Cambridge A Level Physics 9702 — 2010 Oct/Nov Paper 3 · Variant 5

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 9702/35 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_35/4RP © UCLES 2010 *4471498678* For Examiner’s Use Total 1 2

2 9702/35/O/N/10 © UCLES 2010 BLANK PAGE

3 9702/35/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 resistivity of a metal in the form of a wire. (a) (i) Measure and record the diameter d of the short sample of wire that is attached to the card. You may remove the wire from the card. d = … (ii) Calculate the cross-sectional area A of the wire using the formula A = . A = … (b) (i) Set up the circuit shown in Fig. 1.1 and close the switch. Fig. 1.1 metre rule wire x Y A + – R (ii) Position the crocodile clip labelled ‘Y’ half-way along the wire. (iii) Measure and record the distance x of wire between the two crocodile clips, and the ammeter reading I. x = … I = … πd 2 4

4 9702/35/O/N/10 © UCLES 2010 For Examiner’s Use (c) Change x and repeat (b)(iii) until you have six sets of readings of x and I. Include values of in your table. (d) (i) Plot a graph of 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. gradient = … y-intercept = … 1 I 1 I

5 9702/35/O/N/10 © UCLES 2010 [Turn over For Examiner’s Use

6 9702/35/O/N/10 © UCLES 2010 For Examiner’s Use (e) The quantities I and x are related by the equation = Mx + N where M and N are constants and = where is the resistivity of the material of the wire and the resistance R of the fi xed resistor is given on a card. Use your answers in (a)(ii) and (d)(iii) to determine a value for . = … 1 I M N AR

7 9702/35/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 the equilibrium of a wooden strip. (a) (i) Attach masses to the apparatus as shown in Fig. 2.1. x nail string wooden strip loop of string mass A 60 g mass B 50 g bench Fig. 2.1 Mass A is suspended from the wooden strip using the loop of string. The distance between this loop and the nearest end of the wooden strip is x. (ii) Change x until the wooden strip is balanced and approximately parallel to the bench. Measure and record x. x = …

8 9702/35/O/N/10 © UCLES 2010 For Examiner’s Use (b) (i) Remove both masses. Thread the string for mass B over the pulley, and then attach the masses again, as shown in Fig. 2.2. x mass A m mass B M Fig. 2.2 θ pulley (ii) Transfer 10 g from mass A to mass B. (iii) With x at the same value as in (a)(ii), adjust the position of the pulley until the wooden strip is parallel to the bench. Measure and record the angle that the string for mass B makes with the vertical, as shown in Fig. 2.2. = … (iv) Estimate the percentage uncertainty in your value of . percentage uncertainty = …

9 9702/35/O/N/10 © UCLES 2010 [Turn over For Examiner’s Use (v) Record the mass m of mass A and the mass M of mass B. m = … M = … (vi) Calculate . = … (c) Transfer another 10 g from mass A to mass B. Repeat (b)(iii), (b)(v) and (b)(vi). = … m = … M = … = … (d) It is suggested that the relationship between m, M and is cos = k where k is a constant. (i) Using your data, calculate two values of k. fi rst value of k = = … second value of k = = … m M m M m M m M

10 9702/35/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 9702/35/O/N/10 © UCLES 2010 For Examiner’s Use (e) (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 9702/35/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 9702/35 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 35 © UCLES 2010 1 (a) (i) Value of d to the nearest 0.01 mm or 0.001 mm with consistent unit. [1] 0.20 < d < 0.60 mm. (b) (iii) Value of x in range 40 cm–60 cm with consistent unit. [1] Value of I with units. (c) Six sets of readings of x and I scores 5 marks, five sets scores 4 marks etc. Incorrect trend then –1. Minor help from supervisor –1 ; major help from supervisor –2 [5] Range [1] xmax > 70 cm; xmin < 30 cm Column headings [1] Each column heading must contain a quantity and a unit. There must be some distinguishing mark between the quantity and the unit (solidus is expected but accept, for example, 1/I (A–1). Do not allow 1/I (A)) Consistency of presentation of raw readings. [1] All values of x must be given to the nearest mm. Significant figures [1] S.F. in 1/I must be the same as, or one more than, the least number of significant figures used in raw I. Calculation [1] Correct calculation of 1/I.

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – October/November 2010 9702 35 © UCLES 2010 (d) (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. Scales must be labelled with the quantity which is being plotted. Ignore units. Scale markings should be no more than three large squares apart. Plotting of points [1] All observations must be plotted on the grid. Do not accept blobs (points with diameter > 0.5 small square). Ring and check a suspect plot. Work to an accuracy of half a small square. (ii) Line of best fit [1] Judge by the 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. Lines must not be kinked. Do not accept lines thicker than half a small square. Quality [1] All points in the table (minimum 5) must be plotted for this mark to be scored. All points must be within 2 cm (to scale) in x direction of a straight line. (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. 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 graph. (e) Values obtained in (a)(ii) and (d)(iii) substituted correctly into equation: AR N M ρ = [1] Do not allow substitution methods to find M or N Value for ρ in range: 1 × 10–7 Ω m – 5 × 10–6 Ω m with consistent unit. [1] [Total: 20]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – October/November 2010 9702 35 © UCLES 2010 2 (a) (ii) Measurement of x to nearest mm. x < 15.0 cm with consistent unit. [1] –1 for supervisor’s help. (b) (iii) Measurement of θ (less than 90°) with unit. [1] (iv) Absolute uncertainty in θ in the range 2°–10°. [1] If repeated readings have been taken, then the uncertainty can be half the range. Correct method of calculation of percentage uncertainty. (v) m = 50 g with consistent unit [1] M = 60 g with consistent unit [1] (vi) Correct calculation of m/M (0.83 or 0.833). No units. [1] (c) Measurement of θ [1] m = 40 g; M = 70 g [1] Quality: θ2 > θ1 [1] (d) (i) Correct calculation of two values of k. [1] (ii) Justification of sf in k linked to θ, m and M [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 35 © UCLES 2010 (e) Identifying limitations (4 marks) and suggesting improvements (4 marks) (i) Limitations [4] (ii) Improvements [4] Do not credit A Two readings are not enough (to draw a conclusion. Take more readings and plot a graph/calculate more k values (and compare). Few readings. Take more readings and calculate average. Only one reading. B Difficult to balance with reason e.g. unstable or effect of fans/draughts/a.c. Drill hole higher up/switch off fans/a.c./close windows. Closed room. C Difficult to judge when wooden strip horizontal/parallel (to the bench). Method of ensuring strip is horizontal/parallel to bench e.g. use a spirit level or metre rule(s) to measure height of both ends/sight against window. Allow detailed use of set square. Strip not straight/parallel/ horizontal. Use set square. D Difficult keeping x constant/ weights move. Method of fixing cotton loop to rule e.g. tape, glue. E Difficult to measure θ because hard to judge vertical/movement of hand. Use a plumb line/clamped ruler/clamp protractor. Bigger protractor. Paper behind protractor. F Friction at pulley/between nail and wooden strip. Use lubricant/method of reducing friction. Friction. Better pulley/ smooth(er) string/thin(ner) string. Friction between string and pulley. Lubrication between string and pulley. G Mass (values) not accurate. Use balance/method of weighing mass. Weigh masses. Do not credit ‘parallax problems’, ‘use assistant’ or references to sensors, computers or videos. [Total: 20]