Cambridge IGCSE Physics 0625 — 2025 May/June Paper 6 · Variant 1

1 A student determines the density of a ball. (a) He places the ball between two wooden blocks, as seen from above in Fig. 1.1. He takes two measurements, d1 and d2. d1 d2 Fig. 1.1 (i) On Fig. 1.1, measure the lengths d1 and d2. d1 = ......................................................... cm d2 = ......................................................... cm [1] (ii) Using your measurements, calculate the diameter d of the ball. Show your working. d = ................................................... cm [1] (iii) Explain why this method is used to measure the diameter of the ball. ........................................................................................................................................... ..................................................................................................................................... [2] (b) Calculate the volume V of the ball using the equation V = 0.52d 3. Include the unit. V = ......................................................... [2] (c) The student measures the mass mD of a dish. 102.5 mD = ............................................................ g He places the ball in the dish and measures the combined mass mC of the dish and the ball. Fig. 1.2 shows the dish and the ball on a balance. Record the reading shown on the balance. 114.1 g Fig. 1.2 mC = ............................................................ g Calculate the mass mB of the ball. Show your working. mB = ............................................................ g [2] (d) Calculate the density ρ of the ball using the equation: mB ρ = V . Give your answer to a suitable number of significant figures for this experiment. Include the unit. ρ = ......................................................... [3] [Total: 11]

Mark scheme: Question Answer Marks 1(a)(i) two measurements in cm 2.7 and 2.5, both given to nearest mm 1 1(a)(ii) correct average: expect 2.6 (cm) 1 1(a)(iii) any reasonable advantage for the method in the question given OR it is difficult to measure the diameter directly OR hard to 1 find centre of ball a ruler for measuring the diameter directly would give rise to parallax errors 1 1(b) V = 9.1(4) 1 unit: cm3 1 1(c) correct method for calculation of mB shown 1 mB = 11.6 (g) 1 1(d) on answer line correctly calculated to 2 or more significant figures 1 unit: g / cm3 1 answer given to 2 or 3 significant figures 1

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2 A student investigates the cooling of hot water in a beaker. The apparatus is shown in Fig. 2.1. thermometer beaker bench Fig. 2.1 (a) The student uses a thermometer to measure room temperature θ R. Room temperature is 22 °C. On Fig. 2.2, show clearly the reading θ R. –10 0 10 20 30 100 110 °C Fig. 2.2 [1] (b) The student pours 100 cm3 of hot water into an empty beaker. She records the temperature θ of the hot water in the V = 100 cm3 row of Table 2.1, as shown. Without delay, she pours 20 cm3 of cold water into the beaker. She stirs the water and measures the temperature of the mixture of hot and cold water. She repeats the procedure until she has added a total of 100 cm3 of cold water to the beaker. All the readings are shown in Table 2.1. V is the total volume of water in the beaker. Complete the column headings in Table 2.1. [1] Table 2.1 V / θ/ 100 87 120 73 140 65 160 59 180 54 200 49 (c) Plot a graph of temperature θ (y-axis) against total volume of water V (x-axis). You do not need to start the axes at the origin (0, 0). Draw the best-fit curve. [4] (d) In the experiment, the student aims to investigate the effect on the temperature of the hot water as cold water is added. (i) Complete the sentence to explain why it is important to add the cold water without delay at each stage. The cold water is added without delay .............................................................................. ........................................................................................................................................... ..................................................................................................................................... [1] (ii) Complete the sentence to explain the reason for stirring the water at each stage. The student stirs the water before recording the temperature .......................................... ........................................................................................................................................... ..................................................................................................................................... [1] (e) Suggest two ways to minimise the loss of thermal energy from the beaker during the experiment. 1 ................................................................................................................................................ ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... [2] (f) Name the apparatus that the student uses to measure the volume of water. ............................................................................................................................................. [1] [Total: 11]

Mark scheme: 2(a) 22 (°C) correctly shown 1 2(b) cm3, °C 1 2(c) axes correctly labelled with quantity AND unit AND right way round 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)(i) so that temperature change is due to cold water added rather than heat losses to the surroundings 1 2(d)(ii) to ensure even / constant temperature (throughout the liquid) 1 2(e) any two from: 2 • some form of insulation • add a lid • shield from draughts • white / shiny surface 2(f) measuring cylinder 1

