Cambridge IGCSE Physics 0625 — 2023 Oct/Nov Paper 6 · Variant 2

1 A student investigates the period of a pendulum. Fig. 1.1 shows the set-up. clamp d bob Fig. 1.1 (a) The distance d is measured from the bottom of the clamp to the centre of the bob. The student adjusts the length of the pendulum until d = 50.0 cm. He displaces the bob slightly and releases it so that it swings. He uses a stop-watch to measure the time t for 10 complete oscillations. min sec 1/100th 00:14 21 Fig. 1.2 (i) Fig. 1.2 shows the reading on the stop-watch. Record, in Table 1.1, the time t for 10 complete oscillations. [1] (ii) Calculate and record in Table 1.1, the period T of the pendulum. The period is the time for one complete oscillation. [1] (iii) Calculate T 2 and record your value in Table 1.1. [1] (iv) Write the units in the column headings. [2] Table 1.1 d / t / T / T 2 / 50.0 100.0 20.20 2.02 4.08 (b) The student repeats the procedure in (a) using d = 100.0 cm. The readings and results are shown in Table 1.1. Another student suggests that T 2 is directly proportional to d. Explain briefly how to test the suggestion using the results in Table 1.1. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (c) The procedure can be repeated to plot a graph. Suggest additional values of d that are suitable for the experiment. ................................................................................................................................................... ............................................................................................................................................. [1] (d) Explain how you would measure the distance d as accurately as possible. Draw a diagram to help your explanation. ................................................................................................................................................... ............................................................................................................................................. [2] (e) Explain why timing 10 oscillations gives a more accurate result for the period T than timing one oscillation. ................................................................................................................................................... ............................................................................................................................................. [1] [Total: 11]

Mark scheme: Question Answer Marks 1(a)(i) t = 14.21 1 1(a)(ii) T = 1.42(1) 1 1(a)(iii) T2 = 2.02 1 1(a)(iv) cm, s, s 1 s2 1 1(b) calculate T2 / d (or reciprocal of this) 1 judge if (close enough to be considered) equal 1 OR compare the T2 and d values judge if the second value is (close enough to) double the first value OR plot a graph of T2 against d (if directly proportional) it will be a straight line passing through the origin 1(c) at least three values between 10 (cm) and 100 (cm) 1 1(d) diagram to show (correct use of) a horizontal aid (e.g., a set-square / ruler) 1 matching wording 1 OR measure the diameter of the bob with two blocks and a ruler / micrometer divide by 2 to find the radius and add this on to the length of the string OR measure to the top and the bottom of the bob find the average 1(e) reduces the effect of (reaction) timing errors / reduces the percentage error / uncertainty / the (reaction time) error is spread 1 over 20 oscillations

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2 A student investigates the resistance of a wire. Fig. 2.1 shows the circuit used. A l B C resistance wire V sliding contact S Fig. 2.1 (a) The student places a sliding contact S at a distance l = 40.0 cm from B. She measures the potential difference (p.d.) V across the length l of the resistance wire. She measures the current I in the circuit. The meters are shown in Fig. 2.2 and Fig. 2.3. 2 3 0.4 0.6 1 4 0.2 0.8 0 5 0 1.0 V A Fig. 2.2 Fig. 2.3 (i) Write down the current I. I = ......................................................... [1] (ii) Record the potential difference V reading in the first row of Table 2.1. [1] (b) The student repeats the procedure in (a) using l = 50.0 cm, 60.0 cm, 70.0 cm and 80.0 cm. The readings are shown in Table 2.1. (i) Calculate, and record in Table 2.1, the values of resistance R using the equation V R = . I [2] (ii) Complete the column headings in Table 2.1. [1] Table 2.1 l / V / R / 40.0 50.0 1.5 60.0 1.8 70.0 2.1 80.0 2.4 (c) Plot a graph of R (y-axis) against V (x-axis). Start both axes at the origin (0,0). Draw the best-fit line. 0 0 [4] (d) Determine the gradient G of the graph. Show clearly on the graph how you obtained the necessary information. G = ......................................................... [2] [Total: 11]

Mark scheme: 2(a)(i) I = 0.34 (A) 1 2(a)(ii) V = 1.2 (V) 1 2(b)(i) R values correct 1 all R given to a consistent 2 or all to a consistent 3 significant figures 1 2(b)(ii) cm, V,  1 2(c) axes labelled with quantity and unit 1 suitable scales (occupying at least ½ the grid) 1 plots correct to  ½ small square and precise plots 1 good best-fit line judgement, thin, continuous line 1 2(d) (triangle) method shown clearly on graph using at least ½ of candidate’s line between extreme plots – either R ⩾ 1.5 1 or V ⩾ 0.6 gradient = 2.8 to 3.2 inclusive 1

