STUDENT NAME________________________________SCHOOL_________

CENTRAL WEST EDUCATION DIVISION

2025 MALAWI SCHOOL CERTIFICATE OF EDUCATION
MOCK EXAMINATION

PHYSICS
Subject Number: M164/I
Friday 4 April Time Allowed: 2 hours
8:00 – 10:00 am

PAPER I

THEORY
(100 marks)

Instructions
1. This paper contains 12 pages.
Please check.
2. Fill in your Name and School name at the top
of each page.
3. This paper contains two sections, A and B. In
Section A there are ten short answer questions
while in Section B there are three restricted
essay questions.
4. Answer all the thirteen questions in the spaces
provided.
5. Use of electronic calculators is allowed.
6. The maximum number of marks for each
question is indicated against each question.
7. In the table provided on this page, tick against
the number of the question you have answered.

2025 CWED Turn over

NAME OF STUDENT________________________________SCHOOL_____________

SECTION A (70 marks)

1.a. Give any two positive effects of unusual expansion of water.

_____________________________________________________________________
_____________________________________________________________________
(2 marks)
b. In terms of relative direction of motion, what type of waves are electromagnetic waves?
______________________________________________________________________
(1 mark)
c. Give any two applications of infrared waves.
______________________________________________________________________
______________________________________________________________________
(2 marks)
d. Why is the focal length in a camera fixed?
______________________________________________________________________
(1 mark)
e. Name the two variables which are kept constant in Charles’ law of gases.
______________________________________________________________________
______________________________________________________________________

(2 marks)
2. a. Figure 1 is a diagram of a wave motion from position A to position B.

Figure 1

Page 2 of 12
NAME OF STUDENT________________________________SCHOOL_____________

(i) On the diagram indicate the region representing wavelength using a straight line.
(1 mark)
(ii) Calculate speed of the wave given that its wavelength is 80 cm

(3 Marks)
b. Mention the two sources of energy losses in a swinging pendulum.
______________________________________________________________________
______________________________________________________________________
(2 Marks)

3. a. Explain any two ways in which evaluating a science investigation is important.

______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
(2 marks)

b. Explain any two reasons why it is necessary to draw a line of best fit when
plotting a graph.

____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
(2 mark)
Page 3 of 12
NAME OF STUDENT________________________________SCHOOL_____________

c. Why is displacement a vector quantity?

____________________________________________________________________
(1 mark)
4. a. Figure 2 is a diagram showing two spheres connected by a straight rod of
negligible mass of length 20cm suspended in air with the centre of gravity G.

Figure 2
(i) Why is the centre of gravity towards the heavier mass of 3 kg?
____________________________________________________________________
(1 mark)
(ii) Calculate the position of G from the 2 Kg mass.

(3 marks)
b. List down any three applications of torque in everyday life.
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
(3 marks)
5. a. State the advantage of using a zener diode as a safety devise over using a fuse in an
electric circuit.
_______________________________________________________________________
(1 mark)
Page 4 of 12
NAME OF STUDENT________________________________SCHOOL_____________

b. Describe the operation of NAND logic gate using a truth table.

(4 marks)
c. How much effort is required to lift a 200 N load using a frictionless pulley
system with four pulleys?

(4 marks)
6. a. Figure 3 shows mud stuck on a rotating bicycle wheel.

Figure 3
(i). Indicate on the diagram the direction of centripetal force acting on the mud at the
position shown in Figure 3. (1 mark)

Page 5 of 12
NAME OF STUDENT________________________________SCHOOL_____________

(ii). Explain why the stuck mud would eventually skid off when the bicycle wheel is
rotated at greater speed.

__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________

(3 marks)
b. Explain why it is easier to stretch a spring during plastic deformation.
____________________________________________________________________
____________________________________________________________________
(2 marks)

7. a. Calculate work done on an object of mass 5kg when accelerated on a

frictionless surface from a velocity of 2 m/s to a velocity of 8 m/s.

(4 marks)
b. Describe how rowing causes a boat to move forward
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________

(2 marks)
Page 6 of 12
NAME OF STUDENT________________________________SCHOOL_____________

8. a. Figure 4 shows a diagram of a xylophone with wooden bars labeled A, B, C, D and E.

Figure 4
(i). What is the purpose of guards placed under the wooden bars?
__________________________________________________________________
(1 mark)
(ii). Explain why wooden bar labeled E produces the lowest pitch.
__________________________________________________________________
__________________________________________________________________
(2 marks)
b. Calculate half – life of a radioisotope whose amount reduces from 32g to 2g
in 20 days.

