Why we get brownish icky color and not white on mixing seven colours of rainbow?

Answer 1

Some of the colors are dark. when you mix colors, you usually end up with something darker,

or the same color. so in mixing the colors of a rainbow, it would make a darker, (Icky) color

instead of getting lighter.

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Answer #2:

-- How are you "mixing colors" ? Are you mixing light, or mixing paint ?

Mixing paint is not the same as mixing light.

-- There are more than seven colors in the rainbow. Every color that you

or anyone else has ever seen is in the rainbow, as well as every color of

paint ever mixed, every color of fabric ever woven or dyed, every color that

can be produced on the screen of your computer monitor, every color ever

named, and those without names. All are present in the rainbow.

-- The combination of all possible colors of light, in the correct proportions,

produces white when they enter your eye and "mix" there.