Question

A 5 amp 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 1

Answer: (D)

$0.04\Omega$

Given: Power $\left(P\right)=1W$

Current $\left(I\right)=5A$

Resistance $\left(R\right)=?$

The power of a resistor is the rate of flow of energy through it. Maximum power is the limiting energy flow after which the resistor (or wire here) would fuse.

We know that,

$P=I^{2}R$

$\Rightarrow R=\frac{P}{I^2}=\frac{1W}{25A^2}=0.04\Omega$