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

The angle of polarisation for a medium with respect to air is $60^{\circ}$. The critical angle of this medium with respect to air is

An object is placed at a distance of 18 cm in front of a mirror. If the image is formed at a distance of 4 cm on the other side, then focal length, nature of the mirror and nature of image are respectively