With the help of a diagram,explain the formation of a rainbow in the sky.

(N/A) rainbow is a natural spectrum appearing in the sky after a rainfall. It is caused by the dispersion of sunlight by tiny water droplets present in the atmosphere.
$1$. When sunlight enters a water droplet,it undergoes refraction and dispersion.
$2$. The light then undergoes internal reflection inside the droplet.
$3$. Finally,the light undergoes refraction again as it exits the droplet.
Due to these phenomena (refraction,dispersion,and internal reflection),different colours reach the observer's eye at different angles,resulting in the formation of a rainbow. The observer must always have their back towards the Sun to see a rainbow.