Visible light

Visible light is the range of the electromagnetic spectrum our eyes are sensitive to — a very small part of the whole.

Its frequencies run from 4.28 × 10¹⁴ Hz to 7.69 × 10¹⁴ Hz, which corresponds to wavelengths from 690 nm down to 400 nm.

From violet to red

The shortest wavelength (highest frequency) in this range looks violet to us. As the wavelength gets longer — the frequency lower — the colour changes through indigo, blue and so on, all the way to red. These are the seven colours of the rainbow.

Shortest wavelength, violet (400 nm), to longest, red (690 nm).