Reflection of Light

Reflection of light
   When light is incident on a smooth surface, it is partly sent back by the surface in the same medium through which it had come.This phenomenon is called reflections of light by the surface.

Reflection of light from plane mirror

   Let M1M2 be a plane mirror. A ray of light AO falls on the mirror at a point A and is reflected in a definite direction along AB. The ray  OA is 'incident ray' and the ray AB is 'refleted ray' . The point  ' A' on the mirror is called 'point of incidence' . The line AN drawn perpendicular to the mirror at the point of incidence is called normal. The angle between the incident ray OA and the normal AN is called the angle of incidence (i) and the angle between the reflected ray AB and the normal AN is called the angle of reflection (r).

    The reflection of light follows two laws :
1. The incident ray, the normal at the point of incidence and the reflected ray all lie in the same plane.
2. The angle of incidence (i) and the angle of reflection (r) are equal. 

   The experimental observation are called law of reflection.

     For normal incidence, i=0 and so r=0. Hence , a ray falling normally on a mirror is reflected back along its own path.