(emf)attheinstantwhenthe

loopsenterthemagneticfield?

A.Zonly

B.Yonly

C.YandZonly

D.XandYonly

16

21.[1mark]

Twocapacitorsofdifferentcapacitanceareconnectedinseriestoasourceofemfofnegligibleinternal

resistance.

Whatiscorrectaboutthepotentialdifferenceacrosseachcapacitorandthechargeoneachcapacitor?

17

22.[1mark]

Afullychargedcapacitorisconnectedtoaresistor.Whentheswitchisclosedthecapacitor

willdischargethroughtheresistor.

Whichgraphscorrectlyshowhowthechargeonthecapacitorandthecurrentinthecircuitvarywith

timeduringthedischargingofthecapacitor?

18

23.[1mark]

Whichofthefollowingreducestheenergylossesinatransformer?

A.Usingthinnerwiresforthewindings.

B.Usingasolidcoreinsteadofalaminatedcore.

C.Usingacoremadeofsteelinsteadofiron.

D.Linkingmorefluxfromtheprimarytothesecondarycore.

24.[1mark]

Thesecondarycoilofanalternatingcurrent(ac)transformerisconnectedtotwodiodesasshown.

WhichgraphshowsthevariationwithtimeofthepotentialdifferenceVXYbetweenXandY?

19

25.[1mark]

Aparallel-platecapacitorisconnectedtoabattery.Whathappenswhenasheetofdielectricmaterialis

insertedbetweentheplateswithoutdisconnectingthebattery?

A.Thecapacitanceisunchanged.

B.Thechargestoreddecreases.

C.Theenergystoredincreases.

D.Thepotentialdifferencebetweentheplatesdecreases.

26.[1mark]

Threecapacitorsarearrangedasshown.

Whatisthetotalcapacitanceofthearrangement?

A.1.0F

B.2.5F

C.3.0F

D.4.0F

20

27.[1mark]

AcoilofareaAisplacedinaregionofuniformhorizontalmagneticfieldB.Att=0,thecoilstartsto

rotatewithconstantangularspeedωaboutahorizontalaxis.

WhatistheemfbetweenXandY?

A.zero

B.ωABsinωt

C.ABcosωt

D.−ωABsinωt

21

28.[1mark]

ThediagramshowsaconductingrodoflengthLbeingmovedinaregionofuniformmagneticfieldB.

Thefieldisdirectedatrightanglestotheplaneofthepaper.Therodslidesonconductingrailsata

constantspeedv.AresistorofresistanceRconnectstherails.

Whatisthepowerrequiredtomovetherod?

A.zero

B.

C.

D.

29.[1mark]

Analternatingcurrent(ac)powersupplygeneratesanemfwithpeakamplitudeV0anddeliversan

averagepower .Whatistherootmeansquare(rms)currentdeliveredbythesupply?

A.

B.

C.

D.

22

30.[1mark]

Afull-wavedioderectificationcircuitismodifiedwiththeadditionofacapacitorinparallelwiththe

loadresistor.Thecircuitisusedtorectifyasinusoidalsignalofperiod6.3ms.Whichgraphshowshow

thepotentialdifferenceVacrosstheloadvarieswithtime?

31.[1mark]

Aparallel-platecapacitorisconnectedtoacellofconstantemf.Thecapacitorplatesarethenmoved

furtherapartwithoutdisconnectingthecell.Whatarethechangesinthemagnitudeoftheelectricfield

betweentheplatesandinthecapacitanceofthecapacitor?

23

32.[1mark]

Threeidenticalcapacitors,eachofcapacitanceC,areconnectedasshown.

Whatisthetotalcapacitanceofthecombination?

A.

B.C

C.

D.3C

33.[1mark]

Whichofthefollowingexperimentsprovidesevidencefortheexistenceofmatterwaves?

A.Scatteringofalphaparticles

B.Electrondiffraction

C.Gammadecay

D.Photoelectriceffect

24

34.[1mark]

Anaircraftwithawingspanof50mflieshorizontallyataspeedof .Theverticalcomponent

oftheEarth’smagneticfieldattheplane’spositionis .

Whatelectromotiveforce(emf)isinducedbetweenpointsAandBontheaircraft?

A.0.1V

B.1V

C.10V

D.100V

35.[1mark]

Analternatingcurrentissinusoidalandhasamaximumvalueof1.5A.Whatistheapproximatevalue

oftherootmeansquared(rms)current?

