Prelim (H2) P4 2021 QP and Solutions

1 Civics Group Index Number Name 20S ST. ANDREW’S JUNIOR COLLEGE JC 2 2021 Preliminary Examination PHYSICS 9749/04 Paper 4 Practical 19 August 2021 2 hours 30 minutes Candidates answer on the Question Paper. Additional Materials: As listed on the Confidential Instructions. READ THESE INSTRUCTIONS FIRST Write your name, index number and Civics Group in the spaces at the top of this page. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. Answer all questions. Write your answers in the spaces provided on the question paper. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. Give details of the practical shift and laboratory where appropriate in the boxes provided. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. This question paper consists of 20 printed pages including this page. Shift Laboratory For Examiner’s Use 1 /15 2 / 6 3 /22 4 /12 Total /55

2 1 In this experiment, you will investigate combinations of resistors in an electrical circuit. Fig. 1.1 shows how resistors of resistance 68.0 Ω can be arranged to give different values of total resistance R. resistor arrangement R / Ω 68.0 136 204 34.0 22.7 45.3 102 Fig. 1.1

3 (a) Set up the circuit as shown in Fig. 1.2 with a resistor of resistance 68.0 Ω between F and G. Fig. 1.2 Record the total resistance R between F and G. R = ………………………………………………. Ω Close the switch. Record the ammeter reading I. I = ………………………………………………. A Open the switch. [1]

4 (b) Use six different arrangements of the 68.0 Ω resistors to provide six different total resistances between F and G. For each arrangement, record R and I in a table. [5] (c) It is suggested that the quantities I and R are related by the equation where E is the electromotive force (e.m.f.) of the power supply and X is the resistance of resistor X. Plot a suitable graph to determine values for E and X. E = ………………………………………………. X = ………………………………………………. [4]

5 [3]

6 (d) Comment on any anomalous data or results you may have obtained. Explain your answer. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ………………………………………………………………………………………………… [1] (e) The experiment is repeated using a power supply with double the e.m.f. On the graph grid on page 5, sketch a second graph to represent the new results. Label this graph G. [1]

7 2 In this experiment, you will experience the equilibrium of a metre rule. (a) (i) You have been provided with a metre rule with two springs attached. The distance between one end of the metre rule and the string is L, as shown in Fig. 2.1. Fig. 2.1 Measure and record L. L = ……………………………………………… [1] (ii) Calculate where n = 3. = ……………………………………………… [1]

8 (b) Set up the apparatus as shown in Fig. 2.2. Fig. 2.2 Adjust the apparatus until the horizontal distance between the centres of the rods of the clamps is equal to your value of . Adjust the heights of the bosses so that the rule is horizontal and the springs are vertical and unstretched when the rule is held in position. Gradually release the rule by lowering your hand. The rule will tilt. The angle between the rule and the horizontal is θ, as shown in Fig. 2.3. Fig. 2.3 Measure and record θ. θ = ……………………………………………… ° [1]

9 (c) Theory suggests that where  M is the mass of the metre rule given on the card  k is the spring constant of the spring system  g = 9.81 m s-2. Determine a value for k. k = ……………………………………………… [1] (d) (i) State one significant source of error in the experiment. …………………………………………………………………………………………………….. …………………………………………………………………………………………………….. ...……………………………………………………………………………………………….. [1] (ii) Suggest one improvement that could be made to the experiment and explain how this addresses the error identified in (d)(i). You may suggest the use of other apparatus or a different procedure. …………………………………………………………………………………………………….. …………………………………………………………………………………………………….. ...……………………………………………………………………………………………….. [1]

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