Eddy currents: Neodymium Magnet Drop.

Ring Magnets drop at different speeds on rods due to eddy current effect. Three strong Neodymium ring magnets (1 inch OD, .5 inch ID, .25 inch thick) can slide along three separate vertical rods (19.5 inch long x .5 inch diameter). One rod is aluminum; one is copper, and one is Plexiglas. The magnets induce eddy currents in the aluminum and copper rods, causing magnetic fields that oppose that of the the falling magnets, thus slowing their descent. The Plexiglas rod is non-metallic, so no eddy currents are induced, and that magnet falls as if dropped. Operation: Initially all magnets are at rest at the base. The apparatus is turned over, and the magnets drop. It takes 4.9 seconds for the magnet to fall on the copper rod. It takes 1.7 seconds for the magnet to fall on the aluminum rod. It takes .3 seconds for the magnet to fall on the Plexiglas rod.