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3 A student investigates the cooling of water under different conditions. Fig. 3.1 shows the set-up. thermometer beaker bench Fig. 3.1 (a) The thermometer in Fig. 3.2 shows the room temperature θR at the beginning of the experiment. Record θR. –10 0 10 20 30 40 50 60 70 80 90 100 110 °C Fig. 3.2 θR = ......................................................... [1] (b) The student pours 200 cm3 of hot water into the beaker. He places the thermometer in the water. He records the temperature θof the hot water at time t = 0. He immediately starts a stop-watch. He records the temperature at 30 s intervals. The temperature readings are shown in Table 3.1. (i) Write the times in the first column of Table 3.1. [1] (ii) Complete the column headings in Table 3.1. Table 3.1 t / θ / 95 86 78 72 68 66 65 [1] (c) (i) Calculate the decrease in temperature Δθ1 between time t = 0 and time t = 90 s. Δθ1 = ......................................................... [1] (ii) Calculate the difference in temperature ΔθS between the temperature at time t = 0 and room temperature θR. ΔθS = ......................................................... [1] (iii) Calculate the decrease in temperature Δθ2 between time t = 90 s and time t = 180 s. Δθ2 = ............................................................... Calculate the difference in temperature ΔθT between the temperature at time t = 90 s and room temperature θR. ΔθT = ............................................................... [1] (d) A student suggests that the decrease in temperature of the water in 90 s should be greater when the starting temperature is greater. (i) State whether the results agree with this suggestion. Justify your statement by reference to the results. statement .......................................................................................................................... justification ........................................................................................................................ ........................................................................................................................................... ........................................................................................................................................... [2] (ii) Suggest how you would continue the experiment, using the same apparatus and method, to investigate the suggestion. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [2] (e) Refer to Table 3.1. Estimate the temperature of the water in the beaker after cooling for a further 90 s. ............................................................................................................................................. [1] [Total: 11]

Mark scheme: 3(a) 22(.0) (°C) 1 3(b)(i) 0, 30, 60, 90, 120, 150, 180 1 3(b)(ii) s, °C 1 3(c)(i) 1 = 23 (°C) ignore any minus signs given in this part 1 3(c)(ii) S = 73 (°C) 1 3(c)(iii) 2 = 7 (°C) and T = 50 (°C) 1 3(d)(i) statement matches results (expect YES) 1 justification matches statement with numbers correctly quoted 1 3(d)(ii) take additional readings at times beyond 180 s 1 for at least another 180 s / until the temperature is close to room temperature or stops decreasing 1 3(e) 59–63 (°C) inclusive 1

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4 A student investigates the effect of changing the colour of light on the focal length of a lens. uv The focal length f of a lens is given by the equation f = (u + v). The distance u is the distance between an object and the lens. The distance v is the distance between the lens and the image that is formed on a screen. Plan an experiment to investigate the effect of changing the colour of light on the focal length of a lens. The following apparatus is available to the student: • illuminated object • a selection of coloured filters to change the colour of the light • converging lens • screen • metre ruler. Other apparatus normally available in a school laboratory can also be used. In your plan, you should: • draw a labelled diagram to show the arrangement of the apparatus • explain briefly how you would do the investigation, including the measurements you would take • draw a suitable table, with column headings, to show how you would display your readings (you are not required to enter any readings in the table) • state how you would use your results to reach a conclusion. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [7]

Mark scheme: 4 MP1 labelled diagram 1 diagram with lens between object and screen, and filter anywhere between the illuminated object and the lens or between the source of illumination and the object, with a least 1 label MP2 method 1 move object / lens / screen to obtain focused / sharp / clear image MP3 measure / record / find / calculate / note u and v 1 MP4 calculate / determine / find the focal length 1 MP5 repeat with different colours / filters 1 MP6 table 1 table with clear columns for (filter) colour, u and v AND with appropriate units MP7 how to reach conclusion 1 plot bar chart of focal length and colour OR compare results to see if / how the change of colour affects the focal length OR compare results to determine the effect of a change in colour on the focal length Additional graph notes: NOTE: – The principle to apply here is ‘could I draw a significantly better line, using these points, under examination conditions?’ If the answer is definitely ‘yes’, do not award the mark. NOTE: – If candidate’s scale consists of actual readings at equal intervals this will produce a perfect straight line! The only marks available in this case are the first (axes right way round and labelled) So maximum 1. If axes are wrong way round, the other 3 marks are still available.

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