Question

What are the types of wavefront?

Answer 1

Hint: The wavefront of a time-varying field is defined as the set (locus) of all places where the wave has the same sinusoid phase. The phrase is only usually applicable to fields that change sinusoidally in time with a single temporal frequency at each location. Wavefronts generally move with the passage of time. The wavefronts of waves propagating in a unidimensional media are generally single points; in a two-dimensional media, they are curves, and in a three-dimensional one, they are surfaces.

Complete answer:
A wavefront is a line or surface in the direction of wave motion that has the same phase of disturbances at all points. Depending on the source of light, wavefronts might be one of three types:
Cylindrical wavefront.
All locations equidistant from a linear source lie on the surface of a cylinder when the source of light is linear. A cylindrical wavefront is the name for such a wavefront.
Spherical wavefront.
When a point source emits waves in three dimensions in an isotropic medium, the wavefronts are spheres centred on the source. A spherical wavefront is one such wavefront.
Plane wavefront
The wavefront formed when a part of a spherical or cylindrical wavefront comes from a distant source such as infinity is known as a plane wavefront.

Note: The wavefronts of a sinusoidal plane wave are planes perpendicular to the propagation direction that move in the same direction as the wave. The wavefronts of a sinusoidal spherical wave are spherical surfaces that grow with it. Refraction can affect the form and/or direction of wavefronts if the propagation speed varies at different places along the wavefront. Lenses, in particular, may transform optical wavefronts from planar to spherical or vice versa.