Rainbows truly are a wonder of nature. This optical and meteorlogical phenomenon always stops people in their tracks to take a moment and appreciate their great beauty!
Rainbows occur when light traveling from our sun hits water droplets in the sky and refracts. Refraction is the bending of light as it moves from one substance, or medium, to another. When light travels towards the prism in the video it moves from the medium of air to the medium of glass. The bending is caused by the difference in the density of the two mediums, as the light changes speed. To better understand, think about running down a beach towards a lake. As you run on the beach you are moving through air. The running is easy and you speedily make it to the water’s edge. But, as soon as you hit the water, it slows you down. No matter how hard you try, you cannot run as fast in the water as you can on the beach! The same is true when light passes from air into water. This change of speed results in a change of direction of the wavelengths of light.
Light is made up of several different colours, or wavelengths, and each wavelength travels at a different speed. In the case of the rainbow, when light hits the droplets of water, it moves from air to water and its speed changes and the wavelengths bend. Each different colour bends at a different angle and thus the colours become visible!
Now the question remains; is there an end to a rainbow? The answer is yes and no! A rainbow is not located at a specific distance, but comes from any water droplets viewed from a certain angle relative to the sun’s rays. What this means is that the sun is just an “image” as opposed to being a physical object that can be touched or approached. As an observer of a rainbow you can see that there is an “end,” but if you try to go and find it, the pot of gold will elude you!