Deviation of light by rotating the mirror

A ray of light is the path along which the lights travel. Rays are observable. They travel along the straight line in a similar homogeneous medium and are represented by straight lines with arrowheads. The arrowhead indicates the path of light. Consider a plane-mirror and a fixed incident ray of light reflecting from the surface at an angle θ. Before the mirror has rotated, the angle of incidence is θ as is the angle of reflection.