Deviation and Dispersion of light by a prism

Light scattering or dispersion occurs when white light is subdivided into various colour combinations due to refraction and Snell’s Law. White light looks white simply because it contains all the hues in the visible spectrum. Despite their proximity, the refraction index for each colour differs in non-vacuous objects. Because of these different indices, the wavelength takes a different direction.

Light dispersion is basically the process in which white light is splitted into its constituent colours splitting into unifying colours due to the refractive index of the surface and wavelength of the light.

Dispersion of White Light

Generally Dispersion is defined as the division of white light into different colours when light is passed to a prism. Light scattering depends on the length of the light. Therefore, it can be argued that the degree of deviation depends on the wavelengths. Deviation from the light path is the opposite of the normal length.

White light is strongly associated with light wavelength (colour). Violet, indigo, blue, green, yellow, and red are the longest length while violet has a very low length.

The red light has a slight deviation and is very violet. As all long distances suffer from various deviations, when the white light passes from one to another, the different colours of light scatter, and this object of light scattering in its parts is due to refraction.

White Light is made up of seven different colours. It consist of these several colours:

• Violet
• Indigo
• Blue
• Green 
• Yellow
• Orange
• Red

Monochromatic Light is expressed as a light that has only one colour or wavelength. For e.g. Sodium Light

Polychromatic Light is a light that has more than two colours or wavelengths such as white light.

Refraction of Light through Prism

When light passes from one medium to another medium the speed of light differs as a result of which the light is refracted or the light is bent. Now as the light passes through the prism, it is refracted towards the base of the triangle.

Different colours in the light range have different wavelengths. Therefore, the speed at which they bend varies depending on the wavelength, in which the violet bends most, the shortest distance and the red deviates by very small angle, and has the longest wavelength.

As a result, the scattering of white light into its constituent colour when it passes through a prism.

Dispersion

Dispersion is defined as the phenomena of scattering of white light into its spectrum on passing through a prism is known as Dispersion. The spectrum has (Violet, indigo, blue, green, yellow, orange and red) in it.

Prism

Prism is a transparent, homogeneous refracting material (like glass) surrounded by two inclined plane refracting surfaces at a fixed angle term as refracting angle of prism. It has two triangular bases and three rectangular lateral surfaces that are inclined toward each other.

Deviation

When a ray of light enters on one refracting surface of the prism, it bends towards the normal and when it gets out from the other refracting surface it bends away from the normal. Hence the angle thus formed between incident ray and emergent ray is called the angle of deviation.

Deviation Produced by a Triangular Prism

Prism is a solid structure consisting of three rectangular and two triangular areas or surfaces. Any two rectangular faces are the refracting surface and the third is the base. 

The angle between the refracting surfaces is the angle of the prism or refracting angle. The edge formed by the two refracting surfaces is the refracting edge.

When a ray of light enters one refracting area or surface of ​​a prism, it bends to the normal and when it exits from another surface it bends away from the normal. That is:

 ∠i+ ∠e = ∠A + ∠d

 A= is the prism angle

d= deviation angle

The Angle of Deviation Mainly Depends on:

• The Angle of Incident falls on the first Surface.
• The Angle of Prism.
• The Refractive index of the material of the prism through which it is made up of.

Conclusion

In the article we are studying about the dispersion of light and refraction of light through prism. As a ray of white light passes through a triangular glass prism, the white light splits into a seven-coloured band on a white screen placed in front of the glass prism. This led to the discovery that white light is actually a mixture of light of seven different colours.