What is the wavelength of the color


Color is the impression that electromagnetic radiation of a certain wavelength creates through the human eye.

This definition also seems a bit cumbersome at first. But in fact, color can only ever be described in terms of people. The physicist can only measure the wavelength of the radiation. He can only try out what color we perceive it as with his own eyes.

The wavelength of light is measured in nanometers, the abbreviation is nm. A nanometer is one billionth of a meter. This means that the distance between the light waves is incredibly small.
We perceive light with a wavelength of 380 nm as violet, light with 750 nm as red. In between lies the entire color spectrum from blue to green and yellow to orange.



The spectrum of visible light.

What is striking about this spectrum is that white and black are not present in it. White and black are actually not colors. White comes about when all the colors of the spectrum meet our eye together. So white is not the radiation of a certain wavelength, but a mixture of all wavelengths in the range between 380 nm and 750 nm.

Black, on the other hand, is anything that does not emit any radiation in this area. In other words, black is actually a "non-color". We see black when we see nothing, when there is no visible light in our eyes.

Findings from Isaac Newton

English physicist Isaac Newton found these principles in 1676. He sent sunlight through a prism (see picture). The light refracts and it fans out into the spectrum of rainbow colors. In fact, the same thing happens with the rainbow: The sunlight breaks, but here on the raindrops in the air.


If sunlight falls through a prism, it is broken down into its different wavelengths.
The rainbow is also created by light refraction. © dpa

Newton went even further to prove that white light actually consists of the spectral colors: he placed a converging lens behind his prism that combined the fanned out spectral colors again. The ray of light leaving the lens was white.