Question

Which of the following phenomena cannot be explained by scattering of light ?

• A. Blue colour of sky
• B. Colour of clouds
• C. Tyndall effect
• D. Formation of rainbow

Answer 1

The correct option is D Formation of rainbow

Answer is D.

The rainbow is caused by light from the sun (or moon) interacting with raindrops falling from the air. These raindrops are mostly round. A ray of light entering such a droplet is bent (refracted) and decomposed into all possible colors (wavelengths) which the white light consists of. The ray then reflects internally in the droplet, and emerges roughly into the direction it came from when it entered the drop. Since the rays of the different colors all exit at slightly different directions, we see a color band in the sky.
The colors are produced by a phenomenon called dispersion. Dispersion causes white light, which consists of all possible colors to break up into all components, when the light travels from one medium (e.g. air) to another (e.g. water). The different colors of light have all slightly different directions, so if we look in a certain direction in the sky we can see the spectrum.