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

An object is placed at a distance of 10 cm from a convex lens of power 5D. Find the position of the

A convex lens of focal length 20 cm is in contact with a concave lens of focal length 40 cm. The pow

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 =

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