Physics Paper 3 Questions and Answers with Confidential - Mokasa II Joint Mock Exams 2023

INSTRUCTIONS TO CANDIDATES

• Mathematical tables and non-programmable calculators may be used.
• This paper consists of section A and section B.
• Attempt all the questions in the spaces provided.
• ALL working MUST be clearly shown.

Question 1

You are provided with the following apparatus

• An Ammeter(0-1.0A)
• A voltmeter(0-3.0V)
• A resistance wire PQ mounted on a mm scale
• Two new dry cells.
• A switch
• A cell holder
• Six connecting wires
• A jockey

Proceed with the experiment as follows

1. Set up the apparatus as shown below.
   
2. Starting with L=0.2 m, close the switch. Record the value of I, the current through the wire and V, the p.d across it. Enter your results in the table drawn below     (8 marks)
   

   L (m)	0.2	0.3	0.4	0.5	0.6	0.7
   I(A)
   p.d(V)
   R = V/I(Ω)
   I/I(A−1)

3. Repeat part (b) above for the value of L, shown in the table.
4. Record the corresponding values of I and V. Calculate the values of R and ^I/_I and enter the values in the table.
5. On the grid provided, plot graph of Ry-axis) against  ^I/_I (x-axis)     (5 marks)
6. Determine the slope, S, of your graph.      (3 marks)
7. If the graph obeys the equation:
   R = ^E/_I − r
   Determine :
   1. The value of E.     ( 1mark)
   2. The value of r.      (2 marks)
8. Draw a simple circuit you can use to determine the E.M.F of a single cell. (1 mark)

Question 2

Part A   

You are provided with the following apparatus:

• Prism
• 4 optical pins
• plain paper
• Protractor
• Soft board

1. Place the plain sheet of paper on the soft board and pin it using the office pins. Trace the triangular prism outline of the prism on the sheet of paper (use the upper part to leave space for two other outlines on the same page). Label the vertices of the outline at L, M and N. Remove the prism from the paper.
2. Measure angle A of the prism using a protractor.      (1mark)
3. On the outline at a point T near the centre of side LM draw a normal along LM. Draw a line PT at an angle of 40° to the normal as shown in the figure below.
4. Replace the prism accurately on the outline. Fix two optical pins P₁ and P₂ to define the incident ray. View P₁ and P₂ from the opposite face (MN). Insert pins P₃ and P₄ so that they appear to be in line with images of P₁ and P₂. Remove the prism and join P₃ to P₄ to give emergent ray. Extrapolate the emergent ray into the prism so as to meet the extrapolated incident ray at Q. (see the figure below).
   
5. Measure angle D the angle of deviation of the emergent ray and record in the table below .Repeat part for other angles of incidence shown in the table below. (Draw a fresh outline of the prism for each angle of incidence)     (3 marks)
   

   Angle of incidence	40°	60°	80°
   Angle of deviation

6. Determine angle D,the average value of the angle of deviation of the emergent ray     (2 marks)
7. Calculate the value of z =        (3marks)
8. What is the significance of z?
   (Attach the plain sheet of paper to your question paper and hand them in).

Part B  

You are provided with the following

• One metre rule
• Two half-metre rules
• A pair of Vernier caliper (to be shared)
• A stopwatch
• Two retort stands, two bosses and two clamps
• Two pieces of thread
• Some cellotape

Proceed as follows

1. Measure the thickness, w, of the half metre rule using the Vernier calipers provided.
   W =.......cm.......m        (1mark)
2. Clamp one metre rule horizontally on the two stands so that it is on a vertical plane. Suspend the half- metre rule so that it balances on one point as shown in the figure below. Note the balance point L as the centre of gravity of the half-metre rule.
   
   L = ...........................................(1 mark)
3. Set up the apparatus as shown in figure below such that D=2p-20cm and q=30cm. Ensure that D is kept constant throughout the experiment (use a piece of cello tape to fix the threads). Ensure also that the loops of thread on the half metre rule are made such that they can slide along the rule. This would enable the adjustments of plater in the experiment
   
   Note that the distance p is measured from the centre of the half-metre rule and q is the vertical distance between the half metre rule and the metre rule).
4. Slightly displace one end of the half metre rule towards you and the other end away from you in a horizontal plane and release so that it oscillates in the horizontal plane. Measure the time t for 10 oscillations and determine the period T of oscillations
   t = .......................................s   (1 mark)
   Period T =.........................................(2 marks)
5. Determine the constant c for the half-metre rule given that       (2marks)
   T = 100√¹/_cg
   Where g=10m/s²
6. Determine the constant k given        (2marks)

CONFIDENTIAL

QUESTION ONE

Each candidate will require the following:

• Two new dry cells
• A resistance wire labelled PQ mounted on metre rule of diameter 0.28mm
• Ammeter (0-3.0A) -
• Cell holder
• Voltmeter (0-3.0)V -
• 6 connecting wires (atleast 3 with crocodile clips)
• A switch
• A jockey

QUESTION TWO

Each candidate will require the following:

PART A

• Triangular Prism
• 4 optical pins
• plain paper
• Protractor (your own)
• Soft board
• Thumb pin
• Ruler (your own)

PART B

• One metre rule
• Two half-metre rules
• A pair of Vernier caliper (to be shared)
• A stopwatch
• Two retort stands, two bosses and two clamps
• Two pieces of thread of length 50.0 cm each
• Some cello tape

MARKING SCHEME

Question 1

(ii) 

(v)

(vi)
Δy =       8 − 2        ✓  (interval shown on graph)
Δx     4.75 − 2.26
      =   6  
          2.5
     = 2.4ΩA ✓ (with units)

(vii) 

1. E → gradient
   E = 2.4V ✓  (with units)
2. −r = y-intercept ✓
   −r = − 3.4
     r = 3.4Ω ✓ ( with units)

(viii)
 
Single cell drawn ✓½
Voltmeter across the cell ✓½

Question 2

Part A

(ii) 60° ± 2°

(v)

(vi)
42.5 + 43 + 48   (working shown)
        3
 = 44.5

(v)
z = Cos[90 − 60 + 44.5]
                          2                    ✓
               Sin ⁶⁰/₂ 
z = Cos(90 − 52.25)    ✓
             Sin 30
   = 1.5814   ✓

(vi) Refractive index of the prism  ✓

Part B

1. w = 0.36 ± 0.02cm  0.0056m
2. L = 25.3cm ± 0.6 ✓ (with units)
3.  
4. t = 15.45s
   15.45  
      10
   Period T = 1.545 seconds   ( with unts)
5. T = 10 × 0.20 √¹/_10c  ✓
   (1.545)²  =   1   
   (     2  )       10c
   C =      1       (correct substitution and working)
           5.958
   C = 0.1657m ✓   (ignore units)
6. K =   Correct substitution. Both should be same units  (cm or m)
      = 7.3053cm    (ignore units)