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S A M P L E
PHYSICSWritten examination
Day Date Reading time: *.** to *.** (15 minutes) Writing time: *.** to *.** (2 hours 30 minutes)
QUESTION AND ANSWER BOOK
Structure of bookSection Number of
questionsNumber of questions
to be answeredNumber of
marks
A 20 20 20B 18 18 110
Total 130
• Studentsarepermittedtobringintotheexaminationroom:pens,pencils,highlighters,erasers,sharpeners,rulers,pre-writtennotes(onefoldedA3sheetortwoA4sheetsboundtogetherbytape)andonescientificcalculator.
• StudentsareNOTpermittedtobringintotheexaminationroom:blanksheetsofpaperand/orcorrectionfluid/tape.
Materials supplied• Questionandanswerbookof43pages• Formulasheet• Answersheetformultiple-choicequestions
Instructions• Writeyourstudentnumberinthespaceprovidedaboveonthispage.• Checkthatyournameandstudent numberasprintedonyouranswersheetformultiple-choice
questionsarecorrect,andsignyournameinthespaceprovidedtoverifythis.• Unlessotherwiseindicated,thediagramsinthisbookarenotdrawntoscale.• AllwrittenresponsesmustbeinEnglish.
At the end of the examination• Placetheanswersheetformultiple-choicequestionsinsidethefrontcoverofthisbook.• Youmaykeeptheformulasheet.
Students are NOT permitted to bring mobile phones and/or any other unauthorised electronic devices into the examination room.
©VICTORIANCURRICULUMANDASSESSMENTAUTHORITY2017
Version3–May2017
SUPERVISOR TO ATTACH PROCESSING LABEL HEREVictorian Certificate of Education Year
STUDENT NUMBER
Letter
PHYSICS(SAMPLE) 2 Version3–May2017
SECTION A – continued
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SECTION A – Multiple-choice questions
Instructions for Section AAnswerallquestionsinpencilontheanswersheetprovidedformultiple-choicequestions.Choosetheresponsethatiscorrectorthatbest answersthequestion.Acorrectanswerscores1;anincorrectanswerscores0.Markswillnotbedeductedforincorrectanswers.Nomarkswillbegivenifmorethanoneansweriscompletedforanyquestion.Unlessotherwiseindicated,thediagramsinthisbookarenotdrawntoscale.Takethevalueofgtobe9.8ms–2.
Question 1Whichoneofthefollowingdiagramsshowstheelectricfieldpatternsurroundingtwoequal,positivepointcharges?
A. B.
C. D.
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SECTION A – continuedTURN OVER
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Question 2ThethreediagramsX,YandZbelowrepresentdifferenttypesoffields.
X Y Z
Whichoneofthefollowingstatementsaboutthesediagramsiscorrect?A. Xcouldbeanelectricfield,YcouldbeagravitationalfieldandZcouldbeamagneticfield.B. Xcouldbeagravitationalfield,YcouldbeanelectricfieldandZcouldbeamagneticfield.C. Xcouldbeamagneticfield,YcouldbeagravitationalfieldandZcouldbeanelectricfield.D. Xcouldbeagravitationalfield,YcouldbeamagneticfieldandZcouldbeanelectricfield.
Question 3Studentsmeasurethegravitationalforcebetweentwomassesof1.0kgand100kg,placed10cmapart.Theuniversalgravitationalconstant,G,is6.67× 10–11Nm2kg–2.Whichoneofthefollowingbestgivesthegravitationalforceofattractionbetweenthetwomasses?A. 1.0×10–3NB. 6.7×10–5NC. 6.7×10–7ND. 1.0×106N
Question 4Thediagrambelowshowsasolenoid.
