2023 JPJC Prelim H2 Phy P2

2023/JPJC/Prelim/9749/02 [Turn over Data READ THESE INSTRUCTIONS FIRST Write your name, class and index number on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. 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 document consists of 23 printed pages and 1 blank page. For Examiner’s Use 1 / 9 2 / 9 3 / 11 4 / 9 5 / 10 6 / 10 7 / 22 Total / 80 JURONG PIONEER JUNIOR COLLEGE JC2 Preliminary Examination 2023 PHYSICS 9749/02 Higher 2 29 August 2023 Paper 2 Structured Questions 2 hours Candidates answer on the Question Paper. No additional Materials are required. Name: _______________________________ Class: ______________

2 2023/JPJC/Prelim/9749/02 Data speed of light in free space 810 00. 3 × =c m s–1 permeability of free space 7 0 104 −× =π µ Hm–1 permittivity of free space 12 0 10 85. 8 −× =ε Fm–1 ( )( ) 910 361 −×= π Fm–1 elementary charge 1910 60. 1 −× =e C the Planck constant 3410 63. 6 −× =h J s unified atomic mass constant 2710 66. 1 −× =u kg rest mass of electron 31 e 9.11 10m −= × kg rest mass of proton 27 p 1.67 10m −= × kg molar gas constant 31. 8=R J K–1 mol–1 the Avogadro constant 23 A 6.02 10N = × mol–1 the Boltzmann constant 2310 38. 1 −× =k J K–1 gravitational constant 1110 67. 6 −× =G N m2 kg–2 acceleration of free fall 81. 9=g m s–2

3 2023/JPJC/Prelim/9749/02 [Turn over Formulae uniformly accelerated motion 2 2 1 at uts + = asu v 22 2+ = work done on/by a gas V p W∆ = hydrostatic pressure ghp ρ= gravitational potential GM rφ =− temperature /K / C 273.15TT = + pressure of an ideal gas 21 3 Nmpc V= mean translational kinetic energy of an ideal gas molecule 3 2E k T= displacement of particle in s.h.m. t x xωsin0= velocity of particle in s.h.m. t v vωcos0= 22 0 x x− ± =ω electric current Anvq=I resistors in series ...2 1+ + =R R R resistors in parallel .../ 1 / 1 / 121 + + =R R R electric potential r QV 04πε= alternating current/voltage t x xωsin0= magnetic flux density due to a long straight wire 0 2B d µ π= I magnetic flux density due to a flat circular coil 0 2 NB r µ= I magnetic flux density due to a long solenoid 0Bn µ= I radioactive decay )exp(0 t x xλ− = decay constant 1 2 ln2 tλ =

4 2023/JPJC/Prelim/9749/02 Answer all questions in the spaces provided. 1 (a) (i) Magnetic flux density B generated by a magnet may be found by determining the magnetic flux φ passing normally through an area A according to the expression φ = BA In one experiment, φ and A were determined to be (50 ± 5) µWb and (4.00 ± 0.01) × 10−4 m2 respectively. Determine the value of B along with its associated uncertainty. B = ……………….. ± ..................... T [3] (ii) Explain why the value of B cannot be more precisely determined even if the precision in the instrument used to measure A is improved. .................................................................................................................................. ............................................................................................................................. [1] (b) A n on-uniform ba r AB makes an angle of 60° w ith a horizontal surface, as shown in Fig. 1.1. Fig. 1.1 20° B A horizontal f T bar 1.2 m 36 N 60° 0.45 m

5 2023/JPJC/Prelim/9749/02 [Turn over The bar is hinged as A and is supported by a light string at B. The string is inclined at an angle of 20° to the vertical. The bar has a length of 1.2 m and a weight of 36 N. The centre of gravity of the bar is 0.45 m from A. (i) Show that the magnitude of the tension T in the string is 8.8 N. [2] (ii) A force F acts on the bar at A. Calculate the magnitude of F. F = ........................................ N [3]

6 2023/JPJC/Prelim/9749/02 2 As part of a physics lesson demonstration, a student stands between a sound speaker and a wall, such that he is 1.10 m from the speaker and 0.30 m from the wall as shown in Fig. 2.1. The speaker emits a sound wave of a single wavelength of 0.40 m. The sound wave hits the wall perpendicularly and is reflected back. Fig. 2.1 The reflection at the wall causes the wave to undergo a phase change of π rad. (a) Calculate the phase difference between the waves that come directly from the speaker and the one that is reflected back from the wall, when they meet at the student ’s location. Leave your answer in multiples of π. phase difference = ................................... rad [3] speaker student wall 1.10 m 0.30 m

7 2023/JPJC/Prelim/9749/02 [Turn over (b) The sound wave is emitted uniformly in all directions by the speaker. When the wave reaches the student directly from the speaker, it has an amplitude of 1.2 × 10−8 m. (i) Calculate the amplitude of the wave that reaches the student after reflection from the wall. State an assumption made in your calculation. amplitude = ..................................... m [2] Assumption: ............................................................................................................. ............................................................................................................................ [1] (ii) Hence calculate the amplitude of the resultant wave experienced by the student. amplitude = ................................... m [1] (c) The intensity of the sound wave that reaches the student directly from the speaker is 1.0 × 10 −6 W m−2. Calculate the intensity of the resultant wave that reaches him. intensity = .................................. W m −2 [2]

8 2023/JPJC/Prelim/9749/02 3 Fig. 3.1 shows lines joining points at the same potential in and around a pair of parallel, charged metal plates. The plates have a separation of 2.5 cm. Fig. 3.1 (a) (i) State the relation between electric field strength E and potential V. .................................................................................................................................. ........................................................................................................................... [1] (ii) By reference to Fig. 3.1, suggest why the electric field between the plates is uniform. .................................................................................................................................. ........................................................................................................................... [1] 0 V −100 V +100 V −200 V +200 V −300 V +300 V −400 V +400 V −500 V +500 V −600 V +600 V metal plate metal plate A B

9 2023/JPJC/Prelim/9749/02 [Turn over (iii) Determine the value of the electric field strength between the plates. electric field strength = ..................................... NC −1 [2] (b) On Fig. 3.1, draw six lines to represent the electric field between the plates. [2] (c) A particle moves from point