A mirror is a material made up of glass having a shiny surface.
When light falls on a mirror, it is reflected back. So a mirror changes the direction of light that falls upon it.
The bouncing back of light from a smooth surface is called reflection.
Smooth polished surfaces called mirrors can reflect light falling on them in any direction.
Formation of the image by a plane  mirror:
Figure 26_07_01.jpg
Ray diagram
  • If the rays of light from the object fall on the mirror, the object's image is formed inside the mirror.
  • The incident rays from the object reflect from the mirror and reach the eyes; thus, the object's image can be seen clearly by our eye and our eye perceives that the rays are coming from the mirror.
Characteristics of the image formed by a plane mirror are the following:
  • The image produced by the plane mirror has the same height as that of the object.
  • The distance between the mirror and the image, and the object and the mirror is always equal.
  • The image formed by the plane mirror is erect or upright and laterally inverted.
  • The image formed is virtual image because it is formed by the apparent intersection of diverging rays.
Image formation by a plane mirror
The distance between the object and the image from the mirror is always equal in the case of plane mirrors.
Lateral inversion: When an image is formed in a mirror, the left side of the object appears at the right side of the image and vice versa. This is called a lateral inversion.
Lateral inversion