Dispersion of Light

The correct answer is option 'B': Dispersion. Rainbow is formed due to the dispersion of light through tiny water droplets.

Explanation:

When light passes through a medium, such as water droplets in the atmosphere, it can undergo various interactions including scattering, reflection, refraction, and dispersion. However, in the case of the formation of a rainbow, the most significant phenomenon is dispersion.

Scattering:

Scattering refers to the process by which light rays are redirected or deflected in different directions when they interact with particles or molecules in the atmosphere. While scattering does play a role in the overall brightness of the sky, it is not directly responsible for the formation of a rainbow.

Reflection:

Reflection occurs when light rays bounce off a surface without entering the medium. In the case of a rainbow, reflection does play a role, but it is not the primary reason for its formation.

Refraction:

Refraction is the bending of light as it passes from one medium to another with a different optical density. It is indeed a crucial factor in the creation of a rainbow. When light enters a water droplet, it undergoes refraction as its speed and direction change. However, refraction alone does not explain the complete phenomenon.

Dispersion:

Dispersion is the process by which light is separated into its constituent colors (wavelengths) when it passes through a medium. Each color of light has a different wavelength, and as a result, they experience different degrees of bending or refraction when passing through a water droplet.

Due to dispersion, the incoming white light is split into its component colors (red, orange, yellow, green, blue, indigo, and violet) as it enters and exits the water droplets in the atmosphere. These different colors of light are then reflected internally within the droplet and undergo further refraction before emerging back into the air.

When we observe a rainbow, we see the result of this dispersion and refraction process. The different colors of light are spread out in a circular arc, with red on the outer edge and violet on the inner edge, forming the characteristic shape of a rainbow.

Therefore, it is the dispersion of light through tiny water droplets that is responsible for the formation of a rainbow.