2013 IJC H2 Physics P3

©IJC 2013 9646/Prelim2/03/13 [Turn over For For INNOVA JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2 in preparation for General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CLASS INDEX NUMBER PHYSICS Paper 3 Structured Questions Candidates answer on the Question Paper No Additional Materials are required 9646/03 24 September 2013 2 hours 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 on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. For Section A Answer all questions. For Section B Answer any two questions. At the end of the examination, fasten all your work securely together. The number of marks is given in the brackets [ ] at the end of each question or part question. This document consists of 23 printed pages and 1 blank page. Innova Junior College [Turn over For Examiner’s Use Section A 1 7 2 8 3 10 4 7 5 8 Section B 6 20 7 20 8 20 Significant Figures Total 80

2 ©IJC 2013 9646/Prelim2/03/13 [Turn over For Examiner’s Use For Examiner’s Use 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 Formulae uniformly accelerated motion, s v2 = ut + ½at2 = u2 + 2as work done on/by a gas, W = pV mean kinetic energy of a molecule of an ideal gas E  3 2 kT hydrostatic pressure, p = gh gravitational potential,  GM=- r displacement of particle in s.h.m., x = xo sint velocity of particle in s.h.m., v = vo cost =  22 o± x - x resistors in series, R = R1 + R2 + … resistors in parallel, 1/R = 1/R1 + 1/R2 + … electric potential V = Q/4or alternating current/voltage, x = xo sint transmission coefficient T = exp (-2kd) where k =   2 2 8π m U - E h radioactive decay, x = xo exp(-t) decay constant,  12 0.693 t

3 ©IJC 2013 9646/Prelim2/03/13 [Turn over For Examiner’s Use For Examiner’s Use Section A Answer all the questions in this section. 1 Fig. 1.1 shows a rock climber abseiling down a rock face. At the instant shown the climber is stationary. The forces acting on the climber are shown in Fig. 1.1. Fig. 1.1 (a) The rock climber in Fig. 1.1 is in equilibrium. (i) Explain why the reaction force FR by the rock face on the climber’s feet must have a horizontal component and a vertical component. [2] (ii) Draw an arrow in Fig. 1.1 to represent the reaction force FR by the rock face on the climber’s feet. [1]

4 ©IJC 2013 9646/Prelim2/03/13 [Turn over For Examiner’s Use For Examiner’s Use (b) Given that the weight of the rock climber is 590 N, and that the tension in the rope is 610 N and it acts at an angle of 20° to the vertical, calculate the magnitude of the reaction force FR and the angle it makes with the vertical. magnitude of FR = N angle of FR = [4]

5 ©IJC 2013 9646/Prelim2/03/13 [Turn over For Examiner’s Use For Examiner’s Use 2 A block of wood of mass m floats in still water as shown in Fig. 2.1. Fig. 2.1 When the block is pushed down into the water, without totally submerging it, and is then released, it bobs up and down in the water with a frequency f given by the expression √ where f is measured in Hz and m in kg. Surface water waves of speed 0.90 m s-1 and wavelength 0.30 m are then incident on the block. These cause resonance in the up-and-down motion of the block. (a) Calculate (i) the frequency of the water waves, frequency = Hz [1] (ii) the mass of the block. mass = kg [1]

6 ©IJC 2013 9646/Prelim2/03/13 [Turn over For Examiner’s Use For Examiner’s Use (b) Describe and explain what happens to the amplitude of the vertical oscillations of the block after the following changes are made independently: (i) water waves of larger amplitude are incident on the block, [2] (ii) the distance between the wave crests increases, [2] (iii) the block now bobs in oil. [2]

7 ©IJC 2013 9646/Prelim2/03/13 [Turn over For Examiner’s Use For Examiner’s Use 3 Fig. 3.1 shows the current-voltage characteristic graph for an intrinsic semiconductor X. Fig. 3.1 (a) Using relevant features of the graph in Fig. 3.1, explain how it can be deduced that the resistance of the intrinsic semiconductor X decreases with voltage. [2]

8 ©IJC 2013 9646/Prelim2/03/13 [Turn over For Examiner’s Use For Examiner’s Use (b) Using band theory, explain why the resistance decreases with voltage for intrinsic semiconductors like X. [3] (c) The intrinsic semiconductor X is included in a circuit as shown in Fig. 3.2. Fig. 3.2 It was found that the ammeter gave a reading of 90 mA and a current of 47 mA passes through the 180 Ω resistor. (i) Determine the p.d. across X. p.d. across X = V [2] X

9 ©IJC 2013 9646/Prelim2/03/13 [Turn over For Examiner’s Use For Examiner’s Use (ii) Calculate the value of the resistance of resistor R. value of R = Ω [2] (iii) Explain what can be deduced about the 9 V cell in Fig. 3.2. [1]

10 ©IJC 2013 9646/Prelim2/03/13 [Turn over For Examiner’s Use For Examiner’s Use 4 An X-ray spectrum is shown in Fig. 4.1. The current of electrons I is accelerated through a potential difference of V as measured in volts before striking the metal target M inside the X-ray tube. 0 is the minimum wavelength detected in the spectrum. Fig. 4.1. (a) Complete the table below to indicate the change (if any) in Fig. 4.1 with the new adjustments made independently to the experiment. Use one of the following terms for each answer; “ increase”, “ unchanged” or “decrease”. [3] A single change made to the experiment Minimum wavelength, 0 Wavelengths of K spectra lines V is increased I is decreased M is replaced with another metal of a lower mass number (b) (i) Show that o is given by 0 = nm [3] K spectra lines 0