X
Whichone ofthefollowingbestdescribesthedirectionofthemagneticfieldofthecoilatpointX?A. leftB. rightC. upD. outofthepage
PHYSICS(SAMPLE) 4 Version3–May2017
SECTION A – continued
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Question 5Ametalspherehasachargeof1.0× 10–8Conit.Asmallspherewithachargeof1.0×10–9Cisplaced30cmfromit.Assumebothcanbeconsideredpointcharges.Takek=9.0×109.Whichoneofthefollowingbestgivesthemagnitudeoftheforceonthesmallsphere?A. 1.1×10–14NB. 1.0×10–6NC. 3.0×10–6ND. 3.0×10–5N
Question 6Inanexperimentalinvestigation,anindependentvariableisonethatA. theinvestigatorselectsvaluesfor.B. isthekeyvariabletobemeasured.C. isfixedthroughouttheexperiment. D. isindependentoftheinvestigator’scontrol.
Question 7Inanexperimentalinvestigation,adependentvariableisonethatA. theinvestigatorselectsvaluesfor.B. canbefixedthroughouttheexperiment.C. istheleastimportantvariabletobemeasured.D. dependsontheselectedvaluesofanothervariable.
Question 8Inanexperimentalinvestigation,generally,acontrolledvariableisonethatA. isfixedthroughoutaparticularsectionoftheexperiment.B. isdependentontheselectedvaluesofanothervariable.C. istheleastimportantvariabletobemeasured.D. theinvestigatorcontrolsthevaluesfor.
Version3–May2017 5 PHYSICS(SAMPLE)
SECTION A – continuedTURN OVER
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Question 9SomestudentsaremeasuringtheaccelerationduetogravityinaregionofEarth’ssurfacewherethevalueiswellestablishedas9.81±0.01ms–2.Theytakefivemeasurements,asfollows:• 9.83ms–2
• 9.81ms–2
• 9.79ms–2
• 9.78ms–2
• 9.84ms–2
Systematicerrorsarenegligible.ThestudentscouldreasonablydescribethemeasurementuncertaintyoftheirresultsasaboutA. 0.03ms–2
B. 0.10ms–2
C. 0.005ms–2
D. 9.81ms–2
Question 10Anelectrontravellinginthey-directionataknownvelocitypassesthroughanarrowslitinabarrier,asshownbelow.
O
x
y
electron’spath
barrier with a slit
WhichoneofthefollowingstatementsbestdescribeshowHeisenberg’suncertaintyprincipleappliestoanelectron’smotionafteritpassesthroughtheslit?A. TheelectronmustpassthroughpointO.B. TheelectroncanneverpassthroughpointO.C. Thereisanuncertaintyinitsmomentuminthey-direction.D. Thereisanuncertaintyinitsmomentuminthex-directionafterpassingthroughtheslit,dependingonthewidth
oftheslit.
PHYSICS(SAMPLE) 6 Version3–May2017
SECTION A – continued
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Question 11Atestcarisequippedwithacrash-testdummyandanairbag.Thecarcomestoasuddenstopwhenitcollideswithasolidwall,causingtheairbagtoinflate.Theairbagthencompressesby0.10mwhenthecrash-testdummyhitstheairbag.Thediagrambelowshowstherelativepositionofthecrash-testdummy’sheadtotheairbagandsteeringwheel.
airbag
steering wheelcrash-testdummy’shead
Thegraphofretardingforceonthecrash-testdummy’sheadversuscompressiondistanceisshownbelow.
retarding force (N)
0.100
8000
16 000
0.20compression distance (m)
Whichoneofthefollowingbestgivestheworkdoneontheairbaginthiscollision?A. 80 JB. 400JC. 800 JD. 8000 J
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SECTION A – continuedTURN OVER
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Question 12Whichoneofthefollowingbestdescribestheproperlengthofanobjecttravellingwithconstantvelocity?A. thelengthwhenmeasuredwithaproperstandardmeasuringstickB. thelengthwhenmeasuredbyanobserveratrestrelativetotheobjectC. thelengthwhenbothendsoftheobjectaremeasuredatthesametimeD. thelengthwhenmeasuredbyanobserverinaninertialframeofreference
Question 13Whichofthefollowingcorrectlyrelatesthedirectionofoscillationoftheparticlesinamediumtothedirectionofenergypropagationforatransversewaveandalongitudinalwave?
