Question

As the thickness of the atmosphere increases, the colour of scattered light is found in ______ order.
A. Blue, violet, yellow, red
B. Violet, blue, yellow, red
C. Red, yellow, blue, violet
D. Violet, blue, red, yellow

Answer 1

Light or visible light is electromagnetic radiation within the segment of electromagnetic spectrum which can be perceived by the human eye. The phenomenon of deviation of light from its path due to change in medium is known as scattering of light. When light from the sun enters the earth’s atmosphere, it gets scattered by dust particles and air molecules.
Formula Used:
$I \propto \dfrac{1}{{^{{\lambda ^{^4}}}}}$

Complete answer:
We know that white light consists of seven colours which in general are known as VIBGYOR i.e. violet, indigo, blue, green, yellow, orange, and red. The abbreviation stands for colours which are in the order of most deviated to least deviated.
When white light travels from a rarer medium to a denser medium it undergoes scattering. Scattering of light is different for different wavelengths. Now, because we know in the atmosphere molecules are present which act as a denser medium so the light undergoes scattering. According to Rayleigh’s law of scattering, the amount of scattering is inversely proportional to the fourth power of the wavelength, i.e. $I \propto \dfrac{1}{{^{{\lambda ^{^4}}}}}$
Now, using Rayleigh’s law violet with shorter wavelength scatters most and red with longer wavelength scatters least. Thus, short-wavelength blue and violet scatters more and red and yellow scatter less.
The following diagram shows the scattering of white light through a glass prism into its constituent colours.

Therefore, as the thickness of the atmosphere increases the colour of scattered light is found in order: violet, blue, red, yellow order.

Hence, the correct option is (D).

Additional Information:
Wavelengths of different colours in the atmosphere are: \eqalign{ & {\text{Red: 760 - 647nm}} \cr & {\text{Orange:647 - 585nm}} \cr & {\text{Yellow: 585 - 575nm}} \cr & {\text{Green: 575 - 491nm}} \cr & {\text{Blue: 491 - 424nm}} \cr & {\text{Violet: 424 - 380nm}} \cr}

Note:
Scattering of light gives rise to various phenomenons which we see in our day to day life such as blue colour of sky, blue colour of the ocean, redness of the sky during sunrise and sunset, Tyndall effect etc.