How do fuses and circuit breakers differ in protecting electrical circuits?

• A. Fuses interrupt current by melting a link when overloaded.
• B. Circuit breakers trip only on short circuits and cannot be reset.
• C. Fuses store energy to smooth out surges.
• D. Fuses interrupt current by melting a link when overloaded; circuit breakers trip mechanically or thermally/magnetically and can be reset.

Answer: (D)

Fuses and circuit breakers both protect a circuit by cutting off current when a fault occurs, but they do it in different ways and have different use implications. A fuse contains a thin metal link that melts when current exceeds its rating. Once that link melts, the circuit is opened and the device must be replaced. A circuit breaker, on the other hand, uses a trip mechanism that opens the contacts when excessive current is detected—this can be thermal (overload) or magnetic (a short circuit). Unlike a fuse, a breaker can be reset after the fault is cleared, making it reusable. Because breakers can be reset, they’re often preferred in situations where quick restoration after fault checking is desirable. Fuses are simple and inexpensive but single-use.