What is wavefront ? State its relation with ray of light.

Explanation

A wavefront is defined as the locus of all the particles of a medium, which are vibrating in the same phase.
Depending upon the shape of source of light, wavefront can be of three types:
(i) Spherical wavefrontn : When the source of light is a point, then the shape of the wave front will be spherical with source of light at the centre of sphere.

(ii) Cylindrical wavefront : When the source of light is linear, For example, in case of slit, the wavefront formed is cylindrical.
(iii) Plane wavefront : When the source of light (point source or linear source) is at very large distance, then a small portion of spherical or cylindrical wavefront appears to be plane. Such a wavefront is called plane wavefront.