A current-carrying wire in the field of a horseshoe magnet experiences a force a
ID: 1498529 • Letter: A
Question
A current-carrying wire in the field of a horseshoe magnet experiences a force as shown in the two cases below. In each case, the north pole of the horseshoe magnet is the rightmost pole. The force arrow shown in each case represents the force on the current-carrying wire by the magnet. In the left-hand picture, the horseshoe magnet is positioned with its open mouth pointed towards the top of the page. The north pole is on the right side, and the horseshoe is slightly rotated about its long axis so that the north pole is closer to the viewer -- the south pole, on the left, is thus farther from the viewer. A current-carrying wire passes between the north and south pole; the wire length is oriented perpendicular to the plane of the horseshoe and the current runs from left to right and slightly away from the viewer. The force on the wire is thus towards the top of the page. In the right-hand picture, all is the same except that the direction of the current is reversed; thus, the force on the wire is towards the bottom of the page. (a) In each case, what is the direction of the force ON the magnet BY the current-carrying wire? The force ON the magnet BY the wire is in the direction of the south pole in the left-hand picture and in the direction of the north pole in the right-hand picture. downward in the left-hand picture and upward in the right-hand picture. in the direction of the north pole in the left-hand picture and in the direction of the south pole in the right-hand picture. out of the page in the left-hand picture and into the page in the right-hand picture. into the page in the left-hand picture and out of the page in the right-hand picture. (b) Which is stronger, the force on the wire by the magnet, or the force on the magnet by the wire? The two forces are equally strong. The force on the wire by the magnet is stronger. The force on the magnet by the wire is stronger.
Explanation / Answer
(a) In each case, what is the direction of the force ON the magnet BY the current-carrying wire?
The force ON the magnet BY the wire is -
downward in the left-hand picture and upward in the right-hand picture.
(b) Which is stronger, the force on the wire by the magnet, or the force on the magnet by the wire?
The two forces are equally strong.