How does a magnet work?

A magnet stuck to the fridge seems utterly trivial, but it holds one of the most fascinating phenomena in physics: the ability to attract or repel other objects without touching them. Where does that invisible force come from? The answer lies in the tiny world of electrons.

Every magnet has two poles

The first striking thing is that a magnet always has two poles: north and south. And here comes the golden rule of magnetism: like poles repel, opposite poles attract. Bring two norths together and you’ll feel them push apart; face a north against a south and they’ll snap together.

Another curious detail: if you cut a magnet in half, you do not get a single loose pole. Each piece has its own north and south again. No matter how much you divide it, there will always be two poles.

The invisible force: the magnetic field

Around every magnet there’s a region where its force acts: the magnetic field. We can’t see it, but it can be “drawn”: if you scatter iron filings on a paper with a magnet underneath, they line up into curved lines running from one pole to the other. As NASA explains, those lines represent the direction and strength of the magnetic force at each point.

Why some materials are magnetic

Here’s the heart of the matter. Magnetism arises from the motion of electrons, the tiny particles spinning inside atoms. Each electron behaves like a microscopic magnet.

In most materials, those little magnets point in disorderly directions and cancel each other out, so the material isn’t magnetic. But in metals like iron, nickel, or cobalt, the electrons can all align in the same direction, forming regions called domains. When many domains point the same way, their forces add up and the material becomes a magnet. As Britannica sums up, magnetism is, in essence, the result of that orderly alignment.

Permanent magnets and electromagnets

There are two main types:

• Permanent magnets: keep their magnetism on their own (like fridge magnets). Their internal alignment is stable.
• Electromagnets: become magnetic only when electric current flows through a coiled wire. Cut the current, and they stop being magnets. They power scrapyard cranes, doorbells, motors, and speakers.

This relationship between electricity and magnetism (electromagnetism) is one of the foundations of modern technology.

A planet that’s also a magnet

Perhaps the most important magnet in your life is enormous: Earth. Its molten iron core generates a giant magnetic field that makes a compass needle point north. That same magnetic shield protects us from part of the Sun’s radiation.

Invisible force, enormous applications

Magnets are far more present than they seem: in motors, hard drives, cards, maglev trains, and medical devices like MRI scanners. All thanks to a simple, elegant principle: when electrons dance in unison, a force appears capable of moving the world without touching it.