A rainbow is formed when sunlight is broken apart by a prism or raindrops. Explain why the colors are always in the same order.

Each color of the rainbow is associated with a different wavelength and frequency. As visible light passes through a prism or raindrop, the light bends or refracts. The wavelength and frequency determine the angle at which each color of visible light refracts after passing through the prism or raindrop. Red, which is the longest wavelength and lowest frequency, is refracted the least. Thus, red is found on the outside edge of a rainbow. Violet, which has the shortest wavelength and highest frequency, is refracted the most. Therefore, violet is found towards the center of the rainbow.  Since the wavelength and frequency of each color are consistent, so is the order of the colors in a rainbow.