If $AB$ is an incident plane wave front,then what will be the refracted wave front for a lens with refractive index $n_2 > n_1$?

What is visible light? Write various views on it.

What is the definition of a wavefront?

What is the most important point of Huygens' wave theory?

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.

The idea of secondary wavelets for the propagation of a wave was first given by