Why does the rainbow display colors and how?

Answer 1

Rainbows are caused by the refraction of the sun's rays in the drops of water in the sky. Refraction is the bending of light when it passes through a surface where the index of refraction changes. This occurrence is similar to what happens when light passes through a prism.

The index of refraction of the water drops is different for different wavelengths. Thus, the light bends more for violet light than for red light. When the light passes through a prism (or water droplet), the different wavelengths of light are refracted by different amounts, separating the different colors of light. This occurs in a rainbow, where the light passes into the water droplet, reflects off the back of the droplet, and come back out through the front. The angle at which it comes back out the front will depend on the color of the light. The shape of the rainbow is determined by the angle between the sun, the observer, and the water drops.