SAJC H1 PHY P2

1 SAJC 2016 Preliminary Examinations / 8866 [Turn Over Class Index Number Name 15 ST. ANDREW’S JUNIOR COLLEGE JC 2 2016 Preliminary Examination Paper 2 PHYSICS, Higher 1 8866/02 13 th Sept 2016 2 hours READ THESE INSTRUCTIONS FIRST Write your name, index number and Civics Group 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.. Section A Answer all questions. 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 brackets [ ] at the end of each question or part question. For Examiner’s Use Paper 1 / 30 Paper 2 Section A / 40 Section B / 40 Total / 110 Percentage / 100 Grade This question paper consists of 24 printed pages including this page.

2 SAJC 2016 Preliminary Examinations / 8866 [Turn Over

3 SAJC 2016 Preliminary Examinations / 8866 [Turn Over Section A – Answer all questions in the space provided 1 (a) Fig. 1.1 Fig 1.1 is a circuit with a 25.0 V e.m.f. source that has negligible internal resistance. Switch Z is closed. (i) Show that the total effective resistance of the circuit is 12.9 . [2] (ii) Calculate the potential difference between points A and B. potential difference =…………………………V [2] (iii) State and explain how the total power dissipated would change when switch Z is left open. ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… …………………………………………………………………………………... [2] switch Z

4 SAJC 2016 Preliminary Examinations / 8866 [Turn Over 2 The graph of Fig. 2.1 shows how g, the acceleration due to gravity, varies with r, the distance from the centre of the Earth. Fig. 2.1 (a) Calculate the gradient of the graph. gradient = ……………..….…. [1] (b) State what can be inferred from the gradient of the graph calculated in (i) with regards to g and r. …………....…….……………………………………………………………………… [1]

5 SAJC 2016 Preliminary Examinations / 8866 [Turn Over 3 (a) In Fig. 3.1, there is a solenoid that causes a magnetic field of flux density, B, in the direction as shown. Describe an experiment to show how the force on a current- carrying conductor can be used to measure this magnetic flux density, B, using a current balance. Derive the expression for B. Use a diagram to support your answer. Fig 3.1 …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… B = [6] (b) In the same magnetic field in (a), electrons are projected upwards as shown in Fig. 3.2. Fig 3.2 State and explain the instantaneous direction of deflection (if any) on the electrons. ………………………………………………………………………………...…………… …………………………………………………………………………………………. [2] B solenoid B solenoid electrons

6 SAJC 2016 Preliminary Examinations / 8866 [Turn Over 4 (a) In 1887, Heinrich Hertz observed that when a metallic surface is exposed to monochromatic light, electrons ma y be emitted. He published these observations in the journal Annalen der Physik and it eventually came to be known as the photoelectric effect. (i) Sketch a graph on the axes below to show the photocurrent-potential (I-V) characteristic obtained from a photoelectric effect experiment. Indicate the stopping potential on your graph. I / A V / V [2] (ii) A student wants to increase the magnitude of the stopping potential in the experiment by increasing the intensity of the incident radiation. This suggestion was disproved in an experiment conducted in his school’s laboratory. 1. Explain why stopping potential is independent of the intensity of the incident radiation. …………………………………………………………………..…………… ………………………………………………………………………..……… ……………………………………………………………………………..… …………………………………………………………………………..... [2] 2. Sketch, on the graph in (i), the actual effect of increasing the intensity of the incident light. [1] 3. Suggest what he should change instead to achieve an increase in stopping potential. ……………………………………………………………………………[1]

7 SAJC 2016 Preliminary Examinations / 8866 [Turn Over (b) Fig. 4.1 shows a high voltage supply set up to produce energetic electrons to bombard the cool sodium gas in the discharge tube, giving rise to an emission line spectrum when the beam is passed through a diffraction grating. Fig. 4.2 shows some energy levels of the sodium atom. Given that the bombarding electrons have a kinetic energy of 3.70 eV, (i) Deduce the number of spectra lines which might be detected. number of spectra lines = …………………. [1] Fig. 4.1 Fig. 4.2 detector

8 SAJC 2016 Preliminary Examinations / 8866 [Turn Over (ii) Sketch the positions of the lines on the emission spectrum below, indicating clearly the various transitions. The line due to the transition from n = 2 to n= 1 has been drawn for you. [2] (iii) Calculate the wavelength of the light that was emitted due to the transition from n = 2 to n = 1. wavelength = ………………………. m [2] (iv) Determine the range of kinetic energy of the recoiling electrons after they have excited the sodium atoms. range = ……….… eV ≤ KE ≤ …………eV [2] 2 to 1 Increasing frequency

9 SAJC 2016 Preliminary Examinations / 8866 [Turn Over 5 Fig. 5.1a shows an alternating signal generator (with varying frequency) connected to a length of copper wire. Fig. 5.1b is ob served in the wire at a specific frequency. Fig. 5.1a Fig. 5.1b Mass M attached to the copper wire that hangs vertically has a mass of 3.00 kg. The signal generator is switched on and causes the copper wire to oscillate. The crocodile clips are moved until the length L for the maximum amplitude of oscillation is recorded as shown in Fig. 5.1b. Length L denotes the length that stationary wave is observed on the wire. Fig. 5.2 shows the variation with frequency f of length L. Fig. 5.2 L M magnet

10 SAJC 2016 Preliminary Examinations / 8866 [Turn Over (a) Derive the expression of v in term of L and f for this mode of stationary wave, where v is the speed of the wave in the wire. [2] (b) The variation between f and m is given by the expression  mg Lcf 2 1 where  and c are constants. f is the frequency when length of wire between the crocodile clips is L. The mass of the load is m. The constant  is dependent on the material of the wire used on which stationary wave is observed. An experiment is carried out to determine  . The values of f are determined at L = 40.0 cm for different values of m. Fig. 5.3 shows the readings obtained. f / Hz m / kg 2 1 kg /m 318 2.00 1.41 324 2.50 1.58 3.00 336 3.50 1.87 341 4.00 2.00 345 4.50 2.12 351 5.00 2.23 Fig. 5.3 (i) Use Fig. 5.2 to complete Fig. 5.3 for m = 3.00 kg. [1]