Which circuit protection device melts a thin strip of metal when overloaded?

Which circuit protection device melts a thin strip of metal when overloaded?

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

Answer: (B)

Overcurrent protection relies on a part that responds directly to excessive current. A fuse uses a very thin metal link that heats up when the current exceeds its rating. When it gets hot enough, the metal melts and the circuit opens, stopping the flow of electricity to prevent damage. This is a one-time protection device. A circuit breaker also protects against overloads, but it works differently: it detects the excess current and trips a switch to open the circuit. It can be reset after the fault, unlike a fuse which must be replaced. Resistors simply limit current and convert some of that energy to heat, not protect by opening the circuit. Switches merely connect or disconnect the circuit but don’t automatically respond to overloads. So, the device that melts a thin strip of metal when overloaded is a fuse.

Overcurrent protection relies on a part that responds directly to excessive current. A fuse uses a very thin metal link that heats up when the current exceeds its rating. When it gets hot enough, the metal melts and the circuit opens, stopping the flow of electricity to prevent damage. This is a one-time protection device.

A circuit breaker also protects against overloads, but it works differently: it detects the excess current and trips a switch to open the circuit. It can be reset after the fault, unlike a fuse which must be replaced. Resistors simply limit current and convert some of that energy to heat, not protect by opening the circuit. Switches merely connect or disconnect the circuit but don’t automatically respond to overloads.

So, the device that melts a thin strip of metal when overloaded is a fuse.