Magnets and Magnetic Fields | 磁铁与磁场

📚 Magnets and Magnetic Fields | 磁铁与磁场

Magnets are objects that produce an invisible region called a magnetic field around them. In KS3 CIE science, understanding magnets and magnetic fields helps explain how compasses work, why only some materials are attracted, and how forces can act at a distance without touching.

磁铁是能在周围产生一种看不见的区域——磁场的物体。在 KS3 CIE 科学课程中，理解磁铁与磁场有助于解释指南针的工作原理、为什么只有某些材料会被吸引，以及力如何在不接触的情况下发生作用。

1. What is a Magnet? | 什么是磁铁？

A magnet is a material or object that produces a magnetic field and can attract certain metals, especially iron, nickel and cobalt. Permanent magnets keep their magnetism for a long time, while temporary magnets behave like magnets only when they are placed inside a strong magnetic field.

磁铁是一种能产生磁场并吸引某些金属（尤其是铁、镍和钴）的材料或物体。永磁体可以长期保持磁性，而暂时磁体只有在放入强磁场时才会表现出磁性。

In KS3 experiments, bar magnets and horseshoe magnets are commonly used because their poles are easy to identify. A permanent magnet does not need electricity to work, which makes it different from an electromagnet.

在 KS3 实验中，条形磁铁和蹄形磁铁很常用，因为它们的磁极容易辨认。永磁体不需要电流就能工作，这一点与电磁铁不同。

2. Magnetic Poles | 磁极

Every magnet has two poles: a north-seeking pole (N) and a south-seeking pole (S). The magnetic force is strongest at these poles. If a bar magnet is hung freely from a thread, it slowly turns so that its N pole points roughly towards Earth’s geographic north.

每块磁铁都有两个磁极：指北极（N）和指南极（S）。磁力在这些磁极处最强。如果用细线把条形磁铁自由悬挂起来，它会慢慢转动，使 N 极大致指向地球的地理北方。

The two poles cannot be separated. If you cut a magnet in half, each piece will still have its own N pole and S pole. This is a key idea in magnetism.

两个磁极无法分离。如果把一块磁铁切成两半，每一半仍会各自具有 N 极和 S

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