發電機的發電性能根什麼有關?

It depends very much on the magnetic coupling between the magnetic field and the rotating solenoid, i.e. on the geometry of the field and the shape of the solenoid.

The rotation speed of the solenoid affects, apart from the induced voltage, mainly the frequency of the current generated.

For example, all electric generators in Hong Kong power stations are rotating at a speed of 3000 revolutions per minute, thus producing electrical supply at a frequency of 50 Hz.