Physics Paper 2 Questions and Answers - Catholic Diocese of Kakamega Mock Exams 2023

INSTRUCTIONS TO CANDIDATES:

1. This paper consists of two sections A and B.
2. Answer all questions in Section A and B in the spaces provided below all questions. 
3. All working MUST be clearly shown.
4. Non-programmable silent electronic calculators may be used.
5. Confirm to ascertain that you have all questions

SECTION A: 25 MARKS
Answer all questions in this section

1. Figure 1 shows two mirrors inclined at an angle of 60° to each other. A ray of light is incident on one mirror as shown
   
   Sketch the path of the ray to show its reflection on the two mirrors.
   (2mks)
2. Figure 3 shows the path of a ray of light CB passing from glass to air, moving along the interface BD
   
   Complete the diagram to show the path of another ray of light AB after it emerges from the glass showing the angle calculated.
   (3mks)
3. Figure 4 shows water waves moving towards an aperture bigger than the wave length of the waves.
   
   
   1. State the property of wave under investigation.
      (1mk)
   2. Show the emergence of the reflected wave after passing the opening
      (1mk)
   3. State why passing of light through narrow opening is a very rare phenomenon
      (1mk)
4. Figure 2 shows a horse - shoe magnet whose poles are labeled and two other magnets near it. Iron nails are attracted to the upper ends of the magnet as shown.
   
   Identify the poles marked X and Y.
   (2 mark)
5. A bulb is rated 100W, 240V. At what rate would it dissipate energy if it is connected to a 220V supply?
   (3marks)
6. The figure 7 below shows parts of an X-Ray tube.
   
   Use figure 7 above to answer the question that follow;
   
   1. Target T is made of a material of high melting point. Give a reason for this.
      (1mark)
   2. State one reason why oil is used for cooling instead of water.
      (1mark)
   3. What property does the material marked R has that makes it suitable for shielding?
      (1mk)
7. Differentiate between primary and secondary cells
   (1mark)
8. The figure 10 represents an oscillation taking place at a particular point while a wave in a gas passes the point. The vertical axis is labeled displacement.
   
   
   1. State what is meant by displacement in this context.
      (1mk)
   2. From the figure determine
      
      1. The period
         (1mk)
      2.  The frequency
         (1mk)
9. Figure 4 shows the table of electromagnetic. Spectrum in the increasing order of wavelengths.
   

   P	x - rays		Q	Infra - red

   
   
   1. Identify the radiation marked
      (1mark)
   2. State the application of radiation marked P
      (1mark)
10. Figure 3 below shows an object, O placed 10 cm in front of a concave mirror whose radius, C is 40 cm.
    
    On the same figure, draw a ray diagram to show the position of the image formed.
    (3marks)

SECTION B( 55MARKS)

11.  
    1. State two ways in which the speed of rotation of a motor can be increased
       (2mks)
    2. The figure 8 below shows a simple electric bell circuit
       
       
       1. Name the parts labeled.
          
          1. X
             (2marks)
          2. Y
             (2marks)
       2. When the switch is closed, the hammer hits the gong repeatedly. Explain why:
          
          1. The hammer hits the gong.
             (2marks)
          2. The hammer hits the gong repeatedly
             (2marks)
       3. If the armature is made of steel metal, it is observed that the bell will take longer to ring.
          Explain this observation.
          (1 mark)
       4. Name two adjustment should be done to the system to make it operate effectively with a lower voltage battery?
          (2mark)
12.  
    1. Two metallic spheres A,B stand in contact as shown. A positively charged rod is held near sphere A.
       
       1. Show the charge on each sphere when the metallic balls are separated and the rod is removed.
          
          (1mk)
       2. Why are the balls supported on insulated stands?
          (1mk)
    2. State two factors that determine capacitance of a parallel plate capacitor.
       (2mks)
    3. The figure shows a circuit where a battery of e.m.f 6V, a voltmeter, switches X and Y, two capacitors of capacitance 2 uF and 4 uF are connected
       
       1. Determine the charge stored in the 2F capacitor when switch X is closed and switch y is open.
          (2mks)
       2. When the switch y is finally closed and switch x is open, determine the potential difference across each capacitor.
          (2mks)
    4.  A dry cell can deliver 0.15 A when connected to an 8.0Ω resistor. When another 8.0Ω is connected in series with the first, the cell can only deliver 0.08A to the combination. Use this information to calculate:
       
       1. The internal resistance of the cell.
       2. The e.m.f of the cell.
13. The figure below shows a connection to the pin plug.
    
