A coil is moved through a magnetic field as shown in Figure 23.59. The field is uniform inside the rectangle and zero outside. What is the direction of the induced current and what is the direction of the magnetic force on the coil at each position shown.

A coil is moved into and out of a region of uniform magnetic field

Whenever a current-carrying conductor is placed inside an external magnetic field, it experiences a force in the direction perpendicular to both the current and the magnetic field. This is known as a magnetic force.

First of all, it should be clear that in positions a, c, and e there is no current since there is no change in the flux while the coil is moving.

In position b, the magnetic field is increasing. Since the magnetic field is directed out of the plane of the paper and the current should be in a direction such that it opposes the field. Therefore from Fleming’s Right-hand rule, we get that the current will be clockwise.

In position d, the magnetic field is decreasing. Since the magnetic field is directed out of the plane of the paper and the current should be in a direction such that it opposes the field. Therefore from Fleming’s Right-hand rule, we get that the current will be counter-clockwise.