Cambridge IGCSE Physics 0625 — 2021 May/June Paper 5 · Variant 3

1 In this experiment, you will investigate the behaviour of a spring and use it to determine the density of modelling clay. A stand and spring have been set up for you. Carry out the following instructions, referring to Fig. 1.1 and Fig. 1.2. clamp l spring 0 Fig. 1.1 (a) Measure the length l0 of the spring without any load. l0 = .................................................... cm [1] (b) Suspend a load of weight W = 2.0 N from the spring, as shown in Fig. 1.2. clamp spring l load Fig. 1.2 (i) Measure the stretched length l of the spring. l = .................................................... cm [1] (ii) Calculate the extension e of the spring for a load of weight W = 2.0 N. Use your values from (a) and (b)(i) and the equation e = (l – l0). e = .................................................... cm [1] (c) Remove the load from the spring. Suspend the load U, which is made of modelling clay, from the spring. Measure the stretched length lU of the spring. lU = .......................................................... cm Calculate the extension eU of the spring with load U. eU = .......................................................... cm The extension of a spring is directly proportional to the weight of the load. Use your values of W and e from (b)(ii) and your value of eU to determine the weight WU of load U. Show your working. WU = ............................................................... [2] (d) Fully immerse load U in the beaker of water, as shown in Fig. 1.3. The load U must not touch either the sides or the bottom of the beaker. clamp spring lW beaker load U bench water Fig. 1.3 Measure the stretched length lW of the spring. lW = .......................................................... cm Calculate the extension eW of the spring with load U in the water. eW = .......................................................... cm Calculate the density ρ of the modelling clay. Use your value of eU from (c), your value of e W and the equation eU ρ = × k , where k = 1.0 g / cm3. (eU – e W) ρ = .................................................... g / cm3 [2] (e) Suggest a possible source of inaccuracy in the determination of ρ in this experiment. ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [1] (f) Describe one precaution that you took when measuring the length of the spring, to ensure an accurate reading. You may draw a diagram. ................................................................................................................................................... ............................................................................................................................................. [1] (g) A student plots a graph of load against extension for the spring, to show that the two quantities are directly proportional. State how his graph line shows that load and extension are directly proportional. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... [2] [Total: 11]

Mark scheme: 1(a) sensible value to nearest mm 1 1(b)(i) suitable value > lo 1 1(b)(ii) correct calculation of e 1 1(c) lU and eU present 1 WU in range 1.0 to 1.4 and unit (N) correct working shown 1 1(d) lW < lU and eW present 1 ρ in range 1.0 to 2.0 (g / cm3) correct to 2/3 significant figures 1 1(e) any valid source of inaccuracy, e.g: part of load U is metal hanger immersed too clay wet when weight measured air holes in clay air bubbles on immersed clay 1 1(f) any valid precaution, e.g: rule close/parallel to spring eye perpendicular to reading/use set square clamp rule 1 1(g) straight line 1 through origin 1

More questions on Physical quantities and measurement techniques

2 In this experiment, you will determine the electromotive force (e.m.f.) and resistance of a cell by using a resistance wire. The circuit has been set up for you. Carry out the following instructions, referring to Fig. 2.1. power supply resistance wire A crocodile clip V resistor Fig. 2.1 (a) Close the switch. Attach the crocodile clip to the resistance wire. Adjust its position until the value V of the potential difference (p.d.) across the cell and the resistor is 5.0 V. Measure, and record in Table 2.1, the value of the current I for the cell and resistor in series. Repeat this procedure for values of V = 4.5 V, 4.0 V, 3.5 V and 3.0 V. Detach the crocodile clip from the resistance wire. Open the switch. Table 2.1 V / V I /A 5.0 4.5 4.0 3.5 3.0 [2] (b) Plot a graph of I / A (y-axis) against V / V (x-axis). Start both axes at the origin (0,0). 0 0 [4] (c) The e.m.f. E of the cell is equal to the value of V when I = 0.0 A. Determine the value of E from the graph. E = ......................................................... [1] (d) (i) Determine the gradient G of the graph. Show clearly on the graph how you obtained the necessary information. G = ......................................................... [1] 1 (ii) The value of is numerically equal to the resistance (r + R) where r is the resistance of G the cell and R = 5.0 Ω. Calculate the resistance r of the cell. r = ...................................................... Ω [1] (e) Suggest how the experiment and graph could be improved to obtain a more accurate value for e.m.f. E. ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] [Total: 11]

Mark scheme: 2(a) 1 all decreasing and < 1.00 A 1 2(b) graph: • axes labelled with quantity and unit 1 • appropriate scales (plots occupying at least 1 2 grid) 1 • plots all correct to 1 2 small square and precise plots 1 • well judged line and thin line 1 2(c) E in range 1.0 to 2.0 (V) 1 2(d)(i) G present and triangle method seen on graph 1 2(d)(ii) sensible value 1 2(e) obtain more values at other potential differences 1 start V axis at 1.0 (V) to expand scale 1

