Question

If the object is shifted by a distance towards the mirror, the image will shift by _____ towards the mirror. Fill in the blank.
(A) double the distance
(B) same distance
(C) half the distance
(D) all

Answer 1

Hint
When the real object is moved by a distance in front of the mirror then the image that is formed due to the object moves closer to the mirror by the same distance. So the distance of separation between the image and the object decreases by twice the amount.

Complete step by step answer
For any plane mirror, its focal length is infinite and the optical power is zero. This means that the image that is produced by a plane mirror is always virtual, upright and of the same shape and side as that of the object.
Now if we place an object in front of the mirror, then the image is virtual. It means that the image is formed behind the mirror. Now the optical power of the mirror being zero tells us that the image is formed at the same distance behind the mirror as the object is placed in front of the mirror.
So now if we move the object closer to the mirror by some distance, then the object that is placed behind the mirror also moves closer to the mirror. And the optical power being zero tells us that the amount by which the image moves towards the mirror is equal to the amount the object moves towards the mirror.
Therefore, if the object is shifted by a distance towards the mirror, the image will shift by the same distance towards the mirror.
Hence the option (B) is correct.

Note
A plane mirror is made by the process called silvering. In this process, silver or aluminium is used to make the surface reflecting or polished. The reflecting surface reflects most of the light that is falling on it until the surface remains untarnished.