Answer all questions from this section.
1. Which one of the following devices converts electrical energy to mechanical energy?
2. A razor blade floating on water sinks when a few drops of paraffin are added to the water because
a. Paraffin is denser than water
b. Surface tension of water increases
c. Surface tension of water reduces
d. Cohesion of water molecules increases
3. Which of the following is true about a periscope? If
a. Gives a laterally inverted image
b. Is used to observe an obscured object
c. Is used for viewing distant objects
d. Gives a magnified image of the object
4. An appliance that uses a current of 3A is connected to the mains by wires that can carry up to SA. The best fuse that can be used for the appliance is
a. 2A fuse
b. 3A fuse
c. 4A fuse
d. 5A fuse
5. In a cathode ray oscilloscope, the
a. Horizontal plates deflect the electron beam in the Y-direction
b. Electrons are accelerated towards the screen by the grid
c. Vacuum hinders the motion of the electrons
d. Electrons are emitted from heated anode
6. Find the source that would give a mass of 400g an acceleration of 8ms-2
7. A hollow glass sphere of mass 60g floats in water such that two-thirds of its volume is under water of density 1g cm-3 . find the volume in cm3 of the sphere.
8. All electromagnetic waves
a. Highly penetrate matter
b. Produce ionization in gases
c. Cause heating effect when absorbed by matter
d. Do not require any material
9. When a steel rod is stroked using a bar magnet, the
(i) Rod attracts small steel pins
(ii) Rod will be charged
(iii) Magnetic dipoles will be aligned
a. (i) only
b. (i) and (ii) only
c. (ii) and (iii) only
d. (i) and (ii) only
10. The radium 22288 Ra nuclide has
a. 138 protons and 88 neutrons
b. 138 neutrons and 88 protons
c. 138 electrons and 88 neutrons
d. 138 protons and 88 electrons
11. An athlete who covers 80m in 10s is timed using the number of heart beat. If the heat beat of the person timing is 72 per minute, find the number of heat beat counted.
12. The fins of a car radiator are painted black because black bodies are
a. Transmitters of heat
b. Reflectors of heat
c. Absorbers of heat
d. Radiators of heat
13.Which one of the following wave patterns on a C.R.O represents sound of the highest pitch?
14. Two bulbs each rated 240V,25W are lit for 5 hours each day. If the cost of each unit is shs.200, find how much it costs to run the bulbs for 30 days.
a. Shs 1,500
b. Shs 12,000
c. Shs 60,000
d. Shs 1,500,000
15. When a body is raised above the ground its gravitational potential energy
a. Is raised
b. Is lowered
c. Remains constant
d. Changes to kinetic energy
16. Which of the following statements is true?
a. The temperature at which water freezes is -2730c
b. The boiling point of water 373k
c. The value of the absolute zero is 00c
d. Evaporation is possible at a temperature of 0k
Figure one represents lines on a sheet of writing paper observed through a convex lens. What is the magnification?
18.The direction of the force on a current carrying conductor in a magnetic field depends on
(i) Direction of current
(ii) Strength of the magnetic field
(iii) Direction of the magnetic field
a. (iii) only
b. (i) and (ii) only
c. (i) and (iii) only
d. (i), (ii) and (iii)
19. In an elastic collision,
a. Bodies move a common velocity
b. Kinetic energy is mot conserved
c. Kinetic energy is conserved
d. Bodies stick together
20. Find the final temperature of a gas when its pressure is doubled and volume is tripled, given that its initial temperature is T.
Two plane mirrors M1 and M2 are inclined to each other at an angle of 700. If the ray AB incident on M1 is reflected as shown in figure 2, find the angle of incident, i
22. An a.c generator can be modified to produce d.c. by
a. Increasing the number of coils
b. Increasing the number of turns in the coil
c. Using an electromagnet instead of a permanent magnet
d. Replacing the slip rings with a split ring
Figure 3 shows a constant force, F acting on a mass placed on a rough surface. Which of the following statements about the mass is correct?
a. Acceleration is constant if F is equal to frictional force
b. Velocity is constant if F is greater than frictional force
c. Momentum is constant if F is equal to frictional force
d. It moves to the left if frictional force is greater than F
24. A concrete bridge develops a notch when overloaded because it is,
25. Three waves pass a post every minute in a lake. If the average distance between the waves is 15m, find the average speed of the waves.
