Dark lamp method | Synchronous Machine Synchronisation with infinite Bus Bar

[bikash]

How the bulb glow in lamp method?
You Need neutral and phase or voltage difference between two terminal to glow?
If both generator are in syncronise then the two terminal of bulb will get either max voltage or zero voltage then how the current will flow and how it will glow?? If voltage and current it is flowing in a circuit it has to go somewhere