A square loop, carrying a steady current $I$, is placed in a horizontal plane near a long straight $\quad$ conductor carrying a steady current $\mathrm{I}_{1}$ 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 perpendicular to the horizontal plane
• C

  a net torque acting downward normal to the horizontal plane
• Correct answer
  D

  a net attractive force towards the conductor

Solution

$\mathrm{F}_{1}>\mathrm{F}_{2}$ as $\mathrm{F} \propto \frac{1}{\mathrm{~d}}$, and $\mathrm{F}_{3}$ and $\mathrm{F}_{4}$ are equal and opposite. Hence, the net attraction force will be towards the conductor. Heat gain $=$ heat lost

Hence, the correct answer is option: 'D'.