PIRA: 5K20.25


  • 3 copper tubes – 1 long, 1 short, 1 wide (shorter tubes with stoppers in each end)
  • Neodymium magnets (1 large – about 1″, 1 small-covered with masking tape)
  • Non-magnetic slug size of small magnet (slug also covered with masking tape)


  1. Drop the slug through the long tube.
  2. Drop the neodymium magnet through the long tube. Note the difference in the fall time. The falling magnet causes eddy currents in the copper tube. These currents oppose the magnet’s motion and slow its fall.
  3. Let the students pass around the short tube with the magnet and the slug.
  4.  Drop the large magnet down the wider copper tube. You can watch it slowly fall and tumble