22086509 - ibdocuments.com PAST PAPERS...D2. This question is about sound and hearing. (a)...

transcript

2208-6509 32 pages

M08/4/PHYSI/HP3/ENG/TZ1/XX+

Wednesday 21 May 2008 (morning)

Physicshigher levelPaPer 3

INSTRUCTIONS TO CANDIDATES

• Write your session number in the boxes above.• Do not open this examination paper until instructed to do so.• Answer all of the questions from two of the Options in the spaces provided.• At the end of the examination, indicate the letters of the Options answered in the

candidate box on your cover sheet.

1 hour 15 minutes

Candidate session number

22086509

2208-6509

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Option D — Biomedical Physics

D1. Thisquestionisaboutscaling.

(a) The rateofoxygendemand,D, of an insect isproportional to themassof the insect.Therateofoxygenabsorption,R,isproportionaltothesurfaceareaoftheinsect.

Determinetheratio DR

intermsofthecharacteristiclength,L,oftheinsect.

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(b) Suggestwhyyouranswerin(a)placesapracticallimitonthesizeofinsects.

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D2. Thisquestionisaboutsoundandhearing.

(a) Distinguishbetweenconductiveandsensoryhearingloss.

Conductive: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Sensory: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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ThediagrambelowshowsasketchofthevariationwithfrequencyfoftheintensitylevelILofsoundheardbyayoungpersonwithnormalhearing.

10 100 1000 10000–20

Frequency/Hz

(b) OnthediagramsketchthevariationwithfoftheILofanelderlyperson. [2]

(c) Atafrequencyof3.0kHzapersonhasahearinglossof15dB.Forthefrequencyof3.0kHzcalculatetheratio

minimumintensityofsoundheardbypersonwithdefectivehearingminimumintensityofsoundheardbypersonwithnormalhearing

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D3. ThisquestionisaboutX-rays.

AparallelbeamofmonochromaticX-raysofphotonenergy30keVisincidentonmuscleasshowninthediagrambelow.Theincidentintensityis 0I andthetransmittedintensityisI.

muscle

transmittedbeamofintensityI

parallelincidentbeamofX-raysofintensityI0

The graph below shows the variationwith the thicknessx of the muscle of the transmittedintensityI.Theunitsofintensityarearbitrary.

thickness, x/mm0 4321

transmittedintensity,I

(This question continues on the following page)

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(Question D3 continued)

(a) Defineattenuation coefficient.

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(b) Usedatafromthegraphtodeterminetheattenuationcoefficientofmuscle.

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(c) Withreferencetotheattenuationcoefficientofmuscleandofbone,outlinetheformationofanX-rayimageofalimb.

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(d) Outlinethebasisofcomputedtomography(CT)scanning.

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D4. Thisquestionisaboutenergychangesinthebody.

Amanofweight700Ndoes“push-ups”as shown in thediagrambelow. Hisbody in theupperpositionmakesanangleof 25°tothehorizontal.Thebody’scentreofmassisadistanceof1.10mfromthefeet.

lowerposition upperposition

centreofmass

(a) Calculatetheworkdoneincompleting40push-ups.

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(b) During the exercise the total energy requirement of the man is approximately 150kJ.Suggest reasons for the difference between this energy requirement and your answerin(a).

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D5. Thisquestionisaboutradiationdosimetry.

(a) Defineexposure.

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(b) Apatientisinjectedwithagammarayemitter.Theradiationfromthesourcecreatesanexposureinthebodyof8.6 10 C kg−3 −1× .

Theaverageenergyrequiredtosinglyionizeanatominthehumanbodyisapproximately40eVandthequalityfactorforgammaradiationis1.Deducethatthiscorrespondstoadoseequivalentof340mSv.

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Option E — The History and Development of Physics

E1. Thisquestionisaboutthemotionofstars.

In thecourseofonenight, starsappear tomovealongarcs. Thediagrambelowshows theimagesofthepathsofthreestarsobtainedbyacamerainwhichtheshutterremainedopenforaperiodoftime.

