ACJC 2025 J2 H2 Physics Prelim P3

This paper consists of 25 printed pages Anglo-Chinese Junior College Physics Preliminary Examination Higher 2 CANDIDATE NAME CLASS CENTRE NUMBER S 3 0 0 4 INDEX NUMBER PHYSICS Paper 3 Longer Structured Questions Candidates answer on the Question Paper. No Additional Materials are required. 9749/03 3 September 2025 2 hours READ THESE INSTRUCTIONS FIRST Write your name, class 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 an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. Section A Answer all questions. Section B Answer one question only. You are advised to spend one and a half hours on Section A and half an hour on Section B. 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. For Examiners’ use only Section A 1 / 6 2 / 10 3 / 13 4 / 11 5 / 10 6 / 10 Total / 60 Section B 7 / 8 / 20 Grand Total / 80

2 Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 3 Preliminary Examination DATA AND FORMULAE Data speed of light in free space, c = 3.00  108 m s−1 permeability of free space, o = 4  10−7 H m−1 permittivity of free space, o = 8.85  10−12 F m–1 (1/(36))  10–9 F m–1 elementary charge, e = 1.60  10−19 C the Planck constant, h = 6.63  10−34 J s unified atomic mass constant, u = 1.66  10−27 kg rest mass of electron, me = 9.11  10−31 kg rest mass of proton, mp = 1.67  10−27 kg molar gas constant, R = 8.31 J K−1 mol−1 the Avogadro constant, NA = 6.02  1023 mol−1 the Boltzmann constant, k = 1.38  10−23 J K−1 gravitational constant, G = 6.67  10−11 N m2 kg−2 acceleration of free fall, g = 9.81 m s−2

3 [Turn over Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 3 Preliminary Examination Formulae uniformly accelerated motion, s = 21 2ut at+ v 2 = u 2 + 2as work done on/by a gas, W = p V hydrostatic pressure, p =  g h gravitational potential,  = − Gm r temperature T/K = T/oC + 273.15 pressure of an ideal gas p = 21 3 Nm c V  mean translational kinetic energy of an ideal gas molecule, E = 3 2 kT displacement of particle in s.h.m., x = xo sin t velocity of particle in s.h.m., v = vo cos t =   22 oxx − electric current I = Anvq resistors in series, R = R1 + R2 +  resistors in parallel, 1/R = 1/R1 + 1/R2 +  electric potential, V = 4 o Q r alternating current/voltage, x = xo sin t magnetic flux density due to a long straight wire B = 0 2 d   I magnetic flux density due to a flat circular coil B = 0 2 N r  I magnetic flux density due to a long solenoid B = 0n I radioactive decay, x = xo exp(−t) decay constant,  = 12 ln2 t

4 Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 3 Preliminary Examination For Examiner’s Use Section A Answer all the questions in the spaces provided. 1 (a) Express the unit of resistivity in SI base units. SI base units = …………………… [2] (b) Estimate the current flowing into a smartphone while it is being charged by a standard phone charger. current = …………………… A [1]

5 [Turn over Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 3 Preliminary Examination For Examiner’s Use (c) Fig. 1.1 shows a circuit set up to measure the resistance R of a resistor. Fig. 1.1 The following readings are obtained: voltmeter: V = (5.02  0.01) V ammeter: I = (0.038  0.001) A Determine the value of R together with its actual uncertainty. R = ……………………  ……………………  [3] [Total: 6]

6 Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 3 Preliminary Examination For Examiner’s Use 2 (a) State Coulomb’s law. ……………………………….….………………………………………………..…..…... …………………………….……….……………………………………………..…..…... …….……………………………………...………………………..………………..… [2] (b) State the relationship between electric field strength and electric potential. ……………………………….….………………………………………………..…..…... …….……………………………………...………………………..………………..… [1] (c) Fig. 2.1 shows two charged isolated conducting spheres. Fig. 2.1 P is a point on the line joining the centres of the spheres. Explain why it is not possible for the total electric potential and the resultant electric field to simultaneously be zero at point P. ……………………………….….………………………………………………..…..…... ……………………………….….………………………………………………..…..…... …………………………….……….……………………………………………..…..…... …….……………………………………...………………………..………………..… [2]

7 [Turn over Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 3 Preliminary Examination For Examiner’s Use (d) A conducting sphere is held midway between two vertical, parallel metal plates in a vacuum, as shown in Fig. 2.2. Fig. 2.2 Plate A is at a potential of +900 V and plate B is earthed. Points K and L are two points on the surface of the sphere. (i) On Fig. 2.2, draw field lines to represent the electric field between the sphere and the two metal plates. [2] (ii) Explain why the electric potentials at points K and L are equal. …………………………….……….………………………………………………... …………………………….……….………………………………………………... …………………………….……….………………………………………………... …….……………………………………...……………………..………………. [2] (iii) Determine the electric potential at point K. electric potential = ……………………… V [1] [Total:10]

8 Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 3 Preliminary Examination For Examiner’s Use 3 (a) State what is meant by the internal energy of a system. …………………………….……….……………………………………………….......... …….……………………………………...……………………..……………………. [1] (b) A square box of volume V contains N molecules of an ideal gas. Each molecule has mass m. Using the kinetic theory of ideal gases, it can be shown that, if all the molecules are moving with speed v at right angles to one face of the box, the pressure p exerted on the face of the box follows the expression 2pV Nmv= (equation 1) This expression leads to the formula 21 3pc = (equation 2) for the pressure p of an ideal gas, where  is the density of the gas and 2c is the mean‑square speed of the molecules. Explain how each of the following terms in equation 2 is derived from equation 1: 1 :3 ……………………………………………………...……………………………...... ………………………………………………………………...………………………….. 2c : ……………………………………………………...……………………………... ………………………………………………………………...………………………….. [2]

9 [Turn over Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 3 Preliminary Examination For