Question

What are the types of wavefront?

Answer 1

A wavefront is a line or surface in the path of wave motion on which the disturbances at every point have the same phase. Wavefronts can be of three types depending on the source of light as follows:

1. Spherical Wavefront :
   
   When the point source is an isotropic medium, sending out waves in three dimensions, the wavefronts are spheres centered on the source, as shown in the figure. Such a wavefront is called a spherical wavefront.
2. Cylindrical wavefront :
   
   When the light source is linear, we obtain a cylindrical wavefront. In a cylindrical wavefront, all the points equidistant from the linear source lie on the surface of a cylinder, as shown in the figure.
3. Plane wavefront :
   
   The wavefront will appear as a plane when viewed from a considerable distance from a source of any kind. Such a wavefront is called a plane wavefront.

Moreover, the plane wavefront is obtained when the small part of the spherical or cylindrical wavefront originates from a distant source, like infinity.