RESTRICTED Singapore-Cambridge General Certificate of Education Advanced Level Higher 2

9646 Physics November 2010 Examiner Report

© UCLES 2010

PHYSICS

Paper 9646/01

Multiple Choice

Question Number

Key Question Number

Key

1 A 21 C

2 C 22 A

3 C 23 A

4 D 24 B

5 A 25 A

6 B 26 B

7 B 27 C

8 A 28 C

9 B 29 D

10 B 30 A

11 D 31 C

12 D 32 C

13 D 33 B

14 B 34 A

15 B 35 D

16 D 36 D

17 B 37 A

18 C 38 B

19 C 39 C

20 D 40 C

This was a well designed paper with all questions showing a positive discrimination. The questions which candidates found more accessible were Questions 9, 16, 18, 27, 33 and 39. There were a few questions that were accessible to only the very best candidates. One of these questions was Question 1. A is the correct answer. High precision implies low random error: good accuracy implies low systematic error.

The next of these questions was Question 10. The key is B. The reason for this is that the gas is doing work on its surroundings. If this pressure is not constant then p varies so a constant external pressure is essential for the equation to be used. The hint in the question is the word ‘must’. If the pressure of the gas is somehow kept constant as it expands but the pressure of the surroundings is changing then the work done by the gas on the surroundings will require a more detailed analysis than just p∆V.

Question 11 was also found to be challenging for many candidates. The correct analysis uses v2 = 2 as for an object starting from rest with constant acceleration. Since a is constant and therefore the force causing the acceleration is constant, the equation power = force x velocity gives power = constant x √s.

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RESTRICTED Singapore-Cambridge General Certificate of Education Advanced Level Higher 2

9646 Physics November 2010 Examiner Report

© UCLES 2010

Question 20 was another question that caused difficulty. This question involved a two dimensional distribution of energy rather than the more usual three dimensional distribution. The energy is spread over a distance 8 times greater so the amplitude is reduced by a factor of √8, i.e. 0.71 mm.

The last of these more challenging questions was Question 32. At any time the magnetic flux is the same for all the coils. The flux density is greatest where the area is least, so the greatest variation of flux density is for coil C. This question had excellent discrimination. From the Examiner’s viewpoint the paper produced a reasonable spread of marks for the candidates sitting the paper.

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