Ultraviolet radiation (UV) is electromagnetic radiation of wavelengths of 100–400 nanometers, shorter than that of visible light, but longer than X-rays. Wavelengths between 10 and 100 nanometers are called extreme ultraviolet and share some properties with soft X-rays. UV radiation is present in sunlight and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs, Cherenkov radiation, and specialized lights, such as mercury-vapor la...
