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A fuse is a piece of wire of a material with a very low melting point, that is, it melts and breaks as soon as its temperature gets higher than its melting point.
The material used for making fuse have low melting points , hence fuse wires are mainly made up of tin, lead or zinc.
How does a Fuse Wire work?
A fuse is used in a circuit to avoid overloading or short circuiting.
When a current higher than the rating of the fuse flows through it, the fuse wire gets heated and melts.
This breaks the circuit and protects the appliances from getting damaged.
Properties of Fuse Wire
An ideal fuse must have the following properties
- Low melting point, so that it breaks as soon as current higher than permissible value passes through it
- High resistance, but made of elements having low resistivity - High resistance is needed so that more heat is produced (Heat = I 2 R), low resistivity is required for the material so that it doesn't interfere with the flow of current
- It should be economical , because even though silver satisfies the above two properties but it is not economical, hence it isn't widely used as a fuse.
Fuses of different appliances have different current ratings.
The appliances which work on large current have fuse of higher current ratings.
The appliances which work on small current have fuse of smaller current ratings.
For example
- Current rating of a fuse used in fans, lights etc are rated 5A
- Current rating of a fuse used in motors are rated 15A
