Cambridge IGCSE Physics 0625 — 2022 Oct/Nov Paper 6 · Variant 3

1 A student investigates the dimensions of a boiling tube. She uses the apparatus shown in Fig. 1.1. boiling tube initial water level h0 bench Fig. 1.1 (a) The student pours a small amount of water into the boiling tube and measures the height h0 from the bench to the initial water level. 2.6 h0 = ......................................................... cm Suggest one precaution that is taken when measuring the height of the water level to ensure the reading is accurate. You may draw a diagram if it helps your explanation. ................................................................................................................................................... ............................................................................................................................................. [1] (b) The student uses a measuring cylinder graduated in cm3 to add a volume of water V = 5.0 cm3 to the boiling tube. Part of the boiling tube, after the water has been added, is shown full size in Fig. 1.2. water boiling tube bench Fig. 1.2 Measure, and record in the first row of Table 1.1, the new height h of the water level from the bench. [1] Table 1.1 V / cm3 h / cm H / cm 5.0 10.0 5.5 2.9 15.0 6.7 4.1 20.0 8.3 5.7 25.0 9.6 7.0 (c) For the value of V = 5.0 cm3, calculate, and record in Table 1.1, the increase in height H of the water in the boiling tube. Use the value of h0 from (a), your value of h in Table 1.1 and the equation H = (h – h0). [1] (d) Plot a graph of V / cm3 (y-axis) against H / cm (x-axis). [4] (e) (i) Determine the gradient of the graph. Show clearly on the graph how you obtained the necessary information. gradient = ......................................................... [1] (ii) Calculate D, the inside diameter of the boiling tube. 4G Use the equation D = , where G is numerically equivalent to the gradient in (e)(i).  π D = .................................................... cm [1] (f) Suggest why it was important for the student to add a small volume of water at the start of the experiment. ................................................................................................................................................... ............................................................................................................................................. [1] (g) Another student uses this experiment, with the same apparatus, to measure D for a small test-tube of diameter approximately 1.2 cm. He adds water in volumes of 1.0 cm3 at a time. State and explain one reason why this is not an accurate method to use for this test-tube. ................................................................................................................................................... ............................................................................................................................................. [1] [Total: 11]

Mark scheme: Question Answer Marks 1(a) precaution for reading water level e.g.: 1 view scale perpendicularly rule close to boiling tube use of set square 1(b) h = 4.0 1 1(c) H = 1.4 / ecf from (b) 1 1(d) axes labelled with quantity and unit 1 appropriate scales (occupying at least ½ grid) 1 plots all correct to ½ small square and precise plots 1 well-judged line and thin line 1 1(e)(i) G present and triangle method shown on graph grid 1 1(e)(ii) D in range 1.9 cm to 2.4 cm 1 1(f) inside diameter near base not uniform / owtte 1 1(g) valid critical comment e.g.: 1 water volumes small – large uncertainty in measuring cylinder test-tube diameter small – large uncertainty in answer / owtte height changes small so unreliable

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2 A student performs an experiment on the cooling of water contained in a beaker. He investigates the effect of the colour of the outside surface of the beaker on the rate of cooling. He uses the apparatus shown in Fig. 2.1. Beaker A is covered with black card. Beaker B is covered with shiny metal foil. thermometer lid beaker B beaker A shiny bench black card metal foil 30 20 10 Fig. 2.1 (a) Record room temperature θR shown on the thermometer in Fig. 2.1. θR = ......................................................... [1] (b) The student pours a volume of 150 cm3 of hot water into beaker A and records the temperature θ at time t = 0. (i) Describe one precaution that can be taken to ensure that the temperature reading is as accurate as possible. ........................................................................................................................................... ..................................................................................................................................... [1] He records, in Table 2.1, the temperature of the water in the beaker every 30 s. The student repeats the process for beaker B. (ii) Add units to the column headings in Table 2.1. [1] Table 2.1 beaker A beaker B with black card with shiny metal foil t / θ/ θ/ 0 86.0 85.5 30 80.5 83.5 60 76.0 82.0 90 73.0 80.5 120 71.0 79.5 150 69.5 79.0 180 68.5 78.5 (c) Write a conclusion stating if the colour of the outside surface of the beaker affects the rate of cooling of the water in the beaker. Justify your answer by reference to values from the results. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (d) (i) Calculate the average cooling rate xA for the water in beaker A during the experiment. Use the readings for beaker A from Table 2.1 and the equation θ0 – θ180 xA = T where T = 180 s and θ0 and θ180 are the temperatures of the water in beaker A at times t = 0 and t = 180 s. Include the unit for the cooling rate. xA = ......................................................... [1] (ii) Calculate the average cooling rate xB for the water in beaker B during the experiment. Use the readings for beaker B from Table 2.1 and the equation θ0 – θ180 xB = T where T = 180 s and θ0 and θ180 are the temperatures of the water in beaker B at times t = 0 and t = 180 s. Include the unit. xB = ......................................................... [1] (e) (i) A student states that the black card is a thermal insulator. He thinks this will affect the result. Suggest an additional experiment to test this theory. ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [1] (ii) Suggest two variables which should be kept the same for the additional experiment so that the comparison with this experiment is fair. Assume that the same type of beaker is used. 1. ....................................................................................................................................... ........................................................................................................................................... 2. ....................................................................................................................................... ........................................................................................................................................... [2] (iii) State how the cooling rate of beaker A from the additional experiment is likely to compare with xA from (d)(i) if the student’s theory is correct. Explain your answer. statement .......................................................................................................................... explanation ....................................................................................................................... ........................................................................................................................................... [1] [Total: 11]

