Induction P1 - YKo penphysicsyko.penphysics.com/wp-content/uploads/Induction_P1.pdfThe graph shows...
Transcript of Induction P1 - YKo penphysicsyko.penphysics.com/wp-content/uploads/Induction_P1.pdfThe graph shows...
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Induction_P1
1.[1mark]
Twoidenticalcircularcoilsareplacedonebelowtheothersothattheirplanesarebothhorizontal.The
topcoilisconnectedtoacellandaswitch.
Theswitchisclosedandthenopened.Whatistheforcebetweenthecoilswhentheswitchisclosing
andwhentheswitchisopening?
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2.[1mark]
ThegraphshowsthevariationwithtimetofthecurrentIintheprimarycoilofanidealtransformer.
Thenumberofturnsintheprimarycoilis100andthenumberofturnsinthesecondarycoilis200.
Whichgraphshowsthevariationwithtimeofthecurrentinthesecondarycoil?
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3.[1mark]
Thediagramshowsadiodebridgerectificationcircuitandaloadresistor.
Theinputisasinusoidalsignal.Whichofthefollowingcircuitswillproducethemostsmoothedoutput
signal?
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4.[1mark]
Aparallelplatecapacitorisconnectedtoacellofnegligibleinternalresistance.
Theenergystoredinthecapacitoris4Jandtheelectricfieldinbetweentheplatesis100NC–1.The
distancebetweentheplatesofthecapacitorisdoubled.Whataretheenergystoredandtheelectric
fieldstrength?
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5.[1mark]
ThecurrentIflowinginloopAinaclockwisedirectionisincreasingsoastoinduceacurrentbothin
loopsBandC.Allthreeloopsareonthesameplane.
WhatisthedirectionoftheinducedcurrentsinloopBandloopC?
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6.[1mark]
Arectangularflatcoilmovesatconstantspeedthroughauniformmagneticfield.Thedirectionofthe
fieldisintotheplaneofthepaper.
Whichgraphshowsthevariationwithtimet,oftheinducedemfεinthecoilasitmovesfromPtoQ?
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7.[1mark]
Thegraphshowsthepowerdissipatedinaresistorof100Ωwhenconnectedtoanalternatingcurrent
(ac)powersupplyofrootmeansquarevoltage(Vrms)60V.
Whatarethefrequencyoftheacpowersupplyandtheaveragepowerdissipatedintheresistor?
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8.[1mark]
Threecapacitors,eachonewithacapacitanceC,areconnectedsuchthattheircombinedcapacitanceis
1.5C.Howaretheyconnected?
9.[1mark]
TheplaneofacoilispositionedatrightanglestoamagneticfieldoffluxdensityB.ThecoilhasNturns,
eachofareaA.Thecoilisrotatedthrough180˚intimet.
Whatisthemagnitudeoftheinducedemf?
A.
B.
C.
D.
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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?
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12.[1mark]
Sixidenticalcapacitors,eachofvalueC,areconnectedasshown.
Whatisthetotalcapacitance?
A.
B.
C.
D.6C
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13.[1mark]
AcapacitorofcapacitanceCdischargesthrougharesistorofresistanceR.Thegraphshows
thevariationwithtimetofthevoltageVacrossthecapacitor.
Thecapacitorischangedtooneofvalue2Candtheresistorischangedtooneofvalue2R.Whichgraph
showsthevariationwithtofVwhenthenewcombinationisdischarged?
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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.
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17.[1mark]
Acapacitorischargedbyaconstantcurrentof2.5μAfor100s.Asaresultthepotentialdifference
acrossthecapacitorincreasesby5.0V.
Whatisthecapacitanceofthecapacitor?
A.20μF
B.50μF
C.20mF
D.50mF
18.[1mark]
Aconductingsquarecoilisplacedinaregionwherethereisauniformmagneticfield.Themagnetic
fieldisdirectedintothepage.Thereisaclockwisecurrentinthecoil.
Whatisacorrectforcethatactsonasideofthecoil?
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19.[1mark]
Thediagramshowsabarmagnetnearanaluminiumring.
Theringissupportedsothatitisfreetomove.Theringisinitiallyatrest.Inexperiment1themagnetis
movedtowardsthering.Inexperiment2themagnetismovedawayfromthering.Foreachexperiment
whatistheinitialdirectionofmotionofthering?
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20.[1mark]
Threeconductingloops,X,YandZ,aremovingwiththesamespeedfromaregionofzeromagnetic
fieldtoaregionofuniformnon-zeromagneticfield.
