Physics KCSE Mock Exams and Answers {Latest Best Collections}

Stability increases since centre of gravity is lowered when ice melt to a smaller volume. 1
The mass slides towards A and settles midway between A and B. This because the wire expands when melted and becomes loose thus enabling the mass to slide freely.
Flow rate = Cross-section area × velocity.

7.7 × 10^-2m³/s = 3.142 × (3.5 × 10^-3)² × V

7.7 × 10^-2m³/s = 3.8489 × 10^-5m²V

3.8489 ×10^-5m² 3.8489 × 10^-5m²

V =2.000s × 10³ m/s

Weight of the machine parts

– Energy lost / used to lift machine parts. any one correct.

Resultant force = 15N – 8N = 7N

F = ma

a = F

= 7N = 1.4m/s²

5kg

Area of cross-section (thickness)

Length of conductor

Type of metal any two correct

1

Heat loss = heat gained

5 × 4200 × 40 = ×4200 × 25

x = 5 × 40

= 8kg

A cm = cm

1.3 × 60 = 1.2 × T

78 = 1.2 T

T = 65N

Section B (55 marks)

12.a) Energy is not created nor destroyed but can be charged from one form to another.

ii) It has a higher V.R.
b) i) Work done = force × distance

AB = 200 × 20 = 4000Nm

CD = 600 × 20 = 12,000Nm

EF = ½ × 10 × 400 = 2000Nm

FG = ½ × 10 × 400 = 2000Mm

GH = 10 × 400 = 4000

24,000 Nm

ii) Power = force × velocity

= 600 × 0.6 m/s

= 360W

c) P = D = 3.6 × 10⁵ × 10 × 400

Time 3600 sec

=400KW

Total power = 400 + 200 = 600 kw

Efficiency = 400 × 100 = 66.67%

600

a) The rate of change of linear momentum is directly proportional to the external ü1 force and takes place in the

direction of the force.

b) The bus has greater momentum ü1 than the saloon car and therefore a greater inertia ü1 (since

mass in higher)

c) i) Momentum before impact

= momentum after impact ü1

m₁u₁ +m₂u₂ = (m₁ + m₂)v

0.02 × 200 + 0.45 × 0 = (0.4s + 0.2)V ü1

V = 4 = 6.154ms^-1ü1

0.65

ii) h = ½ gt²

5 = ½ × 10 × t² ü1

t² = 1

t = 1 sec

iii) R = ut

= 6.154 × 1 ü1

= 6.154m ü1

a) Expands regularly.

Does not wet glass
Good conduct of heat any 2 × 1 mk

b) i) Oil of creosote
ii) On cooling, is leaves space for expansion.

iii) when it is hot, oil of creosote in the bulb expands pushing mercury up arm A of U tube mercury pushes steel

index in A upward to maximum temperature of creosote.

When temperature falls oil of creosote in the bulb contracts pushing mercury towards bulb and pulls steel index up indicating minimum temperature.

iv) Lower ends of indices.
d) Magnet

a) Impurities

Pressure any 1 × 1 mark

iii) VIt = ML_f

8 × 2.25 × 10 × 60 =200Lf

1000

Lf = 8 × 2.25 × 10 × 60

0.2

= 54000Jkg^-1

iii) No heat is absorbed from surrounding environment.

16.a)i) Provide the centrifugal force so that the body is maintained in a circular path without skidding

ii) Water escapes through the holes leaving the clothes dry. This is because the adhesive force between the water particles and the drum is reduced and the water escapes through the holes.

