# Induction motor operation depends on

Electrical Engineering XYZ MCQs

Induction motor operation depends on:

1. Stationary magnetic field
2. Rotating magnetic field
3. Either of these
4. None of the above

Correct answer: 2. Rotating magnetic field

Explanation: The correct answer to this Electrical Engineering XYZ MCQ is: Rotating magnetic field

An induction motor, also known as an asynchronous motor, operates based on the principle of electromagnetic induction. Here’s how it works:

1. Stator Windings and AC Supply: The stator, which is the stationary part of an induction motor, consists of windings that are connected to an alternating current (AC) supply. This AC supply generates a magnetic field around the windings.
2. Creation of a Rotating Magnetic Field: When AC current flows through these stator windings, a rotating magnetic field is created. This is crucial because the nature of the AC supply (changing current direction and magnitude) naturally produces a magnetic field that rotates around the axis of the stator.
3. Rotor and Induction: The rotor, which is the rotating part inside the stator, does not receive electrical power directly by wires or slip rings but instead, has conductors (bars) that are short-circuited by end rings. When the rotor is exposed to the rotating magnetic field produced by the stator, currents are induced in the rotor bars (thanks to Faraday’s law of electromagnetic induction).
4. Torque Production: These induced currents in the rotor create their own magnetic field which interacts with the stator’s rotating magnetic field. This interaction produces torque and causes the rotor to turn. The direction of the rotor’s motion follows the rotating magnetic field of the stator.
5. Synchronization: The speed at which the magnetic field rotates is called the synchronous speed. The rotor does not reach synchronous speed if the motor is operating under normal conditions with load; the difference in speed is known as slip.

Therefore, the correct answer is that induction motor operation depends on a rotating magnetic field. This rotating field is fundamental to the operation of induction motors, enabling the induction of currents in the rotor and the consequent mechanical output.