What circuit-protection device uses a narrow strip of metal to prevent excessive current through a circuit?

What circuit-protection device uses a narrow strip of metal to prevent excessive current through a circuit?

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

Answer: (A)

A fuse protects a circuit by interrupting current when it overheats due to too much current. Inside is a very narrow strip of metal that conducts normally, but when the current exceeds the fuse’s rating, heat from the current melts the strip and opens the circuit, stopping the current flow. Because the strip melts, a fuse is a one‑time protection device and must be replaced after it blows. Other devices handle protection differently: a circuit breaker trips and can be reset, a resistor only limits current, and a switch simply opens or closes the circuit.

A fuse protects a circuit by interrupting current when it overheats due to too much current. Inside is a very narrow strip of metal that conducts normally, but when the current exceeds the fuse’s rating, heat from the current melts the strip and opens the circuit, stopping the current flow. Because the strip melts, a fuse is a one‑time protection device and must be replaced after it blows. Other devices handle protection differently: a circuit breaker trips and can be reset, a resistor only limits current, and a switch simply opens or closes the circuit.