#8 - Mysterious magnets 神秘的磁铁

1.Without magnets there would be no electric motors, computers or loud speakers.
Magnetism is an invisible force to do with atoms - tiny particles that make up everything. Atoms are made of even smaller particles, including electrons. Magnetism is linked to the way that these line up and move. Most magnetic substances contain iron. As iron make up a big part of the metallic substance steel, steel is also magnetic.

V For metal recycling, an electromagnet lifts out only iron-containing or ferrous metals, such as steel. V

2.A magnet is a lump of iron or steel that has all its electrons and atoms lined up.
This means that their magnetic forces all add up. The force surrounds the magnet, in a region called the magnetic field. This is strongest at the two parts of the magnet called the poles.

3.A magnet has two different poles - north and south.
A north pole repels (pushes away) the north pole of another magnet. Two south poles also repel each other. But a north pole and a south pole attract (pull together).
Both magnetic poles attract any substance containing iron, like a nail or a screw.

V The field around a magnet affects objects that contain iron. V

4.When electricity flows through a wire, it makes a weak magnetic around it.
If the wire is wrapped into a coil, the magnetism becomes stronger. This is called an electromagnet. Its magnetic force is the same as an ordinary magnet, but when the electricity goes off, the magnetism does too. Some electromagnets are so strong, they can lift whole cars.

V For metal recycling, an electromagnet lifts out only iron-containing or ferrous metals, such as steel. V

没有磁铁就没有电动机，电脑或扬声器。
磁性是一种与原子无关的力量 - 构成一切的微小粒子。原子由更小的粒子组成，包括电子。磁性与这些排队和移动的方式有关。大多数磁性物质都含有铁。由于铁构成金属物质钢的很大一部分，钢也是磁性的。

V对于金属回收，电磁铁只能提升含铁或含铁的金属，如钢铁。 V

磁铁是一块铁或钢，其所有电子和原子排列在一起。
这意味着他们的磁力全部加起来。该力围绕磁体，在一个称为磁场的区域。这在被称为两极的磁体的两个部分是最强的。

一个磁铁有两个不同的磁极 - 北面和南面。
一个北极排斥（推开）另一个磁铁的北极。两个南极也相互排斥。但北极和南极吸引（拉）在一起。
两个磁极吸引任何含铁的物质，如钉子或螺丝钉。

V磁铁周围的磁场会影响含有铁的物体。 V

当电流通过电线时，会在其周围形成弱磁性。
如果电线缠绕成线圈，则磁性变强。这被称为电磁铁。它的磁力和普通的磁铁一样，但是当电力下降时，磁力也是如此。有些电磁铁是如此强大，他们可以举起整车。

V对于金属回收，电磁铁只能提升含铁或含铁的金属，如钢铁。 V