A.2.3A

B.1.5A

C.1.0A

D.0.75A

25

36.[1mark]

Faraday’slawofelectromagneticinductionstatesthattheelectromotiveforce(emf)inducedina

conductorisproportionalto

A.thechangeofmagneticfluxdensity.

B.thechangeofmagneticfluxlinkage.

C.therateofchangeofmagneticfluxdensity.

D.therateofchangeofmagneticfluxlinkage.

37.[1mark]

Thegraphbelowshowsthevariationwithtimeofanalternatingcurrentinaresistorofresistance2.0

Ω.

Whatistheaveragepowerdissipatedintheresistor?

A.0.25W

B.8.0W

C.16W

D.32W

26

38.[1mark]

Amagnetoscillatesaboveasolenoidasshown.

Themagnetisdisplacedverticallyandreleasedfromitshighestpositionattimet=0.Whichgraph

showsthevariationwithtimetofthecurrentIintheresistor?

27

39.[1mark]

TwoidenticalresistorsRareconnectedinseriestoanalternatingcurrent(ac)powersupply.The

powersupplyhasarootmeansquared(rms)voltageofVandanrmscurrentofI.Whatisthemaximum

powerdevelopedinoneoftheresistorsinthecircuit?

A. VI

B.VI

C.2VI

D.

40.[1mark]

AflatcoilwithNturnshasacross-sectionalareaA.ThecoilhasafluxdensityofBinadirectionof90º

totheplaneofthecoil.

Whatisthemagneticfluxlinkage?

A.0

B.BA

C.NB

D.NBA

28

41.[1mark]

Thegraphshowsthevariationwithtimeofamagneticfluxpassingthroughaloopofwire.

Whatisthemagnitudeoftheemfinducedinthecoil?

A.Theareabetweenthegraphandthetimeaxis

B.Theareabetweenthegraphandthemagneticfluxaxis

C.Thegradientofthegraph

D.Theinverseofthegradientofthegraph

29

42.[1mark]

ThegraphshowsthevariationwithtimetofthepowerPproducedinacoilthatisrotatinginaregion

ofuniformmagneticfield.

Whichofthefollowingdescribestheaveragepowerproducedandtheperiodofrotationofthecoil?

30

43.[1mark]

Abarmagnetisclosetoacoil.Noothermagneticfieldsarepresent.Anammeterisconnectedtothe

coil.

Themagnetandthecoilaremovedinthefollowingways.

I.Themagnetandthecoilbothmovetotherightwiththesamespeed.

II.Themagnetisstationaryandthecoilmovestotheleft.

III.Thecoilisstationaryandthemagnetmovestotheright.

Inwhichofthefollowingwilltheammeterindicateacurrent?

A.IandIIonly

B.IandIIIonly

C.IIandIIIonly

D.Ionly

31

44.[1mark]

ThediagramshowsaloopLofwireinauniformmagneticfieldB.

TheloopenclosesanareaAandthefieldisdirectedatanangleθtothenormaltotheplaneoftheloop.

ThestrengthofBisincreasingatauniformrateR.WhatistheemfinducedinL?

A.

B.RAcosθ

C.

D.RAsinθ

45.[1mark]

Thevoltageoutputofaparticularpowerstationissteppedupbyafactorof103.Asaresultthepower

lossinthetransmissioncablesisreducedbyafactorof

A.103.

B.106.

C.109.

D.1012.

32

46.[1mark]

Capacitanceofacapacitorisdefinedasthe

A.abilitytostoreelectricalcharge.

B.ratioofchargestoredtopotentialdifference.

C.ratioofpotentialdifferencetochargestored.

D.ratioofworkdonetochargedstored.

47.[1mark]

AuniformmagneticfielddirectedintothepageoccupiesaregionofwidthL.Aconductingcoilofwidth

Lmovesatconstantspeedv,fromlefttoright,throughthefield.

Fromtheinstantthatthecoilentersthefielduntiltheinstantthatthecoilleavesthefield,whichof

thefollowingbestdescribesthedirectionofthecurrentinducedinthecoil?

A.Anti-clockwise

B.Clockwise

C.Anti-clockwisethenclockwise

D.Clockwisethenanti-clockwise

33

48.[1mark]

AnidealtransformerhasaprimarycoilwithNpturnsandasecondarycoilwithNsturns.Theelectrical

powerinputtotheprimaryisP.Whichofthefollowingisthepoweroutputfromthesecondary?

A.

B.P

C.

D.