Physics Paper 2 Questions and Answers - Mokasa 1 Joint Pre Mocks Exams 2023

Instructions to Candidates;

• Answer ALL the questions in the spaces provided.
• Mathematical tables and electronic calculator may be used.
• Candidates should answer the questions in English.

Section A; 25 Marks

1. The diagram below shows a ray of light initially incident at an angle of 25° to the horizontal mirror at position one. While the ray is maintained in the same position, the mirror is then turned clockwise through an angle θ to position 2, where the angle between the incident and the reflected ray becomes 62°. Using the diagram, determine:
   
   1. The angle through which the reflected ray is rotated through. (2marks)
   2. Find the angle of rotation of the mirror θ (1mark)
2. The diagram below shows a simple circuit.
   
   1. State the observation made on B₁, B₂ and B₃ when both switches S₁ and S₂ are closed   (1 mark)
   2. Give reason for the above observation (1 mark)
3. The figure below shows a simple cell made of copper and zinc electrodes dipped in dilute sulphuric acid.
   
   1. Write the ionic equation for the reaction at
      1. The Zinc plate (1 mark)
      2. The Copper plate (1 mark)
   2. State the colour of the positive plate of a lead acid accumulator when it is fully charged (1 mark)
4.  
   1. A charged glass rod is brought close but not touching the cap of a lightly charged electroscope. It is observed that the leaf initially falls then rises again.
      1. State the type of charge in the electroscope (1mark)
      2. Give the explanation for the observation made (2 marks)
   2. State two uses of an electroscope (2 marks)
5. The figure below shows one method of making a magnet.
   
   1. Name the method of magnetization shown above (1 mark)
   2. Identify the resulting magnetic pole formed at X; (1 mark)
6.  
   1. Using Domain theory, explain how the above process is achieved (3 marks)
   2. Give the reason why the strength of a magnet is greatest at the poles (1 mark)
7. A student stands between two high walls at a distance 1600m from the nearest wall. Each time the student claps the hands, two echoes are heard; the first after 10s while the second follows 5 seconds later. Calculate the distance between the two high walls. (3 marks)
8. The capacitors in the circuit below are identical and initially uncharged.
   
   When switch S₁ is closed and switch S₂ left open, the voltmeter shows a reading. Explain the observation made (3marks)

Section B (55 Marks)

9. The diagram below shows a coil PQRS lying between two unlike magnetic poles A and B of an electric motor.
   
   
   1. Identify the parts labeled; (2marks)
      • X₁X₂ ……………………………………………………………………………………………..
      • C₁C₂………………………………………………………………………………………………
   2. State the role of parts A and B. (1mark)
   3. Given that the coil rotates in the direction shown, state the polarity of; (1mark)
      1. A ……………………………………………………………………………………………..
      2. B ……………………………………………………………………………………………..
   4. State the observation made when the terminals of the batteries were reversed (1mark)
   5. State two ways in which the speed of rotation of the coil PQRS can be increased. (2marks)
10.  
    1. Define the Principal focus of a convex mirror (1 mark)
    2. The Figure below (drawn to scale) shows an image; I formed by an object placed in front of a convex mirror.
       
       1. On the diagram draw appropriate rays and locate the position of the object. (3marks)
       2. From your drawing determine the magnification produced (2marks)
    3. Using a well labeled diagram, show how a parabolic mirror produces a parallel beam   (2marks)
11. In the circuit shown below a 3µF capacitor is charged from a 10V battery by connecting the switch to terminal X.
    
    1. The switch is then connected to terminal Y to charge the 1µF capacitor from the 3µF capacitor. Calculate:
       1. The energy stored initially in the 3µF capacitor (2 marks)
       2. The final potential difference across the parallel arrangement (2 marks)
       3. The total energy stored in the parallel arrangement. (2 marks)
    2. With the aid of a diagram explain how a lightning arrestor works. (3 marks)
12. The diagram below shows a ray of light from air through a series of media.
    
    Sketch the path of the refracted ray from air through all the media till it emerges in air.  (2 marks)
    1. Determine the angle of incidence at the M₂ – M₃ interface (3 marks)
    2. Determine the refractive index of M₃ with respect to M₁ (2 marks)
    3. The diagram below shows a ray of light meeting the surface of a glass prism of refractive index ³/₂ at 90°. Complete the path of light through the prism till it emerges (show all your working) (3 marks)
       
13.  
    1. The figure below shows a longitudinal wave that takes 5 ms to move from point A to B and at a speed of 320 m/s.
       
       Calculate; 
       1. The frequency of the wave (2 marks)
       2. The wavelength of the wave (2 marks)
    2. Define the term interference as used in waves (1 mark)
    3. In an experiment to observe interference patterns of light waves, a double slit is placed close to the source as shown below.
       
       
       1. State the function of the double slit, S₁ and S₂ (1mark)
       2. State and explain what is observed on the screen. (2 marks)
       3. State the observation on the screen when the slit separation S₁–S₂ is reduced. (1mark)
       4. Explain the mirage; the phenomenon which is experienced in cold polar regions during winter. (2 marks)
14.  
    1. Distinguish between electromotive force and potential difference (2 marks)
    2. Explain the function of a fuse as used in electrical appliances (2 marks)
    3. The diagram below shows a circuit with some electrical appliances connected as shown.
       
