Physics Trial Exams Paper 2 Questions - Alliance Boys High School Mock December 2020

Instruction to candidate

• Answer all the questions in section A and B in the spaces provided
• Where necessary take - Charge of electron=1.602 X 10^-19C

FOR EXAMINER'S USE ONLY.

QUESTIONS

SECTION A (25MARKS)

1. A current of 20Ah passes through a point in a conductor in 8min. Determine the number of electrons that passed through that point in that duration (3marks)
2. Figure 1 below shows two circuits (a) and (b) in which identical cells and identical bulbs have been used
   
   
   1. Which circuit will have brightness for a longer time when switches are closed. (1mark)
   2. Give the reason for your answer in (a) above. (2mark)
3. State the purpose of manganese (IV) oxide in a dry cell (1mark)
4. The displacement between the first crest and the second trough is 90cm. Determine the speed of the wave if it has a frequency of 0.2Hz (3marks)
5. An object was located 12cm in front of a convex mirror. An identical object was placed 12cm in front of pin hole camera of length 15cm. State one similarity and two differences of the two images formed
   Similarity (1mark)
   Differences (2marks)

   Image formed by convex mirror	Image formed by pin hole camera

6. What is the purpose of gas (inert gas) in an electric bulb? (2marks)
7. A positively charged object was brought near a charged electroscope. The leaf was observed to fall then rose. State and compare the charge of the electroscope with that of the object. (2marks)
8. State two factors that affect the electrostatic force. (2marks) 
9. Figure 2 shows negatively charged spheres separated from one another. Draw the electric field pattern produced by the charge (2mark)
   
10. The figure 3 shows plane waves of different wavelengths toward an obstacle. Draw the waves past the obstacle. (2 marks)
    
11. Polonium -230 undergoes Alpha decay to give lead
    
    Determine the values of (2mks)
    A..............................
    B..............................

SECTION B (55 MARKS)

12.                            
    1. Differentiate between electromotive force and terminal potential difference. (1mark)
    2.                            
       1. Determine the ammeter reading in the figure 4 below assuming the cell has a negligible internal resistance. (3marks)
          
       2. What is the potential difference across the 20 resistor? (3marks)
       3. What assumption have you made in (a) and (b) above (1mark)
    3. Figure 5 shows capacitor connected to a DC supply
       
       Determine
       1. The charge stored in 2uF capacitor (3marks)
       2. The resultant capacitance of the arrangement. (3marks)
13. The figure 6 below shows the construction and circuit of the modern x-ray tube
    
    
    1. Indicate on the diagram the path of the x-ray beam (2 marks)
    2. Name the part marked Cand state its function. (2 marks)
    3. Name the metals used in parts A and B and state why they are suitable for the use in the tube (3marks)
    4. Why are cooling fins necessary (2 marks)
14.                        
    1. The figure 7 shows the path of a ray of light through a transparent material placed in air.
       
       If the refractive index of the material is 1.49, find angle C. (3 marks)
    2. Figure 8 shows an object, O, infront of a concave mirror and its image!
       
       
       1. On the same diagram draw appropriate ray(s) to locate focal point F (2 marks)
       2. Define the term focal plane (1mark)
    3. state two conditions for total internal reflection to occur (2 marks)
    4. Figure 9 shows a refracted ray from a transparent prism. If it has a critical angle of 42 draw the incident ray into the prism and the route followed up to emergent ray (2marks)
       
15. Figure 13 shows a graph of stopping potential (V) against frequency(f)
    
    From the graph determine
    1. The threshold wavelength. Given that C = 3.0 x 10⁸m/s (3mks)
    2. Plank's constant h (e = 1.6 x 10^-19c) (3mks)
    3. The work function of the metal in electron volts (Take change on an electron c = 1.6 x 10^-19c) (3mks)
    4. A certain electromagnetic wave of wave length 1.5 x 10^-7m causes photoelectric emission on a metal surface. If the emitted photoelectrons have 1.52 x 10^-18) of energy. Calculate their maximum kinetic energy given that the planks constant h=6.63 x 10^-34s and speed of light C = 3.0 x 10⁸m/s (3mks)
16. A transformer with primary coil of 400 turns and secondary coil of 200 turns is connected to 240V a.c. mains. Calculate
    1. The secondary voltage. (2mks)
    2. If the primary current is 3.0A and secondary current is 5.0A, what is the efficiency? (2mks)
    3. How is energy loss minimized in transformer due to 
       1. Eddy current? (1mark)
       2. Hysteresis loss? (1mark)

Figure , shows a simple generator. The coil is rotated in the clockwise direction as shown

1. Name the part labeled Y. (1mark)
2. Indicate using an arrow on the figure, the direction of the induced current as the coil passes the position shown. (1mark)
3. State two ways of increasing the magnitude of the induced current in this type of generator. (2marks)
4. On the axis provided, sketch the graph of the induced e.m.f against time. (1mk)