White light while passing through a glass prism breaks up into light of different clours because

White light splits into its component colors when passing through a glass prism due to the phenomenon of dispersion [1]. This occurs because the refractive index of glass is not a single fixed value but varies depending on the wavelength (color) of the light. In transparent media like glass, the speed of light decreases as the wavelength decreases; consequently, shorter wavelengths (violet) experience a higher refractive index and bend more than longer wavelengths (red). As white light enters the non-parallel surfaces of a prism, each color is refracted at a slightly different angle [2]. This wavelength-dependent refraction causes the rays to emerge along distinct paths, forming a visible spectrum [1]. Other phenomena like total internal reflection or interference do not cause this specific splitting of white light into a rainbow within a standard prism.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > Activity 10.2 > p. 167
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > 10.3 REFRACTION OF LIGHT THROUGH A PRISM > p. 165