Question

If a mirror forms a virtual image of a real object then
(A) It must be a convex mirror
(B) It must be a concave mirror
(C) It must be a plane mirror
(D) It may be any of the mirrors mentioned above

Answer 1

Hint To answer this question, we need to consider the image formation for each the mirrors mentioned in the options. From there we can find if a particular mirror forms a real image or a virtual image.

Complete step by step answer
We know that for a plane mirror, the distance of the image from the mirror is always equal to the distance of the object from the mirror. So, the image is always formed behind the plane mirror. Since there is no screen behind the mirror, so always a virtual image is formed by a plane mirror.
Now, as we know that a concave mirror converges the light rays which are incident on it. So, for any object which is placed on the front of it, the image is always formed at the same side of the object. So generally, a real image is produced in the case of a concave mirror.
But when we consider the case when the object is placed between the focus and the pole of a concave mirror, then we see that the rays actually get diverged after getting reflected from its surface. So, the rays appear to be originating from a point at the behind of the mirror.
Thus, a concave mirror can also form a virtual image.
Finally, we know that a convex mirror is a diverging mirror. So, the light rays, originating from the object which is placed in front of it, are diverged after getting reflected from its surface. Therefore, the reflected rays are diverging rays which never meet in the front of the mirror. But they appear to diverge from a point situated at the back of the mirror. Thus, always a virtual image is produced in the case of a convex mirror.
Therefore, as we can see from the above cases, we conclude that all the three mirrors given in the options can form a virtual image of a real object.
Hence, the correct answer is option D.

Note
Generally, a concave mirror forms a real image of a real object. The formation of a virtual image is just a special case of the concave mirror. But we are asked about the possibility of the formation of virtual images. So do not be confused as to why we have chosen this special case of concave mirror and concluded the answer on this basis.