Question
A $$5\,A$$ fuse wire can withstand a maximum power of $$1\,W$$ in circuit. The resistance of the fuse wire is
A.
$$0.2\,\Omega $$
B.
$$5\,\Omega $$
C.
$$0.4\,\Omega $$
D.
$$0.04\,\Omega $$
Answer :
$$0.04\,\Omega $$
Solution :
As we know that,
$${\text{Power}}\,P = {i^2}R\,\left[ {_{R\, = \,{\text{resistance}}}^{{\text{where,}}\,i\, = \,\,{\text{current in circuit}}}} \right]$$
$$R = \frac{p}{{{i^2}}}$$
Given, $$P = 1\,W,\,i = 5\,A$$
$$\therefore R = \frac{1}{{{{\left( 5 \right)}^2}}} = 0.04\,\Omega $$