What function does a selector switch serve in electrical systems?

A selector switch in electrical systems is designed to allow the operator to choose between different circuits or sources of power. It does not act as a voltmeter; rather, the primary function is to control which circuit is active, enabling the user to switch from one option to another seamlessly. This is crucial for managing various electrical components or systems that may require separate power sources or configurations.

The other options refer to functions that selector switches do not perform. For example, regulating fuel flow pertains to fuel systems and is unrelated to electrical circuitry. Indicating battery health involves monitoring voltage, current, or overall battery performance, which is typically done using specific diagnostic tools rather than a simple switch. Measuring current flow requires specialized equipment like ammeters, which are designed for that specific purpose. Thus, the role of a selector switch is distinct and centers on circuit management rather than measurement or regulation.