2015 HSC Physics

2015 HIGHER SCHOOL CERTIFICATE EXAMINATION

Physics

1100

General Instructions

•Readingtime–5minutes

•Workingtime–3hours

•Writeusingblackpen

•Drawdiagramsusingpencil

•Board-approvedcalculatorsmaybeused

•Adatasheet,formulaesheetsandPeriodicTableareprovidedatthebackofthispaper

Total marks – 100

Section I Pages2–28

75 marks

Thissectionhastwoparts,PartAandPartB

PartA–20marks

•AttemptQuestions1–20

•Allowabout35minutesforthispart

PartB–55marks

•AttemptQuestions21–30

•Allowabout1hourand40minutesforthispart

Section II Pages29–39

25 marks

•AttemptONEquestionfromQuestions31–35

•Allowabout45minutesforthissection

–2–

Section I75 marks

Part A – 20 marksAttempt Questions 1–20Allow about 35 minutes for this part

Usethemultiple-choiceanswersheetforQuestions1–20.

1 Thecomponentsofagalvanometerareshown.

Scale

SpringPointer

N S

Soft iron coreCurrent-carrying coil

Whatisthepurposeofthespringinthegalvanometer?

(A) Toensureauniformforceonthecoil

(B) Tocompletethecircuitthroughthecoil

(C) Tocounteractthemotoreffectonthecoil

(D) Toincreasethemagneticfluxthroughthecoil

–3–

2 Thediagramshowsanapparatusthatcanbeusedtoinvestigatepropertiesofcrystals.

X-ray tube

Collimator

Crystal

X-ray

Detector

Usingthisapparatus,whatsignificantinformationwasdeterminedaboutcrystalsbytheBraggs?

(A) HowwellcrystalsreflectX-rays

(B) Howtheatomsincrystalsarearranged

(C) Whethercrystalsexhibitthepropertyofsuperconductivity

(D) Whethertheelectricalresistanceofcrystalsisincreasedbyimpurities

3 Thediagramshowsatypeofcathoderaytube.

WhichofthefollowingstatementsCANNOTbeinferredfromobservationsmadewhenusingtheapparatusshown?

(A) Cathoderayspossessenergy.

(B) Cathoderayspossessmomentum.

(C) Cathoderaystravelinstraightlines.

(D) Cathoderayscannotpassthroughmetals.

–4–

4 Aprojectileislaunchedfromaclifftop.Thedotsshowthepositionoftheprojectileatequaltimeintervals.

Assumingnegligibleairresistance,whichdiagrambestshowsthepathoftheprojectile?

(A) (B)

(C) (D)

5 Whydoestheelectricalresistanceofametalincreaseastemperatureincreases?

(A) Latticevibrationsincrease,scatteringmoreelectrons.

(B) Electronspairup,increasingtheirinteractionswiththecrystallattice.

(C) Fewerelectronsarefreetomove,astheyfilltheholesintheconductionband.

(D) Electronsmovemorefreelythroughthemetal,unimpededbythecrystallattice.

6 Whichofthefollowingisatruestatementaboutscientifictheories,suchasEinstein’stheoryofspecialrelativity?

(A) Theyarevalidbutunreliableideas.

(B) Theyareusefulinmakingpredictions.

(C) Theyareconceptsthatlackanexperimentalbasis.

(D) Theyareideasthatcan’tbeaccepteduntiltheyhavebeentested.

–5–

7 Acurrent-carryingwireisplacedperpendiculartoamagneticfield.

Whichgraphcorrectlyshowstherelationshipbetweenmagneticfieldstrength(B)andcurrent(I )iftheforceistoremainconstant?

I

B

(A)

I

B

(B)

I

B

(C)

I

B

(D)

8 Inwhichofthefollowingsituationsdoesthemagneticfieldexertthegreatestforceontheproton( ),giventhatallofthefieldsareofequalmagnitude?

(A) B

v = 0

(B) B

v = 60 m s–1

(C) B

v = 40 m s–1

(D) Bv = 50 m s–1

45°

–6–

9 P, Q and R are straight, current-carrying conductors. They all carry currents of thesamemagnitude(I ).ConductorsPandQarefixedinplace.ThemagnitudeoftheforcebetweenconductorsQandRisFnewtons.

