how does a choke creates a high potential differance in a flouroscent lamp across the filaments on the tube?

Answer 1

A choke is just an inductance. The volage across an inductor is proportional to the rate of change of current through the inductor:

V = L di/dt

One way to use this property to generate momentary high voltages is to have a steady current through the inductor suddenly stopped. This produces a very fast change in current, and a very high voltage across the inductor. In practical terms, the circuit could consist of a resistor and inductor (choke) in series with a voltage source and a switch. The switch is closed, and current will build up slowly. When the switch is opened, a very high voltage spike (enough to start the discharge in a fluorescent tube) will appear across the inductor,