fluorescent light glows in how much volts?

Answer 1

Depends on the country. In India and many other countries the tube is designed for 220V but will work may be upto 170V or so with the make and break contact (starter) and the choke. With an electronic starter, the tube works right down to 110V or so, but the light putput may be less.

Answer 2

Something like 80 Volts but it varies because you don't want constant voltage you want limited current. But you need to start it going with an higher voltage to get the initial spark. Then you need to drop back the voltage or you will destroy the lamp. This is done using a ballast system.