A lighting unit that emits light by the excitation of a gas (such as neon) enclosed within a sealed tube or bulb. The terms "neon tube", "neon" and "fluorescent tube" are all used to designate the source of fluorescent light.
Light sources in which electric current is passed through a gas causing electron excitation in the phosphor atoms composing the coating on the inner wall of the luminaire.
Tubular glass lights, the interior of which has a fluorescent coating. Light is produced by the action of a stream of electrons upon the coating.