A person can see objects clearly when they lie between 40 cm and 400 cm from his eye. In order to increase the maximum distance of distant vision to infinity the type of lens and power of correction lens required respectively, are

The focal length of the objective lens of a telescope is 30 cm and that of its eye lens is 3 cm . It is focussed on a scale at a distance 2 m from it. The distance of objective lens from eye lens to see the clear image is

A ray of light travels from an optically denser to rare medium. The critical angle for the media is $C$. The maximum possible deviation of the ray will be