A long, straight wire carries a 10.0-A current in the +y direction as shown in the figure. Next to the wire is a square copper loop that carries a 2.00-A current as shown. The length of each side of the square is 1.00 m.
-What is the direction of the net magnetic force that acts on the loop?

Question

A long, straight wire carries a 10.0-A current in the +y direction as shown in the figure.  Next to the wire is a square copper loop that carries a 2.00-A current as shown. The length of each side of the square is 1.00 m.
-What is the direction of the net magnetic force that acts on the loop?

Quizplus · Accepted Answer

Using the right-hand rule, we can find that the magnetic field created by the straight wire points into the page inside the loop. Therefore, the magnetic force on each side of the loop is given by the right-hand rule (F = ILBsinθ), where θ is the angle between the current direction and the magnetic field direction.

For the top and bottom sides of the loop, the angle θ is 90° so sinθ = 1 and the forces are in the -x and +x directions, respectively. For the left and right sides of the loop, the angle θ is 0° so sinθ = 0 and there are no forces.

Therefore, the net magnetic force on the loop is the vector sum of the two horizontal forces, which cancel each other out, leaving only the force in the -x direction.

A Long, Straight Wire Carries a 10