Lighting Design Glossary

Wavelength

(Term of photometry/radiometry)

Wavelength is a property of monochromatic light that defines its color. Each wavelength correspondends to a respective frequency, and to a color temperature.

More generally, wavelength and frequency are properties of all electromagnetic radiation, of which the light visible to the human eye is just a small subset. The visible spectrum starts at about 400 THz / 750 nm with red, and ends at about 750 THz / 400 nm with violet.

In practise, most light is composed of many wavelengths, mixed together to create colors of varying intensity. The same visual appearance can be based on more than one combination of wavelengths (metamers).