A square current-carrying loop is placed in a uniform magnetic field B with the plane of the loop parallel to the magnetic field. (See drawing). The dashed line is the axis of rotation. The magnetic field exerts:

a) a net torque, but not a net force, on the loop

b) a net force and a net torque on the loop

c) a net force, but not a net torque, on the loop

d) neither a net force nor a net torque on the loop

(A) a net torque but no net force on the loop.

Explanation:

The total force on the loop is zero because the forces on the opposite sides of the loop are equal but act in opposite directions and as a result they cancel each other out. The two forces on opposite sides to the axis of rotation each give rise to a torque about the axis of rotation. This torque is directed along the axis of rotation.

explanation:

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