Transverse wave Longitudinal wave
A. atrightangles parallel
B. atrightangles atrightangles
C. parallel parallel
D. parallel atrightangles
Question 14Anambulanceissoundingitssirenasitapproachesapedestrian.Whichoneofthefollowingbestdescribesthesoundwavesreachingthepedestrianwhentheambulanceismovingtowardsthepedestrian?A. Thespeedofthesoundwavesinairishigher.B. Thedistancebetweensuccessivewavecrestsreachingthepedestrianislarger.C. Thedistancebetweensuccessivewavecrestsreachingthepedestrianisthesame.D. Thedistancebetweensuccessivewavecrestsapproachingthepedestrianissmaller.
PHYSICS(SAMPLE) 8 Version3–May2017
SECTION A – continued
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Use the following information to answer Questions 15 and 16.Kimplucksoneofhisguitarstrings,causingittovibrateasshownbelow.Twoextremepositionsoftheresultingstandingwaveinthestringareshown.Forthepurposeofthefollowingquestions,theamplitudeofthevibrationshasbeenexaggerated.
ends of guitar string
S
Question 15Whichoneofthefollowingstatementsbestindicateshowweinterpretthemotionoftheguitarstringshownabove?A. Itistheresultoftwotransversewavestravellingalongthestringinthesamedirection.B. Itistheresultoftwotransversewavestravellingalongthestringinoppositedirections.C. Itistheresultoftwolongitudinalwavestravellingalongthestringinthesamedirection.D. Itistheresultoftwolongitudinalwavestravellingalongthestringinoppositedirections.
Question 16Sisapointontheguitarstring,asshownabove.Fortheinstantimmediately afterthatshownabove,thedirectioninwhichpointSontheguitarstringwillmoveisA. upwards.B. totheleft.C. totheright.D. downwards.
Question 17LightcanbepolarisedbecauseitisA. acircularwave.B. atransversewave.C. alongitudinalwave.D. anelectromagneticwaveandhasbothtransverseandlongitudinalcomponents.
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END OF SECTION ATURN OVER
Question 18Whichoneofthefollowingstatementsbestdescribeslightproducedfromarangeofsources?A. Lightfromanincandescentlampisgenerallycoherentandcontainsawidespectrumofwavelengths.B. Lightfromasingle-colourlight-emittingdiode(LED)iscoherentandcontainsaverywidespectrumof
wavelengths.C. Synchrotronlightisalwaysincoherentandcontainsawidespectrumofwavelengths.D. Lightfromalaseriscoherentandhasaverynarrowrangeofwavelengths.
Question 19WhatisthebestdescriptionofhowlightisproducedinanLED?A. thermalmotionofelectronsinthevalencebandB. transitionofelectronsfromtheconductionbandtothegroundstateC. transitionofelectronsfromtheconductionbandtothevalencebandD. transitionofelectronsfromthevalencebandtotheconductionband
Question 20Anabsorptionlineinaspectrumoccursat414nm.
Data
Planck’sconstant h=4.14×10–15eVs
speedoflightinavacuum c=3.0×108ms–1
Whichoneofthefollowingbestgivestheenergyofthephotonforthisabsorption?A. 4.8×10–19eVB. 0.33eVC. 3.0eVD. 4.1eV
PHYSICS(SAMPLE) 10 Version3–May2017
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SECTION B – Question 1–continued
Question 1 (5marks)ThemassoftheplanetMarsis6.4×1023kg.TheradiusofMarsis3.4×106m.Theuniversalgravitationalconstant,G,is6.67×10–11Nm2kg–2.
a. CalculatetheaccelerationduetogravityatthesurfaceofMars.Showyourworking. 2marks
ms–2
SECTION B
Instructions for Section BAnswerallquestionsinthespacesprovided.Writeusingblueorblackpen.Whereananswerboxisprovided,writeyourfinalanswerinthebox.Ifananswerboxhasaunitprintedinit,giveyouranswerinthatunit.Inquestionswheremorethanonemarkisavailable,appropriateworkingmustbeshown.Unlessotherwiseindicated,thediagramsinthisbookarenotdrawntoscale.Takethevalueofgtobe9.8ms–2.
