Cambridge IGCSE Physics 0625 — 2009 Oct/Nov Paper 6 · Variant 1

1 The IGCSE class is investigating the period of oscillation of a simple pendulum. For Examiner’s Fig. 1.1 shows the set-up. Use bob d floor one complete oscillation Fig. 1.1 Fig. 1.2 (a) (i) On Fig. 1.1, measure the vertical distance d from the floor to the bottom of the pendulum bob. d = ...................................................... (ii) Fig. 1.1 is drawn one twentieth actual size. Calculate the actual distance x from the floor to the bottom of the pendulum bob. Enter this value in the top row of Table 1.1. The students displace the pendulum bob slightly and release it so that it swings. They measure and record in Table 1.1 the time t for 20 complete oscillations of the pendulum (see Fig. 1.2). Table 1.1 x / cm t / s T / s T 2 / s2 20.0 20.0 19.0 30.0 17.9 40.0 16.8 50.0 15.5 [4] (b) (i) Calculate the period T of the pendulum for each set of readings. The period is the For time for one complete oscillation. Enter the values in Table 1.1. Examiner’s Use (ii) Calculate the values of T 2. Enter the T 2 values in Table 1.1. (c) Use your values from Table 1.1 to plot a graph of T 2 / s2 (y-axis) against x / cm (x-axis). Draw the best-fit line. [5] (d) State whether or not your graph shows that T 2 is directly proportional to x. Justify your For statement by reference to the graph. Examiner’s Use statement ......................................................................................................................... justification ....................................................................................................................... .................................................................................................................................... [1] [Total: 10]

Mark scheme: 1 (a) (i) d 0.5 cm or 5mm [1] (ii) x 10.0 [1] (b) (i)–(iii) table: T 1.0, 0.95, 0.895 (0.90, 0.9), 0.84, 0.775 (0.78) [1] T2 1.00, 0.903, 0.801, 0.706, 0.601 (if T correct) [1] (c) graph: axes labelled [1] scales suitable, plots occupying at least half grid [1] plots all correct to ½ square [1] well judged line [1] thin line, 5 neat plots [1] (d) statement NO and not through origin/ inverse/negative gradient/ x increases, T2 decreases/ wtte [1] [Total: 10] o

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2 An IGCSE student is investigating the cooling of thermometer bulbs under different For conditions. Examiner’s Use He places a thermometer in a beaker of hot water and records the temperature of the hot h water. –10 0 10 20 30 40 50 60 70 80 90 100 110 °C Fig. 2.1 (a) Fig. 2.1 shows the thermometer. Write down the value of that it shows. h ................................................ [1] h He then moves the thermometer until the thermometer bulb is just above the surface of the water (position A) and immediately starts a stopclock. He records the time t and the temperature reading every 30 s. The readings are shown in Table 2.1. Table 2.1 Position A Position B t / / / 30 65 56 60 58 47 90 54 40 120 52 35 150 50 32 180 48 30 (b) Complete the column headings in the table. [1] The student replaces the thermometer in the hot water and then moves the thermometer For 15 cm away from the beaker to position B and immediately starts the stopclock. He records Examiner’s the time t and the temperature reading every 30 s. The readings are shown in Table 2.1. Use (c) State in which position the thermometer bulb cooled more quickly. Justify your answer by reference to the readings. statement ......................................................................................................................... justification ....................................................................................................................... .................................................................................................................................... [1] (d) To make a fair comparison between the rates of cooling of the thermometer bulbs in the two positions, it is important to control other experimental conditions. Suggest two conditions that should be controlled in this experiment. 1. ...................................................................................................................................... 2. ................................................................................................................................ [2] [Total: 5]

Mark scheme: 2 (a) 91 (oC) [1] (b) t in s, both θ in oC [1] (c) statement B and justified by reference to readings [1] (d) any two from: same starting temperature/temperature of hot water constant room temperature/keep away from draughts/out of direct sunlight same time intervals [2] [Total: 5]