P

10 mm 10 mm

III

RQ

WhatisthenetforceonconductorRwhenitisinthepositionshown?

F(A) newtonstotheleft

2

F(B) newtonstotheright

2

3F(C) newtonstotheleft

2

3F(D) newtonstotheright

2

– 7 –

10 Which of the following represents a doped semiconductor?

(A) Si Si Si Si

Si Si Si Si

Si P Si Si

Si Si Si Si

(B Si C Si C

C Si C Si

Si C Si C

C Si C Si

)

(C) Si Si Si

Si Ge Si

Si Si Si

(D) Si Si Si

Si C Si

Si Si Si

11 Which of the following diagrams correctly represents the force(s) acting on a satellite in a stable circular orbit around Earth?

Fg = gravitational force Fp = propulsive force

Fc = centripetal force Fr = reaction force

(A)Fp

Fg

(B)Fc

FpFg

(C)

Fr

Fc

(D)Fg

–8–

12 AsimpleACgeneratorwasconnected toacathode rayoscilloscopeand thecoilwasrotatedataconstantrate.Theoutputisshownonthisgraph.

Voltage

Time0

1

–1

Voltage(A)

Time

Voltage(B)

Time

0

1

–1

0

1

–1

Voltage(D)

Time0

1

–1

Voltage(C)

Time0

1

–1

Which of the following graphs best represents the output if the rate of rotation isdecreasedtohalfoftheoriginalvalue?

(A) Voltage

Time

Voltage(B)

Time

0

1

–1

0

1

–1

Voltage(D)

Time0

1

–1

Voltage(C)

Time0

1

–1

Voltage

Time0

1

–1

–9–

13 Thefollowingdiagramrepresentsthebandstructureoffourmaterials.

NOTTO SCALE

0.67eV

Ge

1.11eV

Si

1.43eV

GaAs

9eV

SiO2

Which material would absorb a photon of wavelength 8.60×10−7m, causing anelectrontojustjumpthebandgap?

(A) Ge

(B) Si

(C) GaAs

(D) SiO2

14 Apassengerisplayingbilliardsonatrainthatistravellingforwardsonaleveltrack.Theballtakesthepathshownwhenhitbythecue.

Initial positionof ball

Path of ballCue

Motion of cue

Frontof train

Later position of ball

Whatcanbeinferredaboutthemotionofthetrain?

(A) Itisturningleft.

(B) Itisspeedingup.

(C) Itisturningright.

(D) Itisslowingdown.

–10–

15 A circular loop of wire is stationary in a magnetic field. The sides are then pushedtogethertochangetheshape,asshowninthediagram.

Before After

Astheloopiscompressed,acurrentisinduced.

Whichrowofthetableshowsthedirectionofthecurrentandexplainswhyitisinduced?

Current direction Why the current is induced

(A) Clockwise Changeinmagneticflux

(B) Anticlockwise Changeinmagneticflux

(C) Clockwise Changeinmagneticfluxdensity

(D) Anticlockwise Changeinmagneticfluxdensity

16 Astronautstravelatavelocityof0.9ctoAlphaCentauri.Newtonianphysicspredictsthatthisjourneywouldtake4.86years.

Howmanyyearswillthejourneytakeintheframeofreferenceoftheastronauts?

(A) 0.923

(B) 1.54

(C) 2.12

(D) 11.1

–11–

17 Which rowof the table correctly shows ideas thatPlanck andEinstein contributed toquantumtheory?

Planck Einstein

(A) Hotobjectsemitradiationindiscreteamounts.

Lightconsistsofpacketsofenergywithspecificvalues.

(B) Planck’sconstantdeterminestheenergyofphotons.

Objectsemitenergythatincreasesexponentiallywithfrequency.

(C) Noenergyislostfromblackbodyradiators.

Energyisabsorbedifthebandgapislessthanthephotonenergy.

