## 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
• 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
• 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
• 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) 0.7 0.6 0.5 0.4 0.3 0.2 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
−r =  − 0.125
r = 1.25Ω
2. Determine the emf (E) of the battery. (2marks)
Emf E = V − intercept
= 2.8v

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