Describe the operation of a synchronous motor?

A synchronous motor operates on alternating current (AC) power, and its rotor is designed to rotate at the same speed as the rotating magnetic field produced by the stator. This characteristic allows the motor to maintain synchrony with the frequency of the AC power supply.

In the context of this question, while a synchronous motor primarily operates on AC, it often requires a specific starting method involving direct current (DC) for excitation. Once the rotor achieves sufficient speed to match the AC frequency, it can maintain operation using only the AC power, as the rotor's magnetic field is synchronized with that of the stator.

The need for initial DC excitation is crucial for establishing the magnetic field necessary for the motor's operation. Once the motor is running at synchronous speed, it can sustain this state using the AC power alone. This unique characteristic is what makes the answer considered correct.