b) i) w = 2pf

= 60 × 2p

= 2 p rads / sec

= 6.28 rads / sec ü1

ii) V = wr

= 6.28 × 0.18

= 1.1304m/s ü1

a = v² 1.1304² ü1

r 0.18

= 7.099m/s² ü1

a) i) 0.315N ü1

ii) Wgt of liquid displaced = 0.315N ü1

Volume of liquid displaced = 60 × 4.2

= 25.2cm³ ü1

Density, = m

= 31.5gü1

25.2cm³

= 1.25g/cm³

= 1250kg/m³ ü1

b) Weight of solid = weight of liquid displaced

Mass of solid = 5 × 0.8g/cm³

= 4g ü1

Mass of solid = 4g

Volume of solid = 20cm³

Density of solid = 4ü1

= 0.2g/cm³ ü1

MOCKS 1 2023

PHYSICS PAPER 3MARKING SCHEME

232/3

PART A

QUESTION 1

Length l (cm)	I (A)	Pd, V(V)	I(mA)	Pd, v(MV)	log I	log V
20	0.14	0.25	140	250	2.146	2.398
30	0.16	0.35	160	350	2.204	2.544
40	0.18	0.50	180	500	2.255	2.699
50	0.19	0.65	190	650	2.279	2.813
60	0.20	0.85	200	850	2.301	2.929
80	0.24	1.30	240	1300	2.380	3.114
	3mks	3mks	-½ mk	-½ mk	-½ mk	-½ mk

I(A) = x + 0.2A ; 2dp (4sf) (4sf)

V(v) = x + 0.10V ; 2dp

d) Graph attached
e) slope = D log I (from graph not the table)

Dlog V

(238 – 214) x 10^-2 Correct substitution – (1 mk)

(310 – 240) x 10^-2 Correct evaluation – (1 mk)

= 0.3429 (4 sf) ans to 4 sf or exact – (1 mk)

f) log I = n log v + log k

y = mx + C

i) log k = y intercept

log k = 211 x 10^-2 = 2.11ü (1mk)

k = 128.82 (4sf or exact)

ii) n

n = slope

n = answer in e

= 0.3429 ( exact as in e)

PART B

QUESTION I

Time in minutes	0	0.5	1.0	1.5	2.0	2.5	3.0	3.5	4.0	4.5
Temperature of W(⁰C)	80.0	79.0	77.5	76.0	75.0	74.0	72.5	71.0	70.0	69.0
Temperature of L(⁰C)	80.0	76.0	75.0	72.0	70.0	68.0	66.0	64.5	62.5	61.0

Time in minutes	5.0	5.5	6.0	6.5	7.0	7.5	8.0	8.5	9.0	9.5
Temperature of W(⁰C)	68.0	67.0	66.0	65.0	64.5	62.5	62.0	61.5	61.0	60.0
Temperature of L(⁰C)

Temp (⁰C) + 2.0⁰C (4mks)

Graph (as attached)

f i) t_w = 6.5 – 2.0

= 4.5 minutes

Correct readings from graph – 1mk

ii) t_l = 0 – 0.6

= 1.4 minutes

Correct readings from the graph – 1mk

g) r = 2t_l

dt_w

4.2 x 1.4 = 1.6333

0.8 x 4.5

Correct substitution of t_l ,t_w and d – 1mk

Correct evaluation of 4 SF or exact – 1mk

Part B

h) Length, x = 0.8 +2cm – 1mk
i) thickness d = x

0.8cm = 0.04cm

Correct substitution of x – ¹/₂mk

Correct evaluation to 2 dp or exact – ¹/₂mk

j) V =

= 0.1508cm³

Correct substitution of p = 3.142 , d² , L – 1mk

Correct evaluation to 4 s.f or exact – 1mk

Correct unit – 1mk

MOCKS 1 2023

PHYSICS PAPER TWO MARKING SCHEME

232/2

New object distance = 5 – 2 = 3cm

Distance between tip and its image = 3 + 3 ü

= 6cmü

a) Like poles repel, unlike poles attract. ü
b) Pole X is South poleü
Convex mirror gives a wider field of view ofüthe rear (behind) compared to plane mirror.
a) Period, T = 8.0 x 10^-4Sü

Frequency =

= 1250

= 1.25 x 10³ Hz

a) Primary cells cannot be recharged after use while secondary cells can be recharged after use. ü
b) Polarization is reduced by adding a depolarizer

