The wavefront originating from a point source of light at finite distance is a wavefront.

In an isotropic medium, the secondary wavelets centred on every point of a given wavefront are all

Consider a medium through which light is propagating with a speed v. Given a wavefront, in order to determine the wavefront after a time interval $\mathrm{\Delta }t\backslash Delta\; t$, the secondary wavelets are drawn with a radius.

Two points, equidistant from a point source of light, are situated at diametrically opposite positions in an isotropic medium. The phase difference between the light waves passing through the two points is

Wave normals to spherical wavefronts can be

Huygens’ principle is used to

When a ray of light enters air into water?

A parallel beam of light travelling in water is incident obliquely on a glass surface. After refraction, its width

Light of a certain colour has 1800 waves to the millimetre in air. What is its frequency in water? [n = $\frac{4}{3}\backslash frac\{4\}\{3\}$ for water]

A ray of light, in passing from vacuum into a medium of refractive index n, suffers a deviation d equal to half the angle of incidence. Then, the refractive index is