You must be connected to the Internet the first time you view this simulation, at which point the codebase for all the simulations will be downloaded to your computer. This process make take a few minutes, as the codebase is roughly 9MB in size. Subsequent viewings of the applets will run from your local copy.
This applet shows the dynamics of a conducting non-magnetic
ring falling on the axis of a fixed magnet. As the ring
falls under gravity towards the magnet, the changing
magnetic flux through the ring gives rise to a current
which is in a direction such as to slow the fall of
the ring, by Lenz's Law. The ring has mass m, resistance
R, and self-inductance L, and the magnet has magnetic
dipole moment M. You can vary the resistance of the
ring and the strength of the magnetic dipole moment
to see how these parameters affect
the dynamics of the ring. If the resistance is zero
and the dipole moment is strong enough, the ring will
levitate above the magnet. If the resistance is non-zero,
even though small, the ring will eventually fall past
the magnet. We also show the induced current in the
ring in the meter on the lower left.
The mathematics of this application is given here.