Physics Paper 2 Questions and Answers - Alliance Mock Examinations 2022

QUESTIONS
SECTION A (25MARKS)
ANSWER ALL QUESTIONS IN THIS SECTION IN THE SPACES PROVIDED

1. Figure 1 shows a candle placed in front of a plane mirror. Study the diagram and answer the question that follows
   
   Using appropriate rays, locate the position of the image of the candle as seen by the observer (2 marks)
2. Figure 2 shows a positively charged gold-leaf electroscope. Study it and answer the questions that follow
   
   State and explain what happens to the leaf when a negatively charged rod is slowly brought close to the cap but not touching it (2 marks)
3. One of the defects of simple primary cells is polarization. Explain how this defect prevents current flow in the cell (2 marks)
4. The figure shows a current carrying conductor placed in a magnetic field. Study it and answer the questions that follow
   
   Indicate on the diagram the direction of the force acting on the current carrying conductor
5. The figure shows part of an electric circuit. It is observed that the ammeter reading is 2A when the circuit is connected as shown below.
   
   State the value of the current through the 62 resistor. (1mark)
6. The figure shows two wave fronts representing the same wave. Study the diagram and answer the questions that follow
   
   Determine the velocity of the wave (3 marks)
7. The figure shows a three-pin plug with parts labeled A, B and C. Study the diagram and answer the questions that follow
   
   
   1. Name the plugs marked B (1 mark)
   2. Give two reasons why the plug marked A is longer (2 marks)
8. One advantage of using convex mirror as vehicle side mirror is that it has a wider field of view than concave mirror. State the other one advantage it has over concave mirror (1 mark)
9. Intrinsic semi-conductor can be converted to an extrinsic semi-conductor. Name the process (1 mark)
10. The figure below shows three resistors R, R2 and R3 arranged in a circuit with ammeters A1, A2 and A3.
    
    Study the diagram and answer the questions that follow
    When the resistor Ri is steadily heated, the reading of the ammeter A2 decreases while that of A3 increases. Explain this observation (2mks)
11. The figure below shows & bar magnet placed close to a coil connected to a center zero galvanometer. Study the diagram and answer the questions that follow
    
    State and explain what is observed on the pointer of the galvanometer when the bar magnet is plunged into the coil. (2marks)
12. The figure shows a standing wave formed when a string of length 3.0m stretched between two supports is plucked. Study the diagram and answer the questions that follow
    
    
    1. State how the standing wave is formed
    2. Determine the wavelength of the standing wave
13. The figure shows a nail on which a wire is to be wound to make an electromagnet
    
    By drawing show on the diagram how the wire should be wound around the nail so that the end A becomes a north pole and end B south pole

SECTION B (55MARKS)
ANSWER ALL QUESTIONS IN THIS SECTION IN THE SPACES PROVIDED

14.      
    1. The graph shows the variation of magnification and image distance v for an object placed in front of a converging lens. Study the graph and answer the questions that follow
       
       Using the equation m= ^v/_f and the graph, determine
       1. The focal length f of the lens (3 marks)
       2. The position of the cbject when the magnification is 2 (2 marks)
       3. The power of the lens (2 marks)
    2. A certain lens forms a focused image on a screen when the distance between the object and the screen is 81cm. the image size is twice that of the object
       1. State with a reason the type of lens used (2 marks)
       2. Determine the object distance (2 marks)
15.      
    1. The figure shows the displacement of a particle in a progressive wave incident on a boundary between deep and shallow regions,
       
       
       1. Complete the diagram to show what is observed after boundary. (Assume no loss of energy) (1 mark)
       2. Explain the observation in () above. (2 marks)
    2. The figure shows two loud speakers S, and S2 connected to same signal generator. Study the diagram and answer the questions that follow
       
       An observer walks along line PQ and another along the line MM for some distance.
       1. State the nature of sound along each of the paths (2 marks)
       2. Explain the observation along each of the two paths (2 marks)
    3. The output of an a.c generator was connected to the input of the cathode ray oscilloscope whose time base setting was 5 milliseconds per centimeter and the y-gain at 10 volts per centimeter, figure 10 below shows the waveform displayed on the screen of the C.R.O.
       
       Determine
       1. The peak voltage of the generator. (1 mark)
       2. The frequency of the voltage. (3marks)
16.      
    1. The figure shows a bicycle dynamo. The wheel M is connected by an axle to a permanent cylindrical magnet and is rotated by the bicycle wheel. Study the diagram and answer the questions that follow
       
       State two ways through which the brightness of the bulb can be increased in the dynamo (2 marks)
    2. The figure shows an induction coil. Study the diagram and answer the questions that follow
       
       
       1. Give the advantage of winding both the primary and secondary coil on the same soft iron core(1 mark)
       2. Name the part marked A (1mark)
       3. State the purpose of the capacitor in the circuit (1 mark)
       4. When the switch S is closed, a spark is produced between the parts marked X and Y. Explain how the spark is produced (3 marks)
       5. State one difference between induction coil and a step-up transformer (1 mark)
17.        
    1. Distinguish between fission and fusion. (1 mark)
    2. The figure below shows a decay of a certain element. The diagram is drawn to scale.
       
       From the graph determine:
       1. Half-life of the element.
       2. Number of half-lives undergone when the count rate is 10 atoms.
    3. The following is part of a radioactive decay series.
       
