Name: Electromagnetic Spectrum II
Uploaded: 2019-07-19
Duration: 4 min 21 s
Description: Why does the wavelength of high energy radiations decrease from ultraviolet rays to gamma rays, but their frequency increases? Watch this video to learn more.

Question

A glass prism can be used to show the dispersion of white light to form a spectrum. Draw a diagram to show how a ray of white light is dispersed as it passes through a prism.

Accepted Answer

When white light is passed through a glass prism it splits into its spectrum of $7$ colours (in order violet, indigo, blue, green, yellow, orange and red) and this process of white light splitting into its constituent colours is termed as dispersion.

When white light is made to pass through a prism, a spectrum of seven colours is formed which shows that white light is a mixture of seven different colours. Prism only acts as a medium for the separation of the seven colours. When light falls on the glass prism, refraction takes place. Since the wavelength of different components of light is different and the frequency is constant, each component gets deviated by a different angle due to the difference in velocity in the glass medium. The red colour having the maximum wavelength deviates the least and forms the upper part of the spectrum whereas violet having the least wavelength deviates the most.

White light dispersion occurs because, as they pass through a prism, different colours of light bend through different angles with respect to the incident ray. The red light bends the least while the violet bends most as shown below.

A glass prism can be used to show the dispersion of white light to form a spectrum. Draw a diagram to show how a ray of white light is dispersed as it passes through a prism.

Important Questions on Spectra

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