Why do fluorescent lamps need a ballast?
Ballasts are used to regulate the current in the lamp. Current needs to be regulated in order to supply the right amount of power needed to make the arc, and thus the light, in a fluorescent lamp. Fortunately, the current is lower than that needed for a typical incandescent. This is the reason why the fluorescent lamps can provide the same light output for less energy than typical incandescents.