(a) Describehowthesepathsmaybeexplainedin

(i) thePtolemaicmodel.

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(ii) theCopernicanmodel.

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(b) Withreferencetoyouranswerto(a)(ii)estimatethetimeforwhichthecamerashutterwasopen.

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E2. Thisquestionisaboutthemotionofplanets.

(a) OutlinethecontributionsofBraheandKeplertotheunderstandingofplanetarymotion.

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(b) OutlinehowNewton’scontributionstotheunderstandingofthelawsofplanetarymotionlead to theconclusion thatKepler’sunderstandingofplanetarymotionalsoapplies tocomets.

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E3. Thisquestionisaboutthecalorictheoryofheat.

(a) Outlinethecaloric(phlogiston)theoryofheat.

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(b) Stateandexplainonepieceofevidence thatdoesnotsupport thecaloric (phlogiston)theoryofheat.

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E4. Thisquestionisabouttheinversesquarelawinelectrostatics.

ThediagramshowspartoftheapparatusthatmaybeusedtoverifytheinversesquarenatureofCoulomb’selectrostaticlaw.

torsionalbalance

(a) Withtheaidofthediagramdescribehowtheinversesquarenatureofthelawmaybeverified.

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(b) OutlinehowCoulombobtainedchargesofdifferentknownrelativemagnitudes.

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E5. Thisquestionisaboutmodelsofthehydrogenatom.

(a) The Bohr model provides a partially successful explanation of the spectrum of thehydrogenatom.Themodelpredictsthattheenergy,E,oftheelectroninthehydrogenatomisgivenby

−182.18×= −

wheren isanintegerandE isinjoules.

(i) Byreferencetothisequation,describehowtheBohrmodelaccountsforthelinespectrumofthehydrogenatom.

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(ii) Calculatetheshortestwavelengthoflightinthespectrumofatomichydrogen.

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(iii) State one characteristic of the spectrum of atomic hydrogen which cannot beaccountedforbytheBohrmodel.

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(b) Outline by reference to position and momentum how the Schrödinger model of thehydrogenatomisconsistentwiththeHeisenberguncertaintyprinciple.

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Option F — Astrophysics

F1. Thisquestionisaboutcometsandstars.

(a) Stateonedifference(otherthansize)betweentheorbitofatypicalcometandtheorbitoftheEartharoundtheSun.

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(b) Theaveragedistancebetweenthestarsinagalaxyisabout2pc.Atypicalgalaxyhasavolumeof1012pc3.Estimatethenumberofstarsinthegalaxy.

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F2. Thisquestionisaboutmagnitudeandapparentbrightness.

(a) Defineapparent brightnessandapparent magnitude.

Apparentbrightness: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Apparentmagnitude: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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(Question F2 continued)

(b) The table gives information on the peak absolute magnitude and the peak apparentbrightnessoftwoCepheidstars.

star (peak) absolutemagnitude

(peak) apparentbrightness

DeltaCephei –3.47 9.010–10Wm–2

ZetaGeminorum –4.13 7.210–10Wm–2

StateandexplainwhetherDeltaCepheiorZetaGeminorum

(i) appearsbrighterfromEarth.

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(ii) isclosertoEarth.

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(c) TheluminosityofaCepheidstarisvariable.Outlinethereasonforthisvariation.

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ThegraphshowsthevariationwithperiodofthepeakluminosityofCepheidstars.

Period/days

Luminosity

100 1 10 100

Theluminosityisgivenintermsofthesolarluminosityof3.91026W.

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(d) (i) OutlinehowdatafromthegraphmaybeusedtodeterminethedistanceofagalaxyfromEarth.

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(ii) ThepeakapparentbrightnessofZetaGeminorumis7.210–10Wm–2andtheperiodofvariationofluminosityisapproximately10days.

Use data from the graph on previous page to deduce that the distance toZetaGeminorumfromEarthisabout1.11019m.

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F3. Thisquestionisaboutcosmicmicrowavebackgroundradiation.

(a) Statewhatismeantbycosmicmicrowavebackgroundradiation.

