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(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 nearer than 50 cm from his eyes, then the person is suffering from hypermetropia or far-sightedness. The person is unable to see nearby objects clearly and can only see the far object clearly.
The ray diagram given below illustrates this defect:
(b) The two possible causes of hypermetropia are:
1. The focal length of the eye lens is too long.
2. Shortening of the eyeball.
This defect can be corrected by using a convex lens of appropriate focal length.
(b) We see advertisements for eye donation on television or in newspapers, that if eyes are removed within 4 to 6 hours of a person's death, then the eye can be transplanted to the patients who are suffering from blindness.
The importance of such advertisements is to promote and aware more and more people of this cause so that people are encouraged to take the step of eye donation and help more blind people around us.
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