Permanent magnets are commonly used for what part of the starter?

Permanent magnets are primarily used in the field coils of a starter motor to generate a magnetic field. In a starter motor, the interaction between the magnetic field and the current flowing through the armature windings creates torque, which turns the engine's flywheel to start the engine.

Using permanent magnets in the field coils eliminates the need for external power to energize the field windings, simplifying the design and making the starter more compact and efficient. The permanence of these magnets ensures a consistent magnetic field, providing reliable performance during engine startups.

Other components, such as the armature, solenoid, and commutator, have different roles. The armature is the rotating part of the starter that generates torque, while the solenoid is responsible for engaging the starter motor with the engine's flywheel. The commutator, typically found in traditional DC motors, is used for directing current flow to the armature windings. These components do not rely on permanent magnets, which is why the field coils are the correct answer.