Question

What is a long-sighted eye ? State one cause of long-sightedness. Name the lens used for correcting long-sightedness.

Answer 1

An eye is said to be long-sighted if the image of a nearby object is formed behind the retina. It is caused because the eye lens cannot widen enough to reduce the focal length i.e. it is too thin or if the cornea is small. It can be corrected by using $convexlens$ which will first converge the rays before they meet the iris and allow the image to form exactly on the retina.