Cambridge A Level Physics 9702 — 2002 May/June Paper 5 · Variant 1

TIME 1 hour 30 minutes INSTRUCTIONS TO CANDIDATES Write your name, Centre number and candidate number in the spaces at the top of this page. Answer both questions. Write your answers in the spaces provided on the question paper. 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. Marks are mainly given for a clear record of the observations actually made, for their suitability and accuracy, and for the use made of them. INFORMATION FOR CANDIDATES 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. CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Level PHYSICS 9702/5 PAPER 5 Practical Test MAY/JUNE SESSION 2002 1 hour 30 minutes Candidates answer on the question paper. Additional materials: As specified in Instructions to Supervisors Graph paper This question paper consists of 6 printed pages and 2 lined pages. (NH/CG) S14607/3 © CIE 2002 [Turn over FOR EXAMINER’S USE 1 2 TOTAL Candidate Centre Number Number Candidate Name

2 9702/5 M/J/02 It is recommended that you spend about 60 minutes on this question. 1 Decorative lights are sometimes wired in parallel. It is important to know how the current passing through the lights depends on the potential difference applied to them as the number of lights is changed. In this experiment you will investigate the variation of current with potential difference for two identical filament lamps and use the results of your experiment to suggest how current varies with potential difference for any number of identical lamps wired in parallel. (a) Set up the circuit shown in Fig. 1.1 using the filament lamp labelled P. Fig. 1.1 (b) (i) Close switch S. (ii) Measure and record six sets of readings of current I and potential difference V for I in the range 1.0 A ≤I ≤2.0 A. Include in your table of results values for lg (I/A) and lg (V /V). (iii) Open switch S. (c) Connect the second filament lamp (labelled Q) in parallel with lamp P. Measure and record six sets of readings of I and V for I in the range 2.0 A ≤I ≤4.0 A. Include in your table of results values for lg (I/A) and lg (V/V). It is suggested that I and V are related by the equation I = kVn where k and n are constants. S power supply P A V For Examiner’s Use

3 9702/5 M/J/02 [Turn over (d) (i) Plot a graph of lg (I/A) (y-axis) against lg (V/V) (x-axis) for the results obtained in parts (b) and (c). Use the same axes for both sets of results. Draw the line of best fit for each set of results. (ii) Determine the gradient and y-intercept of each of the lines of best fit. (iii) Use your answers from (ii) to find values for n and k in each case. You need not be concerned with the units of these quantities. (iv) Comment on the values of n and k which you have obtained. (e) (i) What values would you expect to obtain for n and k if the experiment were repeated with three identical lamps connected in parallel? (ii) Suggest an equation which describes the relationship between I and V for m identical lamps in parallel. DO NOT WRITE IN THIS SPACE For Examiner’s Use

4 9702/5 M/J/02 For Examiner’s Use M A R Measurements and calculations

5 9702/5 M/J/02 [Turn over Graph grid For Examiner’s Use G

6 9702/5 M/J/02 For Examiner’s Use It is recommended that you spend about 30 minutes on this question. 2 The properties of many magnetic materials are affected by temperature. One effect is the loss of permanent magnetism when the temperature of a magnetic material exceeds a particular value. This temperature is known as the Curie point. Design an experiment to investigate how the magnetic field strength of a magnet depends on the temperature of the magnet in the range from 0 °C to 200 °C. In your account you should pay particular attention to (a) the method of measuring the magnetic field strength (magnetic flux density), (b) how the temperature of the magnet would be measured in the given range, (c) the method of ensuring that the temperature of the magnet is uniform, (d) the procedure to be followed, (e) the control of variables.

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CAMBRIDGE INTERNATIONAL EXAMINATIONS JUNE 2002 GCE Advanced Level MARK SCHEME MAXIMUM MARK 30. SYLLABUS/COMPONENT :9702 /5 PHYSICS (PRACTICAL) B88 Universiry of CAMBRIDGE “QF Local Examinations Syndicate

A Level Examinations — June 2002 9702 5 | Pageiofs | Mark Scheme Syllabus | Paper | l Question 1 Measurements and observations M1 M2 Readings (for one bulb, 1st table only) 5 Write the number of readings as a ringed total by the results table. Check a value for tog /. Tick if correct. If incorrect, write in correct value and -1. Check a value for log V. Tick if correct. If incorrect, write in correct value and -1. Ignore smail rounding errors. Allow values of / outside the stated range. Allow In values to be used. nN 6 sets of readings scores 5 marks. 5 sets of readings scores 4 marks. 4 sets of readings scores 3 marks etc.. If help given by supervisor then -1, excessive help then -2. Ifhelp is given from the Supervisor then write 'SR' in a ring at the top of the front page of the candidate's script. Also, please indicate the type of help given in a written comment by the table of results. Quality of results 1 Judge by scatter of points about both lines of best fit 5 trend plots needed on both lines for this mark to be awarded. Presentation of results R1 Column headings I Apply to V and / in both tables. Do not apply to log quantities. Allow VV, Vin V, VV) or a dividing line. Do not allow VV, Vy or just V (with no unit). Consistency of raw readings given in both tables of results. 1 Apply to raw values of f and V only. All raw readings of a particular quantity must be given to the same degree of precision (e.g. if one value of / is measured to 2 d.p. then all values of J should be given to 2 d.p.). Write “, at the foot of the column for each correct column of raw readings. Ring any inconsistency noted, write X ¢ at the foot of the column, and -1. SF in calculated quantities 1 Apply to values of n. If no values of x, apply to gradient values. Accept two or three sf only.

