- State two properties of the image formed by a plane mirror (2mks)
- Two mirrored walls stand at an angle to each other. A student standing in the room counts nine images of himself in the mirrors. Determine the angle between the walls (3mks)
- The figure below shows a positively charged rod brought near a metallic sphere. Draw the distribution of charges on the sphere (2mks)
- 200 coulombs of charge passes through a point in a circuit for 0.6minutes. What is the magnitude of the current flowing? (3mks)
- Using the domain theory, explain magnetic saturation (2mks)
- The figure below shows a ray of light incident on a plane mirror.
- What is the angle of reflection? (1mk)
- The mirror is rotated clockwise through an angle of 10°.Through what angle does the reflected ray rotate? (2mks)
- Calculate the current through 6Ω resisters. (2mks)
- Draw the magnetic field pattern around the arrangement shown below (2mks)
- State two factors that affect the speed of sound in air. (2mks)
- The figure below shows white light entering a triangular prism. Complete the diagram to show what appears on the screen (2mks)
- Draw a ray diagram to show how a ray of light may be totally internally reflected two times in an isosceles right angled glass prism. (Assume that the critical angle of glass is 42°) (2mks)
SECTION B: (55mks)
-
- With reference to a concave mirror explain the meaning of:
- Focal length (1mk)
- Principal focus (1mk)
- The figure below shows an object placed in front of a concave mirror
- On the same diagram, locate the position of the image (3mks)
- What is the magnification of the image? (3mks)
- The photographic film of a pinhole camera is 15cm away from the pinhole. A girl of height 1.2m stands 6m away from the pinhole. Find the height of the girl’s image. (3mks)
- Draw a diagram to show the appearance of the sun during the annular eclipse (2mks)
- With reference to a concave mirror explain the meaning of:
-
- State two conditions necessary for total internal reflection to occur (2mks)
- The figure below shows a ray of light entering from air into glass.
Determine:- The refractive index of glass (3mks)
- The critical angle of glass (3mks)
- The speed of light in glass (3mks)
(Speed of light in air = 3.0 x 108ms-1)
- State two applications of total internal reflection. (2mks)
- A dam appears 3m deep when viewed from above. If the refractive index of water is 4/3, what is the depth of the dam? (2mks)
-
- Differentiate between longitudinal and transverse waves (2mks)
- A person stands between two high walls d metres apart. He stands 400m from the nearer wall. He blows a whistle and hears two echoes, the first one after 2.5 seconds and the second one 2 seconds later. Determine:
- The speed of sound in air (3mks)
- The value of d (3mks)
- The figure below shows a displacement-time graph for a wave travelling at 0.4ms-1
- How many complete waves are shown? (1mk)
- Determine:
- The periodic time of the wave (1mk)
- The frequency of the wave (2mks)
- The wavelength of the wave (3mks)
-
- State two factors that affect the strength of an electromagnet (2mks)
- Between iron and steel, which one would you recommend for use as the core of an electromagnet and why? (2mks)
- Draw the magnetic field pattern around a conductor carrying current into the page (2mks)
- The diagram below shows a dry leclanche cell
- Name the parts labelled A, B and C (3mks)
- –
- –
- –
- What is the purpose of the part labelled D? (1mk)
- Name the parts labelled A, B and C (3mks)
- State two precautions necessary to maintain the well being of a lead-acid accumulator. (2mks)
MARKING SCHEME
- State two properties of the image formed by a plane mirror
- They are upright
- Same size as the object
- Virtual
- Two mirrored walls stand at an angle to each other. A student standing in the room counts nine images of himself in the mirrors. Determine the angle between the walls
360 – 1 = n 360 – 1 = 9
0 0
360 = 9 + 1 360 = 10 → 0 = 360 → 0 = 36°
0 0 1 - The figure below shows a positively charged rod brought near a metallic sphere. Draw the distribution of charges on the sphere (2mks)
- 200 coulombs of charge passes through a point in a circuit for 0.6minutes. What is the magnitude of the current flowing? (3mks)
Q = It → 200 = I x 0.6 x 60 → I = 200
0.6 x 60
I = 200
36
I = 5.556 A - Using the domain theory, explain magnetic saturation
A magnetic domain is a region within a magnetic material in which the magnetization is in a uniform direction. This means that the individual magnetic moments of the atoms are aligned with one another and they point in the same direction. - The figure below shows a ray of light incident on a plane mirror.
- What is the angle of reflection? (1mk)
- The mirror is rotated clockwise through an angle of 10o.Through what angle does the reflected ray rotate? (2mks)
- Calculate the current through 6Ω resisters.