Adding Manganses (VI) oxideü

2 Distance = Speed x timeü (2d = vt)

2x = 320 x 0.8 ü

x = 320 x 0.8

x = 128m ü

Gamma rays, Ultra violet, Blue light, Red light

Radiation

Increasing wavelength ü

a) Doping ü

b) N – Type semiconductor ü

b) Reduce the amount of current. ü

Reduce magnetic field strength.

a) To reduce power losses ü
b)

I =

= 5A

R =

= 4Wü

P =

= 4W

I =

= 4Wü

I =

= 5A

P =

R =

= 4Wü

a) The current flowing through a conductor is directly proportional to the potential difference

across the conductor provided Temperature and other physical conditions are kept constant. ü

b) Effective Resistance =

= 2Wü

V = IR

I = ü = = 2.5A ü

SECTION B (55 MARKS)

a) The direction of induced current is such as to oppose the change causing it. ü
b) i) Deflects to the right handsideüBecause by Lenz’s law, end A of the solenoid produces a

South pole and there current is flowing in direction X to Z. ü

ii) – Decreasing the strength of the magnet

Decreasing the number of turns in the solenoid.
Decreasing the speed at which the solenoid moves.

Any ü

c) The core is made up of thin sheets of insulated soft iron plate (ie. Core is laminated) instead

of using a block of iron coreü

d) i) The galvanometer deflects in one direction and goes back to zero when switch is closed. ü

When the switch is open the galvanometer deflects in the opposite direction then to zero. ü

ii) The deflection would be smaller.
e) i) Step down transformer. Because the number of turns in the primary coils are more than the

number of turns in secondary coils. ü

ii) ü V_S =

= 24Vü

iii) Power in primary =V_PI_P

= 120 x 0.5

= 60W

Power in secondary = V_S x I_S

= 24 x 2

= 48V

Efficiency = ü

= 80% ü

a) Like charges repel, unlike charges attract. ü
b) As the rod approaches the cap, the positive charges initially attracts the negative charges on the

leaf and plate before the leaf falls. ü As the rod is brought nearer, net positive charges are

induced on the leaf and plate, where they repel each other making the leaf rise again. ü

c) The milliameter record current as the capacitor is charging. ü When the capacitor is fully

charged, it offers an equal P.d in the opposite direction therefore no current flows. ü

d) i) 2 + 10

= 12mFü

C_T =

= 2.4mFü

ii) Q = CV

= 2.4 x 240ü

= 576 mC

= 5.76 x 10^-4 Cü

iii) V = ü

= 48Vü

a) -The ray of light must be travelling from an optically denser medium to an optically rarer

medium.

– The angle of incidence must be greater than the critical angle. Any ü

c) η = ü

Height = Real depth = n x Apparent depth

= 1.48 x 11.4

= 16.872cm ü

d) i) – The mirror absorbs some incident light while the prism does not.

– The mirror silvering peels off but this does not happen in prism.

– The mirror is thick and produces multiple images unlike prism.

Any ü

ii)

e) i) – Object distances, u, using a metre rule. ü

– A image distance, V, using a metre rule. üany

ii) Extrapolate the graph to cut either axis or both.

At intercept, = 0

.: = , = value of intercet

f = = ü

or f = 4cm

At intercept, = 0

.: = à f = = 4cm

f) i) – Too short eyeball ü

– Lens with too long focal lengthü

ii) By wearing converging lens spectacles. ü

a) I – Copper is a good conductor of heat and therefore conducts heat produced. ü

II – To accelerate electrons from the cathode to the anode. ü

To give electrons sufficient kinetic energy.

ii) Decrease the amount of heating current in the filament. ü

iii) X-ray penetrate more in less dense material and penetrate less in denser materials. ü

b i) The emission of electrons from a metal surface when the metal surface is irradiated with

electromagnetic radiation.

b) I E = hf

= 6.63 x 10^-34ü x 6.25 x 10¹⁴

= 4.14373 x 10^-19 Jü

II Wo = Hfo

= 6.63 x 10^-34üx 5.5 x 10^-14

= 3.6465 x 10^-19 Jü

III – KE = hf- Wo

= (4.14375 – 3.6465) x 10^-19ü

= 0.49725 x 10^-19

= 4.972 x 10^-20 Jü

i) E – Filament ü

F – Y – Plateü

ii) Thermionic emissionü
b) i) Alpha particles have higher charge (+2) ü

Compared to Beta particles (-1)

Alpha particles are heavier compared to Beta particles.

