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Which visible colour has the longest wavelength?
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The RYB color model is being illustrated on a color wheel.
Within the visible spectrum, the colour with the longest wavelength is red.
Visible light encompasses wavelengths ranging from approximately 400 nm at the violet end of the spectrum to 700 nm at the red end. Because the speed of light in transparent media, such as glass, depends on the wavelength, red light experiences a different index of refraction than shorter wavelengths like violet, which is the shortest visible wavelength.12