Though the violet color is normally composed of blue and red light, violet color can also be monochromatic, composed only by violet light. Combinations of red and blue lights and monochromatic light of wavelength smaller than blue produce a similar effect for the human eye due to a second resonancy of the red-sensitive cone cells.
Composed-light violet shows two colors when decomposed. Violet light from the rainbow, which can be referred as spectral violet, is composed only by a short wavelength instead. This monochromatic violet light occupies its own place at the end of the visible spectrum, and is one of the seven spectral colors described by Isaac Newton in 1672.
Violet light is at the higher end of the visible spectrum, with a wavelength ~380-450 nanometers (in experiments, people have so far seen to 310 nm). Light with a shorter wavelength than violet but longer than X-rays and gamma rays is called ultraviolet.
Violet objects are normally composed-light violet. Objects reflecting spectral violet appear very dark, because human vision is relatively insensitive to those wavelengths. Monochromatic lamps emitting spectral-violet wavelengths can be roughly approximated by the color named electric violet, which is a composed-light violet producing a similar effect to the human eye.
- J. W. G. Hunt (1980). Measuring Color. Ellis Horwood Ltd. ISBN 0-7458-0125-0.
- Lynch, David K.; Livingston, William Charles (2001). Color and Light in Nature (2nd ed.). Cambridge, UK: Cambridge University Press. p. 231. ISBN 978-0-521-77504-5. Retrieved 12 October 2013.
Limits of the eye's overall range of sensitivity extends from about 310 to 1050 nanometers
- Dash, Madhab Chandra; Dash, Satya Prakash (2009). Fundamentals Of Ecology 3E. Tata McGraw-Hill Education. p. 213. ISBN 978-1-259-08109-5. Retrieved 18 October 2013.
Normally the human eye responds to light rays from 390 to 760 nm. This can be extended to a range of 310 to 1,050 nm under artificial conditions.
- Saidman, Jean (15 May 1933). "Sur la visibilité de l'ultraviolet jusqu'à la longueur d'onde 3130" [The visibility of the ultraviolet to the wave length of 3130]. Comptes rendus de l'Académie des sciences (in French). 196: 1537–9.