Question

A person looks into the mirror by placing it close to his face. The image of his face was erect, laterally inverted and of the same size. Then, the mirror must be:
A) Plane
(B)Concave
(C)Convex
(D)Concave or convex

Answer 1

Images which are real are formed by real meeting of light rays. Plane mirror always forms virtual images and in case of concave it forms both real and virtual images. For convex it only forms virtual images. Real or virtual both the images can be diminished or enlarged depending upon the configuration of the object.

Complete step by step answer:
In this problem it is mentioned that the image of the person is erect. We know that an erect image is formed when the image is virtual. So, the image formed is virtual. The image formed is laterally inverted and this is a clear property of images being formed by plane mirrors. The size of the image is equal to the size of the object. Thus, all these things clearly show that the mirror being used is a plane mirror.

So, the correct answer is “Option A”.

Additional Information:
Also, it is possible that if we can have a look at the mirror by holding it in our hands, we could have easily recognized which kind of mirror it is. Because the plane mirror is perfectly flat, the concave mirror is curved and bulged in while the convex mirror is curved bulged out.

Note:
When the concave mirror is placed very close to the object, a magnified and virtual image is obtained. But in this case the image is not magnified. Had it been a magnified image, the answer would have been concave mirror.