When a light beam falls on a triangular glass prism, a band of colours is obtained. Which one of the following statements is correct in this regard ?

When white light passes through a triangular glass prism, it undergoes dispersion, splitting into its constituent colors [2]. This phenomenon occurs because the refractive index of glass is not constant but varies with the wavelength of light [2]. According to Snell's law, the degree of bending (refraction) depends on the refractive index of the medium. Shorter wavelengths, such as violet light, travel slower in glass compared to longer wavelengths like red light. Consequently, the refractive index of glass for violet light is greater than it is for red light. This higher refractive index causes violet light to deviate or bend the most from its original path, while red light, having the lowest refractive index in the visible spectrum for glass, bends the least [2]. Therefore, violet light bends the most because the refractive index of glass for violet light is the greatest.

Sources

1. [2] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > Activity 9.10 > p. 148