# Interference & Diffraction

## What is wavelet and secondary wavefront?

Wavelet: Wavelets are tiny parts of waves. Secondary wavefront: The envelop of all the secondary wavelets in the forward direction is called the secondary wavefront. The backward envelop is not a secondary wavefront.

## Define wavefront?

Wavefront A wavefront can be defined as the locus of all the points of the medium which are vibrating in phase and are also displaced at the same time. If the distance of the source is small the wavefront is spherical. But when the distance is large then any small portion of the wavefront can …

## What is diffraction grating?

Diffraction grating Diffraction grating is an extremely useful device. In one of its form it consists of a very large number of narrow slits side by side. The slits are separated by opaque spaces. Diffraction gratings are of two types; transmission grating and reflection grating. Transmission grating: When a wavefront is incident on a grating …

## What do you mean by Fresnel and Fraunhofer class of diffraction?

Diffraction phenomena can conveniently divided into two groups. Fresnel Diffraction Phenomena: In the Fresnel class of diffraction, the source or the screen or the both are at finite distances from the aperture or obstacle causing diffraction. In this case, the effect at a specific point on the screen due to the exposed incident wavefront is considered …

## What is diffraction? Explain.

Diffraction The rhythmic variations in intensity and the bending of light around the corners of an obstacle or the encroachment of light into the region of geometrical shadow constitute a class of phenomena known as the diffraction of light.

## What are the Newton’s rings and how are they formed?

Newton’s rings and its formation :  When a Plano-convex lens of long focal length is placed on a plane glass plate, a thin film of air is enclosed between the lower surface of the lens and the upper surface of the plate. The thickness of the air film is very small at the point of …

## What is fringe width?

Fringe width  The distance between any two consecutive bright or dark fringe is known as fringe width. Symbolically the fringe width is β and

## Why two independent source of light can not produce interference?

Two independent sources of light can not produce interference because a large number of difficulties are involved. The two sources may emit light waves of largely different amplitude and wave length and the phase difference between the two may change with time. That’s why interference of light is produced by two coherent sources which are …

## What do you mean by coherent sources? How are they realized in practice?

Coherent sources Two sources are said to be coherent if they emit light waves of same frequency, nearly equal amplitude and are always in phase with each other. Realization in practice In practice it is not possible to have two independent sources which are coherent. But for experimental purpose, two virtual sources formed by a …

## Define and explain interference of light.

Interference of light:  Wave emitted from two coherent sources having the same wavelength, equal or nearly equal amplitude when passes through a point in a medium, then superposition takes place.  During superposition, if the two waves reaching the point in the same phase then the intensity will be maximum that is bright. But if the …

Scroll to Top