Why are there only 7 colours in a rainbow?
A. As I mention in the question before this there are many colours in a rainbow, almost infinite if you want to look very very closely. However we only have specific common words for 7 of them, and thus it is commonly known that a rainbow has the 7 colours red, orange, yellow, green, blue, indigo, violet. Q. How do you remember the colours of a rainbow? A. We commonly say that a rainbow has the colours red, orange, yellow, green, blue, indigo, violet. The common mnemonic I was taught to remember this is Richard Of York Gave Battle In Vain. RichardOfYorkGaveBattleInVain RedOrangeYellowGreenBlueIndigoViolet Q. Why is red on the outside of a rainbow and blue inside? A. The colours are caused by the different wavelengths (same as saying colours) of light having different indexes of refraction (see question above). The maximum angle away from the anti solar point which light from the sun is refracted by the raindrops is greater for red than blue. Thus red is on the outside and blue is on th
