Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level. Published

Size: px

Start display at page:

Download "Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level. Published"

Imogen Hill
5 years ago
Views:

1 Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level PHYSICS 9702/43 Paper 4 A Level Structured Questions MARK SCHEME Maximum Mark: 100 Published This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners meeting befe marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Rept f Teachers. Cambridge International will not enter into discussions about these mark schemes. Cambridge International is publishing the mark schemes f the series f most Cambridge IGCSE, Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level components. IGCSE is a registered trademark. This document consists of 14 printed pages. UCLES 2018 [Turn over

2 Generic Marking Principles These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alongside the specific content of the mark scheme generic level descripts f a question. Each question paper and mark scheme will also comply with these marking principles. GENERIC MARKING PRINCIPLE 1: Marks must be awarded in line with: the specific content of the mark scheme the generic level descripts f the question the specific skills defined in the mark scheme in the generic level descripts f the question the standard of response required by a candidate as exemplified by the standardisation scripts. GENERIC MARKING PRINCIPLE 2: Marks awarded are always whole marks (not half marks, other fractions). GENERIC MARKING PRINCIPLE 3: Marks must be awarded positively: marks are awarded f crect/valid answers, as defined in the mark scheme. However, credit is given f valid answers which go beyond the scope of the syllabus and mark scheme, referring to your Team Leader as appropriate marks are awarded when candidates clearly demonstrate what they know and can do marks are not deducted f errs marks are not deducted f omissions answers should only be judged on the quality of spelling, punctuation and grammar when these features are specifically assessed by the question as indicated by the mark scheme. The meaning, however, should be unambiguous. GENERIC MARKING PRINCIPLE 4: Rules must be applied consistently e.g. in situations where candidates have not followed instructions in the application of generic level descripts. UCLES 2018 Page 2 of 14

3 GENERIC MARKING PRINCIPLE 5: Marks should be awarded using the full range of marks defined in the mark scheme f the question (however; the use of the full mark range may be limited accding to the quality of the candidate responses seen). GENERIC MARKING PRINCIPLE 6: Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should not be awarded with grade thresholds grade descripts in mind. UCLES 2018 Page 3 of 14

4 1(a) fce proptional to product of masses and inversely proptional to square of separation 1(b)(i) idea of fce between point masses velocity changes/direction of motion changes/there is an acceleration/there is a resultant fce so not in equilibrium 1(b)(ii)1. gravitational fce equals/is centripetal fce C1 1(b)(ii)2. GMm / R 2 = mrω 2 and ω = 2π / T Gm / R 2 = mv 2 / R and v = 2πr / T GMm / R 2 = mr (2π/ T) 2 convincing algebra leading to k = GM / 4π 2 crect use of R 3 / T 2 f one planet (c gives ; e and g both give ) 3.5(5) = ( M) / 4π 2 M = kg two three values of R 3 / T 2 crectly calculated and used in a valid way to find a value f M based on me than one k M1 C1 UCLES 2018 Page 4 of 14

5 2(a)(i) straight line through igin indicates acceleration displacement 2(a)(ii) negative gradient shows acceleration and displacement are in opposite directions a = ω 2 y and ω = 2πf 4.5 = (2π f) ( other valid read-off) f = 3.8 Hz C1 2(b)(i) maximum displacement upwards/above rest/above the equilibrium position 2(b)(ii) (just leaves plate when) acceleration = 9.81 m s 2 C = (2π 3.8) 2 y = 563 y 0 amplitude = 17 mm C1 UCLES 2018 Page 5 of 14

6 3(a)(i) sum of potential and kinetic energies (of molecules/atoms/particles) (energy of) molecules/atoms/particles in random motion 3(a)(ii) (in ideal gas) no intermolecular fces so no potential energy internal energy is (solely) kinetic energy (of particles) (mean) kinetic energy (of particles) proptional to (thermodynamic) temperature of gas 3(b) pv = NkT C = N C1 pv = nrt and N = n N A = n (C1) (C1) n = 46.5 (mol) N = N = UCLES 2018 Page 6 of 14

