A person is able to see objects clearly only when these are lying at a distance between 50 cm and 300 cm from his eye.
(a) What kind of defects of vision is he suffering from ?
(b) What kind of lenses are required to increases his range of vision from 25 cm to infinity ? Explain briefly.

Explanation

(a) The person.s eyes are having near point away from 25 cm and far point lesser than infinity. Hence, he suffering from both myopia and hypermetropia.
(b) The person requires bifocal lenses to increases his range of vision. The upper part of the bifocal lens is a concave lens which facilities distant vision while the lower part is a convex lens which facilities near vision.