If `f_(1)` and `f_(2)` represent the first and second focal lengths of a single spherical refracting surface, then

A biconvex lens made of material with refractive index n_(2) . The radii of curvatures of its left surface and right surface are R_(1) and R_(2) . The media on its left and right have refreactive indices n_(1) and n_(3) respectively. The first and second focal lengths of the lens are respectively f_(1) and f_(2) . The ratio, f_(1)//f_(2) , of the two focal lengths is equal to

Write formula for refraction of light from a single spherical surface.

Derive an expression for refraction at single spherical surface.

Derive the equation for refraction at single spherical surface.

The focal length (f) of a spherical mirror of radius of curvature R is