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→Fluorescents
Fluorescents have electrodes at both ends of a tube coated inside with phosphor. Inside the tube, a gas contains argon and mercury vapour. A stream of electrons flows through the gas from one electrode to another. This excites the mercury atoms, giving off ultraviolet photons. In turn these excite the phosphor, giving off visible light.
Invented by A.E. Becquerel of France in 1857, today’s fluorescents are available in full spectrum types with quiet electronic ballasts replacing noisy magnetic ones [5]. Cycling rates have been increased to reduce flicker. Because of the mercury, be careful not to break fluorescents, and dispose of them in an environmentally safe way. The USA Environmental Protection Agency publishes guidelines on what to do if a bulb breaks [57]. Also, don’t use fluorescents in places where you would be at risk if a tube broke. Use LEDs instead.
==== Cold Cathode Fluorescents ====