# Physics Paper 3 Questions and Answers - Form 3 Term 2 Opener Exams 2023

1. You are provided with the following;
• a rectangular glass block
• 4 optical pins
• a soft board
• a plain paper
Proceed as follows:
1. Place the glass block on the plain paper with one of the largest face upper most. Trace round the glass block using a pencil as shown below.
2. Remove the glass block and construct a normal at B. Construct an incident ray AB of angle of incidence, i = 20° .
3. Replace the glass block and trace the ray ABCD using the optical pins.
4. Remove the glass block and draw the path of the ray ABCD using a pencil. Measure length L and record it in the table below.
 Angle i° L (cm) L2 (cm2) 1/L2(cm−2) Sin2i 20 0.1170 30 0.2500 40 0.4132 50 0.5868 60 0.7500 70 0.8830
(6 marks)
5. Repeat the procedure above for the angles of incidence given.
6. Calculate the value of L2 and 1/L2 Record in the table.
7. Plot a graph of 1/L2 (y-axis) against Sin2i . (5 marks)
8. Calculate the gradient, S. (3 marks)
Given that the equation of that graph is : 1/L2 = −   1    .   Sin2i + 1/b2
n2b2
9. (Determine the 1/L2 – intercept C and the Sin2i – intercept B.
C = _______________________________________ (1 mark)
B = _______________________________________ (1 mark)
10. Calculate the value of Q given by; (2 marks)
Q = − (c/s) ÷ B
11. Hand in your constructions on the plain paper together with the answer script. (2 marks)
2. You are provided with the following;
• A pendulum bob
• Two pieces of wood
• A retort stand
• A boss
• A clamp
• A ctop watch
• A metre rule/or half metre rule
Proceed as follows;
1. Suspend a pendulum bob on a retort stand as shown below.
2. Displace the bob for a small angle. As it is oscillating time ten oscillations for every length of the string shown in the table below (9marks)
 Length, l(m) 0.4 0.6 0.8 1.0 1.2 1.4 Time ,t, for 10 oscillations(s) Periodic time, T(s) F =1/T (Hz) F2 (Hz2) 1/L(m−1)
3. Plot a graph of F2 against 1/L. (5 marks)\
4. Determine the slope,S, of the graph. (3 marks)
5. Given that the relationship between F and L is given by, F2    g    ,use the graph to determine the value of g giving its units.    ( 3marks)                                                                      4π2L

CONFIDENTIAL

1. You are provided with the following;
• a rectangular glass block
• 4 optical pins
• a soft board
• a plain paper
2. You are provided with the following;
• A pendulum bob
• Two pieces of wood
• A retort stand
• A boss
• A clamp
• A ctop watch
• A metre rule/or half metre rule

### MARKING SCHEME

Q1.

 Angle i° L (cm) L2 (cm2) 1/L2(cm−2) Sin2i 20 6.9 47.61 0.0210 0.1170 30 7.1 50.41 0.0198 0.2500 40 7.3 53.29 0.0188 0.4132 50 7.9 62.41 0.0160 0.5868 60 8.2 67.25 0.0149 0.7500 70 8.6 73.96 0.0135 0.8830

g)

h) Slope = rise
run
(0.70, 0.0152) (1.02, 0.012)

Slope =   (0.152 − 0.012) = 0.0032 = − 0.01
(0.70 − 1.02)      −0.32
i) C = 0.0224
B = 2.20
j) Q =  − 0.0222 ÷ 2.20
−0.01
= 2.24 =  1.020

Q.2

You are provided with the following;

• A pendulum bob
• Two pieces of wood
• A retort stand
• A boss
• A clamp
• A stop watch
• A metre rule/or half metre rule
• Proceed as follows;
1. Suspend a pendulum bob on a retort stand as shown below.

2.  Length, l(m) 0.4 0.6 0.8 1 1.2 1.4 Time ,t, for 10 oscillations(s) 13 15.2 18.11 20.01 22 24.14 Periodic time, T(s) 1.1 1.52 1.811 2.001 2.2 2.414 F =1/T (Hz) 0.9091 0.6579 0.5522 0.4998 0.4545 0.4143 F2 (Hz2) 0.8265 0.4328 0.3049 0.2498 0.2066 0.1716 1/L(m−1) 2.5 1.667 1.25 1 0.8333 0.7143
3. Plot a graph of  F2 against 1/L.                                                                           (5 marks)
4. Determine the slope ,S, of the graph.     (3 marks)
Change in F2            ;                =    0.25 ;
Change in 1/L
4.0 x 10-1      ;
1.6
5. Given that the relationship between  F and L is given by ,   F2  =   g  ,  use the graph to determine the value of g giving its units  .      ( 3marks)                                                                                   4π2L
s=   g
4π2 ;
g = 4 x π2 x 0.2486 ;
= 9.814m/s2

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