Question

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 the plane:

Answer 1

Consider a point source of light O placed on a plane mirror MM'. A ray of light OA coming from O is incident at point A on the mirror and gets reflected in the direction AX according to the law of reflection of light. Another ray of light OB coming from O strikes the mirror at a 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 the plane mirror is at the same distance behind the mirror as

the object is in front of the mirror.

(v)

The image formed by the plane mirror is

laterally inverted.