Question 15

  The drawing shows an end-on view of three parallel wires that are perpendicular to the plane of the paper. In two of the wires the current is directed into the paper, while in the remaining wire the current is directed out of the paper. The two outermost wires are held rigidly in place. Which way will the middle wire move? Explain.

SOLUTION: Two wires with current moving in the same direction attract, while in the opposite direction repel. Therefore, the middle wire will be attracted to the left wire and repelled by the right wire, and since the outer wires are held fixed, the middle wire will move to the left.