Question

What is the dispersion of light? Name seven colours of white light.

Answer 1

Hint:In this question, we can recall the colours of a rainbow which can remind us of the concept of dispersion of light. Dispersion of light is found in the visible light only. This visible light is also known as white light.

Complete step by step solution: -
In optics, the splitting of the visible light into its components is called the dispersion of light. This phenomenon is caused by the change in speed of light rays of each wavelength by a certain amount. In this phenomenon, the phase velocity of different waves depends on their different frequencies.

The optical element which is used for dispersion of light is Prism. Prism is made of glass. It has a three-dimensional shape with four sides. All the sides are in triangular shapes. The surfaces of the Prism are flat and polished which helps in the refraction of light.

When a white light or visible light incident on the Prism then the speed of the propagation of the light ray changes. This makes the light ray to bend or to refract. In the case of refraction of light by Prism, refracted lights bend towards the base of the prism.
When the white light ray is dispersed by the prism then it is split into different light rays of different colour. These light rays of different colours have different wavelengths and different speeds.

Visible light is also known as white light. The seven colours of white light after dispersion are- Violet, Indigo, Blue, Green, Yellow, Orange, Red which are known as VIBGYOR in combined form.

Additional Information: - When a light ray incident on a surface then the light ray changed its direction of propagation in the medium of the surface when passing through, then it is known as refraction of light.

Note: - We have to remember that the refraction of light rays is the phenomenon which causes dispersion of light. The main difference between the refraction of light and dispersion of light is that in refraction of light, the incident ray incident on the flat surface (a plain glass plate) while in the dispersion of the light, the incident light is incident on the one side of the prism which tilts on an angle.