I = V → 6V → I 6Ω = 1A
R 6Ω - Draw the magnetic field pattern around the arrangement shown below.
- State two factors that affect the speed of sound in air. (2mks)
- Humidity
- Direction of wind
- Temperature
- The figure below shows white light entering a triangular prism. Complete the diagram to show what appears on the screen (2mks)
- Draw a ray diagram to show how a ray of light may be totally internally reflected two times in an isosceles right angled glass prism. (Assume that the critical angle of glass is 42°) (2mks)
SECTION B (55mks)
-
- With reference to a concave mirror explain the meaning of:
- Focal length (1mk)
- This is the distance between the principal focus and the pole of the mirror.
- Principal focus
- This is the point where rays close and parallel to he principal axis converge for concave mirror or appear to diverge from the convex mirror after reflection.
- Focal length (1mk)
- On the same diagram, locate the position of the image (3mks)
- What is the magnification of the image? (3mks)
M = hi = v
ho 4
3cm
1.5 = 2
- The photographic film of a pinhole camera is 15cm away from the pinhole. A girl of height 1.2m stands 6m away from the pinhole. Find the height of the girl’s image. (3mks)
V = 15cm hi = v hi = 15 x 120
h0 = 1.2m → h0 4 → 600
4 = 6m hi = 15
120 600 = 3cm - Draw a diagram to show the appearance of the sun during the annular eclipse (2mks)
- With reference to a concave mirror explain the meaning of:
-
- State two conditions necessary for total internal reflection to occur (2mks)
- Ray must be moving from a more optically denser medium to a leser optically denser medium.
- The angle of incidence should be greater than the critical angle.
- The figure below shows a ray of light entering from air into glass.
Determine- The refractive index of glass (3mks)
Sin i → Sin 30
Sin r Sin 19 = 0.9993 - The critical angle of glass (3mks)
Sin c = 1 → Sin c = 1 → Sin c = 1
n 0.9993 = 90° - The speed of light in glass (3mks)
(Speed of light in air = 3.0 x 108ms-1)
Speed of light in air = 0.9993 → 3.0 x 108 = 0.9993 → 3.0 x 108 = light glass
Speed of light in glass light glass 0.9993 = 3.002 x 108ms
- The refractive index of glass (3mks)
-
State two applications of total internal reflection. (2mks)
- Mirage
- Fibre optic cable
- A dam appears 3m deep when viewed from above. If the refractive index of water is 4/3, what is the depth of the dam? (2mks)
Real depth = n → R.D = 4 → R.D = 4 x 3
Apparent depth 3 3 3 = 4m
- State two conditions necessary for total internal reflection to occur (2mks)
-
- Differentiate between longitudinal and transverse waves (2mks)
- Longitudinal waves have rarefactions and compressions while transverse has troughs and crests.
- Longitudinal (parallel) Transverse (perpendicular)
- A person stands between two high walls d metres apart. He stands 400m from the nearer wall. He blows a whistle and hears two echoes, the first one after 2.5 seconds and the second one 2 seconds later. Determine:
-
The speed of sound in air (3mks)
Speed = 2D → 4000 x 2
t 2.5 = 320m/s -
The value of d (3mks)
Speed = 2D → 320 x 4.5 = D → = 720
t 2
320 = 2D → 1440 = D → d = 720 + 400
4.5 2 = 1120m
-
- The figure below shows a displacement-time graph for a wave travelling at 0.4ms-1
- How many complete waves are shown? (1mk)
2½ cycles - Determine:
- The periodic time of the wave (1mk)
0.4 sec - The frequency of the wave (2mks)
F = 1 → 1
T 0.4 = 2.5 Hz - The wavelength of the wave (3mks)
V = fλ
λ = v → 0.4
f 2.5 = 0.16m
- The periodic time of the wave (1mk)
- How many complete waves are shown? (1mk)
- Differentiate between longitudinal and transverse waves (2mks)
-
- State two factors that affect the strength of an electromagnet (2mks)
- Number of turns/ coils
- Amount of current
- Shape of the core
-
Between iron and steel, which one would you recommend for use as the core of an electromagnet and why? (2mks)
- Iron
It's easily magnetized and demagnetized.
- Iron
-
Draw the magnetic field pattern around a conductor carrying current into the page (2mks)
-
The diagram below shows a dry leclanche cell
-
Name the parts labelled A, B and C (3mks)
- Carbon rod
- Zinc can
- Amonium chloride
- What is the purpose of the part labelled D? (1mk)
- Depolarizer
-
- State two precautions necessary to maintain the well being of a lead-acid accumulator (2mks)
- Never store directly on the floor
- Do not short-circuit
- State two factors that affect the strength of an electromagnet (2mks)
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