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

INSTRUCTIONS TO CANDIDATES:

• You are supposed to spend the first 15 minutes of the 2 ½ hours allowed for this paper reading the whole paper carefully before commencing your work.
• Marks are given for a clear record of the observation actually made, their suitability, accuracy and the use made of them.
• Candidates are advised to record their observations as soon as they are made
• Non-programmable silent electronic calculators may be used.

QUESTION 1

You are provided with the following apparatus

• One stand with the clamp and the boss
• One 100g mass
• 100cm long thread
• Two pieces of wood
• Stop watch

1. Set up the apparatus as shown below.
   
2. Adjust the length L of the thread so that L=70cm. Give the mass m a slight displacement and release so that it oscillates freely. Measure the time t for twenty oscillations and record in the table below.
3. Repeat the procedure above for other values of L as shown and complete the table.
   

   Length L (cm)	70	60	50	40	30	20
   Length L(m)
   Time for 20 oscillation
   Period T(s)
   T2(s2)

   (9 marks)
4. On the grid provided plot a graph of T²(s²) (y-axis) against L(cm)   (5 marks)
   1. Determine the slope of the graph (3 marks)
   2. Given that T² = 4π² l determine the value of the constant g (3 marks)
                                 g

QUESTION 2

You are provided with the following apparatus

• A wire mounted on a mm scale
• 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

Procedure.

1. Using the micrometer screw gauge, determine the diameter d of the wire at three different points.
   d₁=……………………………………mm, d₂=……………………………….mm, d₃……………………………… mm,
   Average d = ………………………………..m (2 marks)
2. Calculate the cross- sectional area A of the wire in m²      (2 marks)
3. Set up the circuit as shown below.
   
4. Vary the length by using the crocodile clip along the wire from (when L =0). Record the voltmeter and ammeter readings in the table below. (5 marks)
   

   Length L (cm)	80cm	60cm	40cm	20cm	0cm
   Current I (A)
   Voltage (V)

5. Plot the graph of voltage V against current I (A) (5 marks)
6. Determine the slope of the graph. (2 marks)
7. Given that V = −Ir +E,
   1. calculate the internal resistance of the cell. (2 marks)
   2. Determine the emf (E) of the battery. (2marks) 

CONFIDENTIAL

QUESTION 1

Provided the following apparatus

• One stand with the clamp and the boss
• One 100g mass
• 100cm long thread
• Two pieces of wood
• Stop watch

QUESTION 2

Provided the following apparatus

• A wire mounted on a mm scale
• 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

QUESTION 1

You are provided with the following apparatus

• One stand with the clamp and the boss
• One 100g mass
• 100cm long thread
• Two pieces of wood
• Stop watch

1. Set up the apparatus as shown below.
   
2. Adjust the length L of the thread so that L=70cm. Give the mass m a slight displacement and release so that it oscillates freely. Measure the time t for twenty oscillations and record in the table below.
3. Repeat the procedure above for other values of L as shown and complete the table.
   

   Length L (cm)	70	60	50	40	30	20
   Length L(m)	0.70	0.60	0.50	0.40	0.30	0.20
   Time for 20 oscillation  Range (36-15)	34.07	31.57	29.16	26.25	22.78	18.61
   Period T(s)  4s.f (a must)	1.704	1.579	1.458	1.313	1.139	0.9305
   T2(s2)  4s.f (a must)	2.902	2.492	2.126	1.723	1.286	0.8658

   (9 marks)
4. On the grid provided plot a graph of T²(s²) (y-axis) against L(cm)   (5 marks)
   
   
   1. Determine the slope of the graph (3 marks)
      Slope = ΔT²
                    ΔL
                = 2.5 − 1.25
                   0.6 − 0.3
                = 4.1667s²/m
   2. Given that T² = 4π² l determine the value of the constant g (3 marks)
                                 g
      slope = 4π²
                    g
      g =   4π²   
            4.1667
        = 9.475 m/s² 

QUESTION 2

You are provided with the following apparatus

• A wire mounted on a mm scale
• 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

Procedure.

1. Using the micrometer screw gauge, determine the diameter d of the wire at three different points.
   d₁=………… 0.35…………………mm, d₂=……………0.34………….mm, d₃……………0.36………… mm,
   Average d = 0.35 + 0.34 + 0.36   m (2 marks)
                                    3
                   = 0.35mm    = 3.5 × 10⁻⁴
2. Calculate the cross- sectional area A of the wire in m²      (2 marks)
   A = πr²  
      = 3.142 × (3.5 × 10⁻⁴)²  
                             2
     = 9.625 × 10⁻⁸m
3. Set up the circuit as shown below.
   
4. Vary the length by using the crocodile clip along the wire from (when L =0). Record the voltmeter and ammeter readings in the table below. (5 marks)
   

   Length L (cm)	80cm	60cm	40cm	20cm	0cm
   Current I (A)	0.25	0.30	0.40	0.60	2.0
   Voltage (V)	2.5	2.4	2.3	2.2	0.2

5. Plot the graph of voltage V against current I (A) (5 marks)
   
6. Determine the slope of the graph. (2 marks)
   Slope = ΔV
                 ΔI
             = 2.0 − 2.75
                0.65 − 0.05
             =  − 0.75
                   0.6
             = − 1.25Ω
7. Given that V = −Ir +E,
   1. calculate the internal resistance of the cell. (2 marks)
      V =  −Ir + E 
      Gradient =  −r
      −r =  − 0.125
       r = 1.25Ω
   2. Determine the emf (E) of the battery. (2marks) 
      Emf E = V − intercept
                 = 2.8v