Mark scheme: 2(a) R = 22 (°C) 1 2(b)(i) suitable precaution e.g.: 1 view scale reading perpendicularly wait until reading stops rising avoid thermometer touching beaker 2(b)(ii) s, °C, °C all correct 1 2(c) statement matching readings in table – ‘beaker B cools more slowly’ / owtte 1 comparison of temperature changes over 180 s, matching statement (need to see values used in justification) 1 2(d)(i) unit °C / s 1 2(d)(ii) xA = 0.097 and xB = 0.039 1 2(e)(i) paint surfaces black OR other appropriate suggestion 1 2(e)(ii) any two suitable control variables e.g.: 2 starting / initial temperature same volume of water same room temperature 2(e)(iii) beaker A cooling rate > xA and suitable explanation 1 cooling rate of A greater than xA

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3 Some students investigate circuits containing resistors in parallel. They use the circuit shown in Fig. 3.1. All numeric answers must have appropriate units. S A P Q Fig. 3.1 (a) On Fig. 3.1, complete the circuit to show a voltmeter connected to measure the potential difference (p.d.) across the parallel combination of resistors P and Q. [1] (b) A student measures the potential difference V across the parallel combination of resistors P and Q and measures the current IT in the circuit. The readings are shown in Fig. 3.2 and Fig. 3.3. 2 3 0.4 0.6 1 4 0.2 0.8 0 5 0 1.0 V A Fig. 3.2 Fig. 3.3 (i) Read the values of V and IT shown on the meters in Fig. 3.2 and Fig. 3.3. V = ............................................................... IT = ............................................................... [2] (ii) Calculate the resistance RPQ of the parallel combination of resistors P and Q. V Use your readings from (b)(i) and the equation RPQ = . IT RPQ = ............................................................... [2] (c) The student connects the voltmeter to measure the potential difference VS across resistor S. The reading is shown in Fig. 3.4. 2 3 1 4 0 5 V Fig. 3.4 Read the value of the potential difference VS across resistor S shown in Fig. 3.4. VS = ............................................................... Calculate the resistance RS of resistor S. Vs Use your readings from (c) and (b)(i) and the equation RS = . IT RS = ............................................................... [1] (d) The student connects the ammeter to measure the current IP in resistor P. He then connects the ammeter to measure the current IQ in resistor Q. The readings are shown in Fig. 3.5 and Fig. 3.6. 0.4 0.6 0.4 0.6 0.2 0.8 0.2 0.8 0 1.0 0 1.0 A A Fig. 3.5 Fig. 3.6 (i) Read the value of the current IP in resistor P shown in Fig. 3.5. IP = ............................................................... Read the value of the current IQ in resistor Q shown in Fig. 3.6. IQ = ............................................................... [1] (ii) A student suggests that IT from (b)(i) should be equal to IP + IQ. State whether your results support this suggestion. Justify your statement by reference to values from your results. statement .......................................................................................................................... justification ........................................................................................................................ ........................................................................................................................................... ........................................................................................................................................... [2] (e) (i) A student changes the circuit and uses a variable resistor to control the current in the circuit. In the space provided, draw the circuit symbol for a variable resistor. Mark with an X on Fig. 3.1 where a variable resistor is connected to control the current in resistor S without affecting the resistance of either of the parallel branches. [1] (ii) The current in the circuit can be controlled by connecting a range of different resistors in place of resistors P and Q. State one disadvantage of this method instead of using a variable resistor to control the current. ........................................................................................................................................... ..................................................................................................................................... [1] [Total: 11]

Mark scheme: 3(a) correct voltmeter symbol in parallel with P and Q combination 1 3(b)(i) V = 1.4 (V) 1 IT = 0.76 (A) 1 3(b)(ii) RPQ = 1.8 / ecf () 1 all units correct A, V,  1 3(c) VS present 1 and both RS and RPQ to either 2 or 3 significant figures 3(d)(i) both ammeter readings present and to 2 decimal places 1 3(d)(ii) statement matching results 1 with values / comparative values seen justification – ‘within limits of experimental accuracy’ / owtte 1 3(e)(i) rectangle with strike-through arrow only 1 and X on series part of circuit 3(e)(ii) any one from: 1 cannot obtain continuous set of values less straightforward to change current more difficult to obtain a greater number of values

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4 A student investigates the effect of temperature on the bounce height of a squash ball. A squash ball is a hollow rubber ball approximately 4 cm in diameter. Plan an experiment to investigate how the bounce height of the ball changes as the temperature of the ball rises. The apparatus available includes: • a selection of squash balls • standard laboratory heating equipment • a beaker large enough for the squash ball to fit inside • a supply of cold water. In your plan, you should: • list any additional apparatus needed • explain briefly how to do the experiment, including any precautions to ensure reliable results (you may draw a diagram below if it helps to explain your plan) • state the key variables to be kept 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. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [7]

Mark scheme: 4 apparatus 1 MP1 thermometer, metre rule method 1 MP2 valid procedure: heat ball in water and measure temperature drop ball measure height ball bounces to MP3 repeat for at least 2 new temperatures 1 control variable 1 MP4 height of drop table 1 MP5 columns with units for temperature and bounce height analysis 1 MP6 compare readings in the table to see if change in temperature produces change in dependent variable OR plot line graph of temperature vs bounce height additional point 1 MP7 any one from: keep in water until sure whole ball at same temp as water use of water bath at least 5 sets of data taken repeat each measurement and take average repeat experiment for different variation (e.g. different bounce surface / height of drop) same ball / diameter of ball, bounce surface / type of floor

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