MS P3

Sec4PurePhysicsPrelimMarkingScheme(Paper3)SectionAQn Answer Marks Remarks1(a) lA =2.2cmor22mmlB =2.2cmor22mm 1 1(c) Usethehalf-metreruletocheckandensurethattheheightsfrombothendsofthemetreruleabovethebenchareequal. 1 1(d) LA =7.2cmor72mmLB =10.2cmor102mm 111(e) CorrectcalculationofeA andeB .eA =5.0cmor50mmeB =8.0cmor80mm 1 1(f) Correctcalculationof . =5.0/8.0=0.625=0.63(2s.f.) 1 1(g) Thespringconstantandthemasssuspendedonthemetrerulemustremainconstant. Steps(a)to(f). Repeatsteps(b)to(f)toobtainfivemoresetsofvaluesbyplacingthemassatdifferentpositions. Recordx,LA , LB , eA , eB , and1/xinatable.x/cm LA /cm LB /cm eA /cm eB /cm 1/x/cm -1 Plotagraphof against1/x. Graphisastraightlinestartingfrom–1. Gradient=DIntercept=–1 1 1 1 1 2(c) 4 Vtotheclosest0.05V.[1]

V/V I/A R/Ω onelamp 1.30 0.32 4.1 twolampsinseries 1.60 0.24 6.7 twolampsinparallel 0.90 0.52 1.7 Itothecloset0.01A.[1] CorrectrecordingofVandI.[1] CorrectcalculationofRwithcorrectnumberofs.f..[1] 2(d) Correctcalculationbasedon2(c).(i) resistance=R/2=3.4Ω(ii) resistance=Rx2=3.4Ω 11 2(e)(i)Whentwolampsareconnectedinseries,thecombineresistanceishigher,resultinginlowercurrentinthecircuit,andhencetheresistanceofthelampsislower. 1 2(e)(ii)Whentwolampsareconnectedinparallel,thecombinedresistanceislower,resultinginlowerp.d.acrossthelamps.Thecurrentthroughthelampsisthereforelower,andtheresistanceofthelampsisalsolower. 1 1 2(f) Whenlampsareconnectedinseries,thepotentialdifferenceacrosseachoneofthemislowerascomparedtowhenthelampsareconnectedinparallel. 1 SectionBQn Answer Marks Remarks3(b) x=10mm 1 Tothenearestwholenumber3(e) i=23°r=113° 11 Tothenearestwholenumber3(f) Correctcalculationofyy=0.261 1 3s.f. 3(g) x/mm i/° r/° y/cm 1/x/mm -1 10 23 105 0.261 0.10015 35 113 0.399 0.06720 42 116 0.456 0.050 4 Correctheadings[1] Correctmeasurements[1]

25 50 121 0.545 0.04030 55 123 0.587 0.03335 61 126 0.649 0.029 Correctd.p.ands.f.[1] Correctcalculationofyand1/x[1] 3(h) 4 Axesarecorrectlylabelledwithunits[1] Appropriatescale[1] Correctlyplottedpoints[1] Best-fitstraightline[1]3(i) G=(0.21–0.64)/(0.11–0.02)=–4.8 C=0.74 3 1 Selecttwopoints(coordinateswrittenbesidethepoints)onthelineanddrawaright-angledtriangleusingdottedlines[1] Applythecorrectformula[1] Correctcalculationands.f.[1]3(j) yand1/xarelinearlyrelated.As1/xincreases,ydecreases. 113(k) Theholesmadebythepinsmaybetoobig.Thismayaffectthedrawingoftherequiredlines,andcauseinaccuracyinthemeasurementoftheangles. or Theglassblockhasbevellededges.Thismayaffectthedrawingofthelinesalongitsedges,andcauseinaccuracyinthemeasurementoftheangles. 11 11