Cambridge IGCSE Physics 0625 — 2014 Oct/Nov Paper 5 · Variant 1

1 In this experiment, you will take measurements of a drinks cup. Carry out the following instructions referring to Fig. 1.1. G7 K G% Fig. 1.1 (a) (i) Measure and record the height h of the cup supplied. h = ................................................ cm (ii) Measure and record the diameter dT of the top of the cup. dT = ................................................ cm (iii) Measure and record the diameter dB of the bottom of the cup. dB = ................................................ cm dT + dB (iv) Calculate the average diameter dA using the equation dA = . 2 dA = ................................................ cm (v) Calculate an approximate value for the volume V of the cup, using the equation πdA2h V = . 4 V = ...................................................... [4] (b) (i) Use the string and the metre rule to determine the average circumference (distance around the outside) C of the cup. Show your working. C = ........................................... cm [3] (ii) Draw a diagram of the cup to show where you used the string to determine the average circumference C. [1] (c) Place the cup in the container provided. The container is to catch any water that may spill. (i) Use the measuring cylinder to determine the volume VW of water required to fill the cup to the top. VW = ................................................. [1] (ii) State which of the two values, VW or V obtained in (a)(v), you would expect to be the more reliable value for the volume of the cup. Explain your answer. more reliable value ............................ explanation ........................................................................................................................ ........................................................................................................................................... [1] [Total: 10]

Mark scheme: 1 (a) h, dT and dB, recorded in cm and sensible values [1] h > dT > dB and dA correct [1] V correctly calculated [1] unit cm3 [1] (b) (i) use of at least two values for circumference C [1] correct value for C and 3 × dA ±10% [1] 2 or 3 significant figures [1] (ii) diagram showing measurement half way up, or at top and bottom or a series of measurements all the way up [1] (c) (i) VW between 140 cm3 and 300 cm3 [1] (ii) sensible explanation e.g. Vw: lots of measurements to obtain V leads to greater inaccuracy [1] [Total: 10]

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2 In this experiment, you will investigate the cooling of hot water under different conditions. Carry out the following instructions, referring to Figs. 2.1 and 2.2. (a) Measure and record room temperature θR. θR = ................................................. [1] (b) Pour hot water into the beaker labelled A until it is about two-thirds full. Place the thermometer in the beaker of hot water, as shown in Fig. 2.1. clamp stand thermometer water Fig. 2.1 (i) Wait until the thermometer reading stops rising. Read the temperature θ of the hot water and immediately start the stopclock. Record the temperature θ in Table 2.1 at time t = 0 s. (ii) After 30 s, measure the temperature θ shown on the thermometer. Record the time t = 30 s and the temperature reading in Table 2.1. (iii) Continue recording the time and temperature readings every 30 s until you have six sets of readings. Table 2.1 without insulation with insulation t / θ/ θ/ [5] (c) Complete the column headings in the table. (d) Pour hot water into the insulated beaker until it is about two-thirds full. Place the thermometer in the beaker of hot water, as shown in Fig. 2.2. clamp stand thermometer insulation water Fig. 2.2 (i) Wait until the thermometer reading stops rising. Read the temperature θ of the hot water and immediately start the stopclock. Record the temperature θ in Table 2.1 at time t = 0 s. (ii) After 30 s, measure the temperature θ shown on the thermometer. Record the time t = 30 s and the temperature reading in Table 2.1. (iii) Continue recording the time and temperature readings every 30 s until you have six sets of readings. (e) State whether the cotton wool insulation increases, decreases, or has no significant effect on the rate of cooling of the water, compared with the rate of cooling with no insulation. Justify your answer by reference to your results. statement .................................................................................................................................. justification ................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... [2] (f) A student suggests that a significant cause of loss of thermal energy from the beakers is evaporation. Suggest how you would reduce the evaporation in this experiment. ...............................................................................................................................................[1] (g) Suggest one condition that should not be changed when this experiment is repeated. ...............................................................................................................................................[1] [Total: 10] Question 3 begins on page 8