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SECTION B – continuedTURN OVER
b. Aprobeofmass0.20kgisreleasedfromaheightof10mabovethesurfaceofMars.Assumethatthegravitationalfieldstrengthisuniform(thesameasatthesurface).Ignoreairresistance.
SketchthegravitationalpotentialenergyoftheprobeasafunctionofheightabovethesurfaceofMarsontheaxesprovidedbelowandlabelthisasUg.TakepotentialenergyatthesurfaceofMarsaszero.Includetheinitialpotentialenergyvalueontheenergyaxis.
Onthesameaxes,sketchthekineticenergyoftheprobeandlabelthisasEK. 3marks
energy (J)
height (m)100
0
1
2
3
4
5
6
7
8
987654321
PHYSICS(SAMPLE) 12 Version3–May2017
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SECTION B – Question 2–continued
Question 2 (8marks)Figure1showspartofaparticleaccelerator.Electronsareacceleratedbyavoltageof10000Vinanelectrongunconsistingoftwoplatesthatare0.10mapart.Afterexitingthegun,theelectronspassintoaregionofuniformmagneticfieldofstrength0.020tesladirectedintothepage.Ignorerelativisticeffects.
Data
massoftheelectron 9.1×10–31kg
chargeontheelectron –1.6×10–19C
strengthofthemagneticfield 0.020tesla
region of uniformmagnetic field
plate plate
10 000 V
0.10 m
Figure 1
a. Calculatethestrengthoftheelectricfieldbetweentheplates.Includeanappropriateunit. 2marks
b. Calculatethespeedoftheelectronsastheyexittheelectrongun. 2marks
ms–1
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SECTION B – continuedTURN OVER
c. Theelectronsnextentertheregionofuniformmagneticfield.
Calculatetheradiusofthepathoftheelectrons. 2marks
m
d. Inanotherpartoftheparticleaccelerator,theelectronsaredeflectedbyauniformelectricfield,asshowninFigure2a,andbyamagneticfield,asshowninFigure2b.
Figure 2a Figure 2b
Explainwhythepathsoftheelectronsinthetwofieldshavedifferentshapes. 2marks
PHYSICS(SAMPLE) 14 Version3–May2017
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SECTION B – continued
Question 3 (5marks)Figure3showsaDCmotorconsistingofasquareloopof100turnsandsidelength5cm,andacommutator.TheDCmotorhasauniformmagneticfieldof3.0× 10–2Tandacurrentof2.0A.
A +
–
F G
E HN S
6.0 V
Figure 3
a. WhatistheforceonthesideEHwhentheloopisinthepositionshowninFigure3?Explainyouranswer. 2marks
N
b. ExplaintheroleandoperationofthecommutatorintheDCmotorshowninFigure3. 3marks
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SECTION B – continuedTURN OVER
CONTINUES OVER PAGE
PHYSICS(SAMPLE) 16 Version3–May2017
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SECTION B – continued
Question 4 (6marks)Figure4showsasimpleACalternator.
N
S
oscilloscope
Figure 4
Thestrengthofthemagneticfieldis0.50T,theloophas20turns,theareaoftheloopis0.020m2andtherateofrotationis10Hz.
a. CalculatethemagnitudeoftheaverageEMFinducedastheloopturnsfromtheinstantshowninFigure4toapointone-quarterofaperiodlater.Showyourworkingandincludeanappropriateunit. 3marks
b. TheACalternatorgraduallyslowstoastop.
Onthegridprovidedbelow,sketchthevoltageoutputexpected.Scalevaluesarenotrequiredontheaxes. 3marks
time
voltage output
0
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SECTION B – continuedTURN OVER
Question 5 (3marks)AnoscilloscopeisconnectedtoasinusoidalACsourcewhosefrequencyandvoltageoutputcanbevaried.Figure5showsthetraceobtainedontheoscilloscopescreen,whereonehorizontaldivisionrepresentsatimeof20msandoneverticaldivisionrepresents10V.
