Tech A says motor action occurs through the interaction of the magnetic fields of the field coils and the armature, which causes a rotational force to act on the armature, creating the turning motion. Tech B says two magnetic fields are required for motor action: one in the casing and the other in the rotating armature. Who is correct

Both A and B

Explanation:

The interaction of magnetic fields and armature results into a rotational force of the armature hence turning motion. It's important to note that you will always need two magnetic fields in order to experience the force since one magnetic field is at the rotating armature and another at the casing. Considering the arguments of these two technicians, both of them are correct in their arguments.