In the circuit shown in the figure 4, the potential difference across
a. R1 and R2 are equal
b. R2 and R4 are equal
c. R1 and R4 are equal
d. R3 and R4 are equal
27. A car engine exerts a force of 500 N in moving 1000 m in 200 s. calculate the power developed by the engine.
a. 200 w
b. 500 w
c. 1000 w
d. 2500 w
Figure 5 shows a transverse wave. What is its length?
a. 4 cm
b. 3 cm
c. 2 cm
d. 1 cm
29. Calculate the charge which flows through a 600Ω resistor when a p.d 0f 20V is applied for 30 s across its ends
a. 900 c
b. 600 c
c. 20 c
d. 4 c
30. Oil of volume 1.0x102cm3 is dropped on the surface of clean water. If it spreads to form a circle of radius 4 cm, find the diameter of a molecule of oil.
Figure 6 shows two forces of 10N acting on a body. What is the value and direction of the force needed to resolve its original shape?
a. 2 N to the left
b. 18N to the left
c. 2N to the right
d. 18N to the right
32.A body which is accelerating
a. Experiences zero force
b. Decreases its velocity to zero
c. Travels with increasing velocity
d. Travels only in a straight line
33. Charge distribution on a conductor depends on.
a. The material out of which the conductor is made
b. Shape of conductor
c. Quantity of charge
d. Nature of the charge
34.A wheel barrow that is used to carry a load across a soft ground should have a
a. Narrow wheel because it exerts greater pressure on the ground
b. Narrow wheel because it exerts less pressure on the ground
c. Wide wheel because it exerts greater pressure on the ground
d. Wide wheel because it exerts less pressure on the ground
Figure 7 shows a block of mass 0.5 kg pulled from rest a long a frictionless table by a steady force F and attained a speed of 8m s-1 in 2 s. find F
a. 0.125 N
c. 2 N
36. The low of electrostatic states that
a. Charges occur in pairs
b. Charges repel each other
c. Like charges attract each other
37. An element X has atomic mass of 228 and atomic number of 90. It emits a B-particle forming an element Y. the symbol for Y is
Figure 8 shows a spring balance supporting a block being lowered into a beaker containing water. When the block is immersed in water, the reading of the spring balance
c. Becomes zero
d. Remains constant
39.When a mass is hanged from a spring balance and removed, the pointer on the spring balance does not return to the initial position because the
a. Spring was too short
b. Extension of the spring was proportional to the mass
c. Spring stretched to proportional limit
d. Spring extended beyond the elastic limit
40. A perfect blows a whistle and hears the echo from a wall after 1.1 s. if the speed of sound in air is 330m-1 , calculate the distance of the wall from the perfect
b. 300.0 m
c. 363.0 m
d. 600.0 m
SECTION B (40 MARKS)
Answer all questions in this section. All working must be shown clearly in the spaces provided.
(a) Figure 9 shows a step-down transformer. Name the coils marked
(b) If the transformer is used to step down mains supply from 480 V to 24V and coil A has 800 turns, determine the number of turns in coil B.
42. Two steel balls A and B of masses 2 kg and 1 kg are released from rest at the same time from heights of 20 m and 5 m respectively. Find the difference in time taken for A and B to strike the ground
43. (a) what is meant by the term radioactivity?
The above equation shows three stages (i), (ii) and (iii) of radioactive series.
(i) Name the particles emitted at stage (ii) and stage (iii) of the series.
(ii) Which of the nuclei A, B, C and D are isotopes?
Figure 10 shows a petrol engine. Name the parts labeled A, B, C, and D
(b)state what happens in the petrol engine during the power stroke.
45. A steel rod of cross-sectional area 32m2 is 4m long. When a force of 1.6x105N is applied to the rod, its length increases by 1 mm, calculate the 1.6x105N is applied to the rod, its length increases by 1mm, calculate the
(i). stress in the rod
(ii). Strain produced
A ray of white light is incident on a glass prism as shown in figure 11. Complete the diagram to show effect of the glass prism on the ray.
(b). find the critical angle for glass in air if the refractive index of the glass is 1.5.
47. (a) Define an ohm as a unit of resistance.
Figure 12 shows two cells E1 and E2 of e.m.fs 1.0 v and 1.5 v and internal resistances of 1.0Ω and 0.5Ω respectively connected in series with an 8.5 Ω respectively connected in series with an 8.5Ω resistor. Calculate the current flowing through the circuit.
