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Form 3 Physics Paper 2 End of Term 3 Exams 2021

Class: Form 3

Subject: Physics

Level: High School

Exam Category: Form 3 End Term 3 Exams

Document Type: Pdf

Exam Summary

SECTION A (25MKS)

1. State one disadvantage of using a pin hole camera to take photographs (1mk)

2. Name two advantages which a lead accumulator has over a dry cell (2mks)

3. A girl observes her face in a concave mirror of a focal length 90cm. If the mirror is 70cm away, state two characteristics of the image observed. (2mks)

4. What property of light is illustrated by formation of shadows? (1mk)

5. Other than local action state another defect of a simple cell and explain how it reduces the current produced. (2mks)

6. The figure below shows a simple experiment using a permanent magnet and two metal bars X and Y. State, with reason, which bar is a soft magnetic material. (2mks)

7.A plain sheet of paper and a plane mirror both reflect light yet only the plane mirror forms images. Explain why the paper cannot form images (2mks)

8.The Figure below shows an ammeter used to measure current through the conductor. The student used the lower scale. State the reading from the meter. (1mk)

9. (a) In an experiment to estimate the diameter of an oil molecule, an oil drop of diameter 0.06cm spread over a circular patch whose diameter is 20cm. Determine:-
(i) The volume of the oil drop (2mks)

(ii) The area of the patch covered by oil. (2mks)

10. Two similar razor blades are placed one on a wooden block and the other on a soft iron
block as shown in the figure below It was observed that the razor blade on the wooden block was attracted to the magnet while the other on the soft iron block was not. Explain. (2 marks)

11. The figure below shows a displacement - time graph for a wave. Determine its frequency. (3mks) 12. Explain two reasons why in domestic electrical wiring bulbs are connected in parallel (2mks)

13. Figure 4 shows conductor carrying current in magnetic field and moves in direction shown. Identify polarities X and Y. (1mks)

SECTION B (55MARKS)

14. a) An uncharged metal rod brought close but not touching the cap of a charged electroscope causes a decrease in the divergence of the leaf. Explain the observation.
(1mark)

(b) In experiment to investigate factors affecting capacitance of a capacitor, a student increased
the area of the plates and decreased the separation of the plates. Explain the effect on the
capacitance when
(i) the area of plates increased (1 mark)

(ii) the distance of the separation of the plates decreased (1 mark)

(c) Figure 7 illustrates a method of charging a metal sphere. (i) Name the method of charging shown in fig 7. (1mark)

(ii) Indicate the final charge on the sphere in fig 7 (1 mark)

(d) Figure 9 shows an arrangement of capacitors connected to a 10V d.c supply. Determine
(i) the combined capacitance (2 marks)

(ii) the total charge in the circuit (1 mark)

(iii) the total energy stored in the circuit. (2marks)

15. (a) Distinguish between e.mf. and terminal voltage of a battery. (2 marks)

(b) The graph in figure 8 shows the variation of potential difference V against current I for a cell when current is drawn from it. (i) From the graph determine
(a)The e.m.f of the cell. (2 marks)

(b)The internal resistance of the cell. (4marks)

(c)on the space provided below, draw a circuit that could be used to obtain the results represented by the graph. (2 marks)

16. (a)Figure 9 is an illustration of a wave pattern. i) State with reason the type of wave shown. (2 marks)

ii)Determine the wavelength of the wave. (1 mark)

iii)Calculate the frequency of the wave given that the speed of the wave is 9m/s. (3 marks)

b) Figure 10 show s monochromatic source of light L behind a barrier with a single slit S placedbehind another barrier with two identical slits S1 and S2. A screen PQ is placed in position as shown. i) Explain what is observed on screen PQ. (2mks) (2 marks)

ii) What is the significance of S1 and S2 ? (1 mark)

17. Figure 11 shows an electromagnetic relay being used to switch an electric motor on and off. The electromagnet consists of a coil of wire wrapped around a core. The motor in figure is switched off. (a)Suggest suitable material for the core. (1mark)

(b)What happens to the core when switch S is closed? (2marks)

(c)Why do the contacts A and B close when the switch S is closed. (2marks)

(d)When the switch S is opened, what will happen to;
(i) The core (1mark)

(ii) Soft iron armature. (1mark)

(b) Give one other application of an electromagnet. (1mark)

(c) State two ways in which an electromagnet could be made more powerful. (2marks)

18. Figure 12 below shows a narrow beam of white light onto a glass prism. (i) What is the name of the phenomenon represented in the diagram? (1mk)

(iii) Name the colour at X and Y. Give a reason. (3mks)

(iii) What is the purpose of the slit? (1mk)

19. The figure 4 shows a circuit with a coil used to warm oil in a beaker. (a) State the Ohm’s Law (1mk)

(b) (i). Explain how heat is produced in the coil. (2mks)

(ii )Given that the reading of the ammeter is 2.5A, determine the resistance of the coil. (3mks)

(iii).How much heat is produced in the coil in a minute? (3mks)

(iv).Give two changes that can be made in the set-up in order to produce more heat per minute. (2mks)

(iii)How much heat is produced in the coil in a minute? (3marks)