You have learnt in the text how Huygens’ principle leads to the laws of reflection and refraction. Use the same principle to deduce directly that a point object placed in front of a plane mirror produces a virtual image whose distance from the mirror is equal to the object distance from the mirror.

Answer –

Consider an item O placed at a distance r in front of the plane mirror MO’. The object is designated as point O, and a circle is drawn around it, just touching the plane mirror at point O’.

The wavefront of incident light, according to Huygens’ Principle, is XY. If the mirror was absent, a wavefront X’Y’ (as XY) would form behind O’ at a distance of r. For the plane mirror, X’Y’ can be thought of as a virtual reflected ray. As a result, putting a point object in front of a plane mirror produces a virtual picture with the same distance from the mirror as the object distance (r).