Figure 5
a. CalculatetheRMSvoltageforthesignalshowninFigure5. 2marks
V
b. CalculatethefrequencyforthesignalshowninFigure5. 1mark
Hz
PHYSICS(SAMPLE) 18 Version3–May2017
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SECTION B – Question 6–continued
Question 6 (5marks)Juanconductsanexperimentusingashallowtrayofwaterinwhichwavescanbeobserved.Hefirstproducesstraightwavesatafrequencyof5Hz.Hemeasuresthewavelengthandfindsitto be10cm.
a. Calculatethespeedofthewaves. 1mark
cms–1
b. Juannowusestwopointsourcesproducingwavesatthesamewavelength(10cm)toinvestigatetwopointsourceinterferencepatterns,asshowninFigure6.
Y X
P
Figure 6
Heobserveslinesofmaximaandminimaintheresultantpattern,asshowninFigure6.Thelinesonthediagramrepresentwavecrests.
PointPisonalineofminima(nodalline). JuanmeasuresthedistancefromsourceXtopointPas16.0cm.
DeterminethedistancefromsourceYtopointP. 2marks
cm
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SECTION B – continuedTURN OVER
c. Juannowproducesstraightwavesandplacesanarrowgapinfrontofthewaves,asshowninFigure7.Henextmeasuresthewidthofthediffractionpattern.
Figure 7
Juanincreasesthefrequencyofthesource.
ExplaintheeffectthatthiswouldhaveonthediffractionpatternshowninFigure7. 2marks
PHYSICS(SAMPLE) 20 Version3–May2017
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SECTION B – Question 7–continued
Question 7 (4marks)Raniisconductingexperimentstostudytherefractionoflight.
a. Ranipassesabeamoflightfromalaserfromairintoaglassslab,asshowninFigure8.
45°
25° glass slab
airn = 1.00
laser
Figure 8
Calculatetherefractiveindexoftheglass. 1mark
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SECTION B – continuedTURN OVER
Raninextshinesarayoflightfromunderwatertoawater–airinterface,asshowninFigure9.
incoming ray
airn = 1.00
watern = 1.33
Figure 9
b. Determinethecriticalangleforthetotalinternalreflectionatthewater–airinterface. 1mark
c. Theangleofincidenceisincreasedtoanangleslightlygreaterthanthecriticalangle,ic.
Onthediagramprovidedbelow,drawinanyrayorraysthatRaniwouldobserve. 2marks
incoming ray
airn = 1.00
watern = 1.33ic
PHYSICS(SAMPLE) 22 Version3–May2017
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SECTION B – continued
Question 8 (2marks)Listthefollowingbandsoftheelectromagneticspectruminorderfromlongestwavelengthtoshortestwavelengthbywritingeachcorrespondingnumberintheappropriateboxbelow:1. infra-redradiation 4. ultravioletradiation2. microwaves 5. visiblelight3. radiowaves 6. X-rays
Longest Shortest
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SECTION B – continuedTURN OVER
Question 9 (2marks)Figure10showstheenergy-leveldiagramforthehydrogenatom.
ionisation energyn = 6n = 5
n = 4
n = 3
n = 2
n = 1 (ground state)0
10.2
12.1
12.8
13.113.213.6
energy (eV)
Figure 10
Anatomofhydrogenisexcitedtothen=4state.
Listthepossibleenergies,ineV,ofphotonsthatcouldbeemittedasthisatomreturnstothegroundstate.
