How magnets attract, repel and point north
A magnet attracts materials such as iron, nickel and cobalt, which are called magnetic materials. Wood, plastic, glass and rubber are not attracted and are non-magnetic. Every magnet has two poles, a north pole and a south pole, and the attraction is strongest near the poles. If you sprinkle iron filings around a bar magnet, they gather mostly at its ends.
When two magnets are brought close, like poles repel and unlike poles attract. A freely hanging magnet always comes to rest pointing in the north–south direction, which is how a compass works. Magnets come in many shapes, including bar, horseshoe, ring and U-shaped magnets. You can make a magnet by stroking an iron nail many times in one direction with a bar magnet. Magnets lose their magnetism if they are heated, hammered or dropped often, so they are stored in pairs with keepers.
Why it matters
Compasses have helped sailors and travellers find direction for centuries. Magnets are used in refrigerator door seals, pencil boxes, speakers, toys and cranes that lift scrap iron. Separating iron from mixed waste uses magnets too. This topic prepares you to learn how electric current produces magnetic effects in higher classes.
Key terms
- Magnetic material
- A material such as iron, nickel or cobalt that is attracted by a magnet.
- Magnetic poles
- The two ends of a magnet, north and south, where its attraction is strongest.
- Compass
- A device with a small magnetic needle that points in the north–south direction.