With the help of a labelled ray diagram, describe how a plane mirror forms an image of a point source of light placed in front of it. State the characteristics of the image formed in a plane mirror.
Consider a point source of light O placed in front of a plane mirror MM’ a ray of light OA coming from O in incident at point A on the mirror and gets reflected in the direction AX according to the laws of reflection of light. Another ray of light OB coming from O strikes the mirror at point B and gets reflected in the direction BY. Rays AX and BY, on producing backwards, meet at point I behind the mirror; which is the image of point source O.
Characteristics of image formed in a plane mirror:
(i) The image formed in a plane mirror is virtual. It cannot be received on a screen.
(ii) The image formed in a plane mirror is erect. It is the same side up as the object.
(iii) The image in a plane mirror is of the same size as the object.
(iv) The image formed by a plane mirror is at the same distance behind the mirror as the object is in front of the mirror.
(v) The image formed by a plane mirror is laterally inverted.