Final answer:
A circuit breaker is a switch that automatically interrupts or shuts off an electric current at the first indication of an overload. It is designed to protect electrical circuits from damage caused by excessive current flow.
Step-by-step explanation:
A switch that automatically interrupts or shuts off an electric current at the first indication of an overload is called a circuit breaker. A circuit breaker is designed to protect electrical circuits from damage caused by excessive current flow. When an overload occurs, the circuit breaker quickly opens the circuit, preventing further flow of current.
Circuit breakers work by utilizing a bimetallic strip that bends and breaks the electrical connection when it overheats due to excessive current. This mechanism allows the circuit breaker to react quickly to overloads and interrupt the current flow.
Unlike fuses, which need to be replaced after they are blown, circuit breakers can be reset after tripping. This makes them more convenient and cost-effective.