Question

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

• A. $\frac{\mu_{0 }}{ 2\pi} \frac{i_{1}i_{2}l}{ab}$
• B. $\frac{\mu_{0 }}{ 2\pi} \frac{i_{1}i_{2}l}{a(a + b)}$
• C. $\frac{\mu_{0 }}{ 2\pi} \frac{i_{1}i_{2}l (b - a)}{ab}$
• D. 0

Answer 1

Answer: (D)

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