Light waves propagate rectilinearly due to:

$A$ parallel cylindrical beam of light propagates in a medium with a refractive index $\mu(I) = \mu_0 + \mu_2 I$,where $\mu_0$ and $\mu_2$ are positive constants and $I$ is the intensity. As the intensity of the light decreases,the radius increases. The initial shape of the wavefront is:

Which of the following generates a plane wavefront?

Which of the following phenomena cannot be explained by Huygens' principle?

$A$ wavefront is the locus of all points where the particles of the medium vibrate with the same:

Which of the following is correct for light diverging from a point source?