PHYSICS(SAMPLE) 24 Version3–May2017
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SECTION B – Question 10–continued
Question 10 (9marks)Aruraltownissuppliedwithelectricityfromasmallhydro-electricpowerplantabout20kmfromthetown.Thealternatorgenerateselectricityat5000V.Thisissteppedupinatransformerto50000V.Electricityistransmittedtothetownthroughatwo-wirehigh-voltagetransmissionline.Theinputvoltagetothetransmissionlineatthealternatorendis50000VRMSAC.Thecurrentinthelineis15ARMS.Attheedgeofthetown,atransformerconvertsthevoltageto250VRMSACforuseinthetown.Thetotalresistanceofthetransmissionlineis40Ω.ThesystemisshowninFigure11.Assumethatthetransformersareideal.
250 VRMS ACto town
transformer
primarycoils
secondarycoils
alternator
20 km
power plant
transmission line
50 000 VRMS AC
Figure 11
a. Calculatethetotalpowerlossinthetransmissionline.Showyourworking. 3marks
W
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SECTION B – continuedTURN OVER
b. Calculatethevoltageinputfromthetransmissionlinetothestep-downtransformeratthetownendoftheline. 3marks
V
c. ExplainwhyACratherthanDCisgenerallyusedforlong-distancepowertransmission.Includethestepsinvolvedintheprocessoflong-distancepowertransmission. 3marks
PHYSICS(SAMPLE) 26 Version3–May2017
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SECTION B – Question 11–continued
Question 11 (6marks)Somestudentsconductanexperimentusingtwotrolleys,AandB,ofmass6.0kgand2.0kgrespectively.Intheexperiment,TrolleyA ismovingat2.0ms–1andTrolleyBisstationarybeforetheycollide.Thereisaspringbetweenthetwotrolleys,attachedtoTrolleyB.Whenthetrolleyscollide,theycompressthespringandthenmoveapartagain.Afterthecollision,TrolleyAismovingat1.0ms–1.Theexperimentalset-upisshowninFigure12.Ignorethemassofthespring.
A 6.0 kg
Before After
B 2.0 kg
u = 2.0 m s–1 u = 0 m s–1
A 6.0 kg B 2.0 kg
v = 1.0 m s–1 v = ? m s–1
Figure 12
a. CalculatethespeedofTrolleyB immediately afterthecollision. 2marks
ms–1
b. Determinewhetherthecollisioniselasticorinelastic.Showyourworking. 2marks
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SECTION B – continuedTURN OVER
c. Apairofstudents,PatandAlex,discusshowthekineticenergyofthesystemwouldvarywithtime. Pat’sopinionisthatthevariationwouldberepresentedbythegraphinFigure13a.
t
Figure 13a
Alex’sopinionisthatthevariationwouldberepresentedbythegraphinFigure13b.
t
Figure 13b
Whoiscorrect?Explainyouranswer. 2marks
PHYSICS(SAMPLE) 28 Version3–May2017
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SECTION B – continued
Question 12 (4marks)Figure14ashowsamodelcarofmass5.00kgmovinginapartofaverticalcircleofradius4.00m.Atthelowestpoint,L,thecarismovingat5.00ms–1.Figure14bshowsthemodelcaratthelowest point,L.
L
Figure 14a
4.00 m
L
Figure 14b
a. OnFigure14b,drawanarrowtoshowtheresultantforceonthecaratpointL. 1mark
b. CalculatethenormalreactionforceofthetrackonthecaratpointL.Showyourworking. 3marks
N
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SECTION B – continuedTURN OVER
Question 13 (3marks)Astoneofmass2.0kgisthrownfromthetopofa15mhighcliffabovetheseaatanangleof 30°tothehorizontaland ataninitialspeedof20ms–1,asshowninFigure15.Ignoreairresistance.
15 m
20 m s–1
30°cliff
sea
Figure 15
Calculatethekineticenergyofthestoneimmediatelybeforeitstrikesthesea.Showyourworking.
J
PHYSICS(SAMPLE) 30 Version3–May2017
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SECTION B – Question 14–continued
Question 14 (10marks)Somestudentstestaspringtodeterminethespringconstant,k.Theexperimentalset-upisshowninFigure16.
