Which component performs both mechanical and electrical functions in an electrical system?

The starter solenoid is a crucial component in an electrical system that uniquely combines mechanical and electrical functions. It serves as a switch that connects the battery to the starter motor, initiating the engine's cranking process. When the ignition key is turned, the solenoid receives an electrical signal, causing it to mechanically engage and close the circuit. This action allows electrical current to flow from the battery to the starter motor, which then mechanically turns the engine over.

This dual functionality is vital because the starter solenoid must not only handle the electrical current but also perform a mechanical operation by moving its internal components to make the necessary connections. This distinct role differentiates it from other components in the electrical system, which typically specialize in either mechanical functions (like the starter motor itself) or pure electrical functions (such as the alternator or battery).