Science labs › Physics › Magnet and Compasses
Slide a magnet and compasses round a desk. Which way do the needles point, and why does a far one wobble slowly?
Magnet and Compasses lab · Last updated: 16 October 2026
A bar magnet sits on a desk, surrounded by small compasses. You slide the magnet and the compasses around and watch the needles swing. Close to the magnet they snap into line; far away one wobbles lazily.
What you'll discover
- A compass needle is a tiny magnet that lines up with the magnetic field around it.
- The needles trace curved field lines running from the north pole to the south pole.
- The field is weaker further away, so a distant needle turns slowly and settles gently.
The science in plain words
Every magnet has two poles, north and south. Like poles repel and unlike poles attract. The region around a magnet where it can push or pull on other magnets, or on iron, is called its magnetic field.
A compass needle is itself a small magnet, able to spin. In a magnetic field, it turns until it lines up with the field. Place many compasses around a bar magnet and their needles show the shape of the field: curved lines that leave the north pole, loop round and enter the south pole. These are called magnetic field lines. Where the lines are close together, near the poles, the field is strong.
Further from the magnet the field is weaker, so it turns the needle more gently. A distant compass swings slowly and takes a long time to settle, while one close by snaps quickly into line.
Earth itself behaves like a giant magnet, which is why a compass far from any other magnet points roughly north. Navigators have used compasses for about a thousand years, and some birds and turtles are thought to sense Earth's field when they migrate.
Where it fits
Common questions
Why does a compass point north?
The compass needle is a small magnet, and Earth acts like a giant magnet. The needle lines up with Earth's magnetic field, so one end points roughly towards the North Pole.
What are magnetic field lines?
They are imaginary lines that show the direction a compass needle would point around a magnet. They run from the north pole to the south pole and crowd together where the field is strongest.
Why do like poles repel?
The magnetic fields of two like poles push against each other, so the magnets move apart. Unlike poles have fields that join up, pulling the magnets together.
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- Electric Fields: Charge a metal ball and hang a tiny pith ball beside it. How far does the invisible push move it?
- Magnet Drop: Drop a magnet through a coil of wire. Can a falling magnet make electricity?
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Try it yourself
The Magnet and Compasses lab is one of the interactive 3D science labs inside Taz. Change one thing, predict what will happen, then run it and watch. Labs open after you sign in.