Fluorescent lamp

The fluorescent lamp is a low-pressure mercury gas-discharge lamp for lighting purposes. It has a filament at each end. The hot filaments emit electrons that fly through the tube to the opposite end. On their way, they collide with mercury atoms. The atoms emit the acquired energy in the form of ultraviolet radiation. The radiation is converted to visible light by a phosphor deposited on the wall of the tube. Compared to other light sources, the fluorescent lamps have much better efficiency. The light color may be altered by phosphor composition. These lamps were invented in the USA in the 1930s and came into widespread use since the 1940s. In Czechoslovakia, they were manufactured since 1949 and were firstly used in rail carriages.