Cambridge IGCSE Physics 0625 — 2013 May/June Paper 6 · Variant 2

1 The IGCSE class is determining the mass of a metre rule using two methods. For Examiner’s Method 1. Use Fig. 1.1 shows the apparatus used. d x y 50.0 cm mark metre rule X pivot Fig. 1.1 A student places a 100 g mass X on the rule so that its centre is at a distance d = 5.0 cm from the zero end of the rule, as shown in Fig. 1.1. He adjusts the position of the rule so that it is as near as possible to being balanced. He measures the distance x from the centre of the mass X to the pivot and the distance y from the pivot to the 50.0 cm mark on the rule. He repeats the procedure using d = 10.0 cm. The readings are shown in Table 1.1. Table 1.1 d / cm x / cm y / cm 5.0 23.7 21.1 10.0 21.0 18.5 (a) (i) Using the values of x and y in the first row of the table, calculate the mass M of the rule using the equation 100x M = . y M = ............................................ (ii) Repeat step (a)(i) using the values of x and y in the second row of the table. For Examiner’s Use M = ............................................ [2] (iii) Calculate the average value of M. average value of M = ........................................[1] Method 2. For Examiner’s (b) The student measures the mass M of the rule, using a spring balance as shown in Use Fig. 1.2. g 0 50 100 150 scale pan metre rule Fig. 1.2 Write down the reading shown in Fig. 1.2. M = ........................................[1] (c) The student expects that the values of the mass M obtained by the two methods will be For exactly the same. Examiner’s Use Suggest two practical reasons why, in spite of following the instructions with care, the values may differ. Assume that the balance used in Method 2 is accurate. 1. ...................................................................................................................................... .......................................................................................................................................... 2. ...................................................................................................................................... .......................................................................................................................................... [2] (d) Explain briefly how you would judge the position of the centre of the mass X when it is on the rule in Method 1. You may draw a diagram. .......................................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[1] [Total: 7]

Mark scheme: 1 (a) (i)(ii) M values 112.3, 113.5 (to 3 or 4 sig. figs only) [1] g at least once, not contradicted (symbols or words) [1] (iii) 113 or 112.9 or correct average of candidate’s values (ignore sig. figs) [1] (b) 114 (g) c.a.o. [1] (c) any two from: centre of mass of rule not at 50.0 cm mass X not uniform / of varying density reference to difficulty in obtaining balance implied o.w.t.t.e. mass of pan mass not exactly 100 g [2] (d) one from: mark line through the centre of the mass (can award from diagram) use position of edges of mass on rule [1] [Total: 7] o

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2 The IGCSE class is investigating the cooling of water. For Examiner’s (a) A student places a thermometer in a beaker of cold water. Use Using Fig. 2.1, record the temperature θC of the cold water supplied to the student. –10 0 10 20 30 40 50 60 70 80 90 100 110 °C Fig. 2.1 θC = . .......................................[1] (b) The student pours 200 cm3 of hot water into a beaker. She measures the temperature of the water at 30 s intervals. The readings are shown in Table 2.1. Table 2.1 t / θ/ 0 80 30 75 60 72 90 69 120 67 150 66 Complete the column headings in the table. [1] (c) The student empties the beaker and pours another 200 cm3 of the hot water into the beaker. She measures the temperature θH of the water in the beaker. 78 °C θH = ............................................ She then empties the cold water from the measuring cylinder shown in Fig. 2.2 into the beaker of hot water. She measures the temperature θA of the water in the beaker. 74 °C θA = ............................................ Using Fig. 2.2, record the volume VA of cold water. For Examiner’s Use cm3 25 20 15 10 water 5 Fig. 2.2 VA = ........................................[1] (d) Estimate the volume V of cold water that, added to the hot water, would give the same temperature drop as allowing the hot water to cool for 150 s. Use the evidence from the table and the readings in parts (b) and (c). Explain briefly how you arrived at your answer. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... V = ........................................[2] (e) This laboratory investigation could be used as a small-scale model for a process in a factory. The laboratory investigation would be repeated many times. Suggest two conditions that should be kept constant in order to provide reliable results. 1. ...................................................................................................................................... 2. ...................................................................................................................................... [2] [Total: 7]

Mark scheme: 2 (a) θC = 19 (oC) [1] (b) s, oC, symbols or words [1] (c) 12 cm3 (unit needed) [1] (d) 40–50 (cm3), (expect 42 cm3 e.c.f. (c)) [1] estimate given to nearest 1 cm3 only and sensible method [1] (e) two from: room / surrounding temperature / other environmental condition initial hot water temperature initial cold water temperature volume / mass / amount of hot water time delay on adding cold water / same time for cooling [2] [Total: 7] IGCSE – May/June 2013 0625 62

