Automotive Electronics Practice Test

The function of the field coils in a starter motor is to provide what?

1. Supply power to the armature

2. Generate magnetic field

3. Hold the rotor in place

4. Control the speed of the motor

The correct answer is: Generate magnetic field

The field coils in a starter motor are essential for generating a magnetic field. When electrical current flows through the coils, it creates a magnetic field that interacts with the armature winding. This interaction is crucial for initiating movement within the motor. The generated magnetic field pulls or pushes against the armature, causing it to rotate. This rotation is what ultimately engages the vehicle's engine, allowing it to start. The strength and direction of this magnetic field can be controlled by the amount of current flowing through the field coils, but the primary function remains focused on the generation of the magnetic field necessary for the starter motor to operate effectively. In contrast, the other options relate to different functions not specific to the role of the field coils. For instance, supplying power to the armature is the responsibility of the power supply system rather than the field coils themselves, while holding the rotor in place and controlling the speed of the motor are not tasks associated specifically with the field coil function in this context.