Any ü

ii) a = 234ü

b = 84 – 2 = 82 ü

iii)

MOCKS 1 2023

CONFIDENTIAL

PHYSICS

PAPER 3

232/3

Section A

– 2 size D dry cells.

– 100cm nichrome wire on a mm scale, labelled P at one end, 0 cm mark.

– A bulb (2.5V) and a bulb holder.

– 8 connecting wires (at least 4 with crocodile clips).

– Cell holder

– A switch

– A volt Meter ( 0 – 5V)

– An ammeter ( 0 – 1A)

– A jockey

Section B

A liquid labelled L (50 ml of paraffin).
A measuring cylinder (50ml or 100ml).
2 boiling tubes.
A thermometer.
50ml of distilled water in a beaker labelled W.
A 250ml beaker containing some water.
A stop watch
A tripoid stand and wire gauze
Clamp and stand
A card board with a hold at the middle (3cm by 3cm)
Copper wire of length 130cm. (0.28mm)
Test tube of diameter 1.5cm (ordinally)
Metre rule

Name:………………………….…………………….…Index No…………………………….

232/1 Candidate’s Signature…………………………

PHYCICS PAPER 1 Date…………………..

Time: 2Hrs.

MOCKS 1 2023

The Kenya Certificate of Secondary Education

PHYSICS

Paper 1

Instructions:

This paper consists of TWO Sections: A and B.
Answer ALL the questions in sections A and B in the spaces provided.
ALLworkingsMUST be clearly shown.
Mathematical tables and electronic calculators may be used.

For Examiner’s Use Only

Section	Question	Maximum Score	Candidate’s Score
A	1 – 11	25
B	12	9
	13	9
	14	7
	15	8
	16	8
	17	9
TOTAL SCORE		80

SECTION A (25 marks)

Answer ALL the questions in the spaces provided.

A rectangular container measures 2cm by 3cm by 5cm. What is the weight of mercury that will fill the container to the brim. (Take g = 10N/kg and density of mercury = 13600 kg/m³). (3 marks)

A vernier calliper has a zero error of -0.02cm. Draw the section of the calliper scale when used to take an actual measurement of 4.85cm. (2 marks)

Figure one below shows a beaker placed on a bench. A block of ice is placed in a beaker as shown below.

Fig 1

State and explain the change in the stability of a beaker when ice melts. (2 marks)

Figure 2 below shows horizontal copper wire tightly fixed on two stands. A mass P is suspended from the wire using a string that can freely slide.

Fig 2

The copper wire is then heated for sometime. State and explain what happens to mass P.(2 marks)

Water flows through a pipe with different cross-section areas at a rate of 7.7 × 10^-2 m³ / s. If the pipe has a diameter of 7mm, determine the velocity of water through the pipe at that particular section. (3 marks)

Apart from friction, name another factor that reduces efficiency in machine. (1 mark)

Two forces act on a trolley as shown below;

Fig 3

Find: the acceleration of the trolley. (3 marks)

State the factors that affect the rate of flow of heat through a metal conductor. (2 marks)

Sketch a graph of volume of a fixed mass of a gas against pressure on the axes below. (1 mark)

A form three student heats 5kg of water to a temperature of 80°C. When he added X kg of water at 15°C, the mixture attains a temperature of 40°C. Determine the value of X. (3marks)

A uniform rod of length of 5m and a mass of 6kg is pivoted at 3.8m mark. The rod is held horizontally by a vertical rope at 5m mark as shown in figure 3 below.

