By Huygen's wave theory of light,we cannot explain the phenomenon of

What is the definition of a wavefront?

Select the correct option regarding the history and nature of light.

An initially parallel cylindrical beam travels in a medium of refractive index $\mu(I) = \mu_0 + \mu_2I$,where $\mu_0$ and $\mu_2$ are positive constants and $I$ is the intensity of the light beam. The intensity of the beam is decreasing with increasing radius. The initial shape of the wavefront of the beam is

Huygens' theory of secondary waves can be used to find:

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