# Physics Paper 2 Questions and Answers - Cekenas Mock Exams 2022

QUESTIONS

SECTION I (25 MARKS)

1. State the number of images formed when three objects are placed between two plane mirrors which parallel to each to each other. (1mk)
2. The figure shows a highly negatively charged electroscope. A pointed pin M which is earthed is brought closer to the metal cap N as shown.

State and explain the observations that will be made. (3mks)
3. The figure below shows an electric circuit. S1, S2 and S3 are switched and L1,L2 and L3 are lamps. A constant potential difference is applied across X and Y.

1. Other than L1 state the lamp that will light when S1 and S2 are closed. (1mk)
2. How does the brightness in L1in (i) above compared with its brightness when all the switches are closed. (1mk)
4. One method of magnetization is by single stroking. State the disadvantage of this method. (1mk)
5. A pendulum bob takes 0.5seconds to move from its mean position to maximum displacement. Calculate its frequency. (2mks)
6. The figure below shows part of a rainbow.

State what happens at part A and B
7. State one factor that affects resistance of metal conductor other than temperature. (1mk)
8. The figure shown a network of three capacitors

Determine the effective capacitance. (2mks)
9. The figure shows sound waves emitted by a drum stick.

Explain way the wave fronts are directed to the ground (2mks)
10. Write a nuclear equation of a radioactive cobalt which undergoes a decay to form element W. (2mks)
11. The figure below show an object O placed in front of concave mirror.

On the same figure construct a ray diagram to locate the image of the object. (3mks)
12.
1. State one property common to all electromagnetic waves. (1mk)
2. On the axis provided, sketch a frequency wavelength graph for electromagnetic waves. (1mk)
13.
1. The figure below shows a p-n junction connected to a cell.

What type of biasing will occur if the terminals of the cell are interchanged (1mk)
2. The graph below shows the output obtained with time during rectification process

State the number of diode used in this process. (1mk)

SECTION II (55 MARKS)
Answer all the question in the space provided

1.
1. State Ohm’s law (1mk)
2. Study the circuit diagram below and answer the question that follows.

Calculate
1. The effective resistance (2mks)
2. Current flowing through the ammeter (2mks)
3. Current flowing through the 4 resister. (3mks)
2.
1. State one use of echoes (1mk)
2. Explain why there is gradual decrease in amplitude of a progressive wave (1mrk)
3.
1. Distinguish between Refraction and reflection of waves (1mk)
2. In the figure below complete the diagram to show how plane wave move in the shallow and deep region there after (2mks)
3. The figure below shows how water wave interferes in a ripple tank. The amplitude and wavelength of each wave is 8cm and 5cm respectively.

Determine the amplitude of the water wave at point A and B
4. If the Vibrator at S1 and S2 in part (iii) above produce coherent waves of frequency 40Hz, determine the speed of the water wave. (2mks)
3.
1. Determine the term principal focus for a convex lens. (1mk)
2. A certain student accommodates objects situated at a distance greater than 80.0cm from the eye.
1. Define the term accommodation in reference to eye vision. (1mk)
2. State with a reason this type of eye defect (2mks)
3. Identify the type of lens that would enable the student to see. (1mk)
3. The graph below is a plot of image distance (v) against object distance (u) for a convex lens.

From the graph determine the focal length of the convex lens. (2mks)
4. An object of height 4cm is placed 2cm from a diverging lens of focal length 3cm calculate:
1. The image distance. (2mks)
2. The height of the image (2mks)
4.
1. The figure below shows a cathode ray oscilloscope (CRO)

1. State the function of the component labeled A B and C (3mks)
2. What would be the effect on the CRO if the temperature of the filament of the electron gun was raised. (1mk)
3. Name and state the function of the part labeled X. (2mks)
2. Apart from thermionic emission name the other method of emitting electrons from a metal surface. (1mk)
3. State two factors that affect photoelectric effect on a metal surface. (2mks)
4. The graph below shows how kinetic energy varies with frequency f in an experiment using a photocell.

