magnetism

How magnetism works: electron spin, magnetic domains, ferromagnetism, Earth's geodynamo, animal navigation, and MRI, explained mechanism by mechanism.

Ampère discovered that electric currents create magnetic fields and developed the mathematical framework of electromagnetism. His laws still govern electrical engineering.

MRI sees inside your body without radiation by making hydrogen atoms in your tissues sing at a specific radio frequency.

Apollo magnetometers revealed anomalous magnetic fields on the Moon surface, proving the Moon once possessed a magnetic field—a surprising discovery about our satellite's geological history.

In 1831, Michael Faraday discovered that changing magnetic fields induce electric currents. This fundamental discovery enabled electric motors, generators, and transformed civilization.