The ultra violet light produced by exited mecury atoms ( which in turn produced by collision of electron from cathod) is converted to visible light by phosphor.
Requirement of Ballast
- Required to regulate current so lamp operates at correct voltage.
- Provides necessary voltage to start and sustain the arc.
- Without a ballast, CFL lamps would draw too much current and burn out straight away.
- Can either be remote (part of the fixture) or built into the lamp (integral).
- Electromagnetic - heavy, large and less efficient.
- Electronic - small, light, efficient and flicker-free