The alternating field causes the rotor to rotate on the shaft, making one revolution for each half -cycle of the input AC power.

Question

Quizplus · Accepted Answer

The alternating field in an AC motor does not cause the rotor to make one revolution for each half-cycle of the input AC power. Instead, the rotor's speed (in revolutions per minute) is determined by the frequency of the AC power supply and the number of magnetic poles in the motor, following the formula: Speed = (120 x Frequency) / Number of Poles. The rotor typically rotates at a speed less than the changing magnetic field, especially in induction motors, where this difference in speed is necessary for inducing current in the rotor.

The Alternating Field Causes the Rotor to Rotate on the Shaft