Question

The distance between two parallel wires carrying current of $1A$ is $1m$. The force per unit length between the conductors is

• A. $2\times {10}^{7}N{m}^{-1}$
• B. $2\times {10}^{-7}N{m}^{-1}$
• C. $4\times {10}^{7}N{m}^{-1}$
• D. $4\times {10}^{-7}N{m}^{-1}$

Answer 1

The correct option is B $2\times {10}^{-7}N{m}^{-1}$

$F=\frac{{\mu }_0}{2Ad}{i}_1{i}_2$
$=\frac{2\times {10}^{-7}\times 1\times 1}{1}=2\times {10}^{-7}N/m$