Calculate tension on the rope. (3 marks)

SECTION B: 55 marks)

a) i) State the law of conservation of energy. (1 mark)

ii) Explain why it is easier to use a thick screw driver than a thin one. (1 mark)

b) The figure below shows a force-distance graph for a car being towed on a horizontal ground.

i) Calculate the total work done. (3 marks)

ii) If the velocity just before reaching point D is 0.6m/s, calculate the power developed by the source providing the force at this point. (1 mark)

c) An electric pump can raise water from a low level reservoir to a high level reservoir at a rate of 3.6 × 10⁵ kg/h. The vertical height that water is raised is 400m. If the rate of energy loss in form of heat is 200kw, calculate the efficiency of the pump. (3 marks

a) State Newton’s second law of motion. (1 mark)

b) Why is it easier to stop a saloon car than a bus moving at the same velocity. (2 marks)

c) A bullet of mass 20g moving at 200ms^-1 hits and gets embedded in a wooden block of mass 450g that is suspended freely on a light inextensible string at a height of 5m above the ground. If the string breaks on impact, calculate:
i) the velocity of the block immediately after impact. (2marks)

ii) the time taken by the block to strike the ground. (2 marks)

iii) the horizontal range of the block. (2 marks)

a) State two properties of mercury that makes it a suitable thermometric liquid. (2 marks)
b) Figure below shows a six’s maximum and minimum thermometer.

i) What is the thermometric liquid in the thermometer (1 mark)

ii) Give a reason why vapour in bulb B is saturated. (1 mark)

iii) Describe how the thermometer above works. (3 marks)

iv) At what points is reading of temperature taken from the thermometer. (1 mark)

a) State one factor that affects freezing point of distilled water. (1 mark)

b) Figure below illustrates an experiment in which electrical energy is used to determine specific latent heat of fusion of ice.

i) Complete the circuit to show connection of essential circuit components. (3 marks)

ii) In the above experiment the following readings were obtained when heater was switched on for 10 minutes.

Voltage – 8.0V

Current – 2.25A

Temperature rise – 10°C

At the end of the experiment 400g of water at 0°C was collected in the beaker. Determine latent heat of fusing of ice. (3 marks

iii) State any assumption made in (ii) above. (1 mark)

a)i) What is the importance of banking a road in corners? (1 mark

ii) Explain why wet clothes put in a drum which has holes at the bottom get dried faster when the drum of drying machine is rotated at high speed. (2 marks)

b) A turntable of a record player makes 60 revolutions per minute. Calculate.
i) Angular velocity in rads/second. (2 marks)

ii) The linear acceleration at a point 0.18M from the centre. (3 marks)

17.a) In an experiment to determine the density of a liquid, uniform metal cylinder of cross-section area 6.0cm² and length of 4.2cm was hang from a spring balance and lowered gradually into liquid. The graph below shows upthrust plotted against, lengths submerged.

From the graph, determine:

i) Value of upthrust when the cylinder is fully submerged. (1 mark)

ii) The density of the liquid in SI units. (5 marks)

b) A solid displaces 5.0cm³ of paraffin when floating and 20cm³ when fully immersed in it. Given that the density of paraffin is 0.8g/cm³, calculate the density of the solid. (3 marks)

Name:………………………….…………………….…Index No…………………………….

232/2 Candidate’s Signature…………………………

PHYCICS PAPER 2 Date…………………..

Time: 2Hrs.

MOCKS 1 2023

The Kenya Certificate of Secondary Education

PHYSICS

Paper 2

Instructions:

This paper consists of TWO Sections: A and B.
Answer ALL the questions in sections A and B in the spaces provided.
ALLworkingsMUST be clearly shown.
Mathematical tables and electronic calculators may be used.

For Examiner’s Use Only

Section	Question	Maximum Score	Candidate’s Score
A	1 – 12	25
B	13	12
	14	9
	15	11
	16	10
	17	8
	TOTAL SCORE		80

Section I (25 marks)

Figure 1 shows a pencil lying in front of a plane mirror. The pencil is moved 2cm towards the mirror in the same orientation.

