Cambridge A Level Physics 9702 — 2010 May/June Paper 3 · Variant 4

This document consists of 9 printed pages and 3 blank pages. DC (LEO/SW) 23039/3 © 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 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. 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 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. * 5 3 2 6 1 2 9 6 8 2 * PHYSICS 9702/34 Paper 32 Advanced Practical Skills 2 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

2 9702/34/M/J/10 © UCLES 2010 BLANK PAGE

3 9702/34/M/J/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 investigate the length of a loaded spring as the load is varied. (a) Measure and record the length L of the metal rod. L = …m (b) (i) Support the rod as shown in Fig. 1.1. clamp spring pivot 5 cm rod h d bench Fig. 1.1 (ii) Adjust the position of the pivot so that it is approximately 5 cm from the free end of the rod. (iii) Adjust the clamp so that the rod is horizontal and the spring is vertical. (c) Measure and record the length h of the coiled part of the spring and the distance d from the pivot to the point where the spring is attached to the rod. h = …m d = …m

4 9702/34/M/J/10 © UCLES 2010 For Examiner’s Use (d) Repeat (b)(iii) and (c) for different positions of the pivot along the rod until you have six sets of readings of d and h. Include values of 1/d in your table of results. (e) (i) Plot a graph of h on the y-axis against 1 d on the x-axis. (ii) Draw the line of best fit. (iii) Determine the gradient and y-intercept of this line. gradient = … y-intercept = …

5 9702/34/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use

6 9702/34/M/J/10 © UCLES 2010 For Examiner’s Use (f) It is suggested that the relationship between d and h is h = A d + B where A and B are constants. The value of A is equal to Wz k where W is the weight of the rod, k is the spring constant of the spring and z is a constant. The values for W and k are given on the card. Use your answer from (e)(iii) and the values on the card to calculate z. Give the appropriate unit. z = …

7 9702/34/M/J/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 effect of an electric current on a nearby magnet. (a) A circuit has been set up for you as shown in Fig. 2.1. Do not adjust the position of the stands. A low voltage supply horizontal copper wire + – I Fig. 2.1 Switch on the current. Use the variable resistor to adjust the current I to about 2 A. Record your value of current. I = …A (b) Switch off the current. Place the thread over the horizontal copper wire, so that the magnet hangs as shown in Fig. 2.2. A + – x crocodile clip insulator in clamp horizontal copper wire magnet thread Fig. 2.2 (c) By moving your hand, adjust the distance x between the copper wire and the dotted line along the side of the magnet to about 7 cm. Record your value of x. x = … cm

8 9702/34/M/J/10 © UCLES 2010 For Examiner’s Use (d) Place the protractor on the bench beneath the magnet. Switch on the current. The magnet will turn through an angle. Wait until the magnet comes to rest. Measure and record the angle θ turned through by the magnet. Switch off the current. θ = …° (e) Estimate the percentage uncertainty in your value of θ. percentage uncertainty in θ = … (f) (i) Reverse the direction of the current in the copper wire. Repeat (d) to find a second value of θ. θ = …° (ii) Use your answers to (d) and (f)(i) to determine an average value of the magnitude of θ. average value of θ = …° (g) Change x to about 4 cm. Adjust the value of I so that the deflection θ is the same as in (f)(ii). Record x and I. x = … cm I = … A

9 9702/34/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use (h) It is suggested that, for a given value of θ, the relationship between I and x is I = kx where k is a constant. (i) Using your data, calculate two values of k. first value of k = … second value of k = … (ii) Explain whether your results support the suggested relationship. … … … (iii) Justify the number of significant figures that you have given for your values of k. … … …

10 9702/34/M/J/10 © UCLES 2010 For Examiner’s Use (i) (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. … …

11 9702/34/M/J/10 © UCLES 2010 BLANK PAGE

12 9702/34/M/J/10 © UCLES 2010 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

