剑桥联盟物理 Cambridge physics A2-9702_w11_ms_43

www.XtremePapers.comUNIVERSITYOFCAMBRIDGEINTERNATIONALEXAMINATIONSGCEAdvancedSubsidiaryLevelandGCEAdvancedLevelMARKSCHEMEfortheOctober/November2011questionpaperfortheguidanceofteachers9702PHYSICS9702/43Paper4(A2StructuredQuestions),maximumrawmark100Thismarkschemeispublishedasanaidtoteachersandcandidates,toindicatetherequirementsoftheexamination.ItshowsthebasisonwhichExaminerswereinstructedtoawardmarks.ItdoesnotindicatethedetailsofthediscussionsthattookplaceatanExaminers’meetingbeforemarkingbegan,whichwouldhaveconsideredtheacceptabilityofalternativeanswers.Markschemesmustbereadinconjunctionwiththequestionpapersandthereportontheexamination.•Cambridgewillnotenterintodiscussionsorcorrespondenceinconnectionwiththesemarkschemes.CambridgeispublishingthemarkschemesfortheOctober/November2011questionpapersformostIGCSE,GCEAdvancedLevelandAdvancedSubsidiaryLevelsyllabusesandsomeOrdinaryLevelsyllabuses.Page2MarkScheme:Teachers’versionSyllabusPaperGCEAS/ALEVEL–October/November2011970243SectionA1(a)(i)weight=GMm/r2C1=(6.67×10–11×6.42×1023×1.40)/(½×6.79×106)2C1=5.20NA1[3](ii)potentialenergy=–GMm/rC1=–(6.67×10–11×6.42×1023×1.40)/(½×6.79×106)M1=–1.77×107JA0[2](b)either½mv2=1.77×107C1v2=(1.77×107×2)/1.40C13–1v=5.03×10msA1or½mv2=GMm/r(C1)v2=(2×6.67x10–11×6.42×1023)/(6.79×106/2)(C1)3–1v=5.02×10ms(A1)[3]3(c)(i)½×2×1.66×10–27×(5.03×103)2=×1.38×10–23×TC12T=2030KA1[2](ii)eitherbecausethereisarangeofspeedsM1somemoleculeshaveahigherspeedA1orsomeescapefrompointaboveplanetsurface(M1)soinitialpotentialenergyishigher(A1)[2]2(a)temperaturescalecalibratedassuminglinearchangeofpropertywithtemperatureB1neitherpropertyvarieslinearlywithtemperatureB1[2](b)(i)doesnotdependonthepropertyofasubstanceB1[1](ii)temperatureatwhichatomshaveminimum/zeroenergyB1[1](c)(i)323.15KA1[1](ii)30.00KA1[1]©UniversityofCambridgeInternationalExaminations2011Page3MarkScheme:Teachers’versionSyllabusPaperGCEAS/ALEVEL–October/November20119702433(a)accelerationproportionaltodisplacement/distancefromfixedpointM1andinoppositedirections/directedtowardsfixedpointA1[2]22(b)energy=½mωx0andω=2πfC1=½×5.8×10–3×(2π×4.5)2×(3.0×10–3)2C1=2.1×10–5JA1[3](c)(i)atmaximumdisplacementM1aboverestpositionA1[2]2(ii)acceleration=(–)ωx0andacceleration=9.81orgC129.81=(2π×4.5)×x0–2x0=1.2×10mA1[2]4(a)e.g.storingenergyseparatingchargeblockingd.c.producingelectricaloscillationstuningcircuitssmoothingpreventingsparkstimingcircuits(anytwosensiblesuggestions,1each,max2)B2[2](b)(i)–Q(induced)onoppositeplateofC1B1bychargeconservation,chargesare–Q,+Q,–Q,+Q,–QB1[2](ii)totalp.d.V=V1+V2+V3B1Q/C=Q/C1+Q/C2+Q/C3B11/C=1/C1+1/C2+1/C3A0[2](c)(i)energy=½CV2orenergy=½QVandC=Q/VC1=½×12×10–6×9.02=4.9×10–4JA1[2](ii)energydissipatedin(resistanceof)wire/asasparkB1[1]©UniversityofCambridgeInternationalExaminations2011Page4MarkScheme:Teachers’versionSyllabusPaperGCEAS/ALEVEL–October/November20119702435(a)supplyconnectedcorrectly(toleft&right)B1loadconnectedcorrectly(totop&bottom)B1[2](b)e.g.powersuppliedoneveryhalf-cyclegreateraverage/meanpower(anysensiblesuggestion,1mark)B1[1](c)(i)reductioninthevariationoftheoutputvoltage/currentB1[1](ii)largercapacitanceproducesmoresmoothingM1eitherproductRClargerorforthesameloadA1[2]6(a)unitofmagneticfluxdensityB1fieldnormalto(straight)conductorcarryingcurrentof1AM1–1forceperunitlengthis1NmA1[3](b)(i)forceonparticlealwaysnormaltodirectionofmotionM1(andspeedofparticleisconstant)magneticforceprovidesthecentripetalforceA1[2](ii)mv2/r=BqvM1r=mv/BqA0[1](c)(i)themomentum/speedisbecominglessM1sotheradiusisbecomingsmallerA1[2](ii)1.spiralsareinoppositedirectionsM1sooppositelychargedA1[2]2.equalinitialradiiM1soequal(initial)speedsA1[2]©UniversityofCambridgeInternationalExaminations2011Page5MarkScheme:Teachers’versionSyllabusPaperGCEAS/ALEVEL–October/November20119702437(a)(i)packet/quantumofenergyM1ofelectromagneticradiationA1[2](ii)minimumenergytocauseemissionofanelectron(fromsurface)B1[1](b)(i)hc/λ=Φ+EmaxM1candhexplainedA1[2](ii)1.eitherwhen1/λ=0,Φ=–Emaxorevidenceofuseofx-axisinterceptfromgraphorchoosespointclosetothelineandsubstitutesvaluesof1/λandEmaxintohc/λ=Φ+EmaxC1Φ=4.0×10–19J(allow±0.2×10–19J)A1[2]2.eithergradientofgraphis1/hcC1gradient=4.80×1024→5.06×1024M1h=1/(gradient×3.0×108)–34–34=6.6×10Js→6.9×10JsA1orchoosespointclosetothelineandsubstitutesvaluesof1/λandEmaxintohc/λ=Φ+Emax(C1)valuesof1/λandEmaxarecorrectwithinhalfasquare(M1)–34–34h=6.6×10Js→6.9×10Js(A1)[3](Allowfullcreditforthecorrectuseofanyappropriatemethod)(Donotallow‘circular’calculationsinpart2thatleadtothesamevalueofPlanckconstantthatwassubstitutedinpart1)8(a)(i)probabilityofdecay(ofanucleus)M1perunittimeA1[2](ii)λt½=ln2λ=ln2/(3.82×24×3600)M1=2.1×10–6s–1A0[1](b)A=λNC1200=2.1×10–6×NC1N=9.5×107ratio=(2.5×1025)/(9.5×107)=2.6×1017A1[3]©UniversityofCambridgeInternationalExaminations2011Page6MarkScheme:Teachers’versionSyllabusPaperGCEAS/ALEVEL–October/November2011970243SectionB9(a)anyvaluegreaterthan,orequalto,5kΩB1[1](b)(i)‘positive’shownincorrectpositionB1[1](ii)V+=(500/2200)×4.5≈1VB1V–>V+sooutputisnegativeM1greenLEDon,(redLEDoff)A1[3](allowfullecfofincorrectvalueofV+)(iii)eitherV+increasesorV+>V–M1greenLEDoff,redLEDonA1[2]10quartz/piezo-electriccrystalB1p.d.acrosscrystalcauseseithercentresof(+)and(–)chargetomoveorcrystaltochangeshapeB1alternatingp.d.(inultrasoundfrequencyrange)causescrystaltovibrateB1crystalcuttoproduceresonanceB1whencrystalmadetovibratebyultrasoundwaveM1alternatingp.d.producedacrossthecrystalA1[6]11(a)sharpness:easewithwhichedgesofstructurescanbeseenB1contrast:differenceindegreeofblackeningbetweenstructuresB1[2]–µx(b)(i)I=I0eC1I/I0=exp(–0.20×8)=0.20A1[2](ii)I/I0=exp(–µ1×x1)×exp(–µ2×x2)(couldbethreeterms)C1I/I0=exp(–0.20×4)×exp(–12×4)C1–22I/I0=6.4×10orI/I0≈0A1[3](c)(i)sharpnessunknown/noB1[1](ii)contrastgood/yes(ecffrom(b))B1[1]©UniversityofCambridgeInternationalExaminations2011Page7MarkScheme:Teachers’versionSyllabusPaperGCEAS/ALEVEL–October/November201197024312(a)e.g.carrierfrequenciescanbere-used(withoutinterference)(M1)soincreasednumberofhandsetscanbeused(A1)e.g.lowerpowertransmitters(M1)solessinterference(A1)e.g.UHFused(M1)somustbeline-of-sight/shorthandsetaerial(A1)(anytwosensiblesuggestionswithexplanation,max4)B4[4](b)computeratcellularexchangeB1monitorsthesignalpowerB1relayedfromseveralbasestationsB1switchescalltobasestationwithstrongestsignalB1[4]©UniversityofCambridgeInternationalExaminations2011