Final answer:
Field coils in a starter motor are located inside the stator and generate magnetic fields, which interact with the rotor to produce torque. Back emf opposes the applied voltage, and brushes reverse the current for continuous rotation. The direction of magnetic fields in loops and coils is determined by the right-hand rule.
Step-by-step explanation:
The field coils are located on the inside part of the starter motor, specifically on the stator or the stationary part of the motor. These coils are energized with direct current to create a magnetic field that interacts with the armature (rotor) to generate the torque needed to start the engine. In any electric motor, including starter motors, a phenomenon known as back emf (electromotive force) is generated as the armature rotates, which opposes the applied voltage. The direction in which the current is reversed to keep the coil rotating is managed by automatic switches called brushes.
Concerning the direction of the fields in the center of the loop and coils, it is determined by the right-hand rule for coils, with the thumb representing the direction of current flow and the fingers the resulting magnetic field direction. The relationship between the magnetic fields, their induced emf, and the current is a principle described in physics and particularly in the study of electromagnetism.