This experiment and animation illustrate Faraday's Law.
As a permanent magnet is moved back and forth in the
vacinity of a coil of conducting wire, a current is
induced in the coil (as measured by the ammeter in the
video). This induced current is proportional to the
rate of change of magnetic flux through the enclosed
area of the coil, and flows in such a direction as to
generate a field whose change in flux opposes that change.
In the animations, we show the evolution of the magnetic
field during this process.
Note that the current induced in the is in such a sense such that it takes the agent moving the magnet additional effort to move the magnet into the coil, and also it takes that agent additional effort to move the magnet back out of the coil once it is in the coil.
The associated forces are either pressures in the field (as the agent moves the magnet in toward the coil) are tensions in the field (as the agent moves the magnet back out of the coil).
Click on the apppropriate image to see the corresponding animation.