How to create UV light?
UV is a spectrum of light located just below the visible range for the human eye. The UV-C spectrum (185 – 280 nm) is known as the germicidal spectrum because it is the area with the maximum germicidal wavelength (260 nm). UV reactors for water treatment include at least one UV lamp that usually contains argon and a small amount of mercury, sometimes in the form of an alloy: amalgam.
UV lamps also contain filaments that, in the presence of electricity, generate an electric charge that causes the mercury inside the lamp to vaporize. This evaporated mercury generates electric arcs that generate ultraviolet radiation at 254 nm, very close to the optimum at 260 nm. Germicidal lamps still emit some visible light because of the other spectra emitted by mercury. All germicidal lamps require an external ballast to regulate the current flowing through them.