Physics Paper 3 Questions and Answers - Pavement Pre-Mock Exams 2021/2022

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Instructions To The Candidates

  • Answer all the questions in the spaces provided in the question paper.
  • You are supposed to spend the first 15 minutes reading the whole paper carefully before commencing your work.
  • Marks are given for clear record of the observations accurately made, their suitability and accuracy and the use made of them.
  • Mathematical tables and electronic calculators may be used

Question 1

You are provided with the following;

  • A piece of candle
  • Plane mirror
  • Metre rule
  • A thin lens mounted on a lens holder
  • A cardboard with cross-wire at its centre
  • A piece of plasticine
  • A white screen

Proceed as follows;

  1. Set up the apparatus as shown in figure 1.
    Phys PP3 Q1a PVPM 2122
    Ensure that the candle frame is at the same height as the cross-wires. The plane mirror should also be attached to the lens as shown using a piece of cello tape. Plasticine can be used to fix the metre rule to the table.
  2. Place the cardboard with cross-wire at the centre at the O mark of the metre rule.
  3. Move the object along the metre rule until a sharp image of the cross-wire is formed alongside the object cross-wire.
    Measure the length d using the metre rule.
    d: ………………………………………………………………m (2 marks)
  4. Now arrange the candle flame, the lens the object and the screen as shown below.
    Phys PP3 Q1d PVPM 2122
  5. Adjust the distance between the lens and the object O to each of the distances given in the table. For every value of u, adjust the position of the screen until a sharp image of the cross-wires appears on the screen. Measure the value of v and record in the table.
  6. Repeat the procedure (e) above for each of the other values of u and complete the table below.
     u (cm)   35   40   45   50   55   60   70 
     v (cm)              
     uv(cm3              
     u + v (cm)               
    (7 marks)
  7.  
    1. Plot the graph of uv against u + v. (5 marks)
    2. From your graph, calculate the slope, S (2 marks)
    3. Use the graph to determine the focal length. (2 marks)
  8. How is the focal length obtained in (i) above related to d obtained in c).
    Explain your answer. (2 marks)

Question 2

PART I

You are provided with the following:

  • A spiral spring
  • One stand, one boss and one clamp
  • A metre rule
  • A stop watch
  • A set of masses
    Proceed as follows:
  1. Arrange the set-up as shown below
    Phys PP3 QTwo1a PVPM 2122
  2. Note the reading of the pointer of the spring when no mass is suspended from its hook.
    Lo = _____________________ cm (1 mark)
  3. Attach a 50g mass on the spiral spring and measure the length L of the spring with the mass 50g on the spring, slightly displace the spring downwards and note the time for 20 oscillations. Record your results in table 2 below
  4. Repeat procedure in c) above for 100g, 120g, 150g, 200g and 250g. Complete the table.
    Table 2
     Mass M(g)   50   100   120   150   200   250 
     L (cm)            
     e = L – Lo (cm)             
     time, t for 20 oscillations (s)             
     Log t            
     Log e            
    (8 marks)
  5. Plot the graph of log t against log e. (5 marks)
  6. Given that
    Log t intercept = ½ log (16π²)   Determine the value of A (2 marks)
                                             A

PART II

You are provided with the following apparatus

  • One new dry cell
  • One cell holder
  • Switch, K
  • An ammeter
  • A voltmeter
  • A variable resistor, rheostat or potentiometer
  • Seven connecting wires, at least 4 of which with crocodile clips
  • A bulb holder
  • A torch bulb 2.5V (for 2 dry cells)
  1. Set up the apparatus as shown below
    Phys PP3 QTwo2a PVPM 2122
  2. Set the ammeter reading to 0.04A, 0.06A and 0.08A using the rheostat. Get the corresponding readings and fill the table below. (3 marks)
     Current (A)   Voltage (V)   Resistance (Ω) 
      0.04    
      0.06    
      0.08    
  3. From the table, calculate the average resistance of the bulb filament. (1 mark)

CONFIDENTIAL

QUESTION 1

Provided the following apparatus

  • One stand with the clamp and the boss
  • One 100g mass
  • 100cm long thread
  • Two small pieces of wood. (0.5cm by 2cm by 5cm)
  • Stop watch

QUESTION 2

Provided the following apparatus

  • A wire mounted on a mm scale (0.35mm in diameter)
  • A voltmeter (0-3 or 0- 5.v)
  • An ammeter
  • A switch
  • Two dry cells and a cell holder.
  • Six connecting wire with at least two crocodile clips.
  • A micrometer screw gauge


MARKING SCHEME

 Q1 (i)   d = 0.20 ± 0.01 m conversion to metre; accuracy   1 mark 
 1 mark   
   (f)   
 u (cm)   35   40   45   50   55   60   70 
 v (cm)  46.7   40.0   36.0   33.3   31.4   30.0   28.0 
 uv(cm3  1635   1600   1620   1665   1727   1800   1960 
 u + v (cm)   81.7  80.0   81.0   83.3   86.4   90.0   98.0 

 5 mks

 1mk

 1mk

 g(i)  Phys PP3 Ans1g PVPM 2122

 2mks

 1mk

 1mk

 1mk

   Slope = 1600 – 0 ;
                 80 – 0
            = 20cm; ± 2

 1mk

 1mk

   Slope = Focal length;
           = 20cm;
 1 mk
 1 mk
   d is also the focal length;
if the object is placed at the principal focus, the rays emerge parallel. The rays are then reflected by the plane mirror along the same path and hence the image is next to the object cross-wire;

 1mk

 1mk

 Q2(b)  Lo = 56.2cm (accept students value);   1mk
    (d)  
 Mass M(g)   50   100   120   150   200   250 
 L (cm)  58.2   60.3   61.1   62.2   64.8   66.6 
 e = L – Lo (cm)    2.0   4.1    4.9    6.0    8.6   10.6 
 time, t for 20 oscillations (s)   6.70  8.74   9.25   10.25   11.82   13.20 
 Log t  0.8261   0.9415   0.9661   1.0107  1.0726   1.1212 
 Log e  0.3010  0.6128   0.6902   0.7782   0.9345   1.0253 

 1 mk

 2 mks

 3 mks

   Phys PP3 AnsTwo1a PVPM 2122

 1 mk

 1mk

 2mks

 1mk

  log t intercept = 0.67;
0.67 = ½ log (16π²)
                         A
log 4.677 = log (16π²) ½
                             A 
16π²) ½  = 4.677
   A 
A=7.219;

 1mk

 

 

 

 1mk

  (b)  
 Current (A)   Voltage (V)   Resistance (Ω) 
  0.04    0.15     3.75 
  0.06    0.20     3.33 
  0.08    0.30     3.75 
Readings 2mks

Resistance 1mk
 (c)  Average resistance = 3.75 + 3.33 + 3.75
                                                  3
                                = 3.61Ω;
  1 mk
                                                                                                                             GRAND TOTAL   40 MKS
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