Question

A square loop, carrying a steady current $I$, is placed in horizontal plane near a long straight conductor carrying a steady current $I_{1}$ at a distance $d$ from the conductor as shown in figure. The loop will experience

• A. a net repulsive force away from the conductor
• B. a net torque acting upward perpencicular to the horizontal plane
• C. a net torque acting downward normal to the horizontal plane
• D. a net attractive force towards the conductor

Answer 1

Answer: (D)

$F_{2} = - F_{4}$
$ F_{1} = \frac{\mu_{0}\,I_{1} \,Il}{2 \pi dl}$
$F_{2} = \frac{\mu_{0} \,I_{1}\,Il}{2\pi\left(d + l\right)}$
$ F_{1} > F_{3}$
$ F_{\text{net}} = F_{1} - F_{3} $
So, wire attract loop .