6 Refraction of light

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What is refraction of light ?

Light changes its direction when going from one transparent medium to another transparent medium. This is called the refraction of light.

What are laws for refraction of light?

1. When a light ray passes from a rarer medium to a denser a medium, it bends towards the normal.
2. When a light ray passes from a denser medium to a rarer medium, it bends away from the normal.
3. When a light ray is incident normally at the boundary between two media, it does not change its direction and hence does not get refracted.

Dispersion of light

The process of separation of light into its component colours while passing through a medium is called the dispersion of light.

Who founded dispersion of light?

Sir Isaac Newton was the first person to use a glass prism to obtain Sun’s spectrum.

When white light is incident on the prism, different colours bend through different angles. Among the seven colours, red bends the least while violet bends the most.

A rainbow is the combined effect of the refraction, dispersion, and total internal reflection of light

Rainbow is a beautiful natural phenomenon. It is the combined effect of a number of natural processes. It is the combined effect of dispersion, refraction and total internal reflection of light. It can be seen mainly after a rainfall.

Small droplets of water act as small prisms. When light rays from the Sun enter these droplets, it gets refracted and dispersed. Then there is internal reflection as shown in the figure, and after that once again the light gets refracted while coming out of the droplet. All these three processes together produce the rainbow.