how do a tubelight works ,the role of choke coil?

Answer 1

A tube light (neon, fluorescent) has a plasma inside that gives off UV light which stimulates a phospher which glows with visible light.
The plasma is created by applying a high voltage and by having very low pressure in the tube.
But a plasma has very low resistance once it is formed, so the choke prevents a high current flow equal to a short circuit. If you were to connect up the tube to a proper running voltage without the choke and kick start it somehow (say RF generator), the current would go very high for a fraction of a second and explode the tube.