Which of the following phenomenon is not involved during the formation of rainbow in the sky?

Total Internal Reflection

Out of the listed phenomena, the one not involved in rainbow formation is: Option 4: Total Internal Reflection

A rainbow is a natural spectrum appearing in the sky after a rain shower.

It is caused by dispersion of sunlight by tiny water droplets, present in the atmosphere.

A rainbow is always formed in a direction opposite to that of the Sun.

The water droplets act like small prisms. They refract and disperse the incident sunlight, then reflect it internally, and finally refract it again when it comes out of the raindrop. Due to the dispersion of light and internal reflection, different colours reach the observer’s eye.