Question

why electronic ballast are used in modern fluorescent lamps? ​

Answer 1

A inductive(normal) ballast is an inductor which does two things to turn on the fluoroscent lamps:

1) Produces high voltage across the lamps to turn it on (>1000V).

2) Limits the flow of current through inductor.

*Use of inductive(normal) ballasts lead to a flickering start of the lamp.

Where as electronic ballasts provide a medium voltage across the lamp (~300V) and provides a high frequency A.C. supply to prevent flickering and start the lamp immediately. Also a small inductor controls the current unlike a big inductor used in inductive(normal) ballasts.