Magnets Quiz: How Magnets Work
Poles and fields
Every magnet has two ends, called poles: north and south. Opposite poles attract each other, and matching poles push each other away.
If you cut a bar magnet in half, you don't get a separate north and south. You get two smaller magnets, each with its own north and south pole.
Around every magnet is an invisible magnetic field. Sprinkle iron filings on paper over a magnet and they line up along the field, showing curved lines running from one pole to the other.
What makes something magnetic
Only a few metals are strongly attracted to magnets: iron, nickel and cobalt, and alloys like steel. Most others, like aluminum, copper and gold, are not.
Inside a magnetic metal are tiny regions called domains, each like a little magnet. In an ordinary nail they point in all directions and cancel out. In a magnet, most of them line up the same way.
That's why a magnet can be ruined. Heating it strongly, or hammering it hard, jumbles the domains again.
Earth is a magnet
Earth itself is a giant magnet. Its field comes from molten iron swirling in its outer core. A compass needle lines up with that field and points toward magnetic north, which is close to, but not at, the geographic North Pole, and it slowly wanders.
The field protects us from particles streaming from the Sun, steering some of them toward the poles, where they light up the sky as auroras.
People can also make magnets with electricity. Running a current through a coil of wire makes an electromagnet, which can be switched off. Electromagnets power motors, speakers, scrapyard cranes and hospital MRI scanners. The first compasses, in ancient China, used lodestone, a naturally magnetic rock.