Question

Ray of light incident through the principle focus of a spherical mirror

Answer 1

If it strikes the mirror, it will be reflected back on itself and pass through the center of curvature again going in the opposite direction.

Answer 2

Explanation:

Any ray travelling parallel to the principal axis in case of concave mirror is supposed to pass through principal focus after being reflected from mirror surface .However a ray of light parallel to principal axis and coincident with it intersects mirror surface at pole and just retraces it's path after reflection therefore satisfying the condition of being parallel to principal axis as well as being reflected at pole of mirror.