A magnet pulls on iron from a distance through its field. Every magnet has two ends where its pull is strongest, called poles, and the rules for poles look a lot like the rules for charges.
Key idea
Every magnet has a north pole and a south pole. Like poles repel; unlike poles attract. Outside the magnet, its field lines run from the north pole to the south pole, and a compass needle lines up along them.
Why it works
A magnet is made of countless tiny magnets: in iron, many of the atoms behave like little magnets, and in a magnet they are lined up. Cut a bar magnet in half and each half still has its tiny magnets lined up, so each half is a whole magnet with its own north and south pole. No one has ever found a north pole by itself.
Worked example: Attract or repel?
The north pole of one magnet is brought near the south pole of another. What happens?
- North and south are unlike poles.
- Unlike poles attract.
Answer: They attract
Worked example: Earth as a magnet
A compass needle's north pole points toward Earth's Arctic. What kind of magnetic pole is near the Arctic?
- The needle's north pole is attracted there.
- Unlike poles attract, so the magnetic pole near the Arctic is a south magnetic pole, even though we call that region "north."
Answer: A magnetic south pole
Common mistake
Thinking that breaking a magnet in half separates its north pole from its south pole. Each piece becomes a complete magnet with both poles, however small you cut it. Check: test each piece's ends with a compass.