SECTION A (25 MARKS)
Answer ALL the questions in this section in the spaces provided.
- An object 10cm tall is placed 20cm infront of a diverging lens of focal length 15cm. Determine the nature, position and magnification of the image by calculation. (3 marks)
- Explain why the image formed in a pinhole camera gets blurred when the hole is enlarged. (1 mark)
- Figure 1 shows a cell of e.m.f 2.5V connected in series with a resistor R and a switch S. Voltmeter, V1 and V2 are connected across the cell and the resistor respectively.
- State the reading of V1with S open. (1 mark)
- With S closed, V1 reads 1.6V. State the reading of V2. (1 mark)
- Figure 2 shows the image of an object formed by reflection in a converging mirror. C is the centre of curvature of the mirror. Complete the diagram to show:
- How incident rays are reflected to form the image. (2 marks)
- The object position. (1 mark)
- The equation below represents a nuclear reaction in which two deuterium nuclei fuse to form helium and X.
- Determine the values of a and b. (1 mark)
- Identify X. (1 mark)
- Figure 3 shows a simple transformer connected to a 24v a.c source and an a.c voltmeter.
By counting the number of turns in each coil, determine the reading on the voltmeter (2 marks)
- In domestic wiring systems lamps in the lighting circuit are required to be in parallel and not in series. Sate two reasons for this requirement. (2 marks)
- Figure 4 shows a narrow beam of x-rays passing between two metal plates in air.
The plates are connected in series with a switch, a cell and a milliameter.
It is observed that when the switch is closed a current flows in the milliameter.
Explain this observation. (2 marks)
- The anode of an x-ray tube becomes hot when the tube is in use. State the reason for this. (1 mark)
- 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 42o) (2 marks)
- Given that the velocity of sound in air is 330ms-1.
Calculate the wavelength of sound produced by a turning fork rated 0.44 kHz. (2 marks)
- Figure 5 below shows two bar magnets and soft iron ring placed between the magnets.
Complete the diagram to show the magnetic field pattern through the soft iron ring. (1 mark)
- Determine the power of a lens whose focal length is 40cm. (2 marks)
SECTION B (55 MARKS)