Question

Draw the intensity pattern for single slit diffraction and double slit interface, hence state two differences between interference and diffraction pattern.

Answer 1

Hint: Interference phenomena occurs when two separate wave fronts originate from two coherent sources, Whereas diffraction occurs when the secondary wavelength originates from different parts of the same wavefront interference based on superposition principle.

Complete step by step solution:
Interference and diffraction are two different phenomenons and it depends on two different principles.

Interference:
When two or more waves overlap, the resultant displacement at any point and at any Instant is equal to the vector of sum of instant displacements that would be produced at the point by the individual waves if each wave is present alone and this is known as principle of superposition.
Interference is produced by superposition of waves from two coherent sources. The width of the central bright band is the same as that of any bright band. The distance or spacing between both dark and bright are the same or in other words both dark and bright bands are equally spaced. Two coherent sources of equal intensity give rise to a pattern in which there is sharp contrast between bright and dark bands and intensity of all bright bands is the same. Fringes are large in number.
Diffraction:
Diffraction is produced by superposition of waves originating from different parts of the same wave front. The central bright band is much broader than other bright bands. Dark bands on either side of the central bright band are equally spaced; In a diffraction, the pattern contract between dark and bright bands is always poor. The intensity of central bright bands is maximum. The intensity goes on decreasing with the order of bright bands on both the sides. Fringes are few in numbers.

Note: The modification in the intensity of light or redistribution of light energy produced by the superposition of two or more light waves is nothing but interference of light. Interference is accompanied by diffraction effect while diffraction effect is not accompanied by interference. Resolving power of optical instruments is not related to interference effects. Resolving power of an optical instrument is related to diffraction effect.