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3 The IGCSE class is investigating resistor combinations in circuits. For Examiner’s The first circuit used is shown in Fig. 3.1. Use power supply A lamp 1 lamp 2 lamp 3 V Fig. 3.1 A student measures the potential difference V1 across lamp 1 and the current I in the circuit. (a) (i) Using Fig. 3.2, record the student’s readings. 2 3 0.4 0.6 1 4 0.2 0.8 0 V 5 0 A 1.0 Fig. 3.2 V1 = ............................................ I = ............................................ [2] V1 (ii) Calculate the resistance R1 of lamp 1 using the equation R1 = . I R1 = ........................................[1] (b) The student uses the voltmeter to measure the potential difference V2 across lamp 2, For Examiner’s and the potential difference V3 across lamp 3. Use (i) Using Fig. 3.3, record the student’s reading of V2. 2 3 1 4 0 V 5 Fig. 3.3 V2 = ............................................ (ii) Using Fig. 3.4, record the student’s reading of V3. 2 3 1 4 0 V 5 Fig. 3.4 V3 = ............................................ [1] (c) Calculate the total potential difference VT across the three lamps using the equation VT = V1 + V2 + V3. VT = ........................................[1] (d) The student rearranges the circuit so that the lamps are in parallel with each other and For Examiner’s the ammeter is connected to measure the total current IT in the circuit. Use He connects the voltmeter to measure the potential difference VP across the lamps. In the space below, draw a circuit diagram of this new circuit using standard symbols. [2] (e) The student measures the potential difference VP and the current IT, and calculates the total resistance RP of the lamps arranged in parallel. 2.1 Ω RP = ............................................ R1 The student suggests that RP should be equal to . 3 State whether the results support this suggestion and justify your answer by reference to the results. statement ......................................................................................................................... justification ....................................................................................................................... .......................................................................................................................................... [1] R1 For because the lamp filaments(f) Another student suggests that RP should not be equal to Examiner’s 3 are hotter when the lamps are connected in parallel than when the lamps are connected Use in series. State one piece of evidence, that you would see during the investigation, that shows that the lamp filaments are hotter in the parallel circuit. .......................................................................................................................................... ......................................................................................................................................[1] [Total: 9]

Mark scheme: 3 (a) (i) V1 = 0.7 (V) [1] I = 0.45 (A) [1] (ii) R1 = 1.56 or 1.6 (Ω) e.c.f. (i) [1] (b) V2 = 0.6 (V) and V3 = 0.5 (V) c.a.o. [1] (c) 1.8 (V) e.c.f. V1, V2, V3 [1] (d) correct symbols for ammeter, lamp, voltmeter [1] correct parallel circuit with ammeter and voltmeter correctly connected [1] (e) statement matches candidate’s results and idea of within/beyond limits of experimental accuracy or that values are too far apart / too different [1] (f) brighter [1] [Total: 9]

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4 A student carries out an experiment using a simple pendulum. For Examiner’s Fig. 4.1 shows the apparatus. Use clamp string x pendulum bob one complete oscillation Fig. 4.1 The student records the time t taken for 20 complete oscillations of the pendulum for a range of different lengths x of the string. The readings are shown in Table 4.1. Table 4.1 x / cm t / s T / s 90.0 38.5 80.0 36.0 70.0 33.4 60.0 31.4 50.0 28.2 40.0 25.5 (a) The period T of the pendulum is the time taken for one complete oscillation. For each set of readings in the table, calculate the period T and enter the results in the table. [2] (b) Suggest a reason for measuring the time for twenty oscillations rather than just one. For Examiner’s .......................................................................................................................................... Use .......................................................................................................................................... ......................................................................................................................................[1] (c) In this experiment, the length x of the string is measured with a metre rule. Suggest one precaution that you would take when measuring the length in order to obtain an accurate reading. .......................................................................................................................................... ......................................................................................................................................[1] (d) The student decides that a more useful result is possible if the length is measured to the centre of mass of the pendulum bob. The pendulum bob is a small metal ball. The student has a 30 cm ruler and two rectangular blocks of wood that are about 10 cm long. Suggest how the student can use this equipment to measure accurately the diameter of the pendulum bob. You may draw a diagram. .......................................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[2] [Total: 6]

Mark scheme: 4 (a) 1.925, 1.800, 1.670, 1.570, 1.410, 1.275 (2 or more sig. figs. ) [1] all T values consistently to 2 or 3 significant figures [1] (b) any one from: gives a more accurate value of T gives an average value (of T) reduces (effect of ) human reaction error reaction time less significant T too small / oscillations are too quick / bob swings too fast [1] (c) avoidance of parallax error explained [1] (d) blocks arranged parallel either side of bob and touching bob [1] rule correctly placed, touching the blocks and spanning the gap [1] [Total: 6]

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5 The IGCSE class is determining the focal length of a lens. For Examiner’s The apparatus is shown in Fig. 5.1. Use illuminated object screen u lens Fig. 5.1 A student places the lens a distance u = 25.0 cm from an illuminated object of height 1.5 cm. She moves the screen until a sharply focused image of the object is seen on the screen. 1 She measures the height h of the image on the screen. She calculates h. She repeats the procedure using a range of u values. Her results are shown in Table 5.1. Table 5.1 1 1 u / cm h / cm h cm 25.0 2.2 0.45 30.0 1.5 0.67 35.0 1.1 0.91 40.0 0.9 1.1 45.0 0.8 1.3 1 1 For(a) Pl ot a graph of u / cm (y-axis) against (x-axis). You do not need to begin the axes h cm Examiner’s at the origin (0,0). Use [5] (b) Determine the gradient G of the graph. Show clearly on the graph how you obtained the necessary information. G = ........................................[2] G (c) Calculate the focal length f of the lens, using the equation f = cm. Give your answer 1.5 to a suitable number of significant figures for this experiment. f = ........................................[2] (d) State two precautions that you would take in this experiment in order to obtain reliable For results. Examiner’s Use 1. ...................................................................................................................................... .......................................................................................................................................... 2. ...................................................................................................................................... .......................................................................................................................................... [2] [Total: 11]

Mark scheme: 5 (a) axes correctly labelled [1] suitable scales (at least half the grid used) [1] all plots correct to ½ small square [1] good line judgement [1] thin continuous line and fine plots [1] IGCSE – May/June 2013 0625 62 (b) triangle method used and shown [1] using at least half of line [1] (c) f = 14.0 – 16.0 (cm) [1] f to 2 or 3 significant figures with unit [1] (d) any two from: darkened room / brighter lamp / no other lights (centre of) lens and object same vertical height from bench mark block at centre of lens clamp rule or place on bench lens, object and screen are vertical / perpendicular to bench repeat the measurements move the screen backwards and forwards (to get sharpest image) [2] [Total: 11]

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