More questions on Electric circuits

3 In this experiment, you will investigate the refraction of light by a transparent block. You will determine a quantity known as the refractive index of the material of the block. Carry out the following instructions, using the separate ray-trace sheet provided. You may refer to Fig. 3.1 for guidance. hole ray-trace sheet E θ N A B 2 cm D F C eye Fig. 3.1 (a) • Place the block approximately in the centre of the ray-trace sheet. Carefully draw round the block and label the corners ABCD as indicated by Fig. 3.1. • Remove the block from the ray-trace sheet. • Draw a normal to line AB at a point N, 2 cm from A. Extend the normal downwards until it crosses the line CD. Label the point at which it crosses CD with the letter F. • Draw a line NE, as indicated by Fig. 3.1, 8 cm long and at an angle θ1 = 20°. [1] (b) • Replace the block in exactly the same position as in (a). • Place two pins, P1 and P2, on line NE, a suitable distance apart for accurate ray tracing. • Label the positions of P1 and P2. • View the images of P1 and P2 through the block from the direction indicated by the eye in Fig. 3.1. Place two pins, P3 and P4, a suitable distance apart, so that pins P3 and P4, and the images of P1 and P2, all appear exactly one behind the other. • Label the positions of P3 and P4. • Remove the block and pins from the ray-trace sheet. • Draw a line joining P3 and P4. Extend this line until it meets NF. • Label the point at which this line meets NF with the letter G. Label the point at which this line crosses CD with the letter H. • Draw a line joining points N and H. [3] (c) Measure the length a of line NH. a = .......................................................... cm Measure the length b of line GH. b = .......................................................... cm a Calculate a value n1 for the refractive index, using the equation n1= b. n1 = ............................................................... [2] (d) Draw a new line NE, as indicated by Fig. 3.1, 8 cm long and at an angle θ2 = 40°. Repeat the steps in (b). (i) Measure the length c of the new line NH. c = .......................................................... cm Measure the length d of the new line GH. d = .......................................................... cm c Calculate a second value n2 for the refractive index, using the equation n2 = d. n2 = ............................................................... [1] (ii) State whether n1 or n2 is likely to be the more accurate value. Explain your answer. statement .......................................................................................................................... explanation ........................................................................................................................ ........................................................................................................................................... [1] (e) (i) Measure the angle α, where α is the smaller angle between the line GH from (b) and the line GH from (d). α = ............................................................... [1] (ii) A student suggests that the angle α should be equal to the difference between the angle θ2 from (d) and the angle θ1 from (a). State whether your results support this suggestion. Justify your answer by reference to your results. statement .......................................................................................................................... justification ........................................................................................................................ ........................................................................................................................................... [1] (f) Suggest why different students, all carrying out this experiment carefully, may not obtain identical results. ................................................................................................................................................... ............................................................................................................................................. [1] Tie your ray-trace sheet into this booklet between pages 10 and 11. [Total: 11]

Mark scheme: 3(a) normal correct 1 3(b) θ = 20° ± 1° 1 pin separation suitable 1 all lines present and neat 1 3(c) a and b lengths correct to nearest mm 1 n1 calculation correct and in range 1.3 to 1.7 1 3(d)(i) n2 within 10% of n1 and no unit for either 1 3(d)(ii) n2 and suitable explanation: e.g. lengths are larger/less effect of errors/smaller % uncertainty 1 3(e)(i) α = 20° ± 2° 1 3(e)(ii) statement matching results and justification matching statement (‘within limits of experimental accuracy’/owtte) 1 3(f) any one of: difficult to align pins/place pins accurately pins (too) thick lines too thick 1

More questions on Light

4 A student investigates the factors affecting the deflection of a wooden strip clamped at one end. Plan an experiment which enables him to investigate how one factor affects the distance D that the free end of the wooden strip moves downwards when loads are placed on it. You are not required to carry out the experiment. The apparatus available includes: a variety of wooden strips that can be clamped as shown in Fig. 4.1 a set of masses with a hanger. In your plan, you should: • list any additional apparatus needed • state the key variables to be kept constant • explain briefly how to carry out the experiment, including how D is to be measured and any precautions that must be taken to ensure reliable results • draw a table, 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. You may add to Fig. 4.1 or draw another diagram if it helps to explain your plan. clamp wooden strip bench D Fig. 4.1 .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [7]

Mark scheme: 4 MP1 apparatus: rule or equivalent 1 MP2 method: identify independent variable detail of deflection measurement and how its measured 1 MP3 repeat for new independent variable 1 MP4 control variable: any variable appropriate to independent variable e.g. width of strip if thickness is the factor 1 MP5 table: columns, with units, for independent variable, deflection 1 MP6 analysis: compare readings in the table to see if change in factor produce change in deflection plot line graph (with axes specified) 1 MP7 additional point (one from): at least 5 sets of data taken repeat each measurement and take average 2nd appropriate control variable stated repeat experiment for different variation (e.g. different mass if thickness is factor) use of fiducial aid 1

More questions on Forces