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

When a plane wave front is incident on a concave mirror as shown in the figure,what is the shape of the reflected wave front?

How can it be said that light possesses wave nature?

The speed of light in water is less than the speed of light in air,confirms the assumption of which theory of light?

Is Huygens' principle valid for longitudinal sound waves?

Given below are two statements:
Statement-$I$: $A$ plane wave after passing through a prism remains a plane wave, but passing through a small pinhole may become a spherical wave.
Statement-$II$: The curvature of a spherical wave emerging from a slit will increase for increasing slit width.
In the light of the above statements, choose the correct answer from the options given below.