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 9702/34 Paper 32 (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 34 © UCLES 2010 1 (a) Apparatus set up without help from Supervisor. [1] Value of L to nearest mm. [1] (d) Table – Six sets of readings of d and h scores 5 marks, five sets scores 4 marks, etc. Incorrect trend –1. [5] Range – Range of values of d [ 15 cm. [1] Column headings – Each column heading must contain a quantity and a unit. Ignore units in the body of the table. There must be some distinguishing mark between the quantity and the unit e.g. 1/d / m–1 or 1/d (m–1). [1] Consistency – All raw values of h must be given to the nearest mm. [1] Significant figures – S.f. for 1/d must be the same as, or one more than, the s.f. given for raw d. Check each row. [1] Calculated values – Check the specified value of 1/d. If wrong, write in the correct value. [1] (e) (i) Graph Axes – 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 a 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 not be more than three large squares apart. [1] Plotting of points – All observations must be plotted. Do not accept ‘blobs’ (points > half a small square). Ring and check a suspect point. Tick if correct. Re-plot if incorrect. Work to an accuracy of half a small square. [1] (ii) Line of best fit – Judge by the 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. Line must not be kinked or thicker than 1 mm. [1] Quality – Judge by scatter of all points about a best line. All plots from table (minimum 5) must be within 0.1 m–1 of a straight line (in 1/d direction). Do not credit if it is the wrong graph or if the trend is wrong. [1]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9702 34 © UCLES 2010 (iii) Gradient – The hypotenuse of the triangle must be at least half the length of the drawn line. Read-offs must be accurate to half a small square – if wrong write in the correct value(s). Check for ∆y/∆x (i.e. do not allow ∆x/∆y). [1] y-intercept – Value must be read from graph to nearest half small square (after checking for false origin) or calculated using ratios or y = mx + c. [1] (f) Correct calculation of z (gradient value must be used). Ignore sign. [1] Value of z given with unit of length (gradient value must be used). [1] [Total: 20] 2 (a) Measurement of I in range 1.5 A–2.5 A and to 0.1A or better. [1] (c) Measurement of x to the nearest mm. [1] (d) Measurement of θ (less than 45°). Raw values to no more than nearest degree or half degree. [1] (e) Percentage uncertainty in θ : Correct method, using ∆θ = half the range, or ∆θ = 2° to 10°. [1] (f) (i) Evidence of repeated measurements either here or in (d). [1] (ii) Correct average value of θ. [1] (g) Second measurement of x. [1] Second measurement of I. [1] Quality: I decreases as x decreases. [1] (h) (i) Correct calculation of two values of k. [1] (ii) Valid conclusion based on the calculated values of k. Candidate must test against a specified criterion. [1] (iii) Statement that the s.f. for k depend on the s.f. for I and x. Ignore any reference to d.p. [1]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2010 9702 34 © UCLES 2010 (i) Identifying limitations and suggesting improvements Limitations (4) Improvements (4) Ignore A Two readings (of x and I) are not enough (to draw a valid conclusion). Take more readings and plot a graph. Repeat readings. B Difficult to measure x / difficult to keep x constant / difficult to keep distance between wire and magnet constant / difficult to keep distance between wire and stick constant. Use a clamped ruler / method of fixing the string Parallax error in measuring x. C Magnet does not come to rest. Practical method of damping / shield from draughts / turn off fans. Magnet swings too fast. D Measured angles are very small Use larger currents / use bigger protractor Use stronger / larger magnet. E Parallax error in measuring θ / reading protractor / reading deflection. Method of bringing protractor closer to wire / shine light from above Increase x / use mirror. F Difficult to alter rheostat while holding string. Method of fixing the string (unless already credited in B) / method of fixing rheostat to bench / use assistant. G (θ affected by) magnetic materials nearby / stray magnetic fields. Use wooden / non-magnetic stands. Move object further away. H Fluctuating current. Method of improving contact with wire (e.g. cleaning contacts, soldered connections). Do NOT credit: Use sensors / use lightgates / use video. [Total: 20]