what is a Fuse?

 Fuse is an electrical safety device that operates to provide overcurrent Protection of an electrical circuit.

Fuse is a pices of wire of a metarial with very low melting point. When a high current flows through the circuit due to overload or short circuit, the wires gets heated and melt, as a result the circuit is broken and the current stop flowing.

Fuse wire

Fuse wire made of lead and tin alloy (63 % tin and 37% lead) having low melting point, Specific resistance is more than aluminium and  copper, so that as result resistance of short and thin fuse is more than connecting wire (basically copper and aluminium).

Its permits current upto its safe limit to passes through it, but an excessive current melt it so circuit will break.

Melting point of fuse wire is about 400 C where copper is 1080 C and aluminium is 660 C