A 9" coil with 120 turns is connected to a sensitive center-zero projection meter. A bar magnet is passed through the center of the coil, inducing a current which is shown on the meter. Reversing the poles or direction of the magnet will reverse the current. Passing the magnet through at different speeds will show different currents.
The magnetic flux through the coil increases over time as the magnet is pushed through the coil. The changing magnetic flux induces an emf, which in turn induces a current. The current always flows in a direction that "cancels out" the change in magnetic flux. The current stops when the magnet is motionless, and reverses when it is pulled in the opposite direction.
See chapter 29, starting page 993, University Physics, for information on electromagnetic induction.
Young, Hugh D., Roger A. Freedman, and A. Lewis Ford. Sears and Zemansky's University Physics: With Modern Physics, 12th ed. San Francisco: Pearson Addison-Wesley, 2008.