The phase difference between any two particles in a given wavefront is . . . . . . rad.

Explain how the Corpuscular theory predicts the speed of light in a medium,such as water,to be greater than the speed of light in a vacuum. Is this prediction confirmed by the experimental determination of the speed of light in water? If not,which alternative picture of light is consistent with the experiment?

$A$ light beam travelling along the $X$-axis with a planar wavefront is incident on a medium of thickness $t$. In the region where light is falling,the refractive index varies such that $(dn/dy) > 0$. The light beam on the other side of the medium will emerge:

On a hot summer night,the refractive index of air is smallest near the ground and increases with height from the ground. When a light beam is directed horizontally,the Huygens' principle leads us to conclude that as it travels,the light beam

$A$ point source of light is placed at the focus of a concave mirror. Consider only paraxial rays. The shapes of the wavefronts of incident and reflected lights respectively are

According to Huygens principle, the phase difference between oscillations of any two particles on the same wave front is . . . . . . rad.