A rainbow is produced due to which one of the following phenomena?

[amp_mcq option1=”Dispersion of light” option2=”Interference of light” option3=”Diffraction of light” option4=”Scattering of light by atmospheric dust” correct=”option1″]

This question was previously asked in

UPSC NDA-2 – 2017

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The correct answer is Dispersion of light.

A rainbow is formed when sunlight passes through raindrops, which act like tiny prisms. White light is dispersed (split) into its constituent colours (spectrum) as it is refracted upon entering and leaving the raindrop, and also undergoing internal reflection. The dispersion of light is the phenomenon responsible for separating the colours.

Refraction and internal reflection are also essential processes in rainbow formation, allowing the dispersed light to reach the observer’s eyes at specific angles for each colour. However, the appearance of the band of colours itself is due to dispersion, the phenomenon by which the angle of refraction of light depends on its wavelength. Interference and diffraction relate to wave properties that are not the primary cause of the colour separation in a rainbow. Scattering by atmospheric dust contributes to phenomena like the blue colour of the sky or the reddish sunset, but not the spectrum seen in a rainbow formed by raindrops.

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