Physics

Reflection of Light
Definition. When light rays are incident on an opaque polished surface (medium), these are returned back in the same medium.
This phenomenon of returning of ray of light in the same medium, is called reflection of light.
Definition of some associated terms :

Reflecting surface : The surface from which the light is reflected, is called the reflecting surface. In diagram, XY is the reflecting surface.
Point of incidence : The point on the reflecting surface at which a ray of light strikes, is called the point of incidence. In diagram, O is the point of incidence.
Normal : A perpendicular drawn on the reflecting surface at the point of incidence, is called the normal. In diagram, ON is the normal.
Incident ray : The ray of light which strikes the reflecting surface at the point of incidence is called the incident ray. In diagram, PO is the incident ray.
Reflected ray : The ray of light reflected from the reflecting surface from the point of incidence, is called the reflected ray. In diagram, OQ is the reflected ray.
Angle of incidence : The angle that the incident ray makes with the normal, is called the angle of incidence. It is represented by the symbol i. In diagram, angle PON is the angle of incidence.
Angle of reflection : The angle that he reflected ray makes with the normal, is called the angle of reflection. It is represented by the symbol r. In diagram, ∠ QON is the angle of reflection.
Plane of incidence : The plane in which the normal and the incident ray lie, is called the plane of incidence. In diagram, the plane of the bookpage, is the plane of incidence.
Plane of reflection : The plane in which the normal and the reflected ray lie, is called the plane of reflection. In diagram, the plane of the book page, is the plane of reflection.