Question

What is the shape of the wavefront in each of the following cases:
(a) Light diverging from a point source.

(b) Light emerging out of a convex lens when a point source is placed at its focus.

(c) The portion of the wavefront of light from a distant star intercepted by the Earth.

Answer 1

(a) Spherical

The point source emits the spherical wavefront as the light diverges from a point source in all directions.

(b) Planar

The shape of the wavefront in case of a light emerging out of a convex lens when a point source is placed at its focus is a parallel grid.

(c) Planar

(A small area on the surface of a large sphere is nearly planar). The portion of the wavefront of light from a distant star intercepted by the Earth is a plane.