Cambridge A Level Physics 9702 — 2009 Oct/Nov Paper 3 · Variant 4

This document consists of 8 printed pages and 4 blank pages. DCA (SHW 00445 4/09) 13786/4 © UCLES 2009 [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 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 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. The working of the answers is to be handed in. Additional answer paper and graph paper should be submitted 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 6 7 1 2 0 6 0 3 6 * PHYSICS 9702/34 Paper 32 Advanced Practical Skills 2 October/November 2009 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. For Examiner’s Use 1 2 Total

9702/34/O/N/09 © UCLES 2009 [Turn over For Examiner’s Use You may not need to use all of the materials provided. 1 In this experiment, you will investigate changes in potential difference in a circuit as one of the resistances is varied. (a) Assemble the circuit of Fig. 1.1. V X Y component holder movable lead 1000 Ω P Fig. 1.1 (b) Connect the movable lead to terminal Y and record the voltmeter reading V0. V0 = … (c) (i) Connect the movable lead to terminal X and leave it connected there for the rest of the experiment. (ii) Select one of the other labelled resistors provided and connect it between the crocodile clips on the component holder. Record the resistance R of your selected resistor and the voltmeter reading V. R = … Ω V = … 3

4 9702/34/O/N/09 © UCLES 2009 For Examiner’s Use (d) Repeat (c)(ii) using a different labelled resistor until you have six sets of readings of R (measured in ohms) and V. Disconnect the cell when you have finished your measurements. In your table of results include columns for the values of 1 V and the values of R (1000 + R) . (e) (i) Plot a graph of 1 V on the y-axis against R (1000 + 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 = …

5 9702/34/O/N/09 © UCLES 2009 [Turn over For Examiner’s Use

6 9702/34/O/N/09 © UCLES 2009 For Examiner’s Use (f) The quantities V and R are related by the equation 1 V = 1000 k P ( R 1000 + R ) + k where k is a constant and P is the resistance of resistor P. Using your answers from (e)(iii), determine the value of P. Give an appropriate unit. P = …

7 9702/34/O/N/09 [Turn over BLANK PAGE Please turn over for Question 2.

8 9702/34/O/N/09 © UCLES 2009 For Examiner’s Use You may not need to use all of the materials provided. 2 In this experiment, you will investigate how the length of a thread of cotton affects the amount of energy it can absorb before breaking. (a) Use the boss to clamp the nail to the retort stand at a height of about 50 cm above the bench. Place the apparatus in the tray. (b) (i) Cut a 45 cm length of thread. (ii) Tie the ends of the thread together to make a large loop. Suspend the loop from the nail and slot the 50 g mass into it, securing the mass with sticky tape, as shown in Fig. 2.1. l nail 50 g mass tape Fig. 2.1 (c) (i) Measure the length l as shown in Fig. 2.1. l = … (ii) Lift the 50 g mass vertically a distance h of 5 cm, as shown in Fig. 2.2. Release the mass. h Fig. 2.2 (iii) Keep repeating (c)(ii), each time increasing the value of h, until the thread breaks. Record the value of h at which the thread breaks. hfinal = … cm

9 9702/34/O/N/09 © UCLES 2009 [Turn over For Examiner’s Use (d) Estimate the percentage uncertainty in your value of hfinal. percentage uncertainty = … (e) Calculate the gravitational potential energy EP given to the 50 g mass when it was lifted the distance hfinal. (EP = mghfinal where g = 9.81 m s–2). EP … J (f) Cut an 85 cm length of thread. Repeat (b)(ii), (c) and (e). l = … hfinal = … cm EP = … J (g) It is suggested that EP and l are related by the equation EP = k l where k is a constant. By calculating values of k, explain whether your results support this relationship. … … … … …