    
    1. Name the parts A, B and C
       (3mks)
       A -
       B -
       C -
    2. Why is the earth pin normally longer than the two pins?
       (1mk)
    3. Identify one mistake in the three pin plug
       (1mk)
    4. What is the purpose of the following?
       

       i). Fuse
       ii). Earthing

       (2mks)12 hrs
    5. A consumer has the following appliances operating in the laboratory for the times indicated in one day
       

       Appliance	Time
       1. 2 Fluorescent tubes (40W)	12 hrs
       2. one 500 W fridge	24 hrs
       3. one 3kW electric heater	3 hrs

       1. Calculate the total power of the appliances used
          (1mk)
       2. If the operating voltage is 240 V. How much current is drawn from the mains?
          (1mk)
       3. Calculate the total electrical energy consumed in 20 days, assuming the power
          Consumption per day is the same.
          (2mks)
14.  
    1. The figure 1 below represent a cathode ray oscilloscope. (C.R.O)
       
       
       1. What are the functions of parts labeled C and D.?
          (2marks)
          C -
          D - 
       2. State how electrons are produced.
          (1mark)
       3. Give a reason why the tube is evacuated.
          (1mark)
    2. Apart from thermionic emission name the other method of emitting electrons from a metal surface.
       (1mk)
    3. State two factors that affect photoelectric effect on a metal surface.
       (2mks)
    4. The graph below shows how kinetic energy varies with frequency f in an experiment using a photocell.
       
       Given the k.e max=hf-Ø determine from the graph:
       
       1. Plank constant h
          (3mks)
       2. The Constant Ø
          (2mks)
15.  
    1. Distinguish between nuclear fusion and nuclear fission.
       (1 mark)
    2. The equation below represents a nuclear reaction
       ²¹⁸ ₈₄Po → ²¹⁸ ₈₅  A + ^p_qy
       
       1. Determine the values of P and q.
          (2 marks)
    3. The figure below represents diffusion of various radiations from a radioactive source S placed in an electric field between two plates X and Y
       
       (1 mark)
       Identify the radiations marked with letters M and P.
       M
       P
       (2 marks)
    4. Given that 5g of cobalt-60 is kept in a laboratory and it has a half-life of 5 years.
       Determine the mass that will have decayed after 15 years.
       (3 marks)

MARKING SCHEME
SECTION A

1. 
   
2. n =   1  
        sin C
   n =      1     
         sin 43.6
   n = 1.581
   1  =   sin 30 
   n        Sin r
   sin r = 1.581 sin 30
   r =  52.23°
3. 1. Diffraction
   2. 
   3. Light waves have much shorter wavelength
4.  Identify the poles marked x and y
   
   X - South pole 
   Y - south pole 
5. l = P 
        V
   = 100w 
       240
   = 0.4167A
   P = VI
   =220×0.4167 
   = 91.674W
6. 
   
   1. Target T is made of a material of high melting point. Give a reason for this. (1mark)
      Most energy of the electron beam is converted into heat energy.(1mk)
   2. State one reason why oil is used for cooling instead of water
      (1mark)
      
      • Oil has higher heat capacity than water
      • Oil has higher boiling point than water.
        Insists on comparative terms (1mk)
   3. What property does the material marked R have that makes it suitable for shielding.
      High density
      (1mark)
7. Primary cells cannot be recharged after use while secondary cells can be recharged after use. 
8.  
   1. Amplitude of the wave
      1. Two seconds
      2. f = ¹ /_T = 1⁄2 = 0.5 Blz
9.  
   1. Q.- visible light
   2. sterilize medical equipment (1mark
10. Figure 3 below shows an object, O placed 10 cm in front of a concave mirror whose radius, C is 40 cm.
    
