ultraviolet

Electromagnetic radiation with a wavelength between that of visible light and that of X rays. It was discovered in 1801 by the German physicist, Johann Wilhelm Ritter. The range of UV is subdivided into UV-A (400-315 nm), UV-B (315-280 nm) and UV-C (280-100 nm). Ultraviolet rays subjected at too high a dose are harmful to health. They can cause skin cancers (melanoma), a premature ageing of the skin or burns (sunburn).