Will there be any electromagnetic resistance to an electric generator if its not producing energy(opencircuit?
When you are producing electricity, the amount of energy you put into the generator will always be greater than the amount of energy you get out. There will always be some inefficiency caused, not only by friction, but also energy lost to heat from eddy currents in the coils. You are asking about electromagnetic effects: If the circuit is open, so that no power is drawn, there may still be some very small flow of electricity into eddy currents and then into heat, but it will not be significant.