Figure 1

Determine the distance between the new position of the tip of the pencil and its image. (2mks)

a) State the basic law of magnetism. (1mks)

b) Figure 2 shows two bar magnets, one whose poles are labelled and a second one whose poles are labelled X and Y. Iron nails are attracted to the lower ends of the magnets as shown.

(1mk)

Figure 2

Identify pole X

State the reason why convex mirror is preferred over a plane mirror for use as driving mirrors in cars. (1mk)

Figure 3 shows the displacement-time graph for a certain wave.

Figure 3

a) Determine the frequency of the wave. (2mks)

b) On the same diagram, draw a wave with half the amplitude and twice the frequency of the one

shown. (1mk)

a) State the main difference between primary chemical cells and secondary chemical cells. (1mk)

b) State how the design of a dry Lechlanche cell reduces polarization. (1mk)

Figure 4 shows a wave incident on a narrow opening.

Figure 4

Draw the appearance of the wave after passing through the opening. (1mk)

A student stands between two classroom walls and claps. After 0.6 seconds, she hears the first echo and hears the second echo after 0.8 seconds. Determine the distance from the student to the further wall. Take speed of sound in air = 320m/s. (3mks)

The list below is some radiations in the electro-magnetic spectrum. Red light, Gamma rays, Ultra violet radiations and Blue light. Arrange the radiations in order of increasing wavelength. (1mk)

A controlled amount of pentavalent (donor) impurity atoms added in to a pure semi conductor such as silicon to improve its conductivity.
a) Give name to the process above. (1mk)

b) What type of semiconductor is obtained in the above process? (1mk)

Figure 5 shows the cross-section of two bar magnets and a current carrying conductor held between them. The direction of current is into the paper.

Conductor

Figure 5

a) indicate with an arrow the direction of force experienced by the conductor. (1mk)

b) State one way in which the force on the conductor above can be reduced. (1mk)

a) State the reason why electrical power is transmitted over long distances at very high voltage

and low current. (1mk)

b) An electric bulb is labelled 100W 20V. Determine the resistance of its filament at its operating

temperature. (2mks)

a) State Ohm’s law. (1mk)

b) Figure 6 shows an electrical circuit.

Switch

Figure 6

Determine the Ammeter reading in a closed circuit. (2mks)

SECTION B (55 Marks)

a) State Lenz’s law of electromagnetic induction. (1mk)

b) Figure 7 shows stationary magnet and a solenoid being moved as shown.

Figure 7

i) State with a reason the direction of deflection of the galvanometer. (2mks)

ii) State one way through which the size of deflection of the galvanometer can be decreased. (1mk)

c) State how energy losses in a transformer through eddy currents is minimized in its design.(1mk)

d) Figure 8 shows two identical coils C and D made of insulated copper wires and are placed close to each other. Coil C is connected to DC power supply and Coil D to a galvanometer.

Figure 8

(i) State and explain what would be observed on the galvanometer immediately switch S is closed

and then opened. (2mks)

ii) How would the observation made in d(i) differ if the number of turns in coil C were doubled

but those in D remain unchanged? (1mk)

e) The primary coil of a transformer has 250 turns and the secondary coil has 50 turns. The

primary coil is connected to a 120V AC supply.

i) State with a reason the type of transformer described above. (1mk)

ii) Determine the voltage in the secondary coils. (1mks)

iii) Given that the current in the primary coil is 0.50A and in the secondary coil is 2.0A. Determine the efficiency of the transformer. (2mks)

a) State the law of electrostatic charges. (1mk)

b) Figure 9 shows a highly positively charged glass rod being brought slowly near the cap of a

negative charged gold leaf electroscope. It is observed that the leaf initially falls and then rises.

