complementary color
A complementary coloris the color that produces white(achromatic) when mixed additively with another color. It is the colors that are opposite each other in the color wheel or color hexagon.
In the case of the primary colorred, the complementary color is cyan: red and cyan produce white in additive color mixing. Likewise blue and yellow or green and magenta. When mixing primary colors of a color model, achromatic is obtained when all three primary colors, either red (R), green (G) and blue (B) or cyan (C), magenta (M) and yellow (Y), are mixed equally.
Wavelengths can be assigned to the colors and their complementary colors. For example, red has wavelengths between 605 nm and 770 nm, while the wavelength of the complementary color blue-green is between 490 nm and 500 nm. If both colors are mixed additively, the color perception is caused by the absorptions and reflections of the white light.