(3 marks)
c. Explain how radioactivity is used in agriculture.
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
(2 marks)

Page 7 of 12
NAME OF STUDENT________________________________SCHOOL_____________

9. a. Calculate the actual value when the observed value of 1.1 gives a relative error of
10%.

(3 marks)
b. Calculate liquid pressure at a point which is 2m from the top of a vertical open
cylindrical pipe filled with the liquid, if the liquid pressure at a point 5 m from the
same top of the same pipe is 680,000 Pa.

(4 marks)
10. a. Describe the effect of eddy currents on the efficiency of a transformer.

____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________

(3 marks)
Page 8 of 12
NAME OF STUDENT________________________________SCHOOL_____________

b. Figure 4 shows a circuit diagram with three identical bulbs B1, B2 and B3, each with
a resistance of 3 .

Figure 4

(i). How does the brightness of bulbs B1 and B2 compare?

__________________________________________________________________
(1 mark)
(ii). Give a reason for the answer to question 10b (i).

__________________________________________________________________
(1 mark)
(iii). Calculate the value of ammeter reading in Figure 4.

(3 marks)

Page 9 of 12
NAME OF STUDENT________________________________SCHOOL_____________

SECTION B (30 marks)

11. a. Describe the application of resonance in a radio.

____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________

(5 marks)
b. With the aid of a graph, describe how a parachutist attains first terminal velocity.

____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
(5 marks)

Page 10 of 12
NAME OF STUDENT________________________________SCHOOL_____________

12. a. Describe how hydraulic car brakes work.

____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________

(5 marks)
b. Explain why there is an electromotive force across the secondary coil when there is
no electrical connection between primary and secondary coils in a transformer.

____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________

(5 marks)
Page 11 of 12
NAME OF STUDENT________________________________SCHOOL_____________

13. a. Explain how two stuck glass tumblers can be separated using thermal expansion.
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
(5 marks)
b. Describe how the n – p – n transistor operates.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________

(5 marks)

END OF QUESTION PAPER

Page 12 of 12
 MARKING KEY

CENTRAL WEST EDUCATION DIVISION

2025 MALAWI SCHOOL CERTIFICATE OF EDUCATION MOCK
EXAMINATION

PHYSICS

Subject Number: M164/I

PAPER I
MARKING KEY

©2025 CWED MOCK

 MARKING KEY
2025 Page 2 of 7 M164/I
1. a. Survival of fish in freezing water bodies, Weathering of rocks, improves circulation of
oxygen in deep waters through convection, etc. (any two points, 1 mark each)
b. Transverse waves / 1 mark
c. - used in photography for medical purposes,
- used in fire alarms,
- used in car spraying to dry out paint (Any two points, 1 mark each)
d. Because camera uses lens with fixed shape /1 mark
e. mass of gas /1 and pressure of gas/1

2. a. (i)

/1 mark
(ii)
m

= 0.14 m/s /1 mark OR 14 cm/s

b. Friction at the pivot /1 and Air resistance/1

3. a. - help to identify errors or bias that might lead to incorrect conclusion

- can lead to improvements in the future investigations
b. - Helps to visualise the overall trend between variables.
- it provides a clear picture of whether variables have positive, negative or no
correlation
- Helps to reduce the effect of outliers
- Helps to make predictions of future or other variables
c. - Because it has both magnitude and direction / 1 mark
 MARKING KEY
2025 Page 3 of 7 M164/I

4. a. (i) Because heavier mass has a greater contribution to the average position of the
system/1 mark
(ii) Let length from 2 kg to G be and the other side be
Clockwise moment = anticlockwise moment /1 (formula = 1)
3kg 10 = 2kg 10 /1 ( substitution = 1 mark)
30 (20-y) = 20y
600 -30y = 20y
600 = 50y
12 =y
Therefore G is 12 cm /1 from the 2 kg mass ( correct value = 1 mark)

b. – Opening/closing a door
- Opening a bottle using a bottle opener
- Using a pair of scissors or garden shears
- Playing on a see-saw
- Wheelbarrow lifting load
- Screwing or unscrewing using a screw driver, etc. ( Any three points, 1 mark each)
5. a. - Conductivity of zener diode is restored when current falls to normal, while
conductivity of a fuse is lost even if current falls back to normal /1
- Zener diode provides voltage regulation and overvoltage protection and it doesn’t get
destroyed while the fuse simply breaks the circuit and itself gets destroyed /1
( 1 mark for any correct answer)
b.