(D) Theenergyofphotonsdecreasesasthewavelengthincreases.

Photonshaveenergyproportionaltotheirfrequency.

18 Thediagramshowsanidealtransformer.

V

Iron core

G

Whentheswitchisclosed,thepointeronthegalvanometerdeflects.

Howcouldthesizeofthedeflectionbeincreased?

(A) Decreasethenumberofprimarycoils

(B) Decreasethenumberofsecondarycoils

(C) Replacetheironcorewithacoppercore

(D) Placearesistorinserieswiththegalvanometer

–12–

19 AnastronautworkingoutsideaspacecraftinorbitaroundEarthisnotattachedtoit.

WhydoestheastronautNOTdriftawayfromthespacecraft?

(A) Theforceofgravityactingontheastronautandspacecraftisnegligible.

(B) ThespacecraftandtheastronautareinorbitaroundtheSunwiththeEarth.

(C) Theforcesduetogravityactingonboththeastronautandthespacecraftarethesame.

(D) Theaccelerationsoftheastronautandthespacecraftareinverselyproportionaltotheirrespectivemasses.

20 Aprojectilewaslaunchedfromtheground.Ithadarangeof70metresandwasintheairfor3.5seconds.

Atwhatangletothehorizontalwasitlaunched?

(A) 30°

(B) 40°

(C) 50°

(D) 60°

©2015BoardofStudies,TeachingandEducationalStandardsNSW

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Office Use Only – Do NOT write anything, or make any marks below this line.

Centre Number

Student Number

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43933103511101 15330


Physics

Section I (continued)

Part B – 55 marksAttempt Questions 21–30Allow about 1 hour and 40 minutes for this part

Answer the questions in the spacesprovided. These spaces provideguidance for the expected length ofresponse.

Showallrelevantworkinginquestionsinvolvingcalculations.

Extra writing space is provided onpages27and28.Ifyouusethisspace,clearly indicate which question youareanswering.

Write your Centre Number andStudent Number at the top of thispage.

Please turn over

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Question 21 (4marks)

Aprojectileisfiredhorizontallyfromaplatform.

Heightof platform

Projectile

Distance travelled from base of platform

NOT TOSCALE

Landing positionof projectile

Measurementsofthedistancetravelledbytheprojectilefromthebaseoftheplatformaremadeforarangeofinitialvelocities.

Initial velocity of projectile (ms–1)

Distance travelled from base of platform (m)

1.4 1.0

2.3 1.7

3.1 2.2

3.9 2.3

4.2 3.0

Question 21 continues on page 15

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Question21(continued)

(a) Graphthedataonthegridprovidedanddrawthelineofbestfit. 2

0 1 2Initial velocity (m s−1)

Dis

tanc

e tr

avel

led

from

bas

e of

pla

tfor

m (

m)

3 4 50

1

2

3

(b) Calculatetheheightoftheplatform.

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ThediagramrepresentsasimpleDCmotor.Acurrentof1.0AflowsthroughasquareloopABCDwith5cmsidesinamagneticfieldof0.01T.

Axis of rotationPowersupply

1.0 A A B

D C

N

S

(a) DeterminetheforceactingonsectionABandtheforceactingonsectionBCduetothemagneticfield,whentheloopisinthepositionshown.

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(b) Howisthedirectionofthetorquemaintainedasthelooprotates360°fromthepositionshown?

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Question 23 (5 marks)

(a) Outline a procedure that could be used to model electrical conduction in a semiconductor.

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(b) Explain a limitation of the model outlined in part (a).

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Apartofacathoderayoscilloscopewasrepresentedonawebsiteasshown.

e−

e−

e−

Heatingfilament

Cathode

5000 V

2 cm

Anode

e–

Deflection plates

Electronsleavethecathodeandareacceleratedtowardstheanode.

(a) Explainwhytherepresentationofthepathoftheelectronbetweenthedeflectionplatesisinaccurate.

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Question 24 (continued)

(b) Calculate the force on an electron due to the electric field between the cathode and the anode.

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(c) Calculate the velocity of an electron as it reaches the anode.

