Error due to non-removl of parallax between pointer and its image in case of magnetic compass needle causes_____.

The minimum distance between the object and its virtual image in case of a concave lens is

What is the minimum distance between an object and its image in case of concave mirror?

Which is more powerful between a magnetic compass needle and a bar magnet ?

What is the minimum distance between an object and its real image in the case of a concave mirror ?

A convex lens is place over a plane mirror. A pin is now positioned so that there is no parallax between the pin and its image formed by this lens-mirror combination . How can this observation be used to find the focal length of the convex lens? Give appropriate reasons in support of your answer.

A convex lens is placed over a plane mirror. A pin is now positioned so that there is no parallax between the pin and its image formed by this lens-mirror combination. How can this observation be used to find the focal length of the convex lens? Give appropriate reasons in support of your answer.