The document discusses the reflection of light off a surface. It defines key terms like the incident ray which strikes the surface, the reflected ray which leaves the surface, and the normal which is an imaginary perpendicular line drawn at the point of reflection. It also defines the angle of incidence as the angle between the incident ray and normal, and the angle of reflection as the angle between the reflected ray and normal.

1. REFLECTION OF LIGHT

3. =The ray of light which strikes the surface is called the incident ray. =The ray of light which leaves the surface is called the reflected ray. =A line perpendicular to the surface is imagined at the point of reflection. This line is called a normal. In this ontext the word normal means perpendicular. =The angle between the incident ray and the normal is called the angle of incidence, or the incident angle. =The angle between the reflected ray and the normal is called the angle of reflection, or the reflected angle.