       Determine the value of 'a' and 'b'.
    4. The figure shows the essential component of an X-ray tube. Study it and answer the questions that follow
       
       
       1. Name the element used in making the parts labeled A
       2. State the use of the part labeled C.
       3. Explain how the X-rays are produced. (2marks)
       4. Give the reason why X-ray tube evacuated (1 mark)
18.      
    1. State one way of increasing the capacitance of a parallel plate capacitor (1 mark)
    2. The figure shows a capacitor network connected to a source of voltage. Study the diagram and answer the questions that follow:
       
       
       1. Determine the effective capacitance of the capacitor network (3 marks)
       2. Determine the charge through the 3uF capacitor (3 marks)
19.      
    1. The diagram on figure shows part of the National Grid system.
       
       
       1. State with a reason the type of transformer that is placed at the location marked X (2 marks)
       2. State two advantages of using circuit breakers in the consumer unit than using fuse wire.(2marks)
    2. Calculate the cost of using the following appliances in one month (30 days) if the company rate is Ksh.9.50 per unit.
       1. A 2000W water heater for 2 hours per day.
       2. A 75W bulb for 10 hours per day.
       3. An 1500W electric iron box for 1 hour per day (3 marks)

MARKING SCHEME

1.    
   
2.      
   • leaf falls/collapses/divergence decreases
   • negative charges are repelled to the leaf to neutralize the charges leaf will now have charges
   • the charges flow to the cap, reducing charges at the leaf
3.      
   • forms local cells whose electron flow oppose the flow of current in the main cell
   • leads to accumulation of hydrogen gas bubbles around the zinc terminal. since hydrogen gas is a poor conductor of electric current, the flow of charges is then hindered
4.    
   
5. I = 2 + 2 = 4A
6. λ = 0.02m
   F = ⁴/₃ x 0.045 = 0.06secs
   v = Fλ
   f = ¹/_0.06
   f = 16.67Hz
   v = 0.02 x 16.67
   v = 0.3333m
7.      
   1. Live
   2. To open both the neutral and live shutters
      to earth the plug to prevent electric shock
8. forms upright images regardless of object position
9. doping
10. heating increases the resistance of resistor R, and therefore less current will pass through A2 while more current from the source will pass through the ammeter A3
11. pointer of G deflect towards one direction and then go back to zero. This occurs becasue there is induced current in the wire/coil since the motion of the magnet into the coil causes changing magnet flux linking with the coil
12.        
    1. it is formed by superposition of two waves when travelling wave is reflected back along the incident path
    2. if 1.5λ = 3m
       1λ = ¹/_1.5 x 3 = 2m
13.  
    
14.    
    1.       
       1. slope = ¹/_f
          f = ¹/_slope
          slope = 3.5 - 3.0
                       45 - 40
          slope = 0.1
          f = ¹/_0.1 = 10cm
       2. at m = 2, v = 30cm
          m = ^v/_u
          2 = ³⁰/_u
          u = 15cm
       3. power = 1/focal length
          = ¹/₁₀ = 0.10
    2.    
       1. converging lens since the image is real
          divergence lens forms only virtual images
       2. u = x, v = 81 - x
          m = ^v/_u
          81 - x = 2
              x
          2x = 81 - x
          3x = 81
          x = 27cm
15.    
    1.    
       1.    
       2. velocity increases, frequency remains the same but wavelength increases. Amplitude is the same since no loss of energy
    2.    
       1. along mm, alternate soft and loud sound
          along PQ, loud sound throughout
       2. along mm, there are alternate constructive and destructive inference of sound waves. for PQ, constructive inference throughout hence loud sound
    3.    
       1. 10 volts
       2. T = 5 x 10^-3 = 40 x 10^-3secs
          f = ^I/_T = ¹/_0.04 = 250Hz
16.    
    1.  
       • using a stronger magnet
       • increasing speed of rotation of the magnet
       • increasing the number of turns in the coil
    2.    
       1. soft iron structure - to reduce magnetic flux leakage between primary and secondary
       2. minimizes sparking at the joints
       3.    
          • current in primary coil magnetizes the soft iron core
          • the armature is then attracted by the core to break the contact and cut the current. armature is pulled back to allow current flow again. charging flux induces an e.m.f in the secondary coil, which produces sparks at the gap due to a large potential in the gaps
          • primary coil in induction coil is connected to a direct current
            primary coil in a step-up transformer is connected to an a.c
17.    
    1. fission is the process where a large nucleus is split into two but equal radioactive particles. fusion is where two light particles are joined together to form a larger nuclide releasing a lot of energy
    2.    
       1. 2.9 years(accept 3)
       2. 3 half-lives (accept 2.2)
    3. a = 232
       b = 89
    4.      
       1. tungsten
       2. to cool the target material
       3.  produced when fast moving electrons produced by thermonic emission are suddenly stopped by a metal target embedded at the anode
       4. to prevent collisions between electrons and any particles before reducing the anode
18.    
    1. increasing area of overlap of plates
       decreasing the distance between the plates
    2.    
       1. parallel 4 + 6 = 10μF
          series CT = 3 x 10
                             3 + 10
          = 30/13 = 2.308μF
       2. φ = cv
          = 2.308 x 10^-6 x 24 
          = 5.5392 x 10^-5C
19.    
    1.    
       1. step-up transformer - the power is to be stepped up for transmission along the overhead cables
       2. circuit breakers do not require replacement
          circuit breakers response is instantaneous
    2. water heater = 2kw x 2 x 30 x 9.50
       = 1140
       Electric bulb = 0.075 x 10 x 30 x 9.50
       = 213.75
       iron box = 1.5 x 1 x 30 x 9.5
       = 427.5
       total costs = 1140 + 213.75 + 27.5
       = ksh1781.25