EJC 2025 J2 H2 PRELIM P3

©EJC 2025 9749/J2H2PRELIM/2025 [Turn over EUNOIA JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATIONS 2025 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CIVICS GROUP 2 4 - REGISTRATION NUMBER PHYSICS Longer Structured Questions 9749/03 September 2025 2 hours READ THESE INSTRUCTIONS FIRST Write your name, civics group and registration number on all the work you hand in. The use of an approved scientific calculator is expected where appropriate. Section A Answer all questions. Section B Answer one question only. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams or graphs. Do not use paper clips, highlighters, glue or correction fluid. The number of marks is given in brackets [ ] at the end of each question or part question. This document consists of 25 printed pages and 3 blank pages. For Examiner’s Use Section A Q1 13 Q2 12 Q3 9 Q4 15 Q5 11 Section B Q6 20 Q7 20 s.f. P3 Total 80

2 ©EJC 2025 9749/J2H2PRELIM/2025 Data speed of light in free space, ( )( ) 81 71 0 12 1 0 91 19 34 27 31 e 27 p 11 23 1 A 23 1 10 m s 10 H m 10 F m 10 F m 10 C 6 63 10 J s 1 3 00 4 8 85 1 36 1 60 9 11 1 67 66 10 kg 10 kg 10 kg J K mol 6 02 10 8 31 1 38 mol 10 J K c. . / e h. u. m m . . . R. N k . . G    − −− −− −− − − − − − −− − −−      = = = =   = = = = = = = =  11 2 2 2 10 N m kg m 67 81 s 6 9 . g. −− − = =  permeability of free space, permittivity of free space, elementary charge, the Planck constant, unified atomic mass constant, rest mass of electron, rest mass of proton, molar gas constant, the Avogadro constant, the Boltzmann constant, gravitational constant, acceleration of free fall,

3 ©EJC 2025 9749/J2H2PRELIM/2025 [Turn over Formulae uniformly accelerated motion, ( ) ( ) 2 22 2 0 0 22 0 12 12 0 0 0 0 0 0 1 2 1 2 2 / K / C 273 15 1 3 3 2 sin cos 1 1 1 4 sin 2 2 exp ln2 at u as V p gh Gm r T T . Nmpc V kT x x t v v t xx R / R / R / R QV r x x t B d NB r s ut v Wp t E Bn t Anvq RR xx              =+  = =− =  + = = = = − ++ = + + = = = = = − = =+ = = = = = I I I I work done on/by a gas, hydrostatic pressure, gravitational potential, temperature, pressure of an ideal gas, mean translational kinetic energy of an ideal gas molecule displacement of particle in s.h.m. velocity of particle in s.h.m. electric current, resistors in series, resistors in parallel, electric potential, alternating current/voltage, magnetic flux density due to a long straight wire magnetic flux density due to a flat circular coil magnetic flux density due to a long solenoid radioactive decay, decay constant

4 ©EJC 2025 9749/J2H2PRELIM/2025 Section A Answer all the questions in this section in the spaces provided. 1 A vertical tube of length 0.60 m is open at both ends, as shown in Fig. 1.1. Fig. 1.1 An incident sinusoidal sound wave of a single frequency travels up the tube. A stationary wave is then formed in the air column in the tube with antinodes A at both ends and a node N at the midpoint. (a) Explain how the stationary wave is formed from the incident sound wave. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ………………………………………………………………………………..………………… [3]

5 ©EJC 2025 9749/J2H2PRELIM/2025 [Turn over (b) (i) On Fig. 1.2, sketch a graph to show the variation of the amplitude of the stationary wave with height h above the bottom of the tube. [2] Fig. 1.2 (ii) On Fig. 1.3, sketch a graph to show the variation of the intensity of the stationary wave with height h above the bottom of the tube. [1] Fig. 1.3 (c) For the stationary wave, state: (i) the direction of the oscillations of an air particle at a height of 0.15 m above the bottom of the tube. ………………………………………………………………………………………...…… [1] (ii) the phase difference between the oscillations of a particle at a height of 0.10 m and a particle at a height of 0.20 m above the bottom of the tube. phase difference = ........................................................ ° [1] (iii) the phase difference between the oscillations of a particle at the top of the tube and a particle at the bottom of the tube. phase difference = ........................................................ ° [1]

6 ©EJC 2025 9749/J2H2PRELIM/2025 (d) The speed of the sound wave is 340 m s−1. Calculate the frequency of the sound wave. frequency = .................................................... Hz [2] (e) The frequency of the sound wave is gradually increased until a stationary wave is next formed. (i) Determine the frequency of this stationary wave. frequency = .................................................... Hz [1] (ii) The microphone is initially placed at the bottom of the tube and moved upwards. Determine the shortest distance from bottom of the tube when the microphone detects a displacement node. distance = ........................................................... m [1] [Total: 13]

7 ©EJC 2025 9749/J2H2PRELIM/2025 [Turn over 2 (a) A piece of resistance wire PQ of length 120 cm and diameter 1.1 mm has resistivity 1.1 × 10−6 Ω m. (i) Show that the resistance of the wire PQ is 1.4 Ω. [1] (ii) Wire PQ is now connected to a circuit as shown in Fig. 2.1 below. A voltmeter is connected to point X and Y, where X is the mid-point between PQ. Fig. 2.1 Determine the reading on the voltmeter. voltmeter reading = ……………………… V [3]

8 ©EJC 2025 9749/J2H2PRELIM/2025 (b) Two long straight parallel wires A and B carrying currents IA and IB respectively are positioned 5.0 cm apart as shown in Fig. 2.2. Currents IA and IB are directed along the same direction. Fig. 2.2 (i) Explain why the two wires are attracted to one another. ...................................................................................................................................... ...................................................................................................................................... .................................................................................................................................. [2] (ii) The currents are now replaced with alternating currents. IA is represented by the equation: IA = −3.0 cos (200πt) IB is represented by the graph shown in Fig. 2.3. Fig. 2.3 IB / A

9 ©EJC 2025 9749/J2H2PRELIM/2025 [Turn over 1. Determine the instantaneous force per unit length acting on wire A when t = 6.5 ms. force per unit length = ……………………….. N m−1 [3] 2. A diode is connected in series to wire A such it is reversed biased. Sketch in in Fig. 3.2 the graph of the attractive force per unit length acting on wire A against time t from t = 0 ms to t = 15 ms. Numerical value of the force per unit length is not required. [2] Fig. 3.2 3. The diode in (b)(ii)2. remains connected. Determine the mean power dissipated across wire A given that the resistance of wire A is 15 Ω. mean power = …………………….. W [1] [Total: 12] force per unit length / N m−1 t / ms 0 2.5 5.0 7.5 10.0 12.5 15.0

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