What is the role of a circuit breaker in an electrical circuit?

The role of a circuit breaker in an electrical circuit is to protect from overload. When an electrical circuit experiences an overload or a fault condition, a circuit breaker interrupts the flow of electricity to prevent damage to the wiring and connected devices. This is crucial because excessive current can lead to overheating, fires, or equipment failure. By automatically opening the circuit when it detects unsafe conditions, circuit breakers help ensure the safety and reliability of electrical systems.

In contrast, increasing resistance would impede current flow rather than protect the circuit. Switching on the current does not accurately describe the protective function of the circuit breaker, as it is not intended to control when current flows but rather to interrupt it in unsafe situations. Finally, changing AC to DC is a function of rectifiers, not circuit breakers, which are specifically designed for overload protection rather than conversion of current types.