Concepts

Class 10
Chapter 11 Class 10 - Human Eye and Colourful World

When we pass white light through a prism,

it splits into different colors

What is Dispersion?

Splitting up of white light into 7 different colors when passed through a transparent medium (like Glass Prism) is called Dispersion

When white light is passes through the prism, it splits into seven colors. They are

• V iolet
• I ndigo
• B lue
• G reen
• Y ellow
• O range
• R ed

What is Spectrum?

Band of coloured components of light are called spectrum

Hence, 7 colors formed on dispersion of light is called spectrum

What causes Dispersion ?

White light is combination of these 7 colors

When light falls on a prism, it changes medium (from air to solid)

Hence, different colors of light bend at different angles

Red light bends the least while violet line bends the most

Hence, different rays of different color emerge along different paths

This causes dispersion of light

Recombination of Spectrum to give White Light

In this case 2 prisms are used together

Firstly sunlight light is made to fall on the prism

This makes white light to form spectrum of 7 colors

This spectrum is made to fall on another prism which was held in inverted position

This leads to emergence of sunlight from second prism

Note: - This method was first used by Isaac Newton

Note: - Any light that gives a spectrum similar to that of sunlight is
often referred to as white light.

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