Concepts

Magnetization of a ferromagnet

Overview

A tube filled with iron filings is magnetized and the magnetization is shown using a compass. Note: this demonstration can be shown on the overhead projector and is appropriate for large lecture halls.

Details

Equipment

• [1] Glass tube filled with iron filings
• [1] NdBFe magnet
• [1] Small compass

Important Notes

• The magnet is strong. Handle with care.

Script

1. Shake the filings into the long thin section of the tube.
2. Magnetize the filings by stroking the length of the tube several times with a magnet.
3. Hold the end of the tube near the compass. Note the movement of the compass needle.
4. Shake the filings into the bulb end and shake several times.
5. Shake the filings back into the tube.
6. Hold the end of the tube near the compass. Note that the iron filings are now unmagnetized as the compass needle no longer moves.

Additional Resources