       1. Switch S₁ is closed while S₂ is open. Determine the;
          1. The ammeter reading (2 marks)
          2. The voltmeter reading (2 marks)
       2. Determine the voltmeter reading when both S1 and S2 are closed. Give a reason for your answer. (2 marks)

MARKING SCHEME

1.  
   1.  
      • Initially angle between ∠i and r = 50°
      • After rotation to 62°, 62−50°= 12°
      • Reflected ray rotated through 12°
   2. Mirror rotation = ^θ/₂ = ¹²/₂ = 6° (working must be shown)
2.  
   1. Only bulb B₁ lights, 
   2. Bulbs B₂ and B₃ are short circuted.
3.   
   1.  
      1. Zn(s) → Zn²⁺_(aq) + 2e
      2. 2H⁺_(aq) + 2e → H_2(g) 
   2. Brown
4.  
   1.  
      1. negative charge
      2. Initially negative charge is attracted and neutralised. Later on, electrons are atttracted from plate and leaf leaving them with positive charge hence leaf rises.
   2.  
      • Test for presence of charge
      • Test for sign of change
      • Test for amount of charge
      • Test for insulation properties of materials
5.  
   1. Single stroking
   2. North pole
6.  
   1.  
      • Before magnetization, domains face different directions.
      • During magnetization, domain start getting aligned to one direction
      • Magnetic saturation, all domains fully aligned in one direction
   2. Magnetic field lines at the poles are closer/ nearer and more at the poles than at the sides.
7. Speed of sound = ^2d/_t = 2 × 1600 = 320m/s
                                              10
   Distance 2x = speed × time
                        = 320 × 15
                    2x = 4800m ⇒ x = 2400m
   Total distance = 1000 + 2400
                          = 3400m
8.  
   • When switch is closed, electrons move from negative terminal to one of the plates of capacitor.
   • At the same rate, negative charge move from the opposite plate of capacitor to the positive terminal of the cell.
   • At the end equal negative and positive charge accumulate on the plates and the final voltage is equal to that of cell,no more charge moves at this maximum p.d.
9.  
   1.  
      • M - Commutator
      • N - Carbon brush
   2. Provide the radial magnetic field/ magnetic field/ flux.
   3.  
      • A - North
      • B - South
   4. Coil rotates in the opposite direction/ anticlockwise/ reverse direction
   5.  
      • Increasing the stremgth of magentic field.
      • Increasing the amount of current
      • Increasing the number of turns.
10.  
    1. Point along the principal axis where paraxial rays parallel and close to the principal axis appear to diverge from after reflection.
    2.   
       1. 
           
       2. v = 6mm ± 1
          u = 2.5mm ± 1
          ⁶/₂₅ = 0.24
          m = ^v/_u = 6.25
              = 0.24
          or
          ho = 1.8mm ± 1
          hi = 7mm
          m = ^hi/_ho = ^7.0/1.3 = 0.538
    3.  
       
11.  
    1.  
       1. E = ½CV²
              = ½ × (3×10⁻⁶) × 10² = 1.5 × 10⁻⁴J
       2. Q = CV
              = 10 × 3 × 10⁻⁶
              = 3.0 × 10⁻⁵c
          Q_T = Q₁ + Q₂
          3.0 × 10⁻⁵ = C₁V₁ = C₂V₂
          3.0 × 10⁻⁵ = V (3+1) × 10⁻⁶
          V = 7,5v
       3. E = ½C₁V₁² + ½,C₂V₂²
              = ½ × 7.5² (3+1) × 10⁻⁶
           E = 1.125 × 10⁻⁴J
    2.  
       
       
       • Opposite charge induced on spikes of arrestor.
       • Negative charge on cloud attracted to spikes hence reducing charge build up on cloud. (excess electrons ar earthed)
       • Incase of lightning discharge, arrestor provides conducting path to the earth hence minimal/ no destructions
12.  
    
    
    1.  
       
    2.  
       
    3.  
         
       n = ¹/_{sin C}
       Sin C = ¹/_1.5 = 0.6667
       Sin⁻¹ 0.6667 = 41.81°
       60° > 41.81° hence total internal reflection
13.  
    1.  
       1.  2½ wave = 5ms
          ∴ 1 wave = T = ⁵/_2.5
                             T = 2ms
          f = ¹/T 
            =     1     
               2×10⁻³
             = 500Hz 
           OR
          =     2.5     
              5×10⁻³
             = 500Hz 
       2. λ = ^v/_f = ³²⁰/₅₀₀ = 0.64m
    2. Superposition/ merging up of waves moving in same medium.
    3. 1. • Provide coherent sources
          • To cause difraction/ spreading of wave from the monochromatic source
       2. • Alternating bright and dark bands/fringes
          • Bright fringes/ spots - constructive interference
          • Dark fringes/spots - destructive interference
       3. Fringes separation increases
       4. 
          
          • Colder air has high refractive index than warmer air.
          • This causes total internal reflection in the optically dense nedium/ continuous refraction
          • Therefore the inverted image appear to be above the observe as shown.
14. 1. 
       

       e.m.f	P.d
       Voltage across the terminals of cell/ battery in an open circuit	Voltage acrosss the cell/ battery in a mclosed circuit

    2. Since its a short wire of low melting point, It melts and breaks when excess current flows through it. To protect/ safeguard electrical mappliances against damage from excess current.
    3. 1. 1. Total resistance = R₁ + R₂
                                        = 3 + 5
                                    R_T = 8Ω
                                      I = ^V/_R
                                        = ²/₈ = 0.25A
          2. V = IR
                = 0.25 × 5
                = 1.25V
       2. Voltmeter reading = 0
          S₁ short circuits the voltmeter/ voltmeter has very high resistance