How Do Magnets Work? The Physics of Magnetism

Magnets seem almost magical — invisible forces that pull and push across empty space. But magnetism is one of the fundamental forces of nature, and it comes down to one thing: the behaviour of electrons.

Magnetism comes from moving charge

A magnetic field is created whenever electric charge moves. In a wire, a current makes a magnetic field. In a permanent magnet, the “current” is subtler: it comes from the electrons inside the atoms themselves.

Every electron has a property called spin, which makes it behave like an unimaginably tiny magnet. In most materials, these tiny magnets point in random directions and cancel out. But in magnetic materials like iron, they can line up.

Why some materials are magnetic

In iron, cobalt and nickel, groups of atoms naturally align their electron spins into regions called domains. In an ordinary iron nail, the domains point every which way, so there’s no overall magnetism. Expose it to a magnetic field and the domains swing into alignment — now their fields add up, and you have a magnet.

• Permanent magnets keep their domains aligned even after the field is removed.
• Temporary magnets (like a paperclip) lose their alignment once the field is gone.

North, south, and field lines

Every magnet has a north and a south pole, and you can never isolate just one — cut a magnet in half and each piece has both poles again. Opposite poles attract, like poles repel. The invisible field runs from north to south, and its shape is what iron filings reveal around a bar magnet.

Electromagnets: magnetism you can switch

Run current through a coil of wire and you create an electromagnet — a magnet you can turn on and off, and make incredibly strong. These power everything from electric motors and speakers to MRI scanners and maglev trains.

Earth is a giant magnet

Our planet’s molten iron core generates a magnetic field that surrounds the Earth. It guides compass needles, shields us from harmful solar particles, and creates the northern lights.

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