A beautiful rainbow on the sky is due to the

A rainbow is a natural spectrum formed by the complex interaction of sunlight with water droplets in the atmosphere. The process involves three primary optical phenomena: refraction, dispersion, and internal reflection [2]. When sunlight enters a spherical water droplet, it first undergoes refraction as it slows down and bends [3]. During this entry, dispersion occurs because different wavelengths (colors) of light bend at different angles, splitting the white light into its constituent colors [1]. The light then hits the back surface of the droplet and undergoes internal reflection [1]. Finally, the light is refracted again as it exits the droplet and reaches the observer's eye [1]. While total internal reflection is often cited, the primary rainbow is fundamentally the result of refraction, dispersion, and at least one internal reflection within the droplet [2].

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] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > Explanation: > p. 335
3. [3] https://www.nesdis.noaa.gov/about/k-12-education/optical-phenomena/what-causes-rainbow