Explore topic-wise InterviewSolutions in .

Divide the slit of width an into n parts, so that the width of each small part of the slit is

a' = \(\frac{a}{n}\)

⇒ a = na'

For a path difference nλ between the waves from two extreme ends of the slit,

θ = \(\frac{n\lambda}{a}=\frac{n\lambda}{na'}= \frac{\lambda}{a'}\)

Each of the n parts of the slit will send zero intensity in the direction 0. Obviously, all the n parts together will also give zero intensity.

(i) ln a beam of unpolarized light, the vibrations of light vectors are in all directions in a plane perpendicular to direction of propagation. In polarised light, these vibrations are only along one direction.

(ii) A polaroid consists of a long chain of molecules aligned in a particular direction. lt polarises light as it allows only one component of tight (electric vector parallel to the pass-axis) to pass through it while the other component is absorbed.

(iii) The observer receives scattered light corresponding to only one of the two sets of accelerated charges, i.e. electron oscillating perpendicular to the direction of propagation.

The locus of all points that are in the same phase.

Or

The surface of constant phase.

Two monochromatic sources, which produce light wave, having a constant phase difference, are known as coherent sources.