Cambridge IGCSE Physics 0625 — 2015 Oct/Nov Paper 6 · Variant 2

1 The class is investigating the masses of two loads, P and Q. Fig. 1.1 shows the apparatus. P Q metre rule pivot bench Fig. 1.1 (a) A student places the metre rule on the pivot at the 50.0 cm mark. He places the load P on the metre rule. He then places the load Q on the metre rule and adjusts its position so that the metre rule is as near as possible to being balanced. (i) On Fig. 1.1, measure the distance x from the centre of load P to the pivot. x = ............................................................... (ii) On Fig. 1.1, measure the distance y from the pivot to the centre of load Q. y = ............................................................... [1] (iii) Fig. 1.1 is drawn 1/10th full size. Calculate the actual distance a from the centre of load P to the pivot. Calculate the actual distance b from the pivot to the centre of load Q. Write the results in Table 1.1. [1] Table 1.1 a / cm b / cm 35.0 17.6 30.0 14.8 25.0 12.7 20.0 10.1 (b) The student repeats the procedure using different positions of P. His readings are shown in the table. Plot a graph of b / cm (y-axis) against a / cm (x-axis). [4] (c) Determine the gradient G of the graph. Show clearly on the graph how you obtained the necessary information. G = ...........................................................[2] (d) The gradient G is the ratio of the masses of the two loads P and Q. Suggest a suitable value for the mass of P in this experiment. Use this, and your value for G, to determine an estimate for the mass of Q. estimated mass of P = ............................................................... estimated mass of Q = ............................................................... [2] [Total: 10]

Mark scheme: 1 (a)(i)(ii) x = 40 mm / 4(.0) cm AND y = 19 mm / 1.9 cm both with correct unit [1] (iii) 40(.0) AND 19(.0) in first line of table [1] (b) graph: • axes both correctly labelled, right way round and with units [1] • suitable scales [1] • all plots correct to within ½ small square [1] • good best-fit line judgement, single, thin, continuous line [1] (c) triangle method using at least half candidate’s line, shown on graph [1] G = 0.41–0.52 (2–3 sig. figs. only) [1] (d) P = 20–500 g [1] Q = 2 × P (exactly) OR Q = P/G [1] [Total: 10]

More questions on Physical quantities and measurement techniques

2 The class is investigating the cooling of a thermometer bulb. Figs. 2.1 and 2.2 show the apparatus. thermometer thermometer stand water beaker Fig. 2.1 Fig. 2.2 (a) In the space in Table 2.1, record the temperature θ1 of the hot water as shown on the thermometer in Fig. 2.3. [1] Fig. 2.3 (b) A student removes the thermometer from the beaker of hot water, as shown in Fig. 2.2. She immediately starts a stopclock, and records the temperature θ1 every 10 s for 1 minute. The temperature readings are shown in Table 2.1. Table 2.1 t / θ1 / θ2 / 0 33 72 30 65 28 59 27 53 26 48 26 43 25 She then adds 100 cm3 of cold water to the water in the beaker and repeats the procedure. She records the temperature readings in the θ2 column of the table. (i) Complete the column headings in the table. (ii) Record the time readings in the table. [2] (c) (i) Using the readings in the θ1 column of the table, calculate the decrease in temperature Δθ1 in 60 s. Δθ1 = ............................................................... (ii) Using the readings in the θ2 column of the table, calculate the decrease in temperature Δθ2 in 60 s. Δθ2 = ............................................................... (iii) State the reason why Δθ2 is less than Δθ1. ........................................................................................................................................... ........................................................................................................................................... [2] (d) State a precaution that you would take when reading the thermometer scale in order to obtain reliable readings. ...............................................................................................................................................[1] (e) Suggest one reason why other students, carrying out this experiment with care, might obtain values of Δθ1 and Δθ2 different from the values in part (c). ................................................................................................................................................... ...............................................................................................................................................[1] [Total: 7]

Mark scheme: 2 (a) θ1 = 82 (°C) [1] (b) (i) s, °C, °C [1] (ii) 10, 20, 30, 40, 50, 60 [1] (c)(i)(ii) ∆θ1 = 39 (°C) AND ∆θ2 = 8 (°C) [1] (iii) temperature θ2 at time t = 0 less than θ1 [1] (d) view thermometer at right angles [1] (e) any one from: • room temperature / other environmental factor • volume / mass / quantity / amount of hot water • initial temperature of the hot water • initial temperature of the cold water • initial temperature of the water [1] [Total: 7]

More questions on Thermal properties and temperature

3 The class is investigating the combined resistance of resistors in series and parallel arrangements. The circuit is shown in Fig. 3.1. power supply A A B C Y X V Fig. 3.1 (a) (i) Record the potential difference V1 across the resistors and the current I1 in the circuit, as shown in Figs. 3.2 and 3.3. 1 2 0 3 V Fig. 3.2 V1 = ............................................................... 0.4 0.6 0.2 0.8 0 1.0 A Fig. 3.3 I1 = ............................................................... [2] V1 (ii) Calculate the combined resistance R1 of the resistors using the equation R1 = . I1 R1 = ...........................................................[1] (b) A student rearranges the circuit shown in Fig. 3.1. He follows these instructions: • Disconnect resistors A and B. • Connect together the resistors A and B in parallel. • Connect one side of this parallel combination to the resistor C at the point labelled Y in Fig. 3.1. • Connect the other side of the parallel combination to the point labelled X in Fig. 3.1. • Do not make any other changes to the circuit. On Fig. 3.4, complete the diagram of this new circuit using standard circuit symbols. power supply A X Fig. 3.4 [2] (c) Using the new circuit, a student measures the potential difference V2 across the three resistors and the current I2 in the circuit. V2 = ................................................................2.1 V I2 = ................................................................0.69 A V2 (i) Calculate the combined resistance R2 of the resistors using the equation R2 = . I2 R2 = ............................................................... R1 (ii) Calculate the ratio . R2 R1 = ............................................................... R2 [2] (d) R1 should equal 2 × R2 when all three resistors are identical. State whether the results indicate that the resistors are identical. Justify your answer by reference to the results. statement .................................................................................................................................. justification ................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... [2] [Total: 9]

