A current carrying square loop is placed near a straight infinitely long current carrying wire as shown in the figure. The torque acting on the loop is

Options

A. `(mu_(0))/(2pi) (i_(1)i_(2)l)/(ab)`
B. `(mu_(0))/(2pi) (i_(1)i_(2)l)/(a (a +b))`
C. `(mu_(0))/(2pi) (i_(1)i_(2)l(b-a))/(ab)`
D. 0

Answer

D

Explanation

The forces acting on the sides of the square due to current I, all lie in the planes of the coil. Therefore, there is no net torque.