NYJC 2023 H2 Physics 9749 P4 Answer

NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME Solution CLASS TUTOR’S NAME CENTRE NUMBER S INDEX NUMBER PHYSICS 9749/04 Paper 4 Practical 21 August 2023 2 hours 30 minutes Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions READ THESE INSTRUCTIONS FIRST Write your name, class, tutor’s name, Centre number and index number 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 a 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 on 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. Shift Laboratory For Examiner’s Use 1 / 15 2 / 6 3 / 22 4 / 12 Total / 55 This document consists of 19 printed pages. H

2 NYJC 2023 9749/04/PRELIM/23 1 In this experiment, you will investigate an electrical circuit. (a) Set up the circuit shown in Fig. 1.1, using a 15  resistor as P and a 22  resistor as Q. Fig. 1.1 K and L are crocodile clips. Place L approximately half-way along the wire. The distance between K and L is y as shown in Fig. 1.1. Record P, Q and y. P = Q = y = Close the switch. Record the ammeter reading I. I = [1] Open the switch. P Q 15  22  50.0 cm 85.2 mA Value of I with unit and in the range 0.010 A ⩽ I ⩽ 0.200 A.

3 NYJC 2023 9749/04/PRELIM/23 [Turn over (b) Change one or both of the resistors in P and Q. Record the new values of P and Q. P = Q = Close the switch. Change the position of L on the wire so that the ammeter reading is as close as possible to the value for I in (a). Record y. y = [1] Open the switch. 12  22  60.2 cm Value of y with unit and in the range 20.0–75.0 cm.

4 NYJC 2023 9749/04/PRELIM/23 (c) Repeat (b) until you have six sets of readings of P, Q and y, using different combinations of the resistors provided as P and Q. Present your results clearly. P / Ω Q / Ω y / cm PQ/(P+Q) 12 15 71.9 6.7 12 22 60.2 7.8 15 18 53.9 8.2 15 22 50.0 8.9 18 22 40.2 9.9 22 27 28.7 12.1 [5] (d) It is suggested that the quantities y, P and Q are related by the expression MPQyN PQ= − ++ where M and N are constants. Plot a suitable graph to determine M and N. 20.5 70.5gradient = 7.8112.80 6.40 − =−− M = - gradient = 7.81 cm Ω-1 y-intercept = 20.5 – (- 7.81 (12.8)) = 120 N = y-intercept = 120 cm M = N = [6] Six sets of readings of P, Q (different pairs) and y without help from the Supervisor Each column heading must contain a quantity & a unit Resistor values include the pair (15 Ω and 12 Ω) and the pair (27 Ω and 22 Ω). All values of y must be given to the nearest mm only. Values of PQ / (P + Q) must be given to 2 or 3 significant figures. Values of PQ / (P + Q) calculated correctly. Gradient: The hypotenuse of the triangle used must be greater than half the length of the drawn line. The method of calculation must be correct. Δx /Δy strictly not allowed. Both read-offs must be accurate to half a small square in both the x and y directions. Sign of gradient on answer line must match graph. y-intercept: Correct read-off from a point on the line substituted into y = mx + c. Read-off must be accurate to half a small square in both x and y directions. or Intercept read directly from the graph with read-off at x = 0, accurate to half a small square. Value of M =–candidate’s gradient and value of N = candidate’s intercept. The values must not be fractions. Units for M (e.g. m–1 or cm–1 or mm–1) and N (e.g. m or cm or mm) correctly given.

5 NYJC 2023 9749/04/PRELIM/23 [Turn over 20 25 30 35 40 45 50 55 60 65 70 75 80 6 7 8 9 10 11 12 13 14 Axes: Sensible scales must be used, no awkward scales (e.g. 3:10 or fractions). Scales must be chosen so that the plotted points occupy at least half the graph grid in both x and y directions. Scales must be labelled with the quantity that is being plotted. Scale markings should be no more than three large squares apart. Plotting of points: All observations in the table must be plotted on the grid only. Diameter of plotted points must be ⩽ half a small square (no “blobs”). Points must be plotted to an accuracy of half a small square. Line of best fit: Judge by balance of all points on the grid about the candidate’s line (at least 5 points). There must be an even distribution of points either side of the line along the full length. Allow one anomalous point only if clearly indicated by the candidate (i.e. circled or labelled). Line must not be kinked or thicker than half a small square. General trend of points on graph must be negative. y/cm PQ PQ / +

6 NYJC 2023 9749/04/PRELIM/23 (e) Theory suggests that NE MI= where E is the electromotive force (e.m.f.) of the cell. Calculate E. Give an appropriate unit. E = [1] (f) M is inversely proportional to r, the resistance per unit length of the wire taped to the meter rule, while N is the ratio of the total resistance in the circuit to r. On the graph on page 5, draw the line that would show the result obtained if the wire taped to the meter rule is changed to one made of the same material, but having a larger diameter. [1] [Total: 15] I 3 120 85.2 10 7.81 1.31 V EN IM E E − = = = Correct calculation of E with correct unit. Graph with higher gradient (and higher y-intercept if graph shows X = 0).

7 NYJC 2023 9749/04/PRELIM/23 [Turn over 2 In this experiment, you will investigate an oscillating system. (a) Place the wooden strip on the pivot, as shown in Fig. 2.1. Fig. 2.1 Adjust the position of the wooden strip on the pivot until it balances. The distance between the centre of the hole in the wooden strip and the pivot is L. Without marking the wooden strip, measure and record L. L = [1] (b) Set up the apparatus as shown in Fig. 2.2. Fig. 2.2 The distance between the bottom of the split cork and the centre of the bob is H.