Given the k.e max=hf-Ø determine from the graph :
1. Plank constant h (3mks)
2. The Constant Ø (2mks)
5.
1. State the Lenz’s low of electromagnetic induction. (1mk)
2. The figure below shows two coil connected using a soft iron core

1. Name the part labeled X (1mk)
2. State and explain what happens when the switch is closed (3mks)
3. State the observation made on X when the D.C supply is replaced with A.C (1mk)
3. A generator produces 250kW is connected to a factory by a cable which has a total resistance of 10 . Determine the voltage at which the generator produces power if the maximum current in the cable is 8.0A (2mks)
4.
1. State two ways through which power loss is minimized in a transmission cables. (2mks)
2. The figure below shows part of a wiring circuit for a house.

Identify three faults made in the wiring. (3mks)

## MARKING SCHEME

1. Infinity
2. Divergence decreases/ leaf falls The cap repels negative charges/ electrons on the pin to earth. High concentration of positive charges at sharp point ionize air molecules near the capü. Positive ions are attracted to the cap and neutralizes electros leading to discharge.
3.
1. L3
2. Will be brighter / more brought
4. Produces magnets in which one pole is nearer the end than the other
F = 1/T
5. T = 0.5 x 4
= 2.05
f = ½
= 0.5Hz
6. A- Refraction and diffraction
B- Total internal refraction
7. Cross- sectional area/ thickness/ length any
8. Parallel C = 10+5=15 μF
CT = C1C2 = 10 x 15
C1+C2    10 +15
= 6μF
9. The wave is refracted towards the ground because wave front travel faster in the upper layers that the lower part.
10.

11. each ray
Total 2mks
Image
12.
1. All are transverse/ travels with same speed in vacuum
Any other correct award 1mk
2.
13.
1. Reverse biasing
2. One diode
14.
1. Current Flowing through a conductor is directly proportional to the p.d across it provided temperature and other physical conditions are kept constant.
2.
1. 1/Kp = ¼ + ½
1/Rp = ¾
Rp = 1.333
RT = 1.333 + 1Ω
=2.333Ω

2. V = IR
I =    6v
2.333Ω
= 2.572A
3. VΩ = 2 - 572 x 1
= 2.572V
= 6 - 2.572
= 3.428V
1Ω = 3.428
4
= 0.857A
15.
1. Determining the speed of sound
Pulse- echo technique to determine to depth of the sea.
2. Energy is spread over on increasingly large area as the wave moves.
3.
1. Refraction is change of direction and speed of wave at they passes through different medium while refraction is bouncing back of waves.
2.
3. A 0cm
B 16cm
4. v = fd
= 40 x 0.05
= 2m/s
16.
1. It is the point on the principal axis at which all rays parallel and close to the principal axis converge after refraction.
2.
1. It is the process by which the eye adjusts the focal length of its own lens in order to focus images of objects at different distances on the retina.
2. Myopia/ Short sightedness
3. Concave/ diverging lens.
3. 2f = r
f = 20cm
2
= 10cm
4.
1. 1/f = 1/u + 1/v
1/-3 = ½ + 1/v
v = -1.2cm
= 1.2cm
2. hi/ho = v/u
hi/4 = 1.2/2
hi = 4.4cm
17.
1.
1. A- produce electrons by thermionic emmission
B- Accelerates electrons to the screen
C- glows fluoresces on impact with electrons
2. The spot will be brighter
3. Grid
Controls the intensity of beam and hence the brightness on the screen
2. Photoelectric effect
3. Type of metal
Energy/ frequency/ wavelength of the radiation (any 2)
1. h = slop =     (1-4) x 10-19
(1.75 - 2.5) x 1015
= 3 x 10-34Js
2. φ = hfo
= 3 x 10-34 x 1.1.125 x 1015
= 3.375 x 10-19J
18.
1. The direction of induced current is such that if produces a magnetic field which opposes the change producing it.
2.
1. Galvanometer
2. The galvanometer cleflects to the right momentarily/ deflection to the right and the come back to zero.
When the switch is closed current increases from zero to maximum. In the primary coil producing a charge in the magnetic flux linkage inducing an emf that produces current.
3. P = VI
= 250 x 1000
8.0A
= 31.25kV
4.
1. Using thick cables/ low resistance cable
Stepping up the voltage
2. The fuse is connected on the neutral wire instead of live.
Bulb B3 is short circuit
Switch S1 is connected on the neutral wire instead of live.
Tapping the lighting circuit from the socket

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