CBSE - X - Physics - The Human Eye and The Colourful World
when a person has a defect in eye like hypermetropia and he uses the corrective lens. Will it make him short sighted?
To correct a myopic eye, the person has to wear spectacle with a concave lens of suitable focal length. The focal length of concave lens is equal to the distance of the far point of the myopic eye, so that the rays are diverged and final image is formed at the retina.
To correct a hypermetropic eye, the person has to wear spectacle with a convex lens of suitable focal length. The focal length of the convex lens is given by f=(x d) / (x-d); where x is the distance of near point of defective eye; d is the distance of near point of normal eye, so as to converge the rays and form the final image at the retina.
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