Input A Input B Output

On On Off
On Off On
Off On On
Off Off On

Note: Alternative for “ On” is “1” and alternative for “Off” is “0”.
Each correct row = 1 mark (Thus input signal combination plus its corresponding
correct output signal = 1 mark) Total = 4 marks.
 MARKING KEY
2025 Page 4 of 7 M164/I
c. /1

MA = 4 (Since the 4 pulleys are in a frictionless system) /1

E = 200/4 /1
E = 50 N /1
6. a. (i)

(ii) When speed increases, centripetal force increases / 1 until it exceeds the adhesion
forces holding the mud to the wheel /1 Adhesion forces are then overcome /1
eventually mud skids off.
b. Particles of a spring are rearranged /1 thereby reducing their elastic resistance /1.

7. a. Work done = change in kinetic energy

Work done = /1 ( formula)

= / 1 ( substitution)

= 160 -10 /1 (subtraction/summation)

= 150 J /1 (correct value)
b. The person pushes water backwards using paddles /1 In return, the water pushes the
person forward /1 thereby making the boat move forward.

8. a. (i) To amplify sound /1 or – enhance the sound /1

(ii) Bar E has lowest frequency /1 because it is longer. Lower frequencies produce low
pitch /1.
b. 1st half- life = ½ x 32g = 16g
2nd half –life = ½ x 16g = 8g ( method = 1 mark)
3rd half –life = ½ x 8g = 4 g
4th half-life = ½ x 4g = 2g
 MARKING KEY
2025 Page 5 of 7 M164/I
4 half-lives = 20 days /1 mark
1 half- life = 20/4 /1 mark
= 5 days /1 mark

Or: ( ) /1 mark ( formula)

( ) /1 mark ( substitution)

( )

( ) ( )

4 = 20/H /1 mark ( method)

H = 5 days /1 mark

c. It is mixed with fertilizer and fed into plants/1 to study uptake of fertilizer./ 1

9. a. /1 mark (formula)

= /1 mark (substitution)

= 1.22 /1 mark (correct value)

b. At 5m high,
LP = dgh / 1 mark (formula)
= d (10)(5),
680,000 = 50D
D = 13,600. (1 mark)
At 2m,
LP = dgh
= 13,600 (10)(2) ( 1 mark)
= 272, 000 Pa ( 1 mark)

10. a Eddy currents result in energy losses in transformers /1. This reduces energy output /1
thereby reducing efficiency in transformers /1.
 MARKING KEY
2025 Page 6 of 7 M164/I
b. (i) B2 is brighter than B1 /1
(ii) because B2 is sharing its voltage with B3 /1
(iii)

/1 ( formula)

Total voltage = 3.0 V

Total resistance: R in series = 3 + 3 = 6

RT = 2 /1 mark

Total current = = 1.5 A /1 mark

SECTION B (30 MARKS)

11.a. Radio waves for a particular station are trapped by the radio’s receiver /1. The current in
a tuning circuit is adjusted accordingly /1 until the two frequencies coincide /1. This
makes the current to resonate /1 and large current is set up and transmitted /1 to produce
sound.

b.

Labels = 1 mark , Graph line = 1 mark graph total: 2 marks

At point O. the parachutist with a closed parachute starts accelerating because
downward force is greater than upward force. / 1 mark
As speed increases, friction force also increases /1 mark until downward force is equal
to upward force /1 mark and the parachutist attains a terminal velocity.
 MARKING KEY
2025 Page 7 of 7 M164/I
12. a. A small force is exerted on the smaller piston./1 This creates pressure on the fluid at the
smaller piston./1 This pressure is transmitted equally /1 to the larger piston on the
brake pads /1 where a greater force output is produced /1.

b. When alternating current flows through the primary coil/ 1, a magnetic field builds up/1
which grows out and collapses i.e moves to and fro. /1. The secondary coil cuts and re-
cuts the field lines as they grow out and collapse/ 1 thereby producing induced EMF/ 1
in the secondary circuit.

13. a. They are separated by placing them upright /1 in warm water /1 and pouring very cold
water /1 in the inner tumbler /1. The inner tumbler contracts while the outer tumbler
expands creating a gap in between them /1 hence can be separated.

b. The base-emitter circuit is in forward bias and the base-collector circuit is in reverse
mode. /1.

Holes from the base circuit enter the p-doped base region of a transistor /1 where they
combine with electrons from the emitter / 1.

Excess electrons are then forced out of the transistor to the base-collector junction /1
and flow through the collector region, thereby conducting current to the main circuit /1

END OF MARKING KEY