Which device contains a thin metal strip that melts if too much current passes through a circuit?

Which device contains a thin metal strip that melts if too much current passes through a circuit?

• A. Geothermal energy
• B. Fuse
• C. Circuit breaker
• D. Solar energy

Answer: (B)

Fuses are safety devices that protect circuits by sacrificing a small piece of conducting material. Inside a fuse is a very thin metal strip. When too much current flows, the strip heats up quickly (I^2R heating) and melts, breaking the circuit to stop the overload. You then need to replace the fuse. A circuit breaker can do the same job but by tripping a switch (and it can be reset), not by melting. The other two options are energy sources, not protective devices. So the device described is a fuse.

Fuses are safety devices that protect circuits by sacrificing a small piece of conducting material. Inside a fuse is a very thin metal strip. When too much current flows, the strip heats up quickly (I^2R heating) and melts, breaking the circuit to stop the overload. You then need to replace the fuse. A circuit breaker can do the same job but by tripping a switch (and it can be reset), not by melting. The other two options are energy sources, not protective devices. So the device described is a fuse.