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(a) OutlinetheconversionofelectricalenergybydevicesinthehomeintoTWOotherformsofenergy.

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(b) Thediagramshowsalabelonatransformerusedinanappliance. 3

Input: 240 V AC 5.0 AOutput: 2 kV AC 1.0 A

Explainwhytheinformationprovidedonthelabelisnotcorrect.Supportyouranswerwithcalculations.

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Consider the following two models used to calculate the work done when a 300 kg satellite is taken from Earth’s surface to an altitude of 200 km.

You may assume that the calculations are correct.

Model X Model Y

Data: −2g = 9.8 m s Data: 10−11G = 6.67 × N m2 kg−2

m = 300 kg = 6.38 × 106 mrEarth

Dh = 200 km = 6.58 × 106 mrorbit

1024M = 6.0 × kg

W = Fs m = 300 kg

= mgDh W = D EP

= 3 × 102 × 9.8 × 2.0 × 105

= 5.9 × 108 J ΔEp = E − Ep final p initial

GMm ⎛ GMm ⎞= − −

r ⎝⎜ ⎠⎟orbit r Earth

= −1.824 ×1010 − −1.881×1010( )= 5.7 ×108 J

(a) What assumptions are made about Earth’s gravitational field in models X and Y that lead to the different results shown?

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(b) Why do models X and Y produce results that, although different, are close in value?

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(c) Calculatetheorbitalvelocityofthesatelliteinacircularorbitatthealtitudeof200km.

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In 1865, James Clerk Maxwell developed the theory of electromagnetism. This theory explained the nature of light. It also predicted the existence of other electromagnetic waves.

How did Hertz test and validate Maxwell’s theory?

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A copper plate is attached to a lightweight trolley. The trolley moves at an initialvelocity,v,towardsastrongmagnetfixedtoasupport.

5

A

v

B

Strong magnet

Trolley

Copper plate

C D

Support

Thedashedlineonthegraphshowsthevelocityofthetrolleywhenthemagnetisnotpresent.

Ontheaxes,sketchthegraphofthevelocityofthetrolleyasittravelsfromAtoD underthemagnet,andjustifyyourgraph.

v

Position of the front of the trolley

Velocityof

trolley

A B C D0

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In the Large Hadron Collider (LHC), protons travel in a circular path at a speed greater than 0.9999 c.

(a) What are the advantages of using superconductors to produce the magnetic fields used to guide protons around the LHC?

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(b) Discuss the application of special relativity to the protons in the LHC.

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ThefollowingisatimelinefortheCassinispaceprobemissiontoSaturn. 6

Earth

Launch15/10/1997

Venus

Slingshot26/4/1998

Venus

Slingshot24/6/1999

Earth

Slingshot18/8/1999

Jupiter

Slingshot30/12/2000

Saturn

Orbit1/7/2004

ExplainhowNewton’sLawsofMotionandUniversalGravitationwereappliedtotheCassinimission.

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Section I Part B extra writing space

If you use this space, clearly indicate which question you are answering.

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–28– © 2015 Board of Studies, Teaching and Educational Standards NSW

8455310354

Section I Part B extra writing space

If you use this space, clearly indicate which question you are answering.

–29–1102


Physics

Section II

25 marksAttempt ONE question from Questions 31–35Allow about 45 minutes for this section

Answerparts(a)–(e)ofonequestionintheSectionIIWritingBooklet.Extrawritingbookletsareavailable.

Showallrelevantworkinginthequestionsinvolvingcalculations.

Pages

Question31 Geophysics.............................................................................30–31

Question32 MedicalPhysics.....................................................................32–33

Question33 Astrophysics...........................................................................34–35

Question34 FromQuantatoQuarks..........................................................36–37

Question35 TheAgeofSilicon.................................................................38–39

–30–

Question 31 — Geophysics (25marks)

Answerparts(a),(b)and(c)ofthequestiononpages2–4oftheSectionIIWritingBooklet.Starteachpartofthequestiononanewpage.

(a) Thetableshowsmeasurementstakenbyastudenttodeterminethedensityoftwotypesofrocks.

