Question

what will be the angle of reflection if a Ray of light strikes a plane mirror at the angle of 90°?

Answer 1

Since, angle of incidence = angle of reflection = 30 degrees. The incidentray will have an angle of reflection of 30 degrees (made with a surface normal to the mirror surface). Thereflected ray will make an angle of 60 degrees (90 - 30 degrees) with themirror surface.