In a three-phase induction motor, the rotor spins due to interaction between the rotor and what?

The rotor of a three-phase induction motor spins due to the interaction between the rotor and the stator magnetic field. In this type of motor, the stator is supplied with three-phase alternating current, which creates a rotating magnetic field. This rotating field induces an electromotive force (EMF) in the rotor, which is typically a squirrel-cage type.

When the rotating magnetic field interacts with the rotor, it induces currents in the rotor bars. These currents produce their own magnetic field, which interacts with the stator's rotating field, resulting in torque. The rotor attempts to catch up with the rotating magnetic field, and this difference in speed is what generates the slip necessary for the induction process to occur.

The yoke assembly does provide mechanical support but does not directly contribute to the motor's operational principles. The current supply is crucial for operating the motor but is not the direct cause of rotor motion; rather, it facilitates the generation of the magnetic fields. An external magnetic field does not play a role in the standard operation of a three-phase induction motor, as it primarily relies on the interaction of the stator and rotor magnetic fields. Thus, the correct answer emphasizes the significance of the stator magnetic field in generating the motion of the rotor.