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My question is simple. Green light is more similar to red light than violet, then why is violet reddish and green not? in the language of frequencies and wavelengths, red and violet should contrast each other. Then why do they don't?


marked as duplicate by John Rennie, Kyle Kanos, tpg2114, Brandon Enright, Stan Liou Mar 15 '14 at 2:21

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    $\begingroup$ possible duplicate of Why does light of high frequency appear violet? $\endgroup$ – John Rennie Mar 14 '14 at 10:31
  • $\begingroup$ By asking this question, i was also questioning the reason why our mind starts with red color while reading the visible lights, and ends up with something similar to red (violet) in order to maintain a cyclic chart of visible colors. Violet has nothing to do with red if we look at it like that, but the fact that mind starts with the color red and ends somewhere where it can complete a circle and come back to red, suggests to me that there is no other alternative but this... $\endgroup$ – Prem kumar Mar 14 '14 at 16:12
  • $\begingroup$ There's too much processing by the brain to draw conclusions like this. The brain controls perception based on what helps us see, not on what frequency is close to which (or which receptor response is closer to which in frequency space... I'm not sure what you mean by "more similar") $\endgroup$ – garyp Mar 14 '14 at 20:49
  • $\begingroup$ By "more similar", i mean the small difference in the 'nature' of two compared lights. By 'nature' i mean their frequency or wavelength. $\endgroup$ – Prem kumar Mar 15 '14 at 7:28

It just a matter of the definition of the word "violet". It often means light of short wavelength, as you suggest, and I think that would be the correct technical definition. But the word is sometimes used to mean red + blue, because the visual appearance is similar. If you viewed that color, you might not know which it is: short wavelength or red + blue. Sometimes "purple" is used to mean red + blue.


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