Question

He force per unit length between two parallel long current carrying conductors is F, If the current in each conductor is tripled what would be the value of force per unit length between them?

Answer 1

force per unit length between two parallel long current carrying conductors is given by :

F = $\frac{\mu_0}{2 \pi}\frac{i_1 i_2}{d}$

Thus if the current in each conductor wire is tripled, the force per unit length becomes 9 times.