Cambridge IGCSE Physics 0625 — 2024 May/June Paper 6 · Variant 3

1 A student determines the density of modelling clay by two methods. Method 1 He uses the block of modelling clay shown in Fig. 1.1. l w h Fig. 1.1 (a) (i) Measure the dimensions of the block of modelling clay shown in Fig. 1.1. Record the values in centimetres to the nearest millimetre. l = ......................................................... cm w = ......................................................... cm h = ......................................................... cm [1] (ii) Calculate the volume VA of the block. Use your measurements from (a)(i) and the equation VA = l × w × h. VA = .................................................. cm3 [1] (b) Suggest why the value of VA is only an approximation of the volume of the block. Describe how the accuracy of VA can be improved. suggestion ................................................................................................................................ ................................................................................................................................................... improvement ............................................................................................................................. ................................................................................................................................................... ................................................................................................................................................... [2] (c) Record the mass mA of the block shown on the top-pan balance in Fig. 1.2. mA = ............................................................ g block top-pan balance bench g 80.4 Fig. 1.2 Calculate a value ρA for the density of the modelling clay. Use your results from (a)(ii) and (c) mA and the equation ρA = . Include the unit for the density. VA ρA = ............................................................... [2] Method 2 (d) The student then uses a smaller block of modelling clay. N force meter 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 modelling clay Fig. 1.3 Record the weight WB of the block of modelling clay shown in Fig. 1.3. WB = ..................................................... N [1] (e) (i) The student pours water into a measuring cylinder. Record the volume V1 of the water in the measuring cylinder shown in Fig. 1.4. V1 = .................................................. cm3 [1] measuring cylinder 60 water 50 Fig. 1.4 (ii) Describe briefly how a measuring cylinder is read to obtain a value for the volume of water. ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [1] (f) (i) The student lowers the modelling clay into the water, as shown in Fig. 1.5. 80 70 Fig. 1.5 Record the new reading V2 of the measuring cylinder. V2 = ........................................................ cm3 Calculate another value ρ B for the density of modelling clay. Use your value for V2, your WB × k readings from (d) and (e)(i) and the equation ρ B = where k = 100 g / N. (V2 – V1), ρ B = ............................................................... [1] (ii) Suggest which of ρA and ρ B is likely to be the more accurate value. Justify your answer by referring to method 1 and method 2. ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [1] [Total: 11]

Mark scheme: 1(a)(i) 1 1(a)(ii) VA = 44.6 cm3 1 1(b) difficult to measure irregular dimensions / owtte 1 repeat in several places (for each dimension) and take averages 1 1(c) mA = 80.4 (g) and A = 1.8 1 unit g / cm3 1 1(d) WB = 0.35 (N) 1 1(e)(i) V1 = 56 (cm3) 1 1(e)(ii) line of sight perpendicular / at eye level / at right angles 1 1(f)(i) V2 present and B = 1.9(4) (g / cm3) 1 1(f)(ii) suggestion supported by valid reason e.g.:  B as volume is measured directly  A as measuring cylinder is less precise 1

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2 A student investigates how the volume of water affects the rate at which water in a beaker cools. She uses the apparatus shown in Fig. 2.1. thermometer beaker bench 30 20 10 Fig. 2.1 (a) Record the room temperature θ R shown on the thermometer in Fig. 2.1. θ R = ......................................................... [1] (b) The student pours a volume of 200 cm3 of hot water into the beaker and records the temperature θ of the water at time t = 0. She records the temperature of the water in the beaker every 30 s. She pours the water out and pours a volume of 75 cm3 of hot water into the beaker. The student repeats the temperature measurements for this volume of water. (i) Describe two precautions that can be taken to ensure that temperature readings in the experiment are as accurate as possible. 1 ........................................................................................................................................ ........................................................................................................................................... 2 ........................................................................................................................................ ........................................................................................................................................... [2] (ii) Her readings are shown in Table 2.1. Add units to the column headings in Table 2.1. Table 2.1 beaker beaker with 200 cm3 of hot water with 75 cm3 of hot water t / θ/ θ/ 0 87.5 85.5 30 85.5 82.0 60 84.0 78.5 90 82.5 75.0 120 81.0 72.0 150 80.0 69.5 180 79.0 67.0 [1] (c) Write a conclusion stating how the volume of water affects the rate of cooling of the water. Justify your answer by reference to the results. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (d) (i) Using the values for 75 cm3 of water, calculate the average cooling rate x1 for the first 90 s of the experiment. Use the readings from Table 2.1 and the equation θ 0 – θ90 x1 = T where T = 90 s and θ0 and θ90 are the temperatures at t = 0 and t = 90 s. Include the unit for the cooling rate. x1 = ............................................................... Using the values for 75 cm3 of water, calculate the average cooling rate x2 for the last 90 s of the experiment. Use the readings from Table 2.1 and the equation θ 90 – θ180 x2 = T where T = 90 s and θ90 and θ180 are the temperatures at t = 90 s and t = 180 s. x2 = ............................................................... [2] (ii) A student states that it is important to start the two experiments in (b) with water at the same initial temperature. Explain whether your values for x1 and x2 support this statement. ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [1] (e) Another student repeats the experiment. State two variables, other than initial water temperature, that he should control to obtain readings that are as close as possible to those in Table 2.1. 1 ................................................................................................................................................ ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... [2] [Total: 11]

