What is the source of ultraviolet light?
The best known energy source of ultraviolet light is the sun. However, by the time the UV light reaches the earth it has been reduced to minimal intensities by such factors as the atmospheric conditions, latitude, and time of the day. Artificial UV light in the germicidal spectrum have been developed for production of UV radiation, e.g. UV-C sterilizer lamps.
UV light (energy) is produced by a low pressure mercury lamp made from a glass formula which permits the passage of light rays of a specific wave length.