The Iron filings bubble is suitable for more simple magnetic field plotting experiments in place of loose iron filings. It comprises a shallow, sealed, clear plastic vessel containing high quality fine iron filings. It can be used on an overhead projector for demonstrations.
In use, the filings are distributed evenly over the base of the bubble by shaking or tapping. The bubble is then placed over the magnet and gently tapped to permit the filings to align themselves in the magnetic field.