Final answer:
The synchronous speed of the rotating magnetic field, with a 4-pole motor operating at 60Hz, is calculated to be 1800 rpm.
Step-by-step explanation:
The synchronous speed of a rotating magnetic field in an electric motor is found by the formula N_s = (120f) / P, where N_s is the synchronous speed in revolutions per minute (rpm), f is the frequency in Hertz (Hz), and P is the number of poles.
Using the information provided, with the number of poles being 4 and the frequency being 60Hz, you can calculate the synchronous speed as follows:
N_s = (120 × 60 Hz) / 4 = 1800 rpm
Therefore, the synchronous speed of the rotating magnetic field is 1800 rpm.