What is magnetism?

Magnetism: F = q v × B. Magnets and electric currents fill the space around them with a magnetic field. Like poles repel and unlike poles attract, and a current in a field gets a sideways push, which is how motors, loudspeakers and MRI scanners work.

Read how it works: What is magnetism? · The history of magnetism · More boxes on Glassbox

Chapters in this interactive model

1. Poles, fields and the tesla: Like poles push, unlike poles pull, and an invisible field fills the space around.
2. Current makes a magnet: A wire with current in it is ringed by a field. Coil it up, add iron, and switch it on and off.
3. A current in a field feels a push: F = B I L. Spin it round with a commutator and you have a motor; shake it and you have a speaker.
4. Magnets hiding in your machines: Scanners, ovens, guitars, chargers and hard drives all run on magnetic fields.
5. A magnetic planet, hot iron and two myths: The Earth is a magnet that flips, iron forgets at 770 °C, and a broken magnet makes two.