2022 RI Prelims H2 Phy Paper 3 Sect B QP

This document consists of 8 printed pages. © Raffles Institution 9749/03 [Turn over Centre Number Index Number Name Class S3016 RAFFLES INSTITUTION 2022 Preliminary Examination PHYSICS Higher 2 Paper 3 Longer Structured Questions 9749/03 21 September 2022 2 hours Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your index number, name and class in the spaces at the top of this page. Write in dark blue or black pen in the spaces provided in this booklet. You may use pencil for any diagrams or graphs. 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 and circle the question number on the cover page. You are advised to spend one and half hours on Section A and half an hour on Section B. The number of marks is given in brackets [ ] at the end of each question or part question. *This booklet only contains Section B. For Examiner’s Use Section B (circle 1 question) 7 / 20 8 / 20 Deduction

2 © Raffles Institution 9749/03 [Turn over Section B Answer one question from this Section in the spaces provided. 7 (a) Fig. 7.1 shows a stretched string connected to an oscillator at one end and a load over a smooth pulley at the other end. The length of the string between the oscillator and the pulley is L. Fig. 7.1 (i) Explain why observable stationary waves are seen on the string when the oscillator is vibrating vertically at certain discrete frequencies. [3] (ii) Show that the discrete frequencies in (a)(i) are integer multiples of 2 v L where v is the speed of the wave on the string. [1] oscillator load pulley L

3 © Raffles Institution 9749/03 [Turn over (iii) When the frequency of the oscillator is 40.0 Hz, a stationary wave with 5 nodes is seen for  0.600 mL . Calculate v. v = 1m s [2] (iv) The speed v of the wave on the string is related to the tension T in the string by vk T where k is a constant. Determine the new frequency of the oscillat or such that a stationary wave with 5 nodes is still seen on the string if the tension is decreased by 2%. new frequency = Hz [2]

4 © Raffles Institution 9749/03 [Turn over (b) (i) Fig. 7.2 shows a point source positioned a distance D from a single slit of width 0.30 mm. The point source emits monochromatic light of wavelength 600 nm. Fig. 7.2 (not to scale) 1. Show that the angle of the first minimu m of the diffraction pattern from the principal axis is 32.0 10 rad . [1] 2. Sketch on Fig. 7.3, the diffraction pattern of the light after passing through the single slit. The maximum intensity of the central bright fringe is 0I . Fig. 7.3 [2] 3. A second identical point source is placed 0.50 m beside the original point source at the same distance D from the single slit. Determine D where the two point sources are just resolved. D = m [2] D point source single slit screen principal axis0.30 mm - 6 - 4 - 2 0246 angular position / 103 rad intensity

5 © Raffles Institution 9749/03 [Turn over (ii) The second point source is now removed. An opaque film with a width of 0.10 mm is positioned at the centre of the single slit such that a double slit is formed as shown Fig. 7.4. Fig. 7.4 (not to scale) 1. Determine the separation between the two slits. separation = mm [1] 2. Besides a change in intensity, state, wi th numerical values, the other changes to the diffraction pattern observed in Fig. 7.3. [3] 3. Determine, in terms of 0I , the maximum intensity of the pattern after the film is applied. maximum intensit y = [3] point source screen principal axis double slit 0.10 mm

6 © Raffles Institution 9749/03 [Turn over 8 A uranium-238 (U) nucleus, originally at re st in a cloud chamber, undergoes spontaneous decay by emitting an -particle to form a thorium (Th) nucleus. (a) State what is meant by the number 238. [1] (b) Complete the nuclear equation below for the decay. 238 4 90UT h H e [2] (c) The -particle travels 40.0 mm in the cloud chamber to produce a track of ion-pairs which causes the -particle’s path to be visible due to condensation taking place on the ions produced. On average, an -particle produces  35.90 10 ion-pairs per mm of track in the cloud chamber and the energy required to produce an ion-pair is  182.70 10 J . (i) Show that the kinetic energy of the -particle is  136.37 10 J . [1] (ii) Determine the momentum of the thorium nucleus. momentum = N s [2]

7 © Raffles Institution 9749/03 [Turn over (iii) Determine the total kinetic energy of the -particle and the thorium nucleus. total kinetic energy = MeV [3] (iv) State an assumption you made in your calculations in (c)(ii) and (c)(iii). [1] (d) Fig. 8.1 shows the variation with nucleon number A of the nuclear binding energy per nucleon BE. The nuclear binding energy per nucleon of ur anium-238 nucleus is 7.57 MeV and that of the -particle is 7.08 MeV. Fig. 8.1 A BE

8 © Raffles Institution 9749/03 [Turn over (i) Explain the term nuclear binding energy. [1] (ii) State the nuclide with the highest BE and its BE to 2 significant figures. nuclide : BE : MeV [2] (iii) Determine the nuclear binding energy per nucleon of the thorium nucleus. binding energy per nucleon = MeV [3] (iv) On the curve in Fig. 8.1, mark the approximate positions of the nuclei of 1. uranium-238 (label the position U), 2. thorium (label the position Th), 3. -particle (label the position ). [2] (v) Nuclear fusion is a nuclear reaction that releases energy. 1. Explain the term nuclear fusion. [1] 2. One such type of nuclear fusion reaction is AB C . On Fig. 8.1, mark the approximate positions of the nuclei of A, B and C. [1] End of Paper 3 Section B