7 4(a) e.g. microphone weighing scales/pressure sens lighters/spark generation watches/clocks/regulation of time 4(b) pulses (of ultrasound) reflected at boundaries (between media) (reflected pulses) detected by (ultrasound) generat Any three from: time delay (between transmission and receipt) gives infmation about depth (of boundary) intensity of reflected pulse gives infmation about (nature of) boundary gel used to minimise reflection at skin/maximise transmission into skin degree of reflection depends upon impedances of two media (at boundary) B3 UCLES 2018 Page 7 of 14

8 5(a)(i) west to east 5(a)(ii) above the Equat 5(a)(iii) value in range (1 300) 10 9 Hz 5(b)(i) gain / db = 10 lg (P 2 / P 1 ) C1 5(b)(ii) 195 = 10 lg (P / 3000) 195 = 10 lg (3000 / P) power = W up-link has been (greatly) attenuated (befe reaching satellite) down-link signal must be (greatly) amplified (befe transmission back to Earth) up-link has (much) smaller intensity/power than down-link (different frequency) prevents down-link (signal) swamping up-link (signal) C1 6(a) fce per unit charge 6(b) E = Q / (4πε 0 r 2 ) C = Q / (4π ) charge = C 6(c) charge (= Q [52 / 26] 2 ) = 4Q C1 additional charge = 3Q UCLES 2018 Page 8 of 14

9 7(a) (capacitance =) charge / potential M1 charge is (numerically equal to) charge on one plate potential is potential difference between plates 7(b)(i) C 7(b)(ii) C 7(b)(iii) capacitance = ( ) / 120 C1 = F 7(c) total capacitance is halved current is halved UCLES 2018 Page 9 of 14

10 8(a)(i) (fraction of) output is combined with the input M1 8(a)(ii) output (fraction) subtracted/deducted from input any two valid points e.g.: greater bandwidth/gain constant over a larger range of frequencies/greater bandwidth smaller gain B2 8(b)(i) gain = ( )9600 / 800 C1 = 12 8(b)(ii) V 2. 6 V 8(b)(iii) replace the 9600 Ω resist with an LDR UCLES 2018 Page 10 of 14

11 9(a) using Fleming s left-hand rule fce on wire is upwards by Newton s third law, fce on magnet is downwards 9(b)(i) F = BIL C1 = = N 9(b)(ii) F = N 9(c) sketch: sinusoidal wave with two cycles amplitude N period 0.05 s 10(a) induced e.m.f. proptional to rate M1 of change of (magnetic) flux (linkage) of cutting (magnetic) flux 10(b) current in coil produces flux (by Faraday s law) changing flux induces e.m.f. in ring current in ring causes field (around ring) (by Lenz s law) field around ring opposes field around coil UCLES 2018 Page 11 of 14

12 11(a)(i) packet/quantum/discrete amount of energy M1 11(a)(ii) of electromagnetic radiation (maximum) energy of emitted electrons is independent of intensity no emission of electrons below the threshold frequency regardless of intensity no emission of electrons when photon energy is less than wk function (energy) regardless of intensity 11(b) in darkness: conduction band empty so high resistance in daylight: electrons in valence band absb photons in daylight: electrons jump to conduction band this leaves holes in valence band me charge carriers in daylight so resistance decreases UCLES 2018 Page 12 of 14

13 12(a)(i) I = I 0 e µx C1 = I 0 exp ( ) = I 0 12(a)(ii) I = I 0 exp [( ) ( )] C1 = I 0 ( ) = I 0 12(b)(i) difference in degrees of blackening M1 between structures 12(b)(ii) large difference in intensities so good contrast UCLES 2018 Page 13 of 14

14 13(a) emission of particles/radiation by unstable nucleus spontaneous emission 13(b)(i) use of graph to determine half-life = 14 minutes hence λ = ln 2 / (14 60) (s 1 ) C1 N at 14 minutes = and A = λn C1 activity = ln 2 / (14 60) = Bq crect tangent drawn at time t = 14 minutes magnitude of gradient of tangent identified as activity crect wking f gradient leading to activity activity = Bq 13(b)(ii) = λ λ = ln 2 / ( ) λ = s 1 () (C1) (C1) () C1 UCLES 2018 Page 14 of 14

Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level. Published

Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level PHYSICS 9702/22 Paper 2 AS Level Structured Questions MARK SCHEME Maximum Mark: 60 Published