The movement of liquid from low to high concentration through a semi-permeable membrane is called
A.diffusion
B.fusion
C.osmosis
D.osmotic pressure
E.Brownian motion.
2.1 mark
What would happen to the planets moving around the sun if the gravitational force suddenly disappeared?
A.The planets would fuse together
B.The planets would fly far away opposite to the sun’s direction
C.The planets would move tangentially to their orbits in a straight line
D.Some planets would fall onto other planets nearby
E.Some of the planets would collide.
6.6 marks
(a)
Define capacitance of a capacitor and state the factors which affect capacitance.
4 mk
(b)
A capacitor is labelled with the capacitance value of 470µF and is charged to a potential difference of 10 V. Calculate the charge stored by the capacitor.
2 mk
((b)(i)
Give one (1) reason why A house with thick walls is likely to be cooler during hot seasons.
1 mk
((c)(i)
Why are passengers in the plane not charged, but an attendant who immediately opens the door from outside after the landing of plane is at risk?
2 mk
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7.8 marks
((a)(i)
Differentiate between x-rays and white light.
2 mk
((b)(i)
A radioactive element has a half-life of 1600 years. What will the fraction of its original mass which has decayed after 6400 years be?
2 mk
((c)(i)
What is A in equation 7 (c) (i) above?
0 mk
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8.5 marks
((a)(i)
How does a junction diode work?
2 mk
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Section B
4.1 mark
Study the circuit diagrams in Fig. 7 (l and m) carefully. Which of the two circuits will light a bulb.
(a(i))
What is A called and what is its focal length?
0 mk
(b)
Show by a ray diagram how a suitably placed eye sees an image of a point object which is placed 10 cm in front of a plane mirror. Show clearly the position of the image and give two reasons why it is described as virtual.
4 mk
(c)
Calculate the critical angle for light emerging from glass of refractive index 1.55 into air.
3 mk
(a(ii))
How far from A is the first image of the distant object?
0 mk
(a(iii)
What is the name of B?
0 mk
(a(iv))
What acts as the ‘object’ for B and how far must B be from it if someone looking through the telescope is to see the final image at the same distance as the distant object?
1 mk
(a(v))
What is the distance between A and B with the telescope set up as in (iv)?
0 mk
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5.5 marks
The semiconductor diode can be used as a rectifier as used in the circuit below; Fig. 5. (i) What does the term rectification mean? (ii) The rectification described by the circuit in Fig. 5 above, is half wave rectification. Sketch its waveform which would be seen on a suitably adjusted CRO and explain why the output voltage is so rectified.
(a(i))
Fundamental interval of a temperature scale
1 mk
(a(ii))
Apparent expansivity of water.
1 mk
((b)(i)
The rectification described by the circuit in Fig. 5 above, is half wave rectification. Sketch its waveform which would be seen on a suitably adjusted CRO and explain why the output voltage is so rectified.
4 mk
(a(iii)
Anomalous expansion of water.
1 mk
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Section C
3.2 marks
(b(i))
State the principle of conservation of momentum.
1 mk
(c)
Draw a block and tackle pulley system with a velocity ratio of 4.
2 mk
(b(ii))
Two cars of the same mass collide head-on and become tangled so that they move on together. If the engines of both were stopped at the moment of impact and the speeds of the cars at impact were 120 m/s and 200 m/s, find the joint velocity immediately after collision.
3 mk
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9.8 marks
Explain the following terms: (a)(i) Saturated vapour. (ii) Unsaturated vapour. (iii) Dew point. (b) The table below gives the results of an experiment to determine the saturation vapour pressure of water at various temperatures. Plot a graph of these results. Use the graph to deduce the: (i) vapour pressure of water in a room where the dew point is 8°C. (ii) boiling point of water at a pressure of 120 mm Hg. (c) Distinguish between heat (thermal) capacity and specific heat capacity. (d) A block of aluminium, 500 g at 20°C was heated in a furnace until it just melted. (i) Find the total quantity of heat required. (ii) If in this process the furnace consumed 100 litres of gas of calorific value 16800 J/litre, find its efficiency.
Results of an experiment to determine the saturation vapour pressure of water at various temperatures.
Temperature (°C)
Vapour pressure (mm Hg)
0
4.6
10
9.2
20
17.5
30
31.8
40
55.3
50
92.5
60
149.4
(9(a)()
Dew point.
1 mk
(9(b))
The table below gives the results of an experiment to determine the saturation vapour pressure of water at various temperatures. Plot a graph of these results.
1 mk
(9(b)()
Use the graph to deduce the: boiling point of water at a pressure of 120 mm Hg.
0 mk
(9(c))
Distinguish between heat (thermal) capacity and specific heat capacity.
1 mk
(9(d)()
If in this process the furnace consumed 100 litres of gas of calorific value 16800 J/litre, find its efficiency.
1 mk
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10.9 marks
List down two (2) factors that affect the magnitude of induced e.m.f. in a moving coil galvanometer. (b) (i) State the laws of electromagnetic induction. (ii) Explain how eddy currents are produced. (iii) How can eddy currents be minimized? (c) A moving coil galvanometer of 30 Ω resistance which carries a maximum current of 15 mA can be converted into an ammeter. (i) How can the galvanometer be made to give ampere readings? (ii) If the device is to give a 1.5 A full scale deflection (f.s.d.), what value of resistance will be required?
(10(a))
List down two (2) factors that affect the magnitude of induced e.m.f. in a moving coil galvanometer.
1 mk
(10(b))
How can eddy currents be minimized?
2 mk
(10(c))
If the device is to give a 1.5 A full scale deflection (f.s.d.), what value of resistance will be required?
3 mk
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11.4 marks
Explain briefly the following: (a)(i) Thermionic emission (ii) The production of a stream of electrons in a cathode ray oscilloscope (c.r.o.). (iii) The principle of the transistor. (b) What method in devices using the thermionic emission principle ensures that the electrons produced: (i) do not accumulate at the source?
(11(a))
The principle of the transistor.
1 mk
(11(b))
What method in devices using the thermionic emission principle ensures that the electrons produced: do not accumulate at the source?
1 mk