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3 The IGCSE class is comparing the combined resistance of lamps arranged either in series For or in parallel. Examiner’s Use The circuit shown in Fig. 3.1 is used. power source A V Fig. 3.1 A student measures and records the current I in the circuit and the p.d. V across the two lamps. Fig. 3.2 shows the readings on the two meters. 0.2 0.3 0.1 0.4 0 0.5 A 2 3 1 4 0 5 V Fig. 3.2 (a) (i) Write the voltage and current readings in Table 3.1, below. For Examiner’s (ii) Complete the column headings in Table 3.1. Use [3] (b) The student then sets up the circuit shown in Fig. 3.3 and records the readings. These readings have already been entered in Table 3.1. power source A V Fig. 3.3 For each set of readings in the table, calculate the combined resistance R of the two lamps using the equation R = V / I. Record the values of R in Table 3.1. [2] Table 3.1 V / I / R / Circuit of Fig. 3.1 Circuit of Fig. 3.3 1.8 0.52 (c) Using the values of resistance you have obtained, calculate the ratio y of the resistances using the equation resistance of lamps in series y = . resistance of lamps in parallel y = ...................................................... [2] (d) Fig. 3.4 shows a circuit including two motors A and B. For Examiner’s Use power source ammeter motor A A variable resistor motor B Fig. 3.4 (i) Draw a diagram of the circuit using standard circuit symbols. The circuit symbol for a motor is: M (ii) An engineer wishes to measure the voltage across motor A. For Examiner’s 1. On Fig. 3.4, mark with the letters X and Y where the engineer should connect Use the voltmeter. 2. State the purpose of the variable resistor. ........................................................................................................................... ........................................................................................................................... [3] [Total: 10]

Mark scheme: 3 (a)–(c) table: V, A, Ω [1] V 1.8 [1] I 0.25 [1] R values 7.20, 3.46(3.5) [1] consistent significant figures for R (2 or more) [1] (d) y 0.48, 0.49, 0.5 (ecf) [1] 2/3 significant figures and no unit [1] IGCSE – October/November 2009 0625 06 (e) (i) correct symbols and circuit (ignore power source symbol) [1] (ii) voltmeter position correct [1] (iii) control current/voltage/resistance/speed of motor [1] [Total: 10]

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4 An IGCSE student is determining the focal length of a lens by two different methods. For Examiner’s The set-up for Method 1 is shown in Fig. 4.1. Use object illuminated screen mirror object f lens Fig. 4.1 The student moves the lens and the mirror slowly towards the object screen until a sharply focused image is obtained on the object screen as shown in Fig. 4.2. image Fig. 4.2 (a) On Fig. 4.1, use your rule to measure the distance f between the lens and the object screen. This is the focal length of the lens. f = ................................................ [2] (b) For Method 2, the student takes measurements of the diameter d and maximum thickness t of the lens. Use your rule to take measurements on Fig. 4.3. Fig. 4.3 (i) Determine an average value for the diameter d of the lens. Record your readings in For the space below. Examiner’s Use d = ...................................................... (ii) Measure the maximum thickness t of the lens. t = ...................................................... (iii) Draw a diagram to show how, in the laboratory you would use two rectangular blocks of wood and a metre rule to measure the thickness of the lens as accurately as possible. (iv) Theory shows that, for a perfectly formed lens, the focal length is given by the formula d 2 f = where k = 4.16. kt Calculate the focal length f of the lens using this formula. f = ...................................................... [7] (c) Explain whether your results from Methods 1 and 2 support the theory in part (b)(iv). For Examiner’s .......................................................................................................................................... Use .......................................................................................................................................... .................................................................................................................................... [1] [Total: 10]

Mark scheme: 4 (a) f 14.95 + 0.05 (cm) [1] unit to match number [1] (b) more than one value shown [1] d 6.5 + 0.1 [1] (c) t 0.85 + 0.05 (cm) [1] d and t both with correct unit [1] (d) diagram showing blocks correctly placed [1] rule shown correctly touching both blocks [1] (e) f 10.9 – 13.1 (cm) (or 109 – 131 (mm)) [1] no, too far out to be explained by experimental inaccuracy (wtte) [1] [Total: 10]

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5 An IGCSE student is carrying out an optics experiment. For Examiner’s The experiment involves using a lens to focus the image of an illuminated object onto a Use screen. (a) Complete the diagram below to show the apparatus you would use. Include a metre rule to measure the distances between the object and the lens and between the lens and the screen. The illuminated object is drawn for you. illuminated object lamp card [3] (b) State two precautions that you would take to obtain accurate results in this experiment. 1. ...................................................................................................................................... .......................................................................................................................................... 2. ...................................................................................................................................... .................................................................................................................................... [2] [Total: 5]

Mark scheme: 5 (a) lens between object and screen (not mirror) [1] lens at least 2 cm from object and screen [1] metre rule on bench or clamped [1] (b) any two from: use of darkened room/brighter object slowly moving lens back and forth to obtain good image avoid parallax, action given lining up object and lens object and lens at same height from bench/object on principal axis repeats screen/lens perpendicular to bench mark centre of lens position on block [2] [Total: 5]

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