The light spectrum is the visible range of the electromagnetic spectrum that can be perceived by the eye. The spectral range visible to humans is between 380 and 780 nanometers, corresponding to a frequency range of about 4·1014 to 7.5·10 14 Hz.
Each wavelength produces a different color, for example green has a wavelength of about 540nm and blue is between 450 and 500nm. If all visible wavelengths are displayed next to each other, a rainbow-like color gradient appears. In addition, there are wavelength ranges that the human eye cannot see or perceive because there is no trigger for a pulse. These ranges are called ultra-violet (10-380nm) and infrared radiation (>780nm). The shorter a wavelength is, the more energy it has. This is also the reason why ultraviolet light is so harmful for our skin and our eyes, because in the long run it stimulates molecules to change their spatial structure and to split off single atoms.