Question

Two 2 m long parallel wires are placed in vacuum at a distance 0.2 m. If current 0.2 A flows in both the wires in the same direction, calculate the force acting per unit length between them.

Answer 1

$F_2=B_2{I}_{1}L$

& $B_2=\frac{{\mu }_0}{2\pi }\times \frac{I_2}{R}$

$\Rightarrow F_2=\frac{{\mu }_0}{2\pi }\times \frac{I_1{I}_{2}L}{R}$

Where, $I_1=I_2=I=0.2A$

$L=2m$, $R=0.2m$

So, force, $F_b=\frac{40\times {10}^{-9}}{2\pi }\times \frac{0.2\times 0.2\times 2}{0.2}=8\times {10}^{-8}N$