Cambridge A Level Physics 9702 — 2010 Oct/Nov Paper 3 · Variant 1

READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the 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 fl uid. 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. PHYSICS 9702/31 Advanced Practical Skills 1 October/November 2010 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confi dential Instructions. UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certifi cate of Education Advanced Subsidiary Level and Advanced Level This document consists of 10 printed pages and 2 blank pages. [Turn over IB10 11_9702_31/3RP © UCLES 2010 *0482195546* For Examiner’s Use Total 1 2

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3 9702/31/O/N/10 © UCLES 2010 [Turn over For Examiner’s Use You may not need to use all of the materials provided. 1 In this experiment, you will determine the resistance of an unknown resistor. You have been supplied with a chain of eight resistors, as shown in Fig. 1.1. terminal terminal Fig. 1.1 Connection to one or more of the resistors can be made by attaching a crocodile clip between individual resistors. The resistance of each individual resistor is 1000 Ω. The formula for the total resistance R of resistors in series is R = R1 + R2 + R3 + … (a) (i) Set up the circuit in Fig. 1.2, with resistor X in the position shown. Fig. 1.2 meter crocodile clip Z crocodile clip Y X metre rule resistance wire a b d.c. power supply Only the fi rst resistor in the chain is included in the circuit. This has resistance R of 1000 Ω. (ii) Place Z on the resistance wire and move Z until the meter reading is zero. Measure and record lengths a and b. a = … b = …

4 9702/31/O/N/10 © UCLES 2010 For Examiner’s Use (b) Vary R by adjusting the position of Y on the chain of resistors. Repeat (a)(ii) until you have six sets of readings of R, a and b. Include values of in your table of results. (c) (i) Plot a graph of on the y-axis against R on the x-axis. (ii) Draw the straight line of best fi t. (iii) Determine the gradient of this line. gradient = … b a b a

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6 9702/31/O/N/10 © UCLES 2010 For Examiner’s Use (d) The quantities a, b and R are related by the equation = where X is the resistance of resistor X. Use your answer in (c)(iii) to determine the value of X. Give an appropriate unit. X = … (e) Using your graph, determine the value of R that would be needed for the lengths a and b to be equal to each other. R = … a b X R

7 9702/31/O/N/10 © UCLES 2010 [Turn over For Examiner’s Use You may not need to use all of the materials provided. 2 In this experiment, you will investigate how the motion of two masses connected by a string passing over a pulley depends on the difference between the two masses. (a) Set up the apparatus with the pulley supported by the clamp. One possible way of doing this is shown in Fig. 2.1. floor tray Fig. 2.1 string mass A mass B pulley Using the masses and hangers provided, make both the mass mA of A and the mass mB of B equal to 100 g. It must be possible to transfer masses from B to A. (b) Adjust the position of the apparatus so that the masses and pulley overhang the bench.

8 9702/31/O/N/10 © UCLES 2010 For Examiner’s Use (c) (i) Adjust the height of the apparatus so that the distance h between the bottom of mass A and the fl oor is approximately 1 metre, as shown in Fig. 2.2. mass A mass B h Fig. 2.2 floor (ii) Measure and record h. h = … (d) (i) Transfer 10 g from mass B to mass A. (ii) Record the mass mA of mass A and the mass mB of mass B. Calculate the difference in mass (mA – mB). mA = … mB = … (mA – mB) = … (iii) Release mass A from height h as recorded in (c)(ii) and determine the time t it takes to reach the fl oor. t = …

9 9702/31/O/N/10 © UCLES 2010 [Turn over For Examiner’s Use (e) Estimate the percentage uncertainty in your value of t. percentage uncertainty = … (f) Transfer another 10 g from mass B to mass A and repeat (d)(ii) and (d)(iii). mA = … mB = … (mA – mB) = … t = … (g) It is suggested that the relationship between (mA – mB) and t is (mA – mB) = where k is a constant. (i) Using your data, calculate two values of k. fi rst value of k = … second value of k = … k t 2

10 9702/31/O/N/10 © UCLES 2010 For Examiner’s Use (ii) Justify the number of signifi cant fi gures that you have given for your values of k. … … … (iii) Explain whether your results support the suggested relationship. … … … … …

