What is Dispersion of Light? Cause and Formation - Explore Study

The dispersion of light is the phenomenon of splitting of a beam of white light into its seven constituent colors when passed through a transparent medium.

What is Dispersion of Light? Cause and Formation

Dispersion of Light was discovered by Isaac Newton in 1666. Newton discovered that light is made up of seven different colors. He passed a beam of sunlight through a glass prism. The glass prism split the light into a band of seven colors on his wall. He called this band of colors the ‘spectrum’. Thus the spectrum is a band of seven colors which is obtained by splitting of white light by a glass prism. The order of colors from the lower end of spectrum is violet (V), indigo (I), blue (B), green (G), yellow (Y), orange (O), and red (R). The sequence of the 7 colors so obtained in a spectrum can be remembered by using the acronym ‘VIBGYOR’. 

Cause of Dispersion of Light

The cause of dispersion of light is that white light consists of seven different colors, and each color has different angle of deviation. Therefore, on passing through the prism different colors deviate through different angles. Hence the seven colors of white light separates and form a spectrum. Out of seven colors, the red color deviates the least, and hence the red color is present at the top of the spectrum. On the other hand, the violet color deviates most that is why violet color is present at the lower end of the spectrum. 

Formation of Rainbow

 The formation of rainbow is based on the process of dispersion of light. It is the most enchanting example of dispersion of light which takes place naturally. Usually a rainbow of seven colors is seen in the sky just after the rain when the Sun is shining. The essential condition to see the rainbow is that the observer must stand with his back towards the sun, when seeing the rainbow. Actually after the rain, a large number of water droplets remain suspended in the atmosphere. These droplets of water function as small prisms. So, when the white light emitted by Sun falls on these water droplets, then the white light is split into seven colors and rainbow is formed.