Figure 9

Explain this observation. (1mks)

c) Figure 10 shows an electric circuit used to charge a capacitor C. When switch is closed, it is

observed that, the millimeter records some current which gradually reduces to zero with time.

Power Supply

Figure 10

Explain the observation (1mks)

d) Figure 11 shows an electrical circuit with three capacitors of 10mF, 2mF and 3mF capacitance

connected to a 240V supply.

3mF

2mF

10mF

240V

Figure 11

Determine

i) The effective capacitance of the capacitor combination. (2mks)

ii) The charged stored in the circuit. (2mks)

iii) The potential difference across the 2mF capacitor (2mks)

a) State one condition necessary for total internal reflection to occur. (1mk)

b) Figure 12 (a) shows a ray of light travelling in an optically denser medium to an optically rarer

medium. The angle of incidence i and angle of refraction r are also shown.

Figure 12 (a) Figure 12 (b)

Complete Figure 12 (b) to show the path of refraction ray when the angle of incidence is increased to reach critical angle. (1mk)

c) An optical pin placed at the bottom of a glass measuring cylinder filled with a liquid and appears to be 11.4cm below the surface of the liquid. If the refractive index of the liquid is 1.48. Determine The height of the column of the liquid in the measuring cylinder. (2mks)

d) i) State one reason why glass prisms are preferred to plane mirrors in their use in periscope. (1mk)

ii) Figure 13 shows two right angled glass prism arranged to be used in a periscope.

An object is placed besides one prism as shown.

object

eye

Figure 13

Complete the diagram by showing the path of rays of light from the object until they reach the eye.(1mk)

e) In an experiment to determine the focal length of a lens, you are provided with the following

apparatus.

A converging lens and a lens holder
A lit candle
A metre rule
A white screen

i) State one measurements that you would take in the experiment. (1mk)

ii) In another experiment similar to the above, a graph showing the relationship between and was plotted as shown in figure 13.

– Use the graph to determine the focal length, f of the lens. (2mks)

e) Figure 14 shows a defeat of the eye

Figure 14

i) State two possible causes of the defect. (2mks)

ii) Explain how the defect is corrected. (1mk)

a) i) In an X-ray tube explain why
The anode is made up of copper. (1mk)

The cathode and the anode are connected to a high potential difference between them. (1mk)
ii) State the adjustments made in an X-ray tube in order to decrease the intensity of X-ray. (1mk)

iii) State the property of X-rays that makes it used in detecting foreign objects in human bodies.

(1mk)

b) i) Explain the meaning of the term photoelectric effect. (1mk)

ii) A monochromatic light frequency 6.25 x 10¹⁴ Hz is incident on a metal surface. The minimum

frequency that can cause photo emmission on the metal surface is 5.5 x 10¹⁴Hz. Given that Planck’s constant, h is 6.63 x 10^-34 Js.

Determine

The energy of the source light. (2mks)

The work function of the metal surface. (2mks)

III. The average kinetic energy of the photo electrons. (2mks)

a) Figure 15 shows some features of a cathode ray tube.

Figure 15

i) Name parts E & F (2mks)

ii) The process through which electrons are produced. (1mk)

b) i) Alpha (a) particles cause more ionization in a gas compared to Beta (b) particles. Give one

reason for this. (1mk)

ii) The following is part of radioactive decay series. The symbols do not represent the actual

symbols of the nuclides.

Determine the values of a and b (2mks)

iii) A radioactive Isotope has a halflife of 5.25 years. Determine the fraction of the original

mass in a sample that will remain after 42 years (2mks)

Name:…………………………………………………IndexNo…………………………….

232/3 Candidate’s Signature:………………

PHYSICS

PRACTICAL Date:…………………………….……

PAPER 3

TIME: HRS

MOCKS 1 2023

Kenya Certificate of Secondary Education (K.C.S.E.)

232/3

PHYSICS

Paper 3

INSTRUCTIONS TO CANDIDATES

Write your name and index number in the spaces provided.
Mathematical tables and non-programmable calculators may be used.
This paper consists of section A and section B.
Attempt all the questions in the spaces provided.
ALL working MUST be clearly shown.

