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KISII BOYS HIGH SCHOOL
FORM 2 PHYSICS
INSTRUCTIONS TO CANDIDATES
Answer all the questions in spaces provided.
- (a) Define the centre of gravity of a body.(1 mark)
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(b) Indicate the centre of gravity of the ring below. (1 mark)
- The figure below represents a rock balanced at point O. Point G is the center of gravity of the rock. Use this information to answer part (i) and (ii) of the questions.
(i) Draw and label on the figure, the forces acting on the rock. (2 marks)
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(ii) If the portion of the rock represented by the shaded part is chopped off explain why the rock may
topple to the right. (2 marks)
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- The diagram below shows a solid cylinder standing on a horizontal surface. The cylinder is in stable equilibrium.
On the horizontal surface provided at the right hand side of the diagram, sketch the cylinder in neutral
equilibrium. (1 mark)
- State how the position of the centre of gravity of a body in stable equilibrium changes to that in the rest position when the body is slightly tilted and then released. (1 mark)
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- Explain why buses should carry heavy luggage compartments situated in the lower parts instead of the roof racks. (2 marks)
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- A uniform metre rule is balanced at the 20 cm mark when a load of 2 N is hung at the zero cm mark. Calculate the weight of the metre rule. (3 marks)
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- The figure below shows a conductor carrying current through a magnetic field.
Sketch the resultant magnetic field between the poles of the bar-magnet. (3 marks)
- A thin copper wire XY is placed over two parallel thick copper conductors connected to a c. power supply as shown below. When the switch in the circuit is closed, the wire XY experiences a force.
(i) Indicate on the diagram direction in which the wire XY experiences the force. (1 mark)
(ii) Explain how you have determined the direction of the force in (i) above. (2 marks)
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(iii) When is the force acting on the wire XY greatest? (1 mark)
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(iv) What is the effect of reversing the direction of flow of the current? (1 mark)
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- In the figurer below, the arrow indicates the directions of the current in the conductor.
Sketch on the diagram the magnetic field pattern due to the current. (2 marks)
- (i) The force of a conductor carrying a current in a magnetic field can be varied by changing a number
of factors. Name any two of the factors. (2 marks)
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(ii) The diagram below shows two parallel conductors carrying current in a direction perpendicular to
the paper.
Draw the magnetic field pattern in the diagram below and indicate the direction of the forces
acting on the conductors. (3 marks)
- (a) State two ways of increasing the strength of an electromagnet. (2 marks)
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- Distinguish between a real and a virtual image. (1 mark)
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- Give a reason why parabolic reflectors are preferred for use in car headlamps.(1 mark)
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- The figure below shows an object placed in front of a concave mirror. C is the centre of the concave mirror.
Complete the diagram by drawing appropriate rays to locate the image formed. (4 marks)
- What advantage does a diverging mirror has over a plane mirror when used as a rear-view in vehicles?
(1 mark)
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- A certain curved mirror of focal length 10 cm formed an upright magnified image which was 8 cm high and 30 cm from the mirror.
(a) State with a reason which type of curved mirror was used. (1 mark)
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(b) Determine:
(i) The object distance. (3 marks)
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(ii) Magnification of the image. (3 marks)
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(iii) Height of object. (3 marks)
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- The graph drawn below shows the variation of magnification, m, with image distance, v, for a concave mirror.
From the graph, determine the:
(i) Focal length of the concave mirror……………………………………………………….. (2 marks)
(ii) Object distance when the image distance is 45 cm. (2 marks)
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