Question

The light-producing element in a fluorescent bulb is the _____.


tungsten filament
mercury vapor
phosphors
electric arc

Answer 1

A fluorescent lamp or fluorescent tube is a very low pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. The electric current (in the gas) excites mercury vapor which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the bulb to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful light much more efficiently than incandescent lamps.

http://en.wikipedia.org/wiki/Fluorescent_lamp