Magnetic Field Of A Bar Magnet
To visualize the magnetic field of a bar magnet.
Bar magnet, plastic box and iron filings with overhead projector.
A bar magnet is positioned beneath a plastic box on an overhead projector. Sprinkle iron filings into the box above the magnet and tap the box slightly so that the filings will align along the magnetic field lines.◙
Gary P. Johnson, Magnetic Field Visualization on the Overhead Projector, Physics Teacher 28, 244, (1990).