11 9702/31/O/N/10 © UCLES 2010 For Examiner’s Use (h) (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. … …

12 9702/31/O/N/10 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. BLANK PAGE © UCLES 2010

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the October/November 2010 question paper for the guidance of teachers 9702 PHYSICS 9702/31 Paper 31 (Advanced Practical Skills 1), 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 October/November 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 – October/November 2010 9702 31 © UCLES 2010 1 (a) (i) No help from Supervisor. [1] (ii) Values of a and b with consistent units to the nearest mm. [1] (b) Six sets of readings of a, b and R scores 5 marks, five sets scores 4 marks etc. [5] Incorrect trend then –1. Correct trend b/a increases, R increases. Major help from supervisor –1. Range: used R = 8000 Ω or 7000 Ω. [1] Column headings (R/Ω, a/m, b/m, b/a). [1] Must have R and either b/a or a and b columns. Each column heading must contain a quantity and a unit where appropriate. Ignore any 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, R (Ω). Consistency of presentation of readings. [1] All values of raw a and b must be given to the nearest mm. Significant figures. [1] Significant figures for b/a must be the same as, or one more than, the least number of s.f. used in a or b. Correct calculation of b/a. [1] (c) (i) Axes: [1] Sensible scales must be used. No awkward scales (e.g. 3:10). Scales must be chosen so that the plotted points occupy at least half the graph grid in both x and y directions. Scales must be labelled with the quantity which is being plotted. Ignore units. Scale markings should be no more than three large squares apart. All observations must be plotted. Ignore any plot off the grid. [1] Write a ringed total of plotted points. Ring and check a suspect point. Work to an accuracy of half a small square. Do not accept blobs (points with diameter > 0.5 small square). (ii) Line of best fit. [1] Judge by balance of at least 5 trend points about candidate’s line. There must be an even distribution of points either side of the line along the full length. Line must not be kinked. Do not allow lines thicker than half a small square. Quality. [1] Scatter of points must be less than ± 200 Ω in the R – axis about a straight line. All points in the table must be plotted (at least 5) for this mark to be awarded. (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.

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – October/November 2010 9702 31 © UCLES 2010 (d) Gradient = X 1 [1] Value of X in range 3000–3600 Ω with unit. (e) a b = 1 [1] Correct reading off graph. [1] [Total: 20] 2 (c) (ii) Measurement of h to nearest mm with consistent unit. 0.900 m < h < 1.100 m [1] (d) (ii) Value of mA – mB = 20 g with consistent unit. [1] (iii) Value of t with unit. t < 5 seconds [1] Evidence of repeated measurements of t. [1] (e) Absolute uncertainty in t in range 0.1–0.6 s. [1] If repeated readings have been taken, then the uncertainty can be half the range. Correct method of calculation to get percentage uncertainty. [1] (f) Second value of mA – mB = 40 g [1] Second value of t. [1] Quality: second value of t < first value of t. [1] (g) (i) Values of k calculated correctly. [1] (ii) Justification of sf in k linked t and (mA – mB) or mA and mB or masses. [1] (iii) Valid conclusion based on the calculated values of k. [1] Candidate must test against a stated criterion.

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – October/November 2010 9702 31 © UCLES 2010 (h) Identifying limitations marks and suggesting improvements (i) Limitations [4] (ii) Improvements [4] Do not credit Ap Two readings are not enough (to draw a conclusion) As Take more readings and plot a graph/calculate more values of k. One reading/few readings/take more readings and average. Bp Masses hit each other/ masses slipping off. Bs Use larger pulley/method of securing masses to hanger. Cp Uncertain starting position Cs Method of fixing rule e.g. clamp rule/electromagnetic release mechanism Dp Difficult to measure time as time short/reaction time large compared with time. Ds Drop through greater height/ expand on trap door mechanism/ light gate with timer/motion sensor with data logger/video timer with timer. Ep Friction at pulley Es Lubricate pulley Friction between pulley and string Fp Retort stand moves Fs Method of fixing to the bench e.g. clamp/add weights Gp Mass (values) not accurate Gs Use balance/method of measuring mass Do not credit parallax error. [Total: 20]