Purple lights has the highest frequency among all visible lights, while the red lights is the least frequent one. However, purple seems to be a mix of red and blue to human eyes, why?
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If I recall correctly, purple paint results from a mix of red paint and purple paint, but purple light does not result from a mix of blue light and red light. Paints and light add colors in a different way. If you want to test this, you can buy plastic colored lenses at your local dollar store and try overlapping them in front of a lamp. – Nullius in Verba Apr 05 '16 at 23:57
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This has to do with the chemical and neurological responses of the human visual system (eye and brain). Physically red and purple are as different as any two other wavelengths of light. – Asher Apr 06 '16 at 00:03
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2Possible duplicate of Why does light of high frequency appear violet? – David Hammen Apr 06 '16 at 01:32
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1Purple is not violet. Violet light is a spectral color, and this is what has the highest frequency visible to the human eye. Purple is a non-spectral color. Purple, and magenta, and a slew of other colors are on the line of purples. – David Hammen Apr 06 '16 at 01:34
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I'm voting to close this question as off-topic because it is about visual perception, not physics – Floris Apr 06 '16 at 03:23
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There are three pigments in the human eye cone cells and combinations of their light sensitivities are the basis of our color vision. These pigments are red, green, and blue. The violet end of the spectrum excites blue pigment only. Less-extreme 'blue' perception includes some slight green pigment response.
The color that results from red and blue pigments excited, but no green, is called 'magenta'.
So, the color we call 'purple' can be violet (all blue) or blue-plus-red, hopefully with not much red (that would merge from purple to magenta). On a color 'wheel' diagram, the purple area is mainly-blue, but away from the green border and toward the magenta (which is equal blue+red).
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