Figure 13 shows the diagram of an x-ray tube
(a). Name the part labeled F
(b) Why is the x-ray tube evacuated?
(c ) What is the function of the part labeled F?
(d)State two precautions to be taken when using x-rays.
49. (a) what is meant by specific latent heat of vaporization?
Figure 14 represents a cooling curve of steam. State what takes place over regions.
(c ).why is a burn from steam more harmful than one due to boiling water?
50 (a) what is longitudinal wave?
Figure 15 shows a sound wave produced from a tuning fork vibrating at 800 Hz. Calculate the velocity of the wave in the medium.
(c ) state two factors which determine the velocity of sound in air.
1.(a) state the
(i) Law of conservation of moment
(ii) Factors on which linear momentum depends
(b)Explain what happens when a balloon is filled with air and then released in space without trying its open end.
(c ) Explain what happens to a passenger in a bus ,when the driver breaks suddenly.
(d)Define the following terms
(e)With the aid of a labeled diagram, describe an experiment to measure a uniform velocity or a body using a ticker timer.
2. (a) Define a moment of force.
(b) describe an experiment to determine the mass of a uniform meter rule using the principle of moments.
Figure 1 shows a uniform pole AB of length 2m and weight 50N supported at the ends A and B. A load of weight 500 N is suspended at a point 50cm from A.
Calculate the reaction forces R1 and R2 at the supports.
(d)(i) Explain what is meant by unstable equilibrium.
(ii) State two ways of increasing the stability of a body
3(a) Define the following terms
(ii) Tensile force.
(b)with the aid of a diagram, describe an experiment to verify hooke's law using a spring.
(c ) (i) A material of mass 2kg requires 4.4x103 J for its temperature to change from 600c to 800c . calculate its specific heat capacity.
(ii)If the material in (d) (i) is placed in a vacuum, state why it cools.
4(a) Describe with the aid of a labeled diagram the operation of a transformer.
(b)A 240 v step-down mains transformer is designed to light ten 12v, 20w ray box lamps and draws a current of 1A in the primary coil .
(i) Power supplied to the primary coil
(ii) Power developed in the secondary coil
(iii) Efficiency of the transformer
(c) With the aid of suitable diagrams, distinguish between an alternating current and a direct current.
(d) Explain how a fuse as a safety device achieves its function in house wiring.
5. (a) Distinguish between thermionic and photoelectric emission.
Ultra violet radiations are incident on a clean zinc plate resting on the cap of a charged gold leaf electroscope as shown in figure 2. Explain what is observed if:
(i) The gold leaf electroscope is positively charged
(ii) Radio waves is used instead of ultra violet radiations
(c ) (i) with the aid of a labeled diagram, describe how X-rays are produced in an X-ray tube.
(ii)Explain why soft x-rays are used instead of hard X-rays to take photographs of internal parts of a patient in hospitals.
6. (a) Define the terms
(b) Draw diagrams to show how circular water ripples are reflected from
(i) concave reflector
(ii) convex reflector
(c ) (i) distinguish between longitudinal waves and transverse waves.
(ii)Give one example of each of the waves in (c ) (i).
(d)State four properties of electromagnetic waves.
(e) the distance between two successive antinodes on a standing wave is 3.0 cm. if the distance between the source of wave and reflector is 24.0cm, find the
(i) number of loops
(ii) wavelength of the wave
7. (a) Define the following terms as applied to curved mirrors
(i) center of curvature
(ii) principal axis
(b) explain with the aid of a ray diagrams, why a parabolic mirror is preferred to a concave mirror as a car head lamp.
(c ) An object of height 5 cm is placed 15 cm in front of a concave mirror of radius of curvature 20cm. by scale drawing, find the
(i) Image distance from the mirror
(ii) Height of the image
(d)(i) with the aid of ray diagrams, explain how regular and diffuse reflections are produced.
(ii) state the characteristics of images formed in plane mirrors
8. (a) what is meant by?
(ii) half life
(b) what happens to the activity of a radioactive material when its
(i) mass is increased
(ii) temperature is increased
(c ) A material is wrapped in a photographic film and kept in a dark room when the photographic film is removed, it is found to be darkened.
(i) Identify the material
(ii) Explain the observation
(d). a radioactive substance of mass 60 g takes 400 years for its mass to be reduced to 15g. find its half life.
(i) two industrial and two medical uses of radioactivity
(ii) two health hazards of radioactivity