A magnet has a permanent magnetic field around it. Moving a magnet across an electrically conductive surface (like a copper or aluminum wire or plate), it will induce a current. But when current flows through a conductive material, it generates a magnetic field. The cool part in all this situation is that the current-generated magnetic field opposite to the magnetic field that caused the current.
Here is an experiment with a huge 2.5Kg magnet - George lets this magnet to free-fall from a short distance directly onto an aluminum plate. The quickly-changing magnetic field generates a current onto the plate which in turn generates an opposite magnetic field. And as we know, opposite magnetic fields repel each other. As a result, the magnet breaks its own fall!
Based on the same principle, here is an excellent experiment that which i posted some time ago. An amazing amount of power in the form of 800 amperes of alternating current at a frequency of 900 Hz is used to power a giant electromagnet and levitate a disk above it! [link]