A square loop, carrying a steady 1, is placed in a horizontal plane near a long staright conductor carryinf a steady current `I`, at a distance `d` from the conductor as shown in Fig. The loop wil experience

Options

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.
D. a net attractive froce towards the conductor

Answer

D

Explanation

The force on sids `QR` and `SQ` is equal and opposite `(F_(2) = -F_(4))` hence no net force due to these sides. Let `F_(1)` and `F_(2)` are the forces on sides `PQ` and `RS` respectively.

`F(1) = (mu_(0) I_(1) II)/(2pi d)` (Towards left)
`F_(3) = (mu_(0) I,II)/(2pi (d + 1))` (Towards right)
As `F_(1) gt F_(3)`
`F_("net") = F_(1) - F_(3)` (Towards left)
So, wire attracts loop.