Which of the following is a common application for a relay in electrical systems?

A relay is an electromechanical switch that is commonly used to control the flow of electricity in a circuit. Its primary application is to switch circuits on and off. When a small control voltage is applied to the relay coil, it creates a magnetic field that pulls a switch contact together, thus completing the circuit and allowing a larger current to flow. This ability to control high-power circuits with low-power signals makes relays a vital component in various electrical systems, including automation, safety systems, and remote control applications.

While voltage regulation, overcurrent protection, and converting AC to DC are important functions in electrical systems, they are typically managed by specific devices such as voltage regulators, circuit breakers, and rectifiers, rather than relays, which are primarily designed for switching.