Cambridge IGCSE Physics 0625 — 2010 May/June Paper 6 · Variant 3

1 The IGCSE class is determining the mass of a load using a balancing method. For Examiner’s Fig. 1.1 shows the apparatus. Use d 50.0 cm mark mass m load X pivot metre rule bench Fig. 1.1 The load X has been taped to the metre rule so that its centre is exactly over the 90.0 cm mark. It is not moved during the experiment. A mass m of 40 g is placed on the rule and its position adjusted so that the rule is as near as possible to being balanced with the 50.0 cm mark exactly over the pivot. This is repeated using a range of masses. The readings are shown in Table 1.1 Table 1.1 1 1 m /g d /cm d / cm 40 30.2 50 23.9 60 20.0 70 17.1 80 15.1 (a) For each value of d, calculate 1/d and record it in the table. [2] 1 1 For(b) Plot a graph of m /g (y-axis) against (x-axis). Examiner’s d / cm Use [4] (c) Determine the gradient G of the graph. Show clearly on the graph how you obtained the necessary information. G = ....................................... [2] (d) Determine the mass μ of the load X using the equation μ = G/k where k = 40.0 cm. μ = ....................................... [2]

Mark scheme: 1 (a) table: 1/d values correct 0.0331, 0.0418, 0.0500, 0.0585 (0.058 to 2 sig. fig.), 0.0662 [1] consistent 2 or 3 significant figures [1] (b) graph: axes labelled [1] scales suitable, plots occupying at least half grid [1] plots all correct to ½ square (ecf) – take centre of plot if large [1] well judged line thin line (Y½ square) [1] (no mark if plots > ½ square) (c) triangle method used and shown (any indication on graph) [1] (triangle) using at least half line (can be seen in calculation) [1] (d) µ 27 – 33 (NO ecf) [1] 2 or 3 significant figures and unit g [1] [Total: 10]

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2 An IGCSE student is investigating the rate of cooling of water in different containers. For Fig. 2.1 shows the two containers. Examiner’s Use thermometer container A thermometer container B Fig. 2.1 Approximately 200 cm3 of hot water is poured into container A. A stopclock is started and the temperature of the water is recorded at 30 s intervals. Hot water is then poured into container B until there is sufficient to cover the thermometer bulb. The stopclock is started and the temperature of the water is recorded at 30 s intervals. All the temperature readings are shown in Table 2.1. Table 2.1 container A container B t / θ / θ / 0 80 78 71 66 65 59 59 55 56 51 55 49 54 48 (a) (i) Complete the column headings in the table. (ii) Complete the time column in the table. [2] (b) Calculate the temperature change of the water in each container over the period of For 180 s. Examiner’s Use Container A temperature change = ............................................ Container B temperature change = ....................................... [1] (c) State which container, A or B, has the greater rate of cooling. Justify your answer by reference to the readings. Statement ........................................................................................................................ Justification ...................................................................................................................... ..................................................................................................................................... [2] (d) To make a fair comparison between the rates of cooling of the hot water in the two containers it is important to control other experimental conditions. Suggest two conditions that should be controlled in this experiment. 1. ...................................................................................................................................... 2. ................................................................................................................................. [2]

Mark scheme: 2 (a) table: t in s, θ in °C (either in words or mixture of symbols and words) (NOT degrees/centigrade) [1] times 30, 60, 90, 120, 150, 180 [1] (b) both temperature falls correct (ignore unit or lack of unit) 26, 30 [1] (c) justification matches statement (expect B) and by reference to readings (need a comparison – not ‘heat’ or ‘it’) B & temp fall [1] in same time [1] (d) any two from: same starting temperature stir/same thermometer position same interval time constant room temperature/carry out at same time same volume/amount/mass of water avoid draughts or wtte [2] (NOT reference to container, insulation, precaution) (extra answers: –1 if incorrect, ignore if neutral) [Total: 7] IGCSE – May/June 2010 0625 63

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3 The IGCSE class is determining the resistances of lamps in different circuit arrangements. For Examiner’s The first circuit is shown in Fig. 3.1. This is Circuit 1. Use power source A Circuit 1 lamp P V Fig. 3.1 A student measures the current I in the circuit and the p.d. V across lamp P. He then replaces lamp P with lamp Q to set up Circuit 2 (not shown) and records the readings of current I and potential difference V. He then returns lamp P to the circuit so that lamps P and Q are in parallel with each other. This is Circuit 3. He again records the readings of current I and potential difference V. All the readings are in Table 3.1. Table 3.1 V / I / R / Circuit 1 1.9 0.31 Circuit 2 1.8 0.30 Circuit 3 1.9 0.61 (a) Draw a diagram of Circuit 3 using standard circuit symbols. [3] (b) (i) Calculate the resistance R of the lamp arrangement for each circuit, using the For equation R = V/ I. Examiner’s Use Record the values of R in Table 3.1. (ii) Complete the column headings in the table. [3] (c) A student suggests that the resistance of lamp P added to the resistance of lamp Q should be equal to the combined resistance of the two lamps when arranged in parallel in Circuit 3. State whether or not the results in the table support this suggestion and justify your answer with reference to the results. Statement ........................................................................................................................ Justification ...................................................................................................................... .......................................................................................................................................... ..................................................................................................................................... [2]

