A point object O and a mirror M move with velocities of 3 cm s−1 and 4 cm s−1 respectively as shown

If M.P. of Gallian telescope is 9 & tube length is 80 cm, then fo & fe will be respectively.

A bird is flying 3 m above the surface of water. If the bird is diving vertically down with speed =

Nature of image of a real object formed by concave lens is

The refractive index of prism for a monochromatic light is √3 and its refracting angle is 60°. For m

Critical angle of incidence for a pair of optical media is 45°. The refractive indices of first and