10 9702/34/O/N/09 © UCLES 2009 For Examiner’s Use (h) (i) State and explain four sources of error or limitations of the procedure in this experiment. 1. … … 2. … … 3. … … 4. … … (ii) Suggest and explain 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 9702/34/O/N/09 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 October/November 2009 question paper for the guidance of teachers 9702 PHYSICS 9702/34 Paper 34 (Advanced Practical Skills 2), 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 2009 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 A/AS LEVEL – October/November 2009 9702 34 © UCLES 2009 1 (b) Value for V0 in range 1.3 to 1.7V, with unit [1] (c) (ii) First value of V less than V0 [1] (d) No help from Supervisor (-1 for minor help, -2 for major help) [2] (d) Measurements table [3] Six sets of readings of R and V scores 3 marks, five sets scores 2 marks etc. Wrong trend in table then –1. (d) Table - range [1] Values of R must include one of 100/220Ω and one of 3300/4700Ω. (d) Table - column headings [1] Each column heading must contain a quantity and a unit where appropriate. There must be some distinguishing mark between the quantity and the unit. Ignore units in the body of the table. R/(1000+R) has no unit. (d) Table - consistency of presentation of raw readings. [1] All values of raw V must be given to the same number of decimal places. (d) Table – calculated values [1] Check the specified value of R/(1000+R) is calculated correctly. If incorrect, write in the correct value. Ignore rounding errors. (d) Table - significant figures [1] S.f. for 1/V must be the same as, or one more than, s.f. for raw V. Check each row in the table. (e) (i) (Graph) 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 plotted. Ignore units. Allow inverted axes, –1 wrong quantities plotted. No more than 3 large squares between scale markings. (Graph) Plotting – [1] All observations must be plotted. Ring and check a suspect plot, tick if correct. Re-plot if incorrect. Plots should be no more than ½ a small square from correct position in x or y direction. Diameter must be less than or equal to ½ small square. (e) (ii) (Graph) Line of best fit – [1] At least 5 trend plots are needed. Judge by scatter of points about the candidate's line. There must be a fair scatter of points either side of the line. Indicate best line if candidate’s line is not the best line. If trend curved allow a smooth drawn curve not straight line. (Graph) Quality of results – [1] All table points must be plotted (minimum of 5 needed). Judge by scatter of all plots which must be within ± 0.02 V –1 of assessors line.

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2009 9702 34 © UCLES 2009 (e) (iii) Gradient – [1] The hypotenuse of the ∆ must be at least half the length of the drawn line. Both read-offs must be accurate to half a small square. Check for ∆y /∆x. Check sign is consistent with trend. (e) (iii) Intercept – [1] Correctly read-off from graph (indicate a false origin) or the method of calculation is correct (check substitution of point on line). (f) Method of calculation of P is correct with gradient and intercept values used. [1] (f) Value for P in range 630 to 730Ω, with unit. [1] Substitution loses both marks. [Total: 20] 2 (c) (i) Value of l < 25cm, with unit. [1] (c) (i) l to nearest mm. [1] (c) (iii) Evidence of repeated measurements of hfinal [1] (c) (iii) Value of hfinal in range 5.0 to 50.0 cm. [1] (d) Percentage uncertainty in hfinal. [1] If repeated readings have been done then the uncertainty could be half the range, otherwise absolute uncertainty must be in range 2 mm to 20 mm. Correct ratio idea required. (e) Ep to no more than 3 s.f. [1] (e) Value for Ep consistent with unit. [1] (f) Second value of l greater than first value. [1] (f) Second value of hfinal [1] (f) Second value of hfinal shows correct trend (i.e. l ↑ h ↑ or l ↓ h ↓). [1] (g) Check calculation of the two values of Ep/√l or equivalent. [1] (g) Valid conclusion based on the calculated values. Consistent with 20% or with candidate’s stated criterion. [1]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2009 9702 34 © UCLES 2009 (h) Limitation (4 max) Improvement (4 max) A Two sets of readings are not enough / only two sets Take more readings and plot a graph B Difficult to take measurements (h/l) because the ruler moves / is not vertical Clamp rule / ensure rule is vertical using a set square on the bench C Change in properties / deterioration of the thread due to repeated drops Use a new thread each time D Poor accuracy due to size of increment / only note measured hfinal values not the values between. Use smaller increments E Obtaining constant loop length for repeats at one value of loop length / variation in hfinal values for repeats at one loop length Sensible method to ensure constant loop length for repeats F Tangling cotton Do not allow ‘repeated readings’, centres of mass, or nail, knots, time ideas. Do not allow use of video, ‘use a computer to improve experiment’, sensors. Do not allow amount of tape/plasticine/glue, thinner/thicker thread, fans. Do not allow ‘eye level’. [Total: 20]