When unlike poles of two magnets are brought close together, they attract each other. For example, the North pole of one magnet attracts the South pole of another. When like poles are brought close together, they repel each other. For example, North repels North, and South repels South.
The magnetic field is the region around a magnet where its force can be felt. We can use iron filings (small pieces of iron) to make the magnetic field visible. When iron filings are sprinkled near a magnet, they line up in curved patterns showing the shape and direction of the magnetic field. The field is strongest near the poles.
Attraction alone cannot confirm that an object is a magnet. A non-magnetised piece of iron or steel is also attracted to a magnet. To confirm that an object is a magnet, it must repel a pole of a known magnet. Only a magnet can repel another magnet. So: attraction is not enough — repulsion proves it is a magnet.
⚠️ Exam trap! If a question asks "how do you confirm an object is a magnet?", the answer must mention repulsion — attraction alone is insufficient. 考试陷阱！答题必须提到"排斥"——仅凭吸引是不够的。
🧭 Freely Suspended Magnet · 自由悬挂的磁铁
A freely suspended magnet is a magnet hung from a string so it can swing freely. When left to rest, it always comes to rest pointing in the North-South direction. The North pole of the magnet always points towards geographic North. This is how a compass works — it uses a magnetised needle that always points North.
Earth behaves like a giant magnet with its own North and South poles. This is why a freely suspended magnet always aligns in the North-South direction. The ancient Chinese discovered this and used a lodestone (natural magnet) shaped like a spoon as the world's first compass. The handle of the spoon always pointed South.