**What is a wavefront?**

Wave Fronts The surface on which all the points of waves have the same phase of vibration is Nose has wavefront.

**Explanation**

Suppose the light emitted from point source propagates outward in all direction with speed c, After time t, the waves •reåches the. The surface of an imaginary sphere with the center as S and radius as ct. As the distance of all these points from the source is all the points on the surface of the sphere have the carrier phase of vibration.. surface ‘is known as the wave front.

**Note**

The wavefront from a point source are spherical. Thus wave propagates in space by the motion of wavefronts.. The distance between twö consecutive wavefronts.is one wavelength. Rav is of Light The line normal to the wavefront which shows the direction of propagation of light is called a ray of light.

**(1) Spherical wavefront**

The wavefront in which the light waves are propagated in spherical form with the source is called spherical wavefront: For a point source of light in -a homogeneous medium, the wave frbpts are the concentric sphere of increasing radii.

**(2) Plane wavefront**

At a substantial distance (i.e., at infinity) from the source, a small portion of spherical wavefront will become very nearly plane. Such a wavefront is known plane wave frontäs shown in the figure. For example, the sunlight reaches the earth in plane wavefronts. On a laboratory scale, in .order to obtain plane wave from a point source, it is placed at the focus of the convex lens.