The main drawback of Huygens' theory was:

The wave theory of light was given by

The wavefront of a wave has what direction with respect to the wave motion?

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

Mark the wrong statement.

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