The wavelength of light of specific colour increases as we go from left to right in the visible colour spectrum: "VIBGYOR".
Wavelength of green lies between wavelengths of blue and yellow. To me, this makes logical sense because when blue and yellow are mixed, it gives green. (By "mixed", i mean the simultaneous presence of two colours at the same place give rise to a new colour).
Wavelength of orange lies between wavelengths of red and yellow. To me, this also makes logical sense because when red and yellow are mixed, it gives orange.
Now, when it comes to violet, its wavelength is the least in the visible spectrum. It is made by the mixture of red and blue. So according to my logic, it should lie between red and blue in the spectrum. But it doesn't, its wavelength is less than wavelength of blue.
How is this possible?
Best Answer
Color is a double valued concept, different in physics and in perception.
In Physics there is a one to one correspondence between color seen in the visible spectrum and the frequency of light.
The whole electromagnetic spectrum covers many frequencies above and below the visible, which are the colors seen in rainbows.
The second value/definition of color comes from biology the way it is perceived by the brain as mixtures of frequencies.
You say:
Because the mixture of frequencies to be perceived as a given color by the brain is seen in the chart. The brain sees the single frequency colors as shown in the first figure, but when frequencies are added new colors and hews are seen.
As the chart is not a simple function it happens that violet does no follow the simplified rule you expect. There is an article in Wikipedia on color vision.