A square loop of wire is carrying current in the counterclockwise direction. There is a horizontal uniform magnetic field pointing to the right.

What is the direction of the net force on the loop?

• The net force on the loop is zero
  • Because it is a loop, the netforce sums to zero

In which direction will the loop rotate? (assume the z axis is out of the screen)

• It will not rotate
  • Because the loop is oriented perpendicular to the magnetic field the torque on the loop is zero.

What is the direction of the net torque on the loop?

• The net torque is zero
  • because of how the loop is oriented with respect to the magnetic field the net torque on the loop is zero.

Three different orientations of a magnetic dipole moment in a constant magnetic field are shown below. Which orientation results in the largest magnetic torque on the dipole?

• b
  • At point b the \sin componet of the equation is 1.

Which orientation has the most potential energy?

• c
  • A this point cos component of potential energy is greatest.

In order to rotate a horizontal magnetic dipole to the three postions shown, which one requires the most work done by the magnetic field?

• b
  • Between the initial point and point b is the greatest change in potential energy.