State the direction of incident ray which after reflection from a spherical mirror retraces it’s path. Give a reason to your answer.

When the incident ray is directed towards the centre of curvature, after reflection from a spherical mirror, it retraces it’s path.

It is because the ray is normal to the spherical mirror, so ∠i (angle of incidence) = 0, therefore, ∠r (angle of reflection) = 0.