Long Answer Type(a) State the laws of refraction of light. Give an expression to relate the absolute refractive index of a medium with speed of light in vacuum.
(b) The refractive indices of water and glass with respect to air are 4/3 and 3/2 respectively. If the speed of light in glass is 2 × 108 ms−1, find the speed of light in (i) air, (ii) water.(a) A person cannot read newspaper placed nearer than 50 cm from his eyes. Name the defect of vision he is suffering from. Draw a ray diagram to illustrate this defect. List its two possible causes. Draw a ray diagram to show how this defect may be corrected using a lens of appropriate focal length.
(b) We see advertisements for eye donation on television or in newspapers. Write the importance of such advertisements.
(a) If a person cannot read newspaper placed nearby, the person is suffering from hypermetropia i.e. far-sightedness. The person is unable to see the nearby objects distinctly and can only see far-by objects with a clear vision. The diagram below illustrates this defect:
The two possible causes of hypermetropia are:
(i) The focal length of the eye lens is too long
(ii) Decrease in the length of the eyeball
By using convex lens of appropriate focal-length, this defect can be corrected. 
(b) Our eye can live even after our death. By donating our eyes, we can give vision to any blind person so that he/she can see the wonderful beauty of this world. By advertising about eye donations, we can make more people aware of this noble cause and help more blind people around us.
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