Fluorescent tubes are fitted with a choke.
The choke coil :
(a) steps up the line voltage
(b) steps-down the line voltage
(c) reduces current in the circuit
(d) chokes low frequency current
(c) A fluorescent lamp or fluorescent tube is a gasdischarge lamp that uses electricity to excite mercury vapour. The excited mercury atoms produce shortwave ultraviolet light that then causes a phosphor to fluoresce, producing visible light .In fluorescent tubes the simplest ballast for alternating current use is an inductor (choke coil ) placed in series, consisting of a winding on a laminated magnetic core. The inductance of this winding limits the flow of AC current on account of its large impedance. The only waste of energy is due to the hysteresis loss in the iron core, which is much less than the waste of energy in comparison to resistance which can also reduce the current if placed instead of the choking coil.