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(b) Describe how the cosmic microwave background radiation provides evidence for theexpandinguniverse.

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F4. Thisquestionisaboutstellarevolution.

ApartiallycompletedHertsprung-Russel(H-R)diagramisshownbelow.

Luminosity

Temperature

The line indicates the evolutionarypath of theSun from its present position,S, to itsfinalposition,F.AnintermediatestageintheSun’sevolutionislabelledbyI.

(a) StatetheconditionfortheSuntomovefrompositionS.

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(b) StateandexplainthechangeintheluminosityoftheSunthatoccursbetweenpositionsSandI.

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(c) Explain,byreferencetotheChandrasekharlimit,whythefinalstageoftheevolutionarypathoftheSunisatF.

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(d) Onthediagramonthepreviouspage,drawtheevolutionarypathofamainsequencestarthathasamassof30solarmasses. [1]

F5. ThisquestionisaboutHubble’slaw.

(a) StateHubble’slaw.

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(b) DeduceanexpressionfortheageToftheUniverseintermsoftheHubbleconstantH.

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Option G — Relativity

G1. Thisquestionisaboutthespeedoflight.

A pion is an unstable particle that decays into two photons. A particular pion, travellingat0.900cwithrespecttoanobserveratrestinalaboratory,decaysintotwophotons,LandR,travellinginoppositedirectionsasshowninthediagram.

0.900cpion

laboratory

photonL photonR

photonsafterdecay

Thespeedofbothphotonsasmeasuredbytheobserveratrestwithrespecttothepionisc.

(a) CalculatethevelocityofphotonRwithrespecttotheobserverinthelaboratoryusing

(i) Galileankinematics.

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(ii) relativistickinematics.

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G2. Thisquestionisaboutrelativistickinematics.

Arocketmovingat0.80c,relativetoEarth,passestheEarthonitswaytoadistantplanet.AsmeasuredbyanobserveronEarththedistancebetweenEarthandtheplanetis6.0ly.

rocketEarthplanet

6.0ly diagramnottoscale

(a) CalculatethedurationofthejourneyfromEarthtotheplanetaccordingtotheobserver

(i) onEarth.

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(ii) intherocket.

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(Question G2 continued)

(b) Therocketpassesaspacestation that isat restwith respect to theEarth. Theproperlengthoftherocketandtheproperlengthofthespacestationareboth40m.

(i) Defineproper length.

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(ii) Determinethelengthofthespacestationaccordingtotheobserverintherocket.

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(Question G2 continued)

(c) Tomisanobserverinarocketthatmovespastaspacestation.Jerryisanobserverinthemiddleofthespacestation.Jerrysendstwolightsignalstowardsmirrorsatthefrontandthebackofthespacestation.ThesignalsareemittedsimultaneouslyaccordingtoTomandaccordingtoJerry.

ThesignalsarereflectedoffthemirrorsandarereceivedbyJerry.

rocket

frontmirror

spacestation

backmirror

Determine,according to Tom,whether

(i) the frontor thebackof thespacestation receives thesignalfirstorwhether thesignalsarrivesimultaneously.

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(ii) thereflectedsignalsarriveatJerrysimultaneously.

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G3. Thisquestionisaboutrelativisticmechanics.

(a) A proton of rest mass 938 MeVc–2 is accelerated from rest through a potentialdifferenceV.Withrespecttoanobserverinthelaboratorythespeedoftheprotonafteracceleration is0.998c. Calculate thevalueof theacceleratingpotentialdifferenceasmeasuredbytheobserver.

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(b) ThegraphbelowshowsthevariationwithacceleratingpotentialdifferenceVofthespeedvofaprotonafteracceleration,accordingtoNewtonianmechanics.

Onthegraph,drawalinetoshowthevariationwithacceleratingpotentialdifferenceVofthespeedvofaprotonaccordingtorelativisticmechanics. [2]

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G4. Thisquestionisaboutarelativisticdecay.

