Angle of Deviation:
The angle of deviation refers to the angle between the incident ray and the emergent ray after passing through a medium, such as a glass prism. It is denoted by the symbol δ.

Splitting of White Light:
When white light passes through a glass prism, it splits up into its constituent colors, forming a spectrum. This phenomenon is known as dispersion. It occurs due to the phenomenon of refraction, where the speed of light changes as it passes from one medium to another.

Explanation:
When white light enters a glass prism, it undergoes refraction. Refraction is the bending of light when it passes from one medium to another, due to the change in its speed. The change in speed of light is dependent on the wavelength of light. The shorter the wavelength, the higher the speed.

The dispersion of white light into its constituent colors occurs due to the phenomenon of refraction. The different colors of light have different wavelengths, and therefore, different speeds when passing through the prism. This leads to the bending of each color at a different angle, causing the colors to spread out and form a spectrum.

Prism Action:
The dispersion of white light in a prism can be explained by the concept of refractive index. The refractive index of a material determines how much the speed of light changes when it passes through that material. In a prism, the refractive index is different for different colors of light.

- Incident Ray: When white light enters the prism, it is incident on the first face of the prism.
- Refraction: The incident light ray is refracted or bent as it enters the prism due to the change in speed. The amount of bending depends on the angle of incidence and the refractive index of the prism.
- Dispersion: As the different colors of light have different wavelengths, they have different speeds inside the prism, leading to different angles of refraction. This causes the colors to spread out or disperse.
- Emergent Ray: After undergoing refraction inside the prism, the light rays emerge from the prism and form a spectrum. The amount of deviation or bending of each color is measured by the angle of deviation (δ).

Angle of Deviation and Spectrum:
The angle of deviation (δ) determines the amount by which the different colors of light are separated. The angle of deviation is different for each color due to their different wavelengths and speeds inside the prism. This results in the formation of a spectrum, where the colors are arranged in order of their increasing wavelengths, from violet to red.

In conclusion, the splitting of white light into a spectrum when passing through a glass prism is due to the phenomenon of refraction. The different colors of light have different wavelengths and speeds inside the prism, causing them to bend at different angles and form a spectrum. The angle of deviation measures the amount of separation between the colors.

It is defined as the angle bw incident ray and emerging ray.180-(i+r)