Mark scheme: 3 (a) (i) V1 = 2(.0) (V) [1] I1 = 0.32 (A) [1] (ii) R1 = 6.25 (Ω) OR e.c.f. (i) AND correct units V, A, Ω in (i) and (ii) [1] (b) correct arrangement of resistors [1] correct position for voltmeter AND correct circuit symbols AND correct labelling of resistors A, B and C [1] (c) (i) 3.0 / 3.04 / 3.043 (Ω) [1] (ii) 2.1 / 2.05 / 2.06 / 2.07 / 2.08 OR e.c.f. AND no unit [1] (d) statement matches results [1] justification including the idea of within (or beyond) the limits of experimental accuracy [1] [Total: 9]

More questions on Electrical quantities

4 The class is investigating reflection using a plane mirror. Fig. 4.1 shows a student’s ray-trace sheet. M R P3 P4 ray-trace eye sheet Fig. 4.1 (a) The student draws the line MR to mark the position of a plane mirror. (i) On Fig. 4.1, draw a normal to this line that passes through its centre. Label the normal NL. Label the point at which NL crosses MR with the letter A. (ii) Draw a line 8.0 cm long from A at an angle of incidence i = 30 ° to the normal, below MR and to the left of the normal. Label the end of this line B. [3] (b) The student places a pin P1 at point B. She places a second pin P2 on line AB. Label a position X on line AB to show a suitable position for pin P2. [1] (c) She views the images of pins P1 and P2 from the direction indicated by the eye in Fig. 4.1. She places two pins P3 and P4, some distance apart, 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 in Fig. 4.1. (i) Draw the line joining the positions of P3 and P4. Extend the line until it meets NL. (ii) Measure the angle r between NL and the line joining the positions of P3 and P4. r = ............................................................... [2] (d) State two precautions that you would take with the pins in this experiment in order to obtain reliable readings. 1. ............................................................................................................................................... ................................................................................................................................................... 2. . .............................................................................................................................................. ................................................................................................................................................... [2] (e) The student turns the ray-trace sheet through 180 °. She draws a line AC at an angle of incidence i = 30 ° to the normal, below MR and to the right of the normal. She repeats the procedure described in parts (b) and (c). Her ray-trace is shown in Fig. 4.2. L B R M A reflecting surface C N ray-trace sheet eye Fig. 4.2 She carried out the experiment very carefully. She expected that the results would show all the incident rays and reflected rays meeting at point A. Suggest a practical reason why the lines may not meet exactly at point A. ................................................................................................................................................... ...............................................................................................................................................[1] [Total: 9]

Mark scheme: 4 (a)(i)(ii) ray-trace: • normal drawn at centre of MR [1] • incident ray at 30° (± 1°) [1] • incident ray 8.0 cm long [1] (b) P1P2 distance ⩾ 5 cm apart [1] (c) (i) all lines correctly drawn AND all lines single, thin, continuous lines [1] (ii) r = 27(°)–30(°) [1] (d) any two from: • ensure pins are vertical / view bases of pins • pins far apart (or ⩾ 5 cm) • thin lines / sharp pencil / thin pins [2] (e) any one from: • thickness of mirror / mirror glass silvered at back surface • thickness of pins • difficulty in lining up pins (and their images exactly) [1] [Total: 9]

More questions on Light

5 The class is investigating the motion of a small steel ball when it is dropped on to a tray full of sand. Fig. 5.1 shows the apparatus. steel ball sand Fig. 5.1 (a) A student is measuring the time it takes for the steel ball to fall through 2.00 m on to the sand. He uses a stopwatch. Suggest a cause of inaccuracy in the timing. ................................................................................................................................................... ...............................................................................................................................................[1] (b) When the steel ball falls into the sand it creates a circular hole. Suggest how you would measure the diameter of the hole as reliably as possible. Name the measuring device that you would use. You may draw a diagram. ................................................................................................................................................... ................................................................................................................................................... ...............................................................................................................................................[2] (c) The student suggests that the diameter of the hole depends on the height from which the ball is dropped, because this affects the speed. Suggest two other variables on which the size of the hole may depend. 1. ............................................................................................................................................... 2. ............................................................................................................................................... [2] [Total: 5]

Mark scheme: 5 (a) (human) reaction time [1] (b) ruler or metre rule [1] repeat for different diameters around the hole [1] (c) any two from: • size / mass / weight / volume / diameter / density of ball • size of the sand grains / type of sand / nature of the sand • dampness / depth of sand [2] [Total: 5]

More questions on Physical quantities and measurement techniques