Question

Calculate force per unit length acting on the wire B due to the current flowing in the wire A.

Answer 1

Since current in both the wire is flowing in same direction, so both wire will attract each other.
Force per unit length acting on the wire B due to A $F=\frac{{\mu }_o{I}_1{I}_2}{2\pi r}$
where $r=1cm=0.01m$
$\therefore$ $F=\frac{4\pi \times {10}^{-7}\times 20\times 75}{2\pi \times 0.01}=0.03N/m$