# A square loop of side $a$ carrying a current $i_1$ is kept at a distance of $a$ from an infinite wire carrying a current $i_2$ as shown. The torque on the loop is

$\begin {array} {1 1} (a)\;\large\frac{\mu_0i_1i_2a}{\pi} & \quad (b)\;\large\frac{\mu_0i_1i_2a}{2\pi} \\ (c)\;\large\frac{\mu_0i_1i_2a}{\pi}In (2) & \quad (d)\;Zero \end {array}$

The forces acting on the loop are all in the plane and hence there is no torque
Ans : (d)
answered Feb 23, 2014