Question

Why a fuse wire is used in electrical circuit ?

• A. to increase resistance.
• B. to protect the electrical appliances.
• C. to reduce power dissipation.
• D. to get more light from appliances.

Answer 1

The correct option is B to protect the electrical appliances.

A fuse consists of a metal strip or wire fuse element, of small cross-section compared to the circuit conductors, mounted between a pair of electrical terminals, and (usually) enclosed by a non-combustible housing.

The fuse is arranged in series to carry all the current passing through the protected circuit. The resistance of the element generates heat due to the current flow.

The size and construction of the element is (empirically) determined so that the heat produced for a normal current does not cause the element to attain a high temperature. If too high a current flows, the element rises to a higher temperature and either directly melts, or else melts a soldered joint within the fuse, opening the circuit and the current stops flowing through it.