70
60
50
40unstretchedspring
ruler (cm) stretchedspring
masses added
30
20
10
0
Figure 16
Five0.50kgmassesaresuccessivelyaddedtotheendofthespringandtheresultinglengthofthespringwasmeasuredeachtime.Theresultsareshowninthetablebelow.
Number of 0.50 kg masses Length of spring
0 40cm
1 45cm
2 53cm
3 57cm
4 63cm
5 70cm
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SECTION B – Question 14–continuedTURN OVER
a. Recordthedatafromthetableasagraphonthegridbelow.Includelabels,scalesandunitsoneachaxis.Giventhatthesemeasurementsweretakenwithametreruler,graduatedto5cmintervalsandheldbyhand,insertrealisticuncertaintybars(orerrorbars).Drawalineofbestfit. 5marks
b. Fromthegraphinpart a.,determinethespringconstant,k,ofthespringandincludeapossibleuncertaintyinyourvalue. 3marks
Nm–1
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SECTION B – continued
c. Allfivemassesareaddedtotheendofthespring.Thespringisthenraisedtothe40cmpositionandreleased.
Calculatehowfarthespringstretchesbelowitsinitialrestposition.Showyourworking. 2marks
cm
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SECTION B – continuedTURN OVER
CONTINUES OVER PAGE
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SECTION B – Question 15–continued
Question 15 (6marks)Muonsareelementaryparticlescreatedintheupperatmospherebycosmicrays.Theyareunstableanddecaywithahalf-lifeof2.2μs(2.2×10–6s)whenmeasuredatrest.Thismeansthatinthereferenceframeofthemuons,halfofthemdecayineachtimeintervalof2.2μs.Inanexperiment,muonswithavelocityof0.995c(γ=10)wereobservedbysomescientiststopassthetopofamountainofheight2627m,asshowninFigure17.Thescientistsmeasuredthenumberofthesemuonsreachinggroundlevel.
muons
top of mountain
ground level
2627 m
Figure 17
a. Calculatethehalf-lifeofthemuonsasmeasuredbyastationaryobserveronthegroundinFigure17. 2marks
s
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SECTION B – continuedTURN OVER
b. Fromtheirreferenceframe,themuonsseethegroundrushingupwardsataspeedof0.995c.
Findtheheightofthemountainasmeasuredbythemuons. 2marks
m
c. Explainwhymanymoremuonsreachedthegroundthanwouldbeexpectedaccordingtoclassicalphysics. 2marks
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SECTION B – Question 16–continued
Question 16 (7marks)Somestudentsstudythediffractionofelectronsbyacrystallattice.TheapparatusisshowninFigure18a.Inthisapparatus,electronsofmass9.1×10–31kgareacceleratedtoaspeedof1.50×107ms–1.Theelectronspassthroughthecrystalandthediffractionpatternisobservedonafluorescentscreen.ThepatternthatthestudentsobserveisshowninFigure18b.
crystal
e– fluorescentscreen
electron gun
Figure 18a Figure 18b
a. CalculatethedeBrogliewavelengthoftheelectrons.Showyourworking. 2marks
nm
b. Thestudentsnextincreasetheacceleratingvoltageandhencethespeedoftheelectrons.
Describethechangetothepatternthattheywillobserveandgiveyourreasoning. 2marks
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SECTION B – continuedTURN OVER
c. ThestudentsreplacetheelectronsourcewithanX-raysourceandfindthatthepatternonthescreenissimilarlyshapedandspacedtothepatternobservedwhentheelectronswereattheoriginalspeedof1.50×107ms–1.
Calculatetheenergy ofaphotonfromthisX-raysource.Giveyouranswercorrecttothreesignificantfigures. 3marks
eV
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SECTION B – Question 17–continued
Question 17 (14marks)SomestudentssetuptheapparatusshowninFigure19tostudythephotoelectriceffect;inparticular,therelationshipbetweenthefrequencyandintensityofincominglightandthemaximumkineticenergyofemittedphotoelectrons.Assumethatallfiltersgivelightofthesameintensity.
