Question

need a detailed answer so much. Thanks a lot! The question is:

"Describe the difference between diffraction and dispersion, by discussing the different physical processes (for example refraction) that give rise to the two phenomena."

Answer 1

diffraction:-

when light (wave) encounter an obstruction that has very small opening and opening dimension is order of wavelength of light then light diffracts into the region beyond that obstruction.

This phenomenon is known as diffraction, the diffraction will be greater if the slit is narrower. If diffracted light falls on a screen, its intensity is maximum and minimum and forms circular pattern. This patterns of avrying pattern can be observed if and only if interference of light takes place so it proves that light is also a type of wave called electromagnetic wave.

So diffraction occurs due to interfference of light.Like interfference of sound wave.

Dispersion:-

Recall Refractive Index of a material depends on wavelength of light, relation between refractive index and wavelength can be written as

u=u0+A/(lambda)^2

Where A is a small constant called cauchy's constant.As per above equation refractive index decreases with increase in wavelength of light.As violet light has least wavelength So violet ray has maximam deviation.When white light passes through a prizm different color of light deviates with different angle forming a color pattern, and light breaks into its constituent colors. This phenomenon of breaking of color of light is known as dispersion.

Dispersion ocuurs due to refraction of light.