The wave theory of light was given by

When a point source of light is placed at the focus of a convex lens,light emerges from the lens. What is the shape of the wavefront of the emerging light?

The idea of secondary wavelets for the propagation of a wave was first given by

Explain the refraction of a plane wave by a thin prism.

Assertion $A$: For light diverging from a point source,the intensity at the wavefront does not depend on the distance.
Reason $R$: In a diverging beam of light from a point source,a spherical wavefront is observed.

What is the shape of the wavefront of light diverging from a point source?