Mark scheme: 2(a) 1 2(b)(i) any two suitable precautions e.g:  view scale reading perpendicularly  wait until readings stops rising  avoid thermometer touching beaker 2 2(b)(ii) s, °C both correct 1 2(c) statement matching readings in table 1 comparison of temperature changes over 180 s, matching statement 1 2(d)(i) x1 = 0.12 and x2 = 0.089 1 unit °C / s 1 2(d)(ii) explanation matching values of x1 and x2 1 2(e) any two from:  volume(s) of water  same / size / material / surface area of beaker  room temperature 2

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3 A student determines the focal length of a converging lens. illuminated object u screen lens bench Fig. 3.1 (a) The student sets up the apparatus as shown in Fig. 3.1. He sets the distance u between the illuminated object and the lens to 25.0 cm. He places the screen near the lens and moves the screen until a focused image of the illuminated object is seen on the screen. Describe a technique for obtaining an image that is as sharp as possible. ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [1] (b) The shapes of the illuminated object and the image seen on the screen are shown full size in Fig. 3.2 and Fig. 3.3. hI hO Fig. 3.2 Fig. 3.3 (i) Measure hO, the height of the illuminated object, as shown in Fig. 3.2. hO = ......................................................... cm Measure hI, the height of the image on the screen, as shown in Fig. 3.3. hI = ......................................................... cm [2] hO (ii) Calculate a value W using your measurements from (b)(i) and the equation W = . hI W = ......................................................... [1] (c) The student repeats this procedure for u = 20.0 cm, 30.0 cm, 40.0 cm, 50.0 cm and 60.0 cm. His results are shown in Table 3.1. Table 3.1 u / cm hI / cm W 20.0 5.0 0.4 30.0 2.0 1.0 40.0 1.3 1.6 50.0 0.8 2.4 60.0 0.7 2.9 Plot a graph of u / cm (y-axis) against W (x-axis). Use the results from Table 3.1. You do not need to start your axes at the origin (0, 0). Draw the best-fit line. [4] (d) (i) Determine the gradient G of the line. Show clearly on the graph how you obtained the necessary information. G = ......................................................... [1] (ii) The focal length f of the lens is numerically equal to the gradient G. Record a value of f for this experiment. f = ................................................... cm [1] (e) A student decides to continue the experiment using larger values of u. Explain why this produces less accurate values for W. ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [1] [Total: 11]

Mark scheme: 3(a) move screen slowly / back and forth 1 3(b)(i) hO = 2(.0) and hI = 3.2 1 both to nearest mm 1 3(b)(ii) W = 0.63 1 3(c) graph:  axes labelled with quantity and unit 1  appropriate scales (plots occupying at least ½ grid between plotted points) 1  plots all correct to ½ small square and precise plots 1  well-judged line and thin line 1 3(d)(i) G present and triangle method seen on graph 1 3(d)(ii) f in range 14.0 (cm) to 17.5 (cm) and to 2 or 3 significant figures 1 3(e) values of hI become very small / difficult to measure or greater % uncertainty 1

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4 A student investigates the relationship between the diameter of a wire and the electrical resistance of the wire. Plan an experiment which enables her to investigate how the diameter of a wire affects the resistance of the wire. V Resistance R is calculated from the equation R = I where V is the potential difference (p.d.) across the wire and I is the current in the wire. The apparatus available includes wires of different known diameters. In your plan: • list any additional apparatus needed • complete Fig. 4.1 to show a circuit suitable for measuring the resistance of a wire • explain briefly how to do the experiment, including the measurements to take so that the resistance can be determined • state the key variables to keep constant • draw a table, or tables, with column headings, to show how to display the readings (you are not required to enter any readings in the table) • explain how to use the readings to reach a conclusion. power supply resistance wire Fig. 4.1 .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [7]

Mark scheme: 4 MP1 apparatus: ammeter and voltmeter 1 MP2 circuit diagram: correct circuit symbols shown in correct connection 1 MP3 method: record diameter measure p.d and current repeat for new diameter 1 MP4 control variable: any one from:  length of wire  material of wire  temperature of wire 1 MP5 table: columns, with units, for diameter, p.d., current, (resistance) any variable mentioned must have correct units 1 MP6 analysis: compare readings in the table to see if change in diameter produces change in resistance plot line graph (with axes specified) 1 MP7 additional point any one from:  at least 5 sets of data taken  repeat for each value of independent variable and take average  2nd appropriate control variable stated 1

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