What will be the angle of reflection if a ray of light strikes a plane mirror normally?
When Incident ray AI moves towards normal OI the reflected ray also moves closer to the normal.
As a result, the angle between normal and reflected ray (angle of reflection) decreases and becomes zero when incident ray overlaps normal.
For normal incidence,
Angle of incidence = 0∘
The angle of reflection = Angle of incidence
Therefore, here the angle of reflection = 0∘