ST.

ALEXANDER NYAMECHEO SECONDARY

232/3 – PHYSICS – Paper 3

OCTOBER 2023 - 2 ½ hours

INSTRUCTIONS TO CANDIDATES
1. Write your name, index number, class, date and signature in the spaces provided above.
2. This paper consists of two questions 1 and 2.
3. Answer all questions in the spaces provided.
4. Non-programmable calculators and mathematical tables may be used.
5. Show all your workings.

QUESTION 1 a d e F g h k TOTAL

Maximum score ½ 1½ 1 3½ 2 6½ 5 20
Candidates score

QUESTION 2 C d E f i j k l TOTAL

Maximum score 2 2 1 2 4 5 2 2 20
Candidates score

This paper consists of 10 printed pages. Candidates should check the question paper to ensure
that all pages are printed as indicated and no questions are missing
QUESTION 1

1
PART A
(a) Light the candle and place it at distance u=20 cm in front of the concave mirror.
Adjust the position of the screen until a sharp image of the candle flame is obtained. See
figure 2.

Read and record the distance v between the screen and the mirror.
V=......................................................... (1mark)
(ii) Determine:
I. The magnification m of the mirror given that; (1marks)
v
M=
u

………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………………
II. The value f 1, given that; (1mark)

mu
f 1=
m+1
………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………………
(f) Repeat part (e) for distance u1=18 cm
(i) Read and record the distance V between the screen and the
mirror.
V1 = ……………………………………………………………... (1mark)
m
(ii) Determine the magnification 1 of the mirror. (1mark)
………………………………………………………………………………………………
………………………………………………………………………………………………
…………… …………………………. .……………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………

2
 (iii) Hence determine f 2, using U 1 , V 1 andm1 (1 mark)
………………………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
(g) Determine the average value of f. (2marks)

PART B
(a) Using the Vernier callipers, measure and record the diameters of the three pipes
d A , d B ∧d C .
1
d A =¿……………………cm…………………….m (1 mark)
2
1
d B=¿……………………cm…………………….m (1 mark)
2
1
d C =¿……………………cm……………………..m (1 mark)
2
(b) Measure and record the thickness X of the half metre rule.
1
X=………………………cm…………………….m (1 mark)
2
(c) Place the pipes marked A on the bench and use the plasticine to stop it from rolling. (see Figure 3
(a)).

Figure 3 (a)
(d) Place the half metre rule onto the pipes such that it balances horizontally. Ensure that the half metre
rule is perpendicular to the axis of the pipe. (see Figure 3(b)).

3
 (e) Push one end of the balance half metre rule slightly downwards and release it so that it oscillates up
and down. Measure and record in Table 3 the time for five complete oscillations.
(f) Repeat the procedure in (g), (h) and (i) for the other pipes B and C. Complete Table 3.
(4mrks)

Pipe A Pipe B Pipe C

Diameter

Time for five

Periodic time T (s)

Z=T
√ 3 (d−x )
2

(g) Determine the average value of Z. (2marks)

QUESTION 2
You are provided with the following:
- An ammeter (0 – 1 A)

4
 - A voltmeter (0 – 3 V or 0 – 5 V)
- A variable resistor
- A 10Ω carbon resistor
- A piece of resistance wire
- Two new dry cells
- A cell holder
- A switch
- Seven connecting wires

Proceed as follows:
a) Take the resistant wire and coil it around the biro pen to make a coil.
b) Set up the apparatus as shown Figure 5 below such that the 10Ω carbon resistor and the coil
are in parallel connection.
Coil

V
A

Figure 5

c) Close the switch and the adjust the variable resistor such that the ammeter read a current of
I1=0.08A and record the corresponding voltmeter reading V1
i) V1 =………………… (1mark)

ii) Calculate resistance (1mark)

d) Repeat (c) above for current of I2 = 0.16A and record the corresponding voltmeter reading V2
i) V2 =………………… (1mark)

5
ii) Calculate resistance (1mark)

e) Find the average value of resistance R (1mark)

f) Determine the resistance, C of the coil (2marks)

g) Now set up the apparatus as shown in Figure 6 below such that the voltmeter is connected
across the cells, 10Ω carbon resistor and the coil are in parallel connection.
Coil

V
A

Figure 6

h) Close the switch and the adjust the variable resistor such that the ammeter reads a current of
0.04A and note the corresponding voltmeter reading. Record the value in the Table 4 below.
i) Repeat (h) above for other values of current and voltage and complete the Table 4 below
Table 4

Current, I (A) 0.04 0.08 0.12 0.16 0.20 0.24

Voltage, V(V)

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 (4marks)

j) On the grid provided plot a graph of Voltage, V (V) against Current, I (A) (5marks)

k) Determine the slope of the of the graph (2marks)

l) Given that graph is related to equation where E and r are the emf and internal
resistance of the cells respectively, use your graph to determine the value of:

7
E =…………………… (1mark)

r =……….…………. (1mark)

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