Whichloop(s)has/havethelargestinducedelectromotiveforce(emf)attheinstantwhenthe
loopsenterthemagneticfield?
A.Zonly
B.Yonly
C.YandZonly
D.XandYonly
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21.[1mark]
Twocapacitorsofdifferentcapacitanceareconnectedinseriestoasourceofemfofnegligibleinternal
resistance.
Whatiscorrectaboutthepotentialdifferenceacrosseachcapacitorandthechargeoneachcapacitor?
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22.[1mark]
Afullychargedcapacitorisconnectedtoaresistor.Whentheswitchisclosedthecapacitor
willdischargethroughtheresistor.
Whichgraphscorrectlyshowhowthechargeonthecapacitorandthecurrentinthecircuitvarywith
timeduringthedischargingofthecapacitor?
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23.[1mark]
Whichofthefollowingreducestheenergylossesinatransformer?
A.Usingthinnerwiresforthewindings.
B.Usingasolidcoreinsteadofalaminatedcore.
C.Usingacoremadeofsteelinsteadofiron.
D.Linkingmorefluxfromtheprimarytothesecondarycore.
24.[1mark]
Thesecondarycoilofanalternatingcurrent(ac)transformerisconnectedtotwodiodesasshown.
WhichgraphshowsthevariationwithtimeofthepotentialdifferenceVXYbetweenXandY?
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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
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27.[1mark]
AcoilofareaAisplacedinaregionofuniformhorizontalmagneticfieldB.Att=0,thecoilstartsto
rotatewithconstantangularspeedωaboutahorizontalaxis.
WhatistheemfbetweenXandY?
A.zero
B.ωABsinωt
C.ABcosωt
D.−ωABsinωt
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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.
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30.[1mark]
Afull-wavedioderectificationcircuitismodifiedwiththeadditionofacapacitorinparallelwiththe
loadresistor.Thecircuitisusedtorectifyasinusoidalsignalofperiod6.3ms.Whichgraphshowshow
thepotentialdifferenceVacrosstheloadvarieswithtime?
31.[1mark]
Aparallel-platecapacitorisconnectedtoacellofconstantemf.Thecapacitorplatesarethenmoved
furtherapartwithoutdisconnectingthecell.Whatarethechangesinthemagnitudeoftheelectricfield
betweentheplatesandinthecapacitanceofthecapacitor?
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32.[1mark]
Threeidenticalcapacitors,eachofcapacitanceC,areconnectedasshown.
Whatisthetotalcapacitanceofthecombination?
A.
B.C
C.
D.3C
33.[1mark]
Whichofthefollowingexperimentsprovidesevidencefortheexistenceofmatterwaves?
A.Scatteringofalphaparticles
B.Electrondiffraction
C.Gammadecay
D.Photoelectriceffect
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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
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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
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38.[1mark]
Amagnetoscillatesaboveasolenoidasshown.
Themagnetisdisplacedverticallyandreleasedfromitshighestpositionattimet=0.Whichgraph
showsthevariationwithtimetofthecurrentIintheresistor?
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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
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41.[1mark]
Thegraphshowsthevariationwithtimeofamagneticfluxpassingthroughaloopofwire.
Whatisthemagnitudeoftheemfinducedinthecoil?
A.Theareabetweenthegraphandthetimeaxis
B.Theareabetweenthegraphandthemagneticfluxaxis
C.Thegradientofthegraph
D.Theinverseofthegradientofthegraph
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42.[1mark]
ThegraphshowsthevariationwithtimetofthepowerPproducedinacoilthatisrotatinginaregion
ofuniformmagneticfield.
Whichofthefollowingdescribestheaveragepowerproducedandtheperiodofrotationofthecoil?
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43.[1mark]
Abarmagnetisclosetoacoil.Noothermagneticfieldsarepresent.Anammeterisconnectedtothe
coil.
Themagnetandthecoilaremovedinthefollowingways.
I.Themagnetandthecoilbothmovetotherightwiththesamespeed.
II.Themagnetisstationaryandthecoilmovestotheleft.
III.Thecoilisstationaryandthemagnetmovestotheright.
Inwhichofthefollowingwilltheammeterindicateacurrent?
A.IandIIonly
B.IandIIIonly
C.IIandIIIonly
D.Ionly
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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.
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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
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48.[1mark]
AnidealtransformerhasaprimarycoilwithNpturnsandasecondarycoilwithNsturns.Theelectrical
powerinputtotheprimaryisP.Whichofthefollowingisthepoweroutputfromthesecondary?
A.
B.P
C.
D.