Page 2 of § + Mark Scheme Syllabus | Paper A Level Examinations — June 2002 97027 | 5 Graphical Work Apply Gi, G2 & G3 to both lines Apply G4 & G5 to the parallel combination (i.e. the top line) Gl G2 G3 G4 GS Axes. Each axis must be labelled with a correct symbol (or description). Ignore units. Scales must be such that the plotted points occupy at least half the graph grid in both the x and y directions (4 x 6 large squares). Do not allow > 3 large squares between scale markings on an axis. Do not allow awkward scales (e.g. 3:10, 7:10, 8:10 etc.) Plotting of points. ( Count the number of plots on the grid and wnite this value by the lines and ring it. Do not allow plots in the margin area. All observations must be plotted. Check one suspect plot. Circte this plot. Tick if correct. If incorrect, mark the correct position with a small cross and use an arrow to indicate where the plot should have been. Allow errors up to and including half a small square. Line of best fit. Apply to both lines. Only a drawn straight line through a linear trend is allowable for this mark. This mark can only be awarded for 5 or more plots. There must be a reasonable balance of points about the line which has been drawn. Do not allow a line which is greater than half a small square thickness. Measurement of gradient. Apply to parailel arrangement only (i.e. the top line) Ignore units. Hypotenuse of A must be > haif the length of the drawn line. Check the read-offs. Work to haif a small square. Do not allow Ax/Ay. y-intercept Apply to parallel arrangement only (i.e. the top line) Tick origin, or label FO if the line x = 0 is not shown. Allow read-off of y-intercept to half a small square. If y = mx + c used, then check the substitution from a point on the line. Can be implied from log & = candidate’s y-intercept.

Page 3 of 5 Mark Scheme | Syllabus | Paper | | A Leval Examinations — June 2002 9702 § Analysis Al logi=nlog¥+logk , 1 Can be implied from candidate’s working (i.e. # = gradient and log & = y-intercept) Allow in {=a ln V+ tink. A2 Value of # (0.45 to 0.60) from second graph 1 A POTE will not score this mark. A3 “Value of k from second graph . ; 1 Method of working must be correct (i.e. k= 10° *iereret oy g cand: yrimercepty Ad Sensible comment } (e.g. (current doubled since lémps in parallel so) k doubled (with V constant); (lamps still heat up so Jaw is 'same' so) n unchanged) AS _ k increased by factor of 3 and unchanged. 1 A6 f=mky" i 20 marks in total Special cases SI Voltmeter misread (but not POTE); MI, -1. Ammeter misread (but not POTE),; Mi,-1. Both meters misread; MI, -2. S82 Plotted wrong graph (e.g. / vs V) A2 = A4= A5 = A6=0. Reversed axes (unless algebra correct); for A2 allow n in range 1.6 to 2.2. $3 No trend (or wrong trend) M1, -2. S4 Drawn curve M2 = G3 = G4=G5=0

Page 4 of 5 Mark Scheme Syllabus | Paper A Level Examinations -- June 2002 9702 5 Al A2 A3 Bl B2 B3 cl C2 Question 2 Use a Hall probe/search coil/current balance/magnetic field sensor with datalogger or meter to measure magnetic field Hall probe connected to a galvanometer/microammeter/voltmeter/calibrated Halt probe/datalogger. Search coil connected to ballistic galvanometer/datalogger. Current balance and measure force or current {n/a Newton meter} If magnetic field sensor used then the meter must be specified. Allow datalogger Insert/remove search coil from field Arrange plane of Hal! probe to be perpendicular to field. Current balance with some detail (e.g. wire perpendicular to field or adjust current until balance) \ Use an appropriate thermometer to measure temperature in the range 0 ~ 200°C e.g. thermocouple thermometer/digital thermometer/thermistor thermometer resistance thermometer/etectric thermometer Do not allow vague ‘thermometer’. If mercury-in-glass thermometer employed, then the range must be specified. Method of heating the magnet uniformly e.g. oven/constant temperature enclosure/heat in oi] Do not allow the magnet to be heated in boiling water/use of Bunsen flame Do not allow vague answers such as ‘heat source’. Do not allow magnet to be heated in coil. Leave magnet for a ‘long time’ in order to achieve uniform temperature Vary temperature of magnet and measure B and @ Only apply to workable arrangements such as Hail probe/search coil/induced e.m.f/ induced current/current balance/force on current-carrying wire. Do not allow iron filings methods/paper clips/force on a nearby magnet Keep the distance of the Hall probe to the magnet constant Allow ‘distance from magnet to ‘detector’ is the same’. Allow ‘move magnet at same speed’ (if magnet has been inserted into coil). Unworkable methods cannot score this mark.

Page 5 of 5 Mark Scheme Syllabus Paper A Level Examinations — June 2002 9702 5 Any good further design features. Some of these might be: Perform the experiment away from other magnetic materials Use datalogger to record/display results (possible three marks for good description) Awareness that Hall probe must not become hot during the experiment Allow magnet to reach thermal equilibrium and then quickly place Hali probe next to magnet; record 8 and then quickly remove the probe. Attach thermocouple to magnet/thermocouple detail. Detail retating to calibration of Hall probe. Use fridge/freezer/ice bath to achieve 0 °C. Any good safety point. Allow other valid points. 11 marking points, but only 10 marks maximum can be scored.