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3 A student investigates reflections in a plane mirror. A ray-trace sheet is shown in Fig. 3.1. M R P3 P4 eye Fig. 3.1 (a) • Draw a normal to the line MR that passes through the centre of MR. Label the normal NL. • Label the point at which NL crosses MR with the letter B. • Draw a line 10.0 cm long from B at an angle of incidence i = 40° to the normal below MR and to the left of the normal. Label the end of this line A. [2] (b) The student places the reflecting face of the mirror vertically on the line MR. He places two pins, P1 and P2, on line AB. Mark the positions of P1 and P2 with crosses (X) on line AB at a suitable distance apart for this type of ray-trace experiment. Label the positions of P1 and P2. [1] (c) The student views the images of pins P1 and P2 from the direction indicated by the eye in Fig. 3.1. He places two pins, P3 and P4, so that pins P3 and P4 and the images of P2 and P1 all appear exactly one behind the other. The positions of P3 and P4 are shown on Fig. 3.1. (i) Draw a line through the positions of P3 and P4. Continue the line until it meets MR. [1] (ii) Measure the acute angle α between this line and the horizontal line MR. An acute angle is an angle less than 90°. α = ....................................................... ° [1] (d) The student turns the mirror through 180°. He draws a new incident ray at an angle of incidence i = 50° to the normal above MR and to the left of the normal. He labels the end of this line C. This line is not shown on Fig. 3.1. You may draw the line on Fig. 3.1. He places two pins on the line CB and views the images of the two pins from near the top right-hand corner of the ray-trace sheet. On Fig. 3.1, draw a reflected ray 10.0 cm long from B with an angle of reflection β equal to the angle of incidence. Label the end of the line D. [2] (e) Suggest a relationship between α and β. Justify your answer by reference to the results. relationship ............................................................................................................................... justification ................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... [2] (f) State two techniques that you use in this type of experiment to obtain an accurate ray trace. 1 ................................................................................................................................................ ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... [2] [Total: 11]

Mark scheme: 3(a) normal neat and at 90° 1 incident ray in correct quadrant at 40°  2° 1 3(b) P1 P2 separation at least 5.0 cm 1 3(c)(i) incident ray and reflected ray and normal meeting at B within 2 mm 1 3(c)(ii) = 48°  2° 1 3(d) new reflected ray drawn above MR in an appropriate quadrant 1 angle of reflection drawn 50°  2° 1 3(e) statement to match results 1 justification to include idea of results being equal within the limits of experimental error OR unequal if beyond the limits of 1 experimental error 3(f) any two from: 2 • thin pins • thin lines / sharp pencil • view bases of pins / pins vertical • pins far apart / at least 5 cm

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4 A student investigates the relationship between the diameter and the resistance of wires. The following apparatus is available: • wires with different diameters • instrument for measuring the diameter of a wire • metre ruler • ammeter • voltmeter • power supply. Other apparatus normally found in a school laboratory is also available. Plan an experiment to investigate how the diameter of a wire affects its resistance. V Resistance R is given by the equation R = I, where V is the potential difference (p.d.) across the wire and I is the current in the wire. You do not need to write about safety precautions. In your plan: • draw a circuit diagram to show the circuit you use • explain briefly how to do the investigation • state one key variable to keep constant • draw a table, or tables, with column headings, to display the readings (you are not required to enter any readings in the table) • explain how to use your results to reach a conclusion. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [7]

Mark scheme: 4 MP1 circuit used: 1 correct circuit diagram MP2 measurements made: 1 measure wire diameter AND measure voltage and current OR record voltmeter and ammeter readings MP3 analysis of readings: 1 calculate / work out resistance of wire MP4 performing the investigation: 1 repeat for at least two other diameters of wire MP5 variable kept constant: 1 length / material of wire MP6 table: 1 with columns for diameter of wire, voltage, current and resistance each column must be labelled with both quantity and unit MP7 conclusion: 1 plot a graph of resistance against diameter OR an answer which suggests comparing values of diameter AND resistance in table

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