Rock sample Initial volume of water (mL)

Volume after adding rock sample (mL)

Mass (g)

granite 150 185 92.4

basalt 150 190 119.0

(i) Quantitativelycomparethedensitiesofgraniteandbasalt. 2

(ii) Describephysicalpropertiesoftheserocks,otherthandensity,thatcanbestudied.

3

(b) (i) Describealong-termchangeinEarth’smagneticfield.

2

(ii) AccountforchangesinEarth’smagneticfield. 3

(c) OnemethodofstudyingEarthusestwosatellitesinthesameorbitasshown. 4

S1

S2220 km

NOT TOSCALE

Orbit

460 km

Microwave signals transmitted between the satellites are used to accuratelymeasurechangesintheirseparation.

ExplainwhatcanbededucedaboutEarthbyusingthesesatellites.


–31–


Answer parts (d) and (e) of the question on pages 6–8 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.

(d) Usethefollowinginformationaboutearthquakewavestoanswerparts(i)and(ii).

5

10

15

5

10

15

Spee

d (k

m/s

)

Depth (km)2000 3000 4000 5000

Density (×

103 kg m

–3)

Density

DensityP wave

P wave

CrustMantleOuter coreInner core

3000 km

2200 km

O

Key P wave path O Focus

(i) What is the relationship between density and P wave speed betweendepthsof3500kmand4500km?

2

(ii) Account for thepathsof thePwavesproducedatO, as shown in theseconddiagram.

3

(e) Assess the impactofapplicationsof remotesensingonsociety.SupportyouranswerusingTHREEexamples.

6

End of Question 31

–32–

Question 32 — Medical Physics (25marks)


(a) (i) Describehowultrasoundcanbeused todistinguishbetweendifferenttypesoftissueinthebody.

2

(ii) Use data from the table below to calculate the acoustic impedance ofbone andhencedetermine the ratio of reflected to initial intensity forultrasoundstrikingamuscle–boneboundary.

3

Material Density(r)

kgm–3Acoustic Velocity (v)

ms–1Acoustic Impedance (Z)

×106kgm–2s–1

MuscleLiverBrainBone

1075 1050 1025 1910

1590157015404080

1.71 1.65 1.58

(b) Afterapatienthadbeentreatedforlungcancer,notumoursweredetectedinanX-rayimageofthelungs.

Thedoctorhasnowrecommendedthatthepatienthaveawhole-bodyPETscan.

(i) OutlineTWOdifferencesbetweenthemethodusedtoproduceanX-rayimageandthemethodusedtoproduceaPETscan.

2

(ii) Justifythedoctor’srecommendationtousethewhole-bodyPETscan. 3

(c) Describehowthestructureofanendoscopeenablesittobeusedtodetectthepresence of a tumour in the stomach wall and to collect a tissue sample foranalysis.

4


–33–



(d) (i) Howdoesamagneticresonanceimage(MRI)scandistinguishbetweengreyandwhitematterinthebrain?

2

(ii) HowistheprocessofresonanceusedintheproductionofanMRIscan? 3

(e) Assesstheimpactofadvancesinunderstandingofwavesonthedevelopmentofimagingtechnologies.SupportyouranswerusingTHREEexamples.

6

End of Question 32

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Question 33 — Astrophysics (25 marks)

Answer parts (a), (b) and (c) of the question on pages 2–4 of the Section II Writing Booklet. Start each part of the question on a new page.

(a) (i) The star Canopus has an absolute magnitude of –5.51. Its distance from Earth is 95.9 pc.

Calculate its apparent magnitude.

2

(ii) Outline TWO methods of determining distances to stars. 3

(b) The light curves of two binary systems are shown.

Time

5

1

0.75

0.5

0.25

Rel

ativ

e br

ight

ness

0.5

1

0.75

0.25

0 0

Rel

ativ

e br

ight

ness

Time

(i) Explain why many binary star systems do not produce the types of light curves shown.

2

(ii) Account for the different shapes of the light curves shown in the graphs. 3

(c) Explain how emission spectra and absorption spectra are produced by specific types of celestial objects.


