Question

Explain why white light is dispersed when passing through the prism.

Answer 1

HintDispersion of light is referred to as the propagation of lightwave through a transparent medium due to the difference in phase velocities of the light waves. When a ray of white light is incident on a transparent prism, it deviates at various angles while emerging through the prism.

Complete step by step answer
A light wave propagates in a certain medium at a rate that is called phase velocity of the wave. When white light with different phase velocity is incident on a prism, it deviates through various angles while emerging thereby indicating dispersion. This results in the splitting of white light into a spectrum of seven different colours i.e. violet, indigo, blue, green, yellow, orange, red. This spectrum of seven different colours is referred to as VIBGYOR. These colours have different respective wavelengths.

Additional Information
A practical example of dispersion of light is seen in the formation of a rainbow in the sky after rains. The formation of the rainbow is the result of the dispersion of white light while passing through water droplets in the atmosphere. This results in the scattering of white light into seven different colours.

Note The refractive index is different for different colours with their respective wavelengths. The propagation of lightwave through any material medium in a vacuum does not undergo dispersion.