PHYSICS PAPER 2 - KCSE 2019 MOKASA PRE MOCK EXAMINATION

SECTION A (25 MARKS)
Answer All questions in this section in the spaces provided

1. The diagram below shows an point object O placed in front of a plane mirror
   
   Draw rays to locate the position of the image as seen by the eye E through the mirror.           (2mks)

2. The diagram below shows a soft iron ring placed between the poles of a magnet.
   
   Sketch the magnetic field pattern produced                                                                 (2mks)

3. State one advantage of a lead acid accumulator over alkaline battery. (1mk)
4. The audible frequency of a normal person ranges between 30Hz and 19.5kHz. Determine the range of wavelength of sound waves in air that this person can detect.
   (Speed of sound in air = 340m/s)                                                                                                                         (3mks)
5. Briefly explain how polarization can be overcome in a simple cell (2mks)       

6. The figure shows a magnet. Point A and B are in front of the magnet.
   
   On the axes provided, sketch a graph showing how the magnetic field strength changes    from A to B on the outside of the magnet       (2mks)
   

7. Arrange the following electromagnetic waves in order of increasing Energy. Visible light; Gamma rays; Ultra violet rays and Microwaves (1mk)
8. Chebet rubbed a glass rod with a cloth to give it a positive charge. Her effort to charge an aluminum rod using the same method didn’t work out. Explain this observation    .          
9. The figure below shows two identical pith balls A and B suspended with insulated    threads .
   
   They are separated by an insulator X. A is positively charged while B is negatively charged. The quantity of charge on B is three times the quantity of charge on A Sketch and explain on the space provided the final position of the pith balls conductor after the insulation is removed.                                                                                 (2mks)          
10. A circuit consists of a battery, a metal wire, an ammeter and a switch connected in parallel. The switch is closed and the ammeter reading noted. The metal wire is then heated while still connected to the circuit. State and explain the observations made on the ammeter reading.                                                                            (3mks)
11. The circuit below shows a student’s work in an attempt to wire three lamps in a household using three switches.
    
    
    1. Briefly explain why this is a poor connection                                                  (2mks)
    2. Redraw the circuit diagram with the right connection                                      (1mk)
12.  
    1. State one disadvantage of plane mirrors as a used in reflection.                                  (1mk)
    2. Calculate the angle between two plane mirrors when five images are formed.              (2mks) 
        
       SECTION II 55 Marks    
          
13.  
    1. State two factors that affect the capacitance of a parallel plate capacitor.                               (2mks)
    2. The figure below shows a circuit consisting of capacitors connected together.
       
       Determine;
       1. The effective capacitance.                                                                               (2mks)
       2. Charge stored by the 60µF capacitor.                                                                         (3mks)
       3. The energy stored by the 100mF capacitor.                                                      (3mks)

14.  
    1. State two conditions necessary for Ohms Law to be obeyed             2 mark
    2. State two factors affecting the resistance of a conductor.                                       2 marks
    3. You are provided with the following set of resistors; 3Ώ; 4Ώ and 6Ώ. Draw a circuit diagram that ca n give an effective resistance of 6Ώ.                                         1 marks
    4. The diagram below shows four resistors connected together in circuit.
       
       Determine;
       1. The effective resistance                                                                                               2 marks
       2. The ammeter reading                                                                                       2 marks
       3. The Voltmeter reading                                                                           `           3 marks

15.  
    1. State Lenz’s law of electromagnetic induction.                                             (1mk)
    2. The figure below shows two coils of insulated copper wires wound on a single soft iron core.
       
       One coil is connected to a battery through a switch and the other is connected to a resistor through a galvanometer. It is observed that as the switch is closed, the pointer of the galvanometer deflects momentarily. The same is observed as the switch is opened
       1. Explain why the pointer deflects momentarily.                                  (3mks)
       2. State one way of increasing the current through resistor R.               (1mk)
    3.  
       1. State two ways in which power is lost in a transformer in form of heat.            (2mk)
       2. A transformer uses 240Va.c supply to deliver 9.0A at 80.0V to a heating coil. Assuming this is an ideal transformer; calculate the current in the primary winding?   (3mks)

16.  
    1. A ray of light makes an angle of incidence i = 60^o with a flat glass surface as shown in below.
       
       Given that the critical angle for glass is 42^o determine;
       1. The refractive index of glass                                                               (2mks)
       2. The angle of refraction r                                                                     (2mks)
       3. Given that the speed of light in air 3.0 x 10⁸ m/s, find the speed of light in glass      (2mks)
    2. State the conditions necessary for total internal reflection to occur                     (2mks)
    3. A microscope is focused on a mark on a horizontal surface. A rectangular glass block 30mm thick is placed on the mark. The microscope is then adjusted 10mm upwards to bring the mark back to focus. Determine the refractive index of the glass.              (3mks)
    4. Give two effects of total internal reflection.                                                        (2mks)

17.  
    1. Define interference.             (1mk) 
    2. Water waves from a given source move from a deep to a shallow end. What effect would this have on the;
       1. Speed      (1mk)
       2. Wavelength(1mk)
    3. A biconvex lens forms an erect image twice the size of the object if the focal length of the lens is 20cm. Determine the object distance        (3mks)
    4.  
       1. In the space provided below sketch a diagram to show how long sightedness can be corrected         (1mk)
       2. The grid below shows a real object placed in front of a convex lens of focal length 16cm. On the same diagram draw appropriate rays to locate the position of its image(3mks)