A motor is disclosed. The motor includes a stator with a stator coil to generate a periodic unidirectional field current flowing through the stator coil and a rotor. An air gap is disposed between the stator and the rotor. The rotor has at least one rotor ring, a portion of the rotor ring is disposed in the air gap. Due to the unidirectional magnetic field, a periodic electric current is induced in the rotor ring. The electric current flowing through the portion of the rotor ring disposed in the air gap flows in a first direction to rotate the rotor relative to the stator.