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I can quote from Wikipedia too!:)

"Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is visible to the human eye and is responsible for the sense of sight. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), or 400×10−9 m to 700×10−9 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths)."

Mine was quoted from the 'Light' article - yours rather tellingly from the 'Frequency' article.
 
...and here are the frequencies and energy to match the wavelengths.

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The human eye is most sensitive to green light. We use red for things like stop signs, because it stands out against the background more, since there isn't as much red in nature.

I wish the nightstand mode was red, as that's less "bright" to our eyes in the dark.
 
As a photographer, I think in terms of temperature. :)
Just to add some wacky irony to the mess.

Warmer colors = lower temperature/lower frequency/lower energy/longer wavelength/toward red
Cooler colors = higher temperature/higher frequency/higher energy/shorter wavelength/toward violet
 
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