How does a fuse protect an electrical circuit?

A fuse protects an electrical circuit primarily by melting and breaking the circuit during an overload. This safety device is designed to interrupt the flow of electricity when the current exceeds a certain level, which can occur due to a short circuit or other faults. When excessive current flows through the fuse, it generates heat, causing the fuse element to melt. This melting action effectively breaks the circuit, stopping the flow of electricity and preventing potential damage to the wiring, components, and possible fire hazards.

In contrast, the other options do not accurately describe the role of a fuse. Increasing the voltage of the circuit does not provide protection; rather, it can lead to further complications. Creating a backup power source misrepresents the function of a fuse, which does not supply additional power. Filtering out temporary surges is more characteristic of surge protectors or voltage regulators, not fuses, which focus solely on preventing current overloads.