A device that automatically interrupts the electrical current.

A device that automatically interrupts the electrical current.

• A. Fuse
• B. Circuit breaker
• C. Switch
• D. Resistor

Answer: (B)

Protecting a circuit from overcurrent relies on devices that open the path automatically when things get out of hand. A circuit breaker fits this role by sensing overloads or fault conditions and tripping to open the circuit on its own; after the fault is cleared, it can be reset and used again. A fuse also interrupts automatically, but it does so by melting its element and is a single-use item—you replace it after it blows. A switch, on the other hand, is a manual device you operate to start or stop current flow, not an automatic protection against faults. A resistor simply limits current and does not interrupt the circuit.

Protecting a circuit from overcurrent relies on devices that open the path automatically when things get out of hand. A circuit breaker fits this role by sensing overloads or fault conditions and tripping to open the circuit on its own; after the fault is cleared, it can be reset and used again. A fuse also interrupts automatically, but it does so by melting its element and is a single-use item—you replace it after it blows. A switch, on the other hand, is a manual device you operate to start or stop current flow, not an automatic protection against faults. A resistor simply limits current and does not interrupt the circuit.