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

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 9702/33 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_33/3RP © UCLES 2010 *9471512454* For Examiner’s Use Total 1 2

2 9702/33/O/N/10 © UCLES 2010 For Examiner’s Use You may not need to use all of the materials provided. 1 In this experiment, you will investigate how the motion of a pendulum bob is affected by the height of the bob above the bench. (a) (i) Set up the apparatus as shown in Fig. 1.1. thread bob Fig. 1.1 clamp x h bench The distance h from the point of suspension to the bench should be as large as possible. The distance x between the centre of the bob and the bench should be approximately 5 cm. (ii) Measure and record distance h. Throughout this experiment, do not change the distance h. h = … (iii) Measure and record distance x. x = …

3 9702/33/O/N/10 © UCLES 2010 [Turn over For Examiner’s Use (b) Displace the bob a small distance to the left. Release the bob and watch the movement. The time the bob takes for each complete swing, fi rst to the right and then back to the left, as shown in Fig. 1.2, is T. Fig. 1.2 By timing several of these complete swings, determine an accurate value of T. T = …

4 9702/33/O/N/10 © UCLES 2010 For Examiner’s Use (c) Keeping h constant, change x and repeat (a)(iii) and (b) until you have six sets of values for x and T. Include values for T 2 in your table of results. (d) (i) Plot a graph of T 2 on the y-axis against x on the x-axis. (ii) Draw the straight line of best fi t. (iii) Determine the gradient and y-intercept of this line of best fi t. gradient = … y-intercept = …

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6 9702/33/O/N/10 © UCLES 2010 For Examiner’s Use (e) The quantities T and x are related by the equation T 2 = A – Bx where A and B are constants. Use your answers to (d)(iii) to determine the value of . Give an appropriate unit. = … A B A B

7 9702/33/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 potential difference across a current-carrying wire depends on its diameter. (a) Measure and record the diameter d of wire A. d = … (b) Connect the circuit shown in Fig. 2.1. The wire A should be connected into the circuit using crocodile clips placed close to the ends of the wire. A V wire A crocodile clip crocodile clip Fig. 2.1 (c) (i) Measure and record the length L of wire between the crocodile clips. L = … (ii) Estimate the percentage uncertainty in your value of L. percentage uncertainty = …

8 9702/33/O/N/10 © UCLES 2010 For Examiner’s Use (d) (i) Close the switch. Adjust the variable resistor until the current is close to 90 mA. Record this current I. I = … (ii) Record the voltmeter reading V and then open the switch. V = … (e) Measure and record the diameter d of wire B. d = … (f) (i) In the circuit, replace wire A with wire B, maintaining the same length L of wire between the crocodile clips as in (c)(i). (ii) Close the switch. Adjust I to the same value as in (d)(i). Record V and then open the switch. V = … (g) It is suggested that the relationship between V, L and d is V = where k is a constant. (i) Using your data, calculate two values of k. value of k for wire A = … value of k for wire B = … kL d 2

9 9702/33/O/N/10 © UCLES 2010 [Turn over 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. … … … … … Question 2 continues on the next page.

10 9702/33/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. … …

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12 9702/33/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 9702/33 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 33 © UCLES 2010 1 (a) (ii) Value of raw h to the nearest mm (unit needed). h > 20 cm. [1] (b) Evidence of repeat times: of one swing repeated several times or the time for a number of swings recorded at least once (not fixed time and count n). [1] Value of 0.5 < T < 3 s. (c) Six sets of readings of x and T scores 5 marks, five sets scores 4 marks etc. [5] Incorrect or no trend then –1 (Correct trend x increases, T2 decreases). SH –1. Write a ringed total next to the table. Maximum value of x at least h/2. [1] Column headings (x / m, x / mm, T / s, T2/s2). [1] Must have x and T2 columns. Each column heading must contain a quantity and a unit. 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, x (m)). Consistency of presentation of raw readings. [1] All values of raw x must be given to the nearest mm and all values of raw time to the same number of d.p. (either 1 or 2). Significant figures. [1] Significant figures for T2 must be the same as, or one more than, the least number of significant figures used in the raw time data. Also if raw time is given to the nearest hundredth of a second accept one less significant figure in T2. Correct calculation of T2. Do not allow t2. [1]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – October/November 2010 9702 33 © UCLES 2010 (d) (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 on the grid. [1] Write a ringed total of plotted points. Ring and check a suspect plot. 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 points about the 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 ± 1 cm (to scale) in the x (cm) direction of a straight line. All points in table must be plotted (at least 5) for this mark to be awarded. (iii) Gradient. [1] Negative sign must be seen on answer line consistent with graph. 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. Intercept. [1] Either: Check correct read-off from a point on the line and substitution into y = mx + c. Read off must be accurate to half a small square. Allow ecf of gradient value. Or: Check read-off of intercept directly from the graph. (e) Value of gradient intercept − − = y B A (Expect value to be approximately equal to h). [1] Unit for A/B correct (e.g. m) consistent with value. [1] Allow candidate’s value 0.5 h < A/B < 1.5 h. [Total: 20]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – October/November 2010 9702 33 © UCLES 2010 2 Measurement of dA in range 0.20 mm < dA < 0.40 mm to nearest 0.01 mm or 0.001 mm with consistent unit. If OOR allow SV ± 0.10 mm. [1] Evidence of repeated measurements of d (or in (e)). [1] (c) (i) Measurement of L to nearest mm with consistent unit. [1] (ii) Absolute uncertainty in L is 2 mm–10 mm. [1] If repeated readings have been taken, then the uncertainty can be half the range. Correct method of calculation to get percentage uncertainty. [1] (d) (ii) Measurement of VA. Any supervisor’s help –1. [1] (e) Value of dB. Major help from supervisor –1. [1] (f) (ii) Measurement of VB to at least nearest 0.1 V with unit. V < 2 V. If > 2 V check SV. [1] Quality: VB < VA. [1] (g) (i) Values of k calculated correctly. [1] (ii) Justification of sf in k linked to L and d and V. [1] (iii) Valid conclusion based on the calculated values of k. [1] Candidate must test against a stated criterion.

Page 5 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – October/November 2010 9702 33 © UCLES 2010 (h) (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 Difficult to measure length because (give a reason) e.g. clips have a width/ clip slips. Difficult to make L the same (for both experiments). Bs Use sliding jockeys/narrower clips/ solder contacts/use longer wire (to reduce % error). Cp Voltmeter scale not sensitive enough/not precise enough/only reads to 0.1 or 0.05 V. Cs Use digital voltmeter/use a voltmeter that reads to 0.01 V. Voltmeter not accurate enough. More accurate voltmeter. Dp Wires kinked/Wires not straight/Difficult to keep wire straight/difficult to prevent short circuiting. Ds Method of keeping wire (during experiment) straight e.g. tape to ruler, hang weights off end, clamp wire. Parallax error. Ep Difficult to make I the same (for both experiments). Es Method to obtain continuous variation in the current e.g. (slide wire) potentiometer/potential divider/finer wire rheostat/longer rheostat. Fp Contact resistance/ fluctuating ammeter or voltmeter readings. Fs Method of cleaning contacts e.g. sand clips. Tighten clips. Ignore reference to parallax error, zero error on meters, heating effects of wire, cell runs down, video the experiment. [Total: 20]