ARRL Technician Practice Exam

What electrical component is used to protect other circuit components from current overloads?

1. Fuse

2. Transformer

3. Inductor

4. Relay

The correct answer is: Fuse

The fuse is an essential electrical component designed specifically to protect circuits from current overloads. It consists of a conductive material that melts and disconnects the electrical circuit when the current exceeds a predetermined level. This interruption prevents excessive current from damaging sensitive components within the circuit, ensuring the safety and longevity of the overall system. When current flows through a fuse, it operates normally until the current surpasses the fuse's rating due to a fault or overload. At that point, the increased heat causes the fuse element to melt, breaking the circuit and stopping the flow of electricity. This is crucial for preventing components such as resistors, capacitors, and integrated circuits from being exposed to damaging amounts of current. The other components mentioned have different functions; for example, a transformer is used to change voltage levels, an inductor stores energy in a magnetic field, and a relay functions as a switch that opens or closes circuits. None of these provide the specific protective feature against current overloads that a fuse does. Therefore, the fuse is identified as the component that specifically serves this protective role in electrical circuits.