For Examiners Use

QUESTIONS	MAXIMUM SCORE	CANDIDATE’S SCORE
1	20
2	20
TOTAL	40

This paper consists of 9printed pages. Candidates should check to ascertain that all pages are printed as indicated and that no questions are missing

Question 1

You are provided with the following apparatus:

– 2 size D dry cells

– 100cm nichrome wire on a mm scale, labelled P at one end.

– A bulb (2.5V) and a bulb holder.

– 8 connecting wires (at least 4 with crocodile clips)

– Cell holder

– A voltmeter (0-5V)

– An ammeter (0-1A)

– A jockey

a) Connect the apparatus provided as shown in the diagram.

b) Place the jockey at L = 20cm from P, then close the switch.

Record the ammeter reading and the voltmeter reading in the table below.

c) Repeat the experiment by placing the jockey at L = 30, 40, 50, 60 and 80cm from P.

Record your readings and complete the table below.

Length l (cm)	I (A)	Pd, V(V)	I(mA)	Pd, v(MV)	log I	log V
20
30
40
50
60
80
	3mks	3mks	-½ mk	-½ mk	-½ mk	-½ mk

d) Plot a graph of log I (y-axis) against log V (5mks)

e) Determine the slope of the graph. (3mks)

f) Give that log I = nlog V + log K where n and k are constants of the lamp. Determine using your graph the value of:
i) K (2mks)

ii) n (2mks)

Question 2

Part A

You are provided with the following:

A retort stand, boss and clamp.
2 boiling tubes
A thermometer
Some distilled water in a beaker labelled W
Some liquid in a beaker, labelled L
A 250ml beaker containing some water.
A measuring cylinder
A stop watch
A tripod stand and wire gauze
A card board with a hole in the middle
A burner.

Proceed as follows

a) Clamp one boiling tube on the retort stand. Measure and pour 45ml, of the distilled water, W

into a boiling tube. Set up the apparatus as shown in the figure below.

b) Heat the water in the large beaker (250ml) until the temperature of the distilled water reached 85⁰ Remove the boiling tube from the hot water by lifting up the retort stand and placing it away from the burner.
c) Stir the water in the boiling tube using the thermometer. Record in the table below the temperature of the distilled water at intervals of 30 seconds starting at 80⁰C until it drops to 60⁰C (stir the distilled water before taking any reading).

Time in minutes	0	0.5	1.0	1.5	2.0	2.5	3.0	3.5	4.0	4.5
Temperature of W(⁰C)
Temperature of L(⁰C)

Time in minutes	5.0	5.5	6.0	6.5	7.0	7.5	8.0	8.5	9.0	9.5
Temperature of W(⁰C)
Temperature of L(⁰C)

(4mks)

d) Using the second boiling tube, repeat the procedure in b and c using 45ml of liquid L instead of distilled water. Record your results in the same table.

e) Using the same axis on the grid provided, plot a graph of temperature (y-axis) against time for
i) Distilled water, W
ii) Liquid L

(Label the graphs of L and W. (7mks)

f) From the graph, determine:
i) the time, t taken for the distilled water to cool from 75⁰C to 65⁰

t_w = _____________ minutes (1mk)

ii) the time, t taken for liquid L, to cool from 75⁰C to 65⁰C

t_L= _____________ minutes (1mk)

g) Determine the constant r given that where d, density of liquid, L = 0.8g/cm³. (2mks)

PART B

You are provided with the following:

Copper wire of length 130cm.
Test tube of diameter 1.5cm (ordinary)
Metre rule.

Procedure

By using the wire provided, make 20 closely packed turns around the said ordinary test tube as shown.

h) Measure the length x = ______ cm (1mk)

i) Use the result “X” to determine the thickness of the wire, d = ______ cm. (1mk)

j) Given that the volume of the wire pd²L, determine the volume, V of the wire if

L = 120cm. (3mks)

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