Mark scheme: 2 (a) sensible value for θR (°C) [1] (b)–(d) table: s, °C, °C [1] correct t values 0, 30, 60, 90, 120, 150 [1] temperatures decreasing in both columns [1] final temperature difference less than initial temperature difference in both columns [1] evidence of temperatures to precision of at least 1°C [1] (e) statement to match results and justified by reference to results [1] reference to same time [1] (f) lid/cover/smaller cross-sectional area [1] (g) any one from: room temperature (or equivalent environmental condition) initial water temperature volume of water same/dry insulation [1] [Total: 10]

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3 In this experiment, you will investigate the resistance of a wire. The circuit shown in Fig. 3.1 has been set up for you. power supply A l A B sliding contact C resistance wire V Fig. 3.1 (a) (i) Switch on. Measure and record in Table 3.1 the current I in the circuit and the potential difference V across a length l = 10.0 cm of the wire AB. Switch off. V (ii) Calculate the resistance R of 10.0 cm of the wire AB, using the equation R = . Record I this value of R in the table. (iii) Repeat steps (i) and (ii) with values of l equal to 20.0 cm, 30.0 cm, 40.0 cm and 50.0 cm. Table 3.1 l / cm V / V I / A R / Ω 10.0 20.0 30.0 40.0 50.0 [3] (b) Plot a graph of R / Ω (y-axis) against l / cm (x-axis). Start both axes at the origin (0,0). 0 0 [4] (c) State whether your graph shows that the resistance R is directly proportional to the length l. Justify your answer by reference to the graph. statement .................................................................................................................................. justification ................................................................................................................................ ................................................................................................................................................... [2] (d) Suggest how you could further test your statement, in part (c), using the same apparatus. You are not asked to carry out any further practical work. ................................................................................................................................................... ...............................................................................................................................................[1] [Total: 10]

Mark scheme: 3 (a) V to at least 1 d.p. and < 3 V and increasing [1] I to at least 2 d.p. and < 1 A and constant to within 10% [1] R calculated correctly [1] (b) graph: axes correctly labelled and correct way round [1] suitable scales, with plots using at least half of grid [1] all plots correct to ½ small square [1] good line judgement, thin, continuous line [1] (c) statement to match results [1] justified by reference to straight line, through the origin [1] (d) additional readings with l values above 50 cm [1] [Total: 10]

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4 In this experiment, you will determine the magnification of an image produced by a lens. Carry out the following instructions, referring to Fig. 4.1. illuminated u v object screen lens x bench Fig. 4.1 (a) Place the lens a distance u = 20.0 cm from the illuminated object. Move the screen until a sharply focused image of the object is seen on the screen. (i) Measure and record the distance v from the centre of the lens to the screen. v = ................................................ cm (ii) Measure and record the height h from the top to the bottom of the image on the screen. h = ................................................ cm [2] (iii) Sketch a diagram of the image seen on the screen. [1] (iv) Switch off the lamp. Measure and record the height x from the top to the bottom of the triangular illuminated object. x = ................................................ cm h (b) (i) Calculate x. h = ...................................................... x v (ii) Calculate u. v = ...................................................... u [3] h (c) The magnification m of the image is given by the equation m = x. A student suggests that the v ratio also gives the magnification m. u State whether your results support this suggestion. Justify your answer by reference to your results. statement .................................................................................................................................. justification ................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... [2] (d) State two precautions that you could take in this experiment to obtain reliable results. 1. ............................................................................................................................................... ................................................................................................................................................... 2. ............................................................................................................................................... ................................................................................................................................................... [2] [Total: 10]

Mark scheme: 4 (a)(i)(ii) v sensible value in cm (55–65) [1] h sensible value (> 3 cm and < 6 cm) in cm [1] (iii) image drawn inverted [1] (iv) x value 1.2–1.8 cm [1] (b) (i) h/x and v/u correct, both with no unit [1] (ii) same within 10% [1] (c) statement to match results (expect yes) [1] justified by reference to results [1] (d) any two from: use of darkened room/brighter lamp mark position of centre of lens on holder place metre rule on bench (or clamp in position) ensure object and centre of lens are same height (from the bench) repeats and average move lens slowly/back and forth (to find sharpest image) screen and lens and object all perpendicular to bench [2] [Total: 10]

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