A
V
metal plate
collector electrode
light source
filter voltmeter variable DC voltage source
photocell
+
–
ammeter
Figure 19
Theapparatusconsistsof:• asourceofwhitelight• asetoffilters,eachofwhichallowsonlylightofaselectedwavelengthtopassthrough• aphotocellconsistingofametalplateandacollectorelectrodeenclosedinanevacuated(noair)glasscase• avoltmeter(V),anammeter(A)andavariableDCvoltagesourceinacircuit,asshownabove.
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SECTION B – Question 17–continuedTURN OVER
a. Withaparticularfilterinplaceandthesamelightsource,thestudentsgraduallyincreasethevoltage,asmeasuredbythevoltmeter,fromzero.Theyplotthecurrentmeasuredbytheammeterasafunctionofthevoltagemeasuredbythevoltmeter.ThisisshowninFigure20.
I (μA)
V (volts)XO
Figure 20
ExplainwhythecurrentdropstozeroatpointX. 2marks
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SECTION B – Question 17–continued
Thestudentsnextusefivefilterstogivefivefrequenciesoflightfallingonthemetalplateandmeasurethestoppingvoltageonthevoltmeterforeachfrequency.Thedatacollectedisshowninthetablebelow.
Frequency (Hz) Stopping voltage (Vs )
4.5× 1014 1.3
5.0×1014 1.5
6.1×1014 2.0
6.9×1014 2.5
7.6×1014 2.8
b. Plotthedatagiveninthetableaboveontheaxesprovidedbelow,thendrawalineofbestfittoshowmaximumkineticenergyoftheemittedphotoelectronsversusfrequencyoflightfallingonthemetalplate. 3marks
0
0.5
1.0
1.5
2.0
2.5
4.0 5.0 6.0frequency (Hz × 1014)
7.0 8.0
EK max ofphotoelectrons
(eV)
c. Fromthegraphplottedinpart b.,determinethevalueofPlanck’sconstant,h,thatthestudentswouldhaveobtained.Giveyouranswercorrecttotwosignificantfigures. 2marks
eVs
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SECTION B – continuedTURN OVER
d. Forthisparticularexperiment,identifyeachofthefollowing. 2marks
Dependentvariable(s)
Independentvariable(s)
e. Forthisparticularexperiment,identifyone importantcontrolledvariableandindicatewhythisvariableshouldbecontrolled. 2marks
f. Studentsperformingthephotoelectricexperimentonadifferentmetalhavecarefullydeterminedtheuncertaintyintheirmeasuredvaluesforthemaximumkineticenergyoftheemittedphotoelectrons.Thisisrepresentedbyanuncertaintybar(orerrorbar)drawnononeofthedatapointsinthegraphbelow.Theuncertaintyinthevaluesforfrequenciesmaybeneglected.
0
1
2
3
frequency (Hz × 1014)
EK max ofphotoelectrons
(eV)
Onthegraphabove,showthestepsneededtodeterminewhetherthedatapointsmaybefittedbyastraightline.Explainyouranswer. 3marks
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SECTION B – Question 18–continued
Question 18 (11marks)a. OutlineYoung’sdouble-slitexperiment.Explaintheimplicationsofthisexperimentforunderstanding
thenatureoflight. 3marks
b. Explainhowasingle-photonYoung’sdouble-slitexperimentcanbeusedasevidenceofthedualnatureoflight. 3marks
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c. OutlinetheconclusionsaboutthenatureoflightthatAlbertEinsteinmadefromtheobservationsofphotoelectricexperiments.Includehowtheseconclusionsarosefromtheexperimentalobservationsandwhytheseconclusionscontradictedthesimplewavemodel. 5marks
END OF QUESTION AND ANSWER BOOK
PHYSICS (SAMPLE – ANSWERS)
© VCAA 2017 – Version 3 – May 2017
Answers to multiple-choice questions
Question Answer
1 C
2 C
3 C
4 A
5 B
6 A
7 D
8 A
9 A
10 D
11 B
12 B
13 A
14 D
15 B
16 D
17 B
18 D
19 C
20 C
