Question

A straight,long wire carries a current of 20 A.Another wire carrying equal current is placed parallel to it.If the force acting on a length of 10 cm of the second wire is $2.0\times {10}^{-5}N$,what is the separation between them ?

Answer 1

Let separation between two wires is d.Then dF=$\frac{u_0{i}_1{i}_2}{2\pi d}dl$

$\Rightarrow 2.0\times {10}^{-5}=\frac{2.0\times {10}^{-7}\times 20\times 20\times 10\times {10}^{-2}}{d}$

$\Rightarrow d=40cm$