A point object O is placed at a distance of `20 cm` from a convex lens of focal length `10 cm` as shown in the figure. At what distance x from the lens should a convex mirror of focal length `60 cm,` be placed so that final image coincide with the object?

Options

A. `10 cm`
B. `40 cm`
C. `20 cm`
D. final image can never coincide with the object in the given conditions.

Answer

C

Explanation

Object is placed at a distance of `2f` from the lens `(f=` focal length of lens `) i.e.,` the image formed by the lens will be at a distance of `2f` or `20cm` from the lens. So, if the concave mirrorr is placed in this position, the first image will be formed at its pole and it will reflect all the rays symmetrically to other side as shown below and final image will coincide with the object.