An AC generator operates by rotating a coil within a magnetic field, which generates an alternating current. As the coil rotates, the changing magnetic flux induces an electromotive force based on Faraday's law of induction. The direction of the current reverses each half turn as one side of the coil moves between the north and south poles of the magnet. Increasing the magnetic field strength, rotation frequency, number of coil turns, or using a stronger magnet can increase the generated electromotive force.