Question

Which type of wavefront is formed when distance between light
source and slit is infinite, whether the source is point-size or linear?​

Answer 1

Answer:

(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.