In a control circuit, a relay is primarily used for what purpose?

A relay serves a crucial role in a control circuit by functioning primarily as a switch for electrical circuits. When an electrical signal is applied to the relay's coil, it activates the switch, allowing current to flow through another circuit. This ability to control a larger electrical load with a smaller control signal is essential in automation and control systems. Relays enable the safe operation of high-power devices by isolating control circuits from those high-power circuits, enhancing safety and efficiency in electronic and industrial applications.

While other options describe functions associated with electrical components, they do not align with the primary function of a relay. For instance, amplifying signals pertains to components like operational amplifiers or transistors, measuring electrical current typically involves ammeters or sensors, and energy storage is associated with capacitors or batteries. Each of these functions plays vital roles in circuits, but none match the relay's specific purpose of switching circuits on and off.