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In a rainbow the colors order is red then orange (made from red and yellow, thus making sense that it appears in between them) the yellow followed by green after which comes blue (again green formed from yellow and blue). The final color is purple, which is next to the blue' but not in any contact with the red.

The question is - is there any actual connection between the colors and there source as known to as (such as orange from yellow and red, the last two being the source) to its appearance in a rainbow? If so, why doesn't the purple follow the same logic? How is the purple seen were it is seen in a rainbow (where there is no red nearby)?


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Tip: Before asking a new question, it is a good idea to search the Phys.SE site to see if an answer to your question already exists. – Qmechanic Mar 24 '13 at 18:14
This question may provide some insight to you:… – Nick Mar 24 '13 at 18:22

It does follow the same logic. There are some barely seen mini rainbows in the outer layers called supernumeraries. The red on the supernumerary overlaps some of the blue on the original.

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There exists an extensive article in wikipedia where color is analyzed both from the physics aspect and the biological aspect.

In short there exists the physics spectrum of light with a one to one correspondence to frequency, and color as perceived by the eye, which has three types of cone cells for light perception, and builds up color recognition from this.

cone cell response

Normalized typical human cone cell responses (S, M, and L types) to monochromatic spectral stimuli

So even though the light spectrum has a color response identified with a frequency, our perception of color allows us to see colors that do not correspond to that spectrum frequency. An interesting effect is the polaroid colored pictures that used red green and blue pigments to generate colored pictures.

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