Electricity and Magnetism

Magnetic Domains

When you look at a magnified view of the magnetic crystal in this exhibit, you’ll see a pattern made up of light and dark areas. The light areas indicate regions in which atoms have south poles facing up, and the dark areas have north poles facing up. Regions of atoms that are aligned the same way are called domains.
If you turn a nearby magnet so that the poles switch direction, you’ll see the domain patterns change: The domains that are aligned with the magnetic field of the magnet grow larger. This happens because atoms bordering these domains reverse their polarity.