Light exhibits various phenomenons like refraction, reflection, dispersion, scattering and many more. In this article we will study about dispersion and scattering of light.
White light is primarily composed of light of different wavelengths (colors) viz. violet, indigo, blue, green, yellow and red with red having the highest wavelength while the violet having the lowest wavelength.
Dispersion is defined as the separation of white light into different colours when the light is passed through the prism. The scattering of light depends on the wavelength of the light. Therefore, it can be said that the degrees of deviation is dependent on the wavelengths. The deviation in the path of the light is inversely proportional to the wavelength.
So when a beam of white light passes through a medium, the material medium splits the white light into different components. This phenomenon is called dispersion.
Splitting of the white light
It is the phenomenon in which white light splits into its constituent colours. White light contains several constituents that vary in their wavelengths (it contains the light of different colours).
- Since the wavelengths of these constituents are different, their speeds differ from each other in a medium. Note that their speed in a vacuum is the same.
- In a material medium, the speed of different wavelengths is different.
When white light passes through a prism, it disperses into a band of seven different colours. This band of colours obtained from the dispersion of light is called a spectrum. Dispersion of light in a prism results in the formation of a spectrum.
Scattering of light:
When light passes from one medium to any other medium say air, a glass of water then a part of the light is absorbed by particles of the medium preceded by its subsequent radiation in a particular direction. This phenomenon is termed as a scattering of light. The intensity of scattered light depends on the size of the particles and the wavelength of the light.
Scattering of light can be defined as the deviation of light rays from their straight trajectory. As light propagates through the atmosphere, it travels in a straight path until comes under obstruction from the gas molecules and dust particles in the atmosphere.
The process in which light gets deflected by the tiny particles in the medium through which the light passes is called scattering.
No splitting of white light
Here the light is not split into its constituent colours. Rather, the incident beam of light just gets redirected after being struck by the atmospheric particles.
- The blue colour of the sky is due to the scattering of sunlight by the molecules of air.
- During sunset, sunlight has to travel a greater distance, so shorter wavelengths get scattered off and removed and only red wavelengths reach us.
- The bending of multicoloured light can be seen in the afternoon due to the refraction and total internal reflection of light. The wavelength of the sunlight forms different colours in different directions.
- The probability for scattering will give a high rise for shorter wavelength and it is inversely proportional to the fourth power of the wavelength of radiation.