Mark scheme: 3 (a) diagram: correct symbols for ammeter, voltmeter and lamps (lamp – cross at least ½ diameter by eye) (ignore power source) [1] voltmeter position correct [1] lamps in parallel in a correct circuit (e.g. single voltmeter) [1] (b) table: V, A, Ω (any in symbols, words or a mixture) [1] Correct R values 6.13, 6.00, 3.11 [1] Consistent 2 or 3 significant figures [1] (c) statement matches readings (expect NO) [1] justification matches statement and by reference to resistance results (don’t need numbers) [1] [Total: 8]

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4 The IGCSE class is investigating refraction and reflection of light in a transparent block. For Examiner’s The block rests on a pin board covered with a sheet of plain paper. Some of the lines and Use labels that a student draws are shown in Fig. 4.1. E A F B D C P3 G P4 Fig. 4.1 (a) The student places the transparent block ABCD on the sheet of plain paper. The student draws a line around the block and then draws a normal to side AB. On Fig. 4.1 label the normal NN'. [1] (b) Line EF shows an incident ray that is at an angle of incidence i = 30° to the normal. The student continues the line to a point G. Draw two neat crosses on line EF and label them P1 and P2 to show suitable positions for two pins that are to be used to trace the direction of the incident ray. [1] (c) The student observes the images of P1 and P2 through side CD of the block from the For Examiner’s direction indicated in Fig. 4.1 so that the images of P1 and P2 appear one behind the other. She then places two pins P3 and P4 between her eye and the block so that P3, P4 Use and the images of P1 and P2, seen through the block, appear in line. The positions of P3 and P4 are marked. (i) Draw a line joining the positions of P3 and P4. Continue the line so that it crosses CD and extends beyond BC to cross line EFG. Label the end of the line H. (ii) Measure the smaller angle θ between EFG and the line joining the positions of P3, P4 and H. θ = ............................................ (iii) Calculate the difference (θ – 2i ). Show your working. (θ – 2i ) = ............................................ [4] (d) The student repeats the experiment using an angle of incidence i = 40° to the normal and obtains a value of θ = 82°. Calculate the difference (θ – 2i ). (θ – 2i ) = ........................................[1] (e) Theory suggests that θ = 2i . State whether the two results in parts (c) and (d) support the theory and justify your answer by reference to the results. Statement ........................................................................................................................ Justification ...................................................................................................................... ......................................................................................................................................[2]

Mark scheme: 4 (a) normal labelled (allow N N’ on end or N, N’ alone) [1] (b) P1P2 distance at least 3 cm [1] (c) line to H drawn neatly and correctly [1] θ correct to ±1° 60 [1] (θ – 2i) correct 0 (ecf) (ignore sign) [1] unit ° at least once in (c) and not contradicted [1] (d) 2° (ignore unit and sign) [1] (e) statement matches results (ecf) expect YES if 0 and 2, NO only if ‘too different’ or wtte in justification [1] justification matches statement and by reference to results (allow almost/nearly the same or within expt accuracy) [1] [Total: 9] IGCSE – May/June 2010 0625 63

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5 An IGCSE student is determining the magnification of an image formed by a lens. The For experimental set up is shown in Fig. 5.1. Examiner’s Use screen x y illuminated lens object bench Fig. 5.1 The screen consists of a sheet of white paper stuck to a vertical board. The position of the screen is adjusted until a focused image of the object is formed on the screen. (a) (i) On Fig. 5.1 measure the distances x and y. x = ............................................ y = ............................................ (ii) Calculate the magnification m using the equation m = y /x. m = ............................................ [3] (b) Suggest two precautions that you would take to obtain reliable results in this experiment. 1. ...................................................................................................................................... .......................................................................................................................................... 2. ...................................................................................................................................... ......................................................................................................................................[2] (c) The student wishes to measure the height of the image on the screen in order to check his result. However he finds that when he tries to do this his hand and the rule prevent the light reaching the screen. Suggest briefly a method he could use to measure the height of the image on the screen that would overcome this problem. .......................................................................................................................................... ......................................................................................................................................[1]

Mark scheme: 5 (a) x = 3.9 and y = 5.4 (any answer correct when rounded to 2 sf) [1] both with correct unit [1] m = 1.38 no unit, 2 or 3 significant figures (allow x for unit) or correct calculation from correct x and y [1] (b) any two from: clamp rule or place on bench use area away from direct sunlight/dark room/bright object ensure object and lens same height (from bench) mark on lens holder (accept on lens) screen and lens perpendicular to bench/aligned/in straight line/on principle axis move lens slowly (backwards and forwards) repeats avoid parallax (or wtte) with action given 2 (c) scale drawn on paper on screen/graph paper on screen/ mark on screen (then) measure/clamp ruler on scale/ use translucent screen and measure from other side [1] [Total: 6]

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