Question

The specific resistance of fuse wire is
A. high
B. low
C. zero
D. infinity

Answer 1

Hint: The purpose of a fuse is to stop the flow of large values of current in a circuit in order to protect the devices connected in the circuit. The wire of the fuse should be such that it does not allow the large values of current to pass through it.

Complete step-by-step answer:
The resistance of a wire is defined as the obstruction that the wire offers to the current flowing through it. The resistance of a wire depends on the area of the wire and the length of the wire. The specific resistance can be defined as the resistance that is offered by a wire which has unit length and unit cross-sectional area.
$R = \rho \dfrac{L}{A}$
Here R represents the resistance of the wire, L is the length and A is the cross-sectional area of the wire while $\rho $ represents the specific resistance of the wire.
The purpose of a fuse is to limit the amount of current flowing through a circuit. The fuse is basically a wire connected to a circuit which needs to have certain characteristics so that it is able to limit the flow of large amounts of current.
Now if the wire has a high specific resistance then it will not allow large amounts of current to flow through the circuit.
Hence, the correct answer is option A that the specific resistance of fuse wire is high.


Note:1. The specific resistance is constant for a wire irrespective of the length or cross-sectional area of the wire.
2. The fuse wire should have high specific resistivity and also low melting point so that it melts as soon as large current flows through the wire.