What device is used to protect an electrical circuit from overloads or short circuits?

A fuse or circuit breaker is used to protect an electrical circuit from overloads or short circuits by interrupting the flow of current when certain conditions are met. When the current flowing through the circuit exceeds a predetermined level due to an overload or a fault, the fuse will melt and break the circuit, or the circuit breaker will trip and open the circuit. This interruption helps prevent damage to the wiring and connected devices, as well as reducing the risk of electrical fires.

The choices of a switch, relay, or ammeter do not serve the purpose of circuit protection. A switch is used to control the flow of electricity by opening or closing the circuit. A relay functions as an electrically operated switch, often used to control a circuit by a low-power signal or to manage multiple circuits. An ammeter is a measuring instrument used to measure the current flowing through a circuit, but it does not have protective capabilities.