Question

A beam of light gets reflected from a plane mirror and a real image is formed. The incident beam should be
A) parallel
B) convergent
C) divergent
D) plane mirror cannot form a real image

Answer 1

We have to analyse the nature of image formation of plane mirrors and also the difference between the real and virtual images.

Complete step by step solution:
When a beam of light falls on any surface, some part of light comes back to the same medium which is known as reflection. Some amount of light passes through the surface which is called transmission. A small amount of light will be absorbed by the surface. This phenomenon is known as absorption. Here we will concentrate on the reflection part. It is just like when you throw a ball on the wall, after hitting the wall it comes back. In the same way light also comes back to the same medium after hitting on any surface. This bombarding back of light is known as reflection. We are able to see all the objects around us as well due to the reflected light which reaches our eyes. Reflection occurs on any surface, but only in a few cases we are able to see the image.
When you stand in front of the dressing mirror, you can see your own image, but if you stand in front of a rough wall, you will not see your own image. Let us analyse which factor is responsible for image formation, in the case of a mirror, the surface is smooth. Hence, we are able to see the image. But we cannot see the image on the wall as it has a rough surface. If the incident rays meet after reflection,then that point is the place where the image is formed.
To answer the given question, we must know the nature of image formation. We can observe that the size of the image formed behind the mirror is exactly the same as the object, the object distance is equal to the image distance. If you raise your right hand you feel like you raised your right hand. i.e. the image is laterally inverted. Now, we analysed the nature of image formation in plane mirrors. Just think, is it your real image or virtual image. First, we must understand the difference between the real and virtual image. In the case of a plane mirror, the image is formed behind the mirror which we can not catch on the screen. These kinds of images are known as virtual images. We can only see the virtual image, but it is not possible to touch it. If the image can be caught on the screen, then it is a real image.
In case of a plane mirror, the image formed will be behind the mirror and it is virtual. We conclude that in case of a plane mirror, it is not possible to get a real image.

The correct answer is option D. i.e. plane mirror cannot form a real image.

Note: Whenever we see images formed behind the mirror, it is always virtual. When the incident rays meet after reflection then it is a real image. If they are not actually meeting after reflection but appear to be meeting after reflection then it is a virtual image.