Cambridge A Level Physics 9702 — 2010 May/June Paper 3 · Variant 1

This document consists of 9 printed pages and 3 blank pages. DC (LEO/CGW) 15331/5 © UCLES 2010 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer both questions. You will be allowed to work with the apparatus for a maximum of one hour for each question. You are expected to record all your observations as soon as these observations are made, and to plan the presentation of the records so that it is not necessary to make a fair copy of them. You may lose marks if you do not show your working or if you do not use appropriate units. Additional answer paper and graph paper should be used only if it becomes necessary to do so. You are reminded of the need for good English and clear presentation in your answers. At the end of the examination, fasten all your work securely together. All questions in this paper carry equal marks. * 2 2 3 1 8 7 9 9 0 7 * PHYSICS 9702/31 Paper 31 Advanced Practical Skills 1 May/June 2010 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. For Examiner’s Use 1 2 Total

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3 9702/31/M/J/10 [Turn over © UCLES 2010 For Examiner’s Use You may not need to use all of the materials provided. 1 In this experiment, you will measure the potential difference (p.d.) across a set of resistors in series and the current through the resistors. (a) Measure and record the e.m.f. of the power supply. e.m.f. = … V (b) (i) Connect the circuit of Fig. 1.1, ensuring that the movable lead is connected between resistors 1 and 2. V movable lead P 1 2 3 etc A Fig. 1.1 (ii) Close the switch and record the voltmeter reading V and the ammeter reading Ι. After recording your results, open the switch. V = … V Ι = … A (iii) Using your answer to (b)(ii), calculate the total resistance R of resistor P in series with resistor 1. (R = V Ι ) R = …Ω

4 9702/31/M/J/10 © UCLES 2010 For Examiner’s Use (c) By adjusting the movable lead, the resistor P may be connected in series with a number N of other resistors, giving different values of the total resistance R. In (b), N = 1. Repeat (b)(ii), for different values of N, until you have six sets of readings for N, V and Ι. Include values of 1 R in your table of results. (d) (i) Plot a graph of Ι on the y-axis against 1 R on the x-axis. (ii) Draw the line of best fit. (iii) Determine the gradient and y-intercept of the line of best fit. gradient = … y-intercept = …

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6 9702/31/M/J/10 © UCLES 2010 For Examiner’s Use (e) The quantities Ι and R are related by the equation Ι = M R + L where M and L are constants. Using your answers from (d)(iii), determine values for M and L. You should include units where appropriate. M = … L = …

7 9702/31/M/J/10 [Turn over © UCLES 2010 For Examiner’s Use You may not need to use all of the materials provided. 2 In this experiment, you will investigate how the time of swing of a tube depends on its length. (a) You are provided with two tubes and a string that has a loop at each end. (i) Pass the string through the shorter tube, as shown in Fig. 2.1a. Pass one loop through the other loop, as shown in Fig. 2.1b, to secure the tube in place, as shown in Fig. 2.1c. Fig. 2.1a Fig. 2.1b Fig. 2.1c (ii) Hang the string from the clamp, as shown in Fig. 2.2. Fig. 2.2

8 9702/31/M/J/10 © UCLES 2010 For Examiner’s Use (b) Displace the tube, as shown in Fig. 2.3. Release the tube. l Fig. 2.3 The time the tube takes to return to the release position for the first time is the time period T. This may be determined accurately by measuring the time taken for the tube to complete several swings, backwards and forwards. Showing all your working, determine an accurate value for the time period T. T = … s (c) (i) Using the vernier calipers, measure the length l of the shorter tube, as shown in Fig. 2.3. l = … (ii) Explain how you have made this measurement as accurate as possible. … … … (iii) Estimate the percentage uncertainty in this measurement of l. Show all your working. percentage uncertainty = …

9 9702/31/M/J/10 [Turn over © UCLES 2010 For Examiner’s Use (d) (i) Pass the string through the longer tube so that it rests above the shorter tube, as shown in Fig. 2.4. total length l Fig. 2.4 (ii) Repeat (b) to determine the new value of T. new value of T = … (iii) Measure the length of the longer tube. length of the longer tube = … (iv) Use your answers to (c)(i) and (d)(iii) to determine the new value of l (the total length of the two tubes), as shown in Fig. 2.4. new value of l = …cm (e) It is suggested that T and l are related by the equation T 2 = k l where k is a constant. By calculating values of k, explain whether your results support this relationship. … … … …

10 9702/31/M/J/10 © UCLES 2010 For Examiner’s Use (f) (i) Describe four sources of uncertainty or limitations of the procedure in this experiment. 1. … … 2. … … 3. … … 4. … … (ii) Describe four improvements that could be made to this experiment. You may suggest the use of other apparatus or different procedures. 1. … … 2. … … 3. … … 4. … … For Examiner’s Use

