Question

why is necessary to have a fuse in every electrical circuit?

Answer 1

A fuse is nothing more than a short length of wire designed to melt and separate in the event of excessive current. Fuses are always connected in series with the component(s) to be protected from overcurrent, so that when the fuse blows (opens) it will open the entire circuit and stop current through the component(s).

Answer 2

it is necessary to have a fuse in every electrical circuit because if there is overloading of current in the circuit which will damage the appliance, the fuse prevents this by breaking the circuit