What happens to a fuse when there is too much electrical current?

When there is too much electrical current flowing through a circuit, the fuse is designed to protect the circuit by melting and breaking the circuit. A fuse contains a thin wire or strip of metal that has a specific melting point. When the current exceeds the fuse's rating, the increased electrical energy causes the wire to heat up and eventually melt. This interruption in the flow of electricity stops the current, thereby protecting both the wires and devices connected in the circuit from potential damage or fire hazards.

While other options mention effects like heat generation or resistance changes, they do not encapsulate the primary function of a fuse, which is specifically to melt and break the circuit in the event of excessive current. Therefore, the correct understanding is that the melting of the fuse is a deliberate safety mechanism to prevent further issues in the electrical system.