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12 9702/31/M/J/10 © UCLES 2010 BLANK PAGE Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the May/June 2010 question paper for the guidance of teachers 9702 PHYSICS 9702/31 Paper 31 (Advanced Practical Skills), maximum raw mark 40 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 before marking began, which would have considered the acceptability of alternative answers. Mark schemes must be read in conjunction with the question papers and the report on the examination. • CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the May/June 2010 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

Page 2 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9702 31 © UCLES 2010 1 (a) Ring e.m.f. value (c) Six sets of values for V and I scores 5 marks, five sets scores 4 marks, etc. [5] Indicate the number of sets of readings. Incorrect trend –1 (wrong trend N increases, I increases). Apparatus correctly set up without help from supervisor. [2] Major help –2, minor help –1 Range of N in table to include 1 or 2 and 11 or 12. [1] Column headings (N (no unit), V/V, I/A, R/Ω, (1/R)/Ω–1) [1] Each column heading must contain a quantity and a unit where appropriate. Ignore units in the body of the table. There must be some distinguishing mark between the quantity and the unit (solidus is expected but accept for example, V(V)). Consistency of presentation of raw readings of I and V. [1] All values of I must be given to the same number of decimal places. All values of V must be given to the same number of decimal places. Significant figures. [1] S.f. for 1/R must be the same as, or one more than, the least number of s.f. used in I or V. Check each row. Values of 1/R correct. Underline and check the specified value of 1/R. [1] If incorrect, write in the correct value. (d) Graph (i) Axes [1] Sensible scales must be used. Awkward scales (e.g. 3:10) are not allowed. Scales must be chosen so that the plotted points occupy at least half the graph grid in both x and y directions. Indicate false origin with FO. Scales must be labelled with the quantity that is being plotted. Ignore units. Allow inverted axes but do not allow the wrong graph. Scale markings should be no more than three large squares apart. All observations must be plotted. [1] Write a ringed total of plotted points. Do not accept blobs (points > 0.5 small square). Ring and check a suspect plot. Tick if correct. Re-plot if incorrect. Work to an accuracy of half a small square. (ii) Line of best fit [1] Judge by balance of at least 5 trend points about the candidate’s line. There must be an even distribution of points either side of the line along the whole length. Indicate best line if candidate’s line is not the best line. Lines must not be kinked. Quality Judge by scatter of all points about a straight line. [1] All plots from table (minimum 5) must be within 1 mA of a straight line. Do not award if wrong graph or wrong trend.

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9702 31 © UCLES 2010 (iii) Gradient [1] The hypotenuse of the triangle must be at least half the length of the drawn line. Both read-offs must be accurate to half a small square. If incorrect, write in correct value. Check for ∆y/∆x (i.e. do not allow ∆x/∆y). y-intercept from graph or substitute correct read-offs into y = mx + c [1] (Expect close to 0). Label FO. (e) M = gradient value. L = y–intercept value. No substitution method. [1] If inverted axes not corrected for –1 Value of M = value from part (a) ± 0.5V. [1] Value of L = 0 ± 1 mA. Appropriate units [Total: 20] 2 (b) Total time over which swings are measured > 10 s. [1] Correct calculation of T = Tn /n. [1] (c) (i) Value of l = 5 cm ± 1 cm [1] Evidence of repeats in length value (here or in d(iii)). [1] (ii) Measure in two different places/check zero error. [1] (iii) Percentage uncertainty in length. Consistent units. ∆l = 0.1 mm [1] If repeated readings have been taken, then the uncertainty can be half the range. Correct ratio idea required (0.1/length × 100%). (d) (ii) Measurement of time for longer tube. [1] t longer tube < t shorter tube [1] (iii) Measurement of length for longer tube to the nearest 1 mm. [1] Consistent unit (iv) Add two lengths together correctly. Allow rounding. [1] (e) Correct calculation of two values of k = T2/l. [1] Valid conclusion based on the calculated values of k. [1] Candidate must test against a specified criterion.

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9702 31 © UCLES 2010 Limitations (4) Improvements (4) Ignore A Ap Two readings not enough (to support conclusion)/too few readings. As Take many readings and plot a graph/compare values of k. Do not allow average k. Repeat readings B Bp (l inaccurate because) gap between long and short tube/ ends of tubes uneven. Tubes not straight/kinked/disjointed. Bs Get one long tube without a break/stick two tubes together/use longer tube on its own. Method of smoothing ends. Parallax error C Cp Tube(s) not vertical when stationary/ not aligned with string. Cs Smaller diameter tube/thicker walled tube/suitable method of alignment. Thicker string D Dp Not swinging in one plane only/idea of non-uniform oscillation. Ds Method of reducing draught e.g. close windows, turn off fans, screen experiment. E Ep Time difficult to measure because difficult to know when oscillation returns to original position/maximum height. Es A marker to time as passes centre/reaches maximum displacement. Light gate at centre with timer/motion sensor at end with data logger/video with timer (playback) in slow motion. Difficult to release from same point each time/ human error/reaction time/unqualified use of light gates/sensors Xp/Xs Other valid suggestions (e.g. knot slipping) with valid method. [Total: 20]