4th Jul '20


When light 'hits' a mirror the light is 'bounced off'. We say it as been reflected. We define the angle at which a ray hits a mirror as the 'angle of incidence'. This is measured, not from the mirror surface but from a line at 90° to it.

We call this imaginary line the 'normal', it is a construction-line to the reflecting/refracting surface at the point of incidence.

The reflect ray leaves the mirror at the 'angle of reflection' which is also measures from the normal.

When light is reflected the angle of reflection is always the angle of incidence.