Explain the reflection by a plane mirror by drawing suitable figure.

MM’ = plane mirror.

AB = object of size ‘h’ on the left - hand side of the mirror at a distance ‘u’.

AP is the incident ray of light from point A of the object which falls on the mirror at point P. This incident ray is reflected back in the same path PA as shown in the figure above.

Another incident ray OC falls on the mirror at a point O and is reflected along the path OC.

Now, since reflected rays PA and OC are diverging and therefore cannot meet each other in front of the mirror, hence we extend these rays behind the mirror by dotted lines as shown in the figure below.

On extending these rays behind the mirror, we see that these rays meet at point A’ at a distance V’. Therefore A’ is the virtual image of point A of the object AB.

Similarly, a virtual image of point B will be formed behind the mirror as B’.

Now, to get a complete image of the object AB, we join the point A and B to point A’ and B’ by a dotted line.

We find that the image A’B’ being formed is virtual, erect and of same shape and size as the object AB; thereby giving us the characteristics of images formed by the plane mirror.