SECTION C : THEORY [35 mks] 1. Diamond has a refractive index of 2.42. The speed of light in a
vacuum is 300000000 m/s. Calculate ;
a. The speed of light in diamond. [3]
b. The critical angle for diamond. [3]
c. The refractive index for water is 1.33, calculate the angle of
refraction if light strikes water at an angle of incidence of 54o
. [3]
d. Write the conditions for which total internal reflection occurs. [2]
e. Give two practical use of optical fibres. [2]
2. When white light passes through a prism, it spreads into a
spectrum of colours.
a. What is the spreading effect called? [2]
b. Which colour is deviated most? [2]
c. Which colour is deviated least? [2]
d. List all the colours of rainbow in the order that they occur. [3]
e. A man stands 20 m in front of a large plane mirror. How far must
he walk before he is 8 m away from his image? [3]
3. With the aid of a well labelled diagram;
a. Draw the magnetic field around a bar magnet. [3]
b. Draw a magnetic field around two magnets with similar poles
facing each other and indicate the neutral point with an arrow. [3]
c. Sort the list below into materials that are magnetic and materials
that are not magnetic: brass, steel, iron, copper, wool, wood, nickel,
cotton. [2]
d. What is a magnetic field? [1]
e. Where is the magnetic field of a magnet strongest?

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