4

–35–



(d) ThepositionoftheSun,starWandstarZareshownontheH-Rdiagram.

O10−4

10−2

1

102

104

B A

Spectral type

Lum

inos

ity (

sola

r un

its)

F G K M

W Z

Sun

ThecurvesA andB show intensityversus frequency for starW and theSun,measuredfromthesamedistance.

Inte

nsity

Frequency

A

B

(i) Identifywhichcurve(AorB)representsstarWandjustifyyourchoice. 2

(ii) AccountfordifferencesbetweenstarsWandZthatcanbededucedfromtheH-Rdiagram.

3

(e) Assess the impact of the development of space-based telescopes on theunderstandingofcelestialobjects.

6

End of Question 33

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Question 34 — From Quanta to Quarks (25marks)


(a) Polonium-218isanunstableisotopethatcandecaytoeitherlead-214byalphadecay,orastatine-218bybetadecay.

(i) How could a Wilson Cloud Chamber, or similar device, be used todistinguishbetweenalphadecayandbetadecay?

2

(ii) The mass of a polonium-218 nucleus is 218.00897u, the mass of a lead-214 nucleus is 213.99981u, and the mass of an alpha particle is4.00260u.

Calculatetheenergyreleasedbythisalphadecay.

3

(b) Aninstrumentusesabeamofneutronswithawavelengthof0.2nmtostudythestructureofnewmaterials.

(i) Calculatethespeedoftheneutrons.

2

(ii) Explainwhythisbeamofneutronsisusefulindeterminingthestructureofmaterials.

3

(c) Explainwhy the spectroscopewas important in thedevelopmentof theBohrmodeloftheatom.

4


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(d) In1927,DavissonandGermerreportedtheresultsofanexperimentinwhichtheyfiredelectronsatacrystalofnickelandobservedhowtheelectronswerescattered.

(i) Statetheirconclusion,withreferencetotheresultstheyobtained. 2

(ii) Explain the significance of this experiment to the Rutherford-Bohrmodeloftheatom.

3

(e) AssesstheimpactofTHREEadvancesinknowledgeaboutparticlesandforcesontheunderstandingoftheatomicnucleus.

6

End of Question 34

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Question 35 — The Age of Silicon (25marks)


(a) Thediagramshowsalogiccircuitwithtwoinputs.

AC

B

(i) Constructatruthtableforthislogiccircuit. 2

(ii) A studentmeasured the inputs andoutput fromanunknowngate andobtainedthefollowingreadings.

3

0.2V4.5V

4.0V

Isitvalidtosubstitutethisgateforthelogiccircuit?Justifyyouranswer.

(b) The diagram shows a circuit incorporating a positive temperature coefficientthermistor.

Relay

1–20 kW

10 kWthermistor

9 V

(i) Calculate the range of possible voltages across the diode when thethermistorhasaresistanceof10kW.

2

(ii) Explainanapplicationforthiscircuit. 3

(c) Explainhowamplifiersandfeedbackloopsareusedincontrolsystems.Supportyouranswerwithadiagram.

4


–39–



(d) (i) Explain ONE advantage of integrated circuits compared to circuitsconstructedfromindividualcomponents.

2

(ii) Between 1970 and 2015 the number of transistors that an integratedcircuitcouldcontaindoubledeverytwoyears.

Explainwhythistrendisunlikelytocontinueintothefuture.

3

(e) Assess the impact on society of applications of transducers other thanthermistors.Useoneinputandoneoutputtransducertosupportyouranswer.

6

End of paper

BLANK PAGE

© 2015 Board of Studies, Teaching and Educational Standards NSW

–40–

–41–1103


Physics

DATA SHEET

k 0

2

–42–

FORMULAE SHEET

lv l0 1v2

c2

tvt0

1v2

c2

mv

m0

1v2

c2

–43–

FORMULAE SHEET

Ir

I0

Z2 Z1

2

Z2 Z1

2

M m 5 logd

10

IAIB

100mB mA 5

1R

1

nf2

1

ni2

–44–

Documents

2015 HSC Physics