Question

The force per unit length between two straight conductors separated by a distance of 0.02 m is 2 × 10^-3 N m^-1. The current in one conductor is 10 A and that in the other conductor is

• A. 20 A
• B. 5 A
• C. 2 A
• D. 10 A

Answer 1

Answer: (A)

Force per unit length between two parallel current carrying wire is given by
$F=\frac{{\mu }_0}{2\pi }\frac{I_1{I}_2}{r}$
Here, $\frac{{\mu }_0}{4\pi }=10^{-7}Nm{A}^{-2},r=0.02m$
$F=2\times 10^{-3}N{m}^{-1},I_1=10A,I_2=?$
So ,$2\times 10^{-3}=2\times 10^{-7}\times \frac{10\times I_1}{0.02}$
$0.02\times 10^4=10I_1=\therefore I_1=20A$