Question

Which of the following phenomena of light are involved in the formation of a rainbow?

• A. Reflection, refraction and dispersion
• B. Refraction, dispersion and total internal reflection
• C. Refraction, dispersion and internal reflection
• D. Dispersion, scattering and total internal reflection

Answer 1

The correct option is C

Refraction, dispersion and internal reflection

Rainbow formation phenomena:

1. A rainbow is a natural spectrum formed by the dispersion, refraction, and internal reflection of different colors after a rain shower (every water droplet acts as a small prism).
2. When white light passes through a glass prism, it splits into its spectrum of colors (in order violet, indigo, blue, green, yellow, orange, and red), and this process of splitting white light into its constituent colors is known as dispersion.
3. Refraction is the change in direction caused by a wave's speed as it travels from one medium to another. Waves, for example, travel faster in deep water than in shallow water.
4. Total internal reflection, in physics, is the complete reflection of a ray of light from the surrounding surfaces back into a medium such as water or glass. The phenomenon occurs when the angle of incidence exceeds a certain limiting angle known as the critical angle.

Formation of the rainbow:

1. Light rays reach the drop near its highest point.
2. There is refraction first, followed by dispersion of white light into colors of different wavelengths.
3. Violet is the most deviated color, while red is the least deviated.
4. Due to the complete internal reflection that hits the drop surface, each color is refracted back into the drop when it reaches the opposite side of the drop.
5. We see the rainbow when the temperature is between 40-42 degrees.