Dramatic, easy—unusual! Drop a nonmagnetic cylinder down a two-foot-long metal tube and watch as it falls through the bottom in less than a second. Next, drop a similar-looking magnetic cylinder down the same tube. Your students will be amazed as they impatiently wait for several seconds before this cylinder finally emerges out the bottom of the tube. Students will discover that it’s not friction that slows the cylinder down—it’s Lenz’s law in action! As the magnetic cylinder falls through the metal tube, electrical (eddy) currents are produced in the tube. Eddy currents produce their own magnetic field that repels the magnetic field of the falling magnet, causing the magnet to slow down and fall at a constant speed. Comes complete with instructions and detailed discussion of eddy currents. Tube comes with end caps to make storage of the cylinders a snap.
Concepts: Eddy currents, Lenz’s law, magnetism. Time Required: 10 minutes Materials Provided: Aluminum tube with end caps, sheathed nonmagnetic and magnetic cylinders.