ParticleXhas restmass3520MeVc–2. Itdecaysat rest ina laboratory, into two identicalparticlesY.Thetwoparticlesmoveinoppositedirectionswithmomentum1490MeVc–1withrespecttothelaboraryasshowninthediagram.

particleY

particleXatrestbeforedecay

1490MeVc–1

Determinetherestenergy,inunitsofMeV,ofparticleY.

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G5. Thisquestionisaboutblackholes.

(a) DefinetheSchwarzchild radiusofablackhole.

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(b) SuggestwhytheSchwarzchildradiusofablackholeislikelytoincreasewithtime.

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(c) ThediagramshowsablackholewithSchwarzchildradiusR.

Schwarzchildradius

blackhole

AnobserveratXsendsasignalthatisreceivedbythespacecraftS.

(i) Onthediagram,drawalinetoindicateapossiblepathoftheradiosignal. [1]

(ii) Explainthepathyouhavedrawn.

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Option H — Optics

H1. Thisquestionisaboutrefraction.

(a) Definerefractive index.

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(b) Thediagrambelowshowsthepathofarayofredlightincidentona 45°prism.

45°90°

airredlight

normal

glassprism

ThelightundergoestotalinternalreflectionatfaceBC.

(i) Statethevalueoftheangleofincidence onfaceBC.

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(ii) DeterminetheminimumrefractiveindexoftheglassoftheprismfortotalinternalreflectionoftherayatfaceBC.

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(c) Theredlightisreplacedbybluelight.Explainwhythepathofbluelightisthesameasthatoftheredlight.

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H2. Thisquestionisaboutimageformationbyaconverginglens.

(a) Definetheprincipal focus (focal point)ofaconverginglens.

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(b) Anobjectisplaced30cminfrontofaconverginglensoffocallength15cm.Theobjectismoved5.0cmclosertothelens.Determinethedisplacementoftheimage. [4]

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2208-6509

H3. Thisquestionisaboutanastronomicaltelescope.

Thediagramshowstwoconverginglensesadjustedtoformanastronomicaltelescope.

objectivelens eyepiecelens

Theobjectivelenshasafocallengthfoandtheeyepiecelenshasafocallengthfe.TheobjectivelensformsanimageofadistantobjectatI.Thefinalimageisformedatinfinity.

(a) State,intermsoffoandfe,theseparationoftheobjectivelensandtheeyepiecelens.

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(b) On the diagram, draw rays to show the formation of the image produced by theeyepiecelens. [4]

(c) (i) Defineangular magnification.

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(ii) State,intermsoffoandfe,,theangularmagnificationofthetelescope.

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H4. Thisquestionisaboutdiffraction.

Monochromaticlightisincidentonasingleslitofwidth1.2 10 m−4× .

incidentlight 1.2 10 m−4×

Diagramnottoscale

screen

Thegraphshowsthevariationwithangle oftheintensityofthelightonthescreen.

relativeintensity

/×10–3rad

–6 –4 –2 0 2 4 6

(a) Usethegraphtoestimatethewavelengthofthelight.

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(b) Monochromaticlightisincidentontwoparallelslits.Afterpassingthroughtheslits,the

lightisincidentonascreen.Theseparationoftheslitsisapproximatelytwicetheslitwidth.Ontheaxesabovedrawagraphtoshowtheintensitydistributionofthelightonthescreen. [2]

2208-6509

H5. Thisquestionisaboutthinfilminterference.

Thediagramshowsmonochromaticlightinair,thatisincidentonathinfilmofsiliconoxideofthicknessd.

incidentray

normal A B

siliconoxide

The light is incident at an angle to the normal to the surface. Light is reflected alongdirectionsAandB.

(a) StatewhylightwavesalongAandBarecoherent.

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(b) Thewavelengthof the light in thesiliconoxidefilmis452nm. The light is incidentnormallyonthesurfacesothat =0.CalculatetheminimumthicknessofthefilmsuchthatlightalongAandBundergoesdestructiveinterference.

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(c) Thelightincidentonthefilmisreplacedbywhitelight.Stateandexplaintheappearanceofthefilminthiscase.

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22086509 - ibdocuments.com PAST PAPERS...D2. This question is about sound and hearing. (a)...

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