Fuse

[diudiu]

How does a fuse help to prevent a circuit from overheating?

[wildwood]

When the circuit is overloaded or shorted out, the fuse burns out so preventing damage or fire to the main circuit.

[kwicky]

The fuse is the weakest link in the circuit.

[mibn2cweus]

Heating is proportional to the amount of current flowing through the circuit. The current that flows through the circuit is delivered from the supply through the fuse. The fuses rating is selected so that it heats up and melts first opening the connection to the current supply.

[chakka35]

It's worth noting in passing that a fuse is not, as many equipment manufacturers claim, to 'protect your appliance' from a naughty outside world. The fuse is there to protect the outside world - the circuits feeding the appliance - from misbehaviour by the appliance. Being the boring pedant that I am, I have succeeded in having a few manufacturers alter their instruction books accordingly.
(Anticipating other pedants, this does not apply to certain internal fuses inside electronic equipment- fuses that the consumer is not concerned with anyway.)

[diudiu]

Thanks

[nightmare]

to mibn2....
surely, you mean that heating is proportional to the current squared ?