Physics
Study Material

Wavefront

The continuous locus of all the particles of a medium ,vibrating in the same phase is called wavefront. It is the locus of the source of wave.

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Posted by Mahak Jain, 8/12/2021

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According to the wave theory of light, a source of light sends out disturbance in all directions. In a homogeneous medium, the disturbance reaches all those particles of a medium in a phase, which are located at the same distance from the source of light and therefore at any instant, all such particles must be vibrating in phase with each other. ‘The continuous locus of all the particles of a medium ,vibrating in the same phase is called wavefront’.

What is Wavefront?

As mentioned above wavefront is the continuous locus of all the particles of a medium ,vibrating in the same phase.

In simple words wavefront shows the shape of propagation of wave. It is the locus of the source of wave. For example locus of point is circle. So, wavefront of wave emitted from point source is a sphere. Thus, types of wavefront depends upon the shape of the source of light. Types of wavefronts are listed below.

Types of Wavefront

Spherical Wavefront

When the source of light is point source , the wavefront is a sphere with centre at the source. Example, a small bulb emits spherical wevefront.

Cylindrical wavefront

When the source of light is linear in shape ( i.e like slits) , a cylindrical wavefront is produced due to all the points which are equidistant from the linear linear source lie on the surface of a cylinder. Example, a tubelight emits cylindrical wavefront.

Plane wavefront

A small portion of spherical or cylindrical wavefront appears to be plane when the point source of light is at very large distance then such a wavefront is called plane wavefront. Example, a laser light emits plane wavefront.