In the given mirror:
C – the centre of the sphere to which the mirror is part of
F – the focus of the mirror
P – pole of the mirror
A – a point on the mirror
D – a point on the principal axis.
If a ray of light starts from C and is incident on the mirror at the point of incidence A, then the reflected ray will pass through which point?
C
CA will fall normal to the concave mirror so by laws of reflection the angle of incidence is 0∘ and so the angle of reflection will also be 0∘. Hence the ray will retrace its path and pass through C (centre of curvature).