A strong magnet is levitated over a spinning aluminum disk in the eddy current levitation demonstration. The motion of the disk induces eddy currents in the aluminum, which create magnetic fields that oppose the magnet's field. These opposing fields generate an upward force that balances the weight of the magnet, causing it to levitate. This demonstration shows the principles of electromagnetic induction and Lenz's law, where induced currents create forces that oppose the original change in the magnetic field.