What device is used to open or close an electrical circuit?

A switch is a fundamental device used to open or close an electrical circuit. When a switch is in the "on" position, it allows electrical current to flow through the circuit, completing the pathway. Conversely, when the switch is in the "off" position, it breaks the circuit, stopping the flow of electricity. This basic functionality is essential in all electrical systems, from household items to complex machinery, providing a simple and effective means of controlling power.

While other devices like relays, fuses, and circuit breakers also play crucial roles in electrical systems, their functions differ from that of a switch. A relay, for example, is an electromechanical switch that allows a low-power signal to control a higher power circuit, while a fuse is designed to protect the circuit by melting and interrupting current flow in case of overload. A breaker serves a similar protective function as fuses but can be reset after tripping. In all these cases, the primary purpose of a switch remains focused on the direct act of opening or closing a circuit.