Q10.13  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.

Answers (1)
P Pankaj Sanodiya

Let an object M is placed in front of a plane mirror AB at a distance r .

 

 

A circle is drawn from the centre, such that it just touches the plane mirror at point P. according to the Huygens’ principle, AB is the wavefront of the incident light .

If the mirror is absent then a similar wavefront A'B' would form behind M at a distance r.

 

 

A'B' can be considered as a virtual reflected ray for the plane mirror.  Hence a point object placed in front of the plane mirror produces an image at the same distance as the object.

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