Barkhausen effect model: Many tiny magnets on pivots on OHP.

Barkhausen effect model: Many tiny magnets on pivots on OHP. This model is a mechanical analogy of the Barkhausen effect. Many small magnets are arranged on needle-points mounted on a clear Lucite base that can be placed on an overhead projector. A large Alnico bar magnet is waved over the model, and the model magnets are put in motion. The model magnets settle down in various patterned 'magnetic domains'.