    On the same figure, draw a ray diagram to show the position of the image formed.
11.  
    1.  
       • Winding the coil on a soft iron core.
       • Using a stronger magnet
       • Increasing the number of turns of the rotating coil.
       • Increasing the amount of current
    2.  
       1.  
          1. X Soft iron core
          2. Y Soft iron armature
             (3 mks)
       2.  
          1. When the switch S is closed, the current flows through the circuit and the core becomes magnetised, the electromagnet induces magnetism in the soft iron strip (armature), which is then attracted to the poles of the electromagnet. The hammer attached to the armature thus strikes the gong.
          2. The attraction of the soft iron armature separates the contacts breaking the circuit. The magnetism in the core therefore dies off and the spring returns the armature to its original position. Contact is made again and the process is repeated.So long as the switch is closed, the hammer strikes the gong repeatedly.
       3. Steel metal takes much time to be magnetized 
       4.  
          • Reducing the contact space between the contact screw and the steel spring
          • Increase the number of turns (1mk)
12.  
    1.  
       1. 
       2. To prevent earthing
    2.  
       • Nature of dielectric
       • Distance of separation
         • Area of overlap
    3.  
       1. Q = CV
          = 2x10^-6 x 6V       substitution of Q = 1mk
          =1.2 x 10^-5C         Calculation of Q = 1mk
       2. Effective capacitance
          1. CT = 2μF +4μF
              = 6μF
             V = Q   = 1.2 x 10      = 2V
                    c        6 x 10
             P.d across each capacitor: 2V
    4.  
       1. E = IR + Ir
          E=0.15 (8) + 0.15r
          E=0.08 (16) + 0.08r E: 1.20.15r.......i)
          E:1.28+0.08r......i)
          Solving these simultaneously, we have
          0.08 = 0.07r
          r = 1.1430
       2. E 1.2 +0.15 (1.143)
          E = 1.372V
          
          
13.  
    1. A - Live wire
       B - Earthing
       C - Neutral
    2. To open the shutters in the socket
    3. wrong colours allocated to the wires
    4.  
       1. To safeguard against excess current in the circuit
       2. At zero potential, to prevent one from receiving an electric
    5.  
       1. P = (2x40W) + 500W+ 3000W
          P = 3580W
       2. P = IV
          I = ^p/_v = ^3580W/_240W
          I = 14.29 A
       3. E = {(80Wx12hrs)+(500Wx24hrs)+(3000Wx3)]-x20days
          :(960+12000+9000) x 20days
          =21.96 x 20 439.2kwh
14.  
    1.  
       1. C -Vertical deflection of beam.
          D - Horizontal deflection of beam
       2. By thermionic emission or heating the filament.
       3. To prevent lonization/energy loss by electron beam.
    2. Photoelectric effect
    3.  
       1. Nature of the metal / work function of the metal.
       2. Energy of the radiation
       3. Intensity of the radiation.
    4.  
       1. h= slope =   (1-4) x 10-¹⁹
                             1.5-2.5 x 10¹⁵
       2. Ø = hfo
          =3 x10-³⁴ x1.2 x 10¹⁵
          = 3.6 x 10-19 J
15.  
    1. Nuclear fission is the splitting of nucleus of radioactive element to release energy while nuclear fusion is the combination of two light nuclei leading to release of energy
    2.  
       1. 218 = 218+ P
              P = 0
            84 = 85+ Q 
          Q = -1
       2. Beta Particle
    3. M - Alpha particle 
       P - Gamma rays/radiation 
    4. 5→2.5→1.25→0.625g
       No. of half lifes =¹⁵/₃ 
       Mass remaining = 5 - 0.625g 
                                 = 4.375g 
       OR
       Mass decayed = 5 -0.625 = 
       N = N_o(¹/₂)^T/_t ¹/₂
       N = 5(¹/₂)¹⁵/₂
       = 5 x ¹/₈
       N = 0.625
        Mass delayed = 5 - 0.625
       = 4.375g