A fridge magnet holds up a drawing. A compass needle points north. Both are magnets.
Key idea
Every magnet has a north pole (N) and a south pole (S). Opposite poles attract (N and S pull together). Like poles repel (N and N, or S and S, push apart).
Magnets pull on things made of iron or steel (and a few other metals, like nickel). They do not pull on wood, plastic, paper, glass, aluminum, copper or gold. The pull works through paper and even through your hand.
Worked example: Push or pull?
The north pole of one magnet faces the north pole of another. What happens?
- Both facing poles are N: like poles.
- Like poles repel.
Answer: They push apart.
Common mistake
Thinking magnets attract all metals. Foil, pennies and soda cans (aluminum) do not stick.
The Earth itself is a giant magnet. A compass needle is a small magnet that turns to line up with it, so its north end points north.
Try it at home
- Take a fridge magnet on a hunt around the kitchen. Test spoons, foil, cans, coins and the fridge door.
- Make two lists: sticks and does not stick. Were any metals on the "does not" list?
Going further. William Gilbert showed in 1600 that the Earth is a magnet: Gilbert: On the Loadstone. Later: Magnets in Physical Science.