Comic : Magnets and magnetism
【明報專訊】The Smarties are gathered together. Dr Panda wants to test the others.
■Know more
A magnet (磁石) is an object which can attract other magnetic (有磁性的) materials towards it. This is done by a natural force called magnetism (磁力).
The area which is affected by a magnet is called a magnetic field (磁場). The strongest magnetic field is at the two ends of a magnet, which are called the north pole and the south pole. Opposite poles attract each other, while the same poles push each other away. We can feel the invisible magnetic force if we hold two magnets with their like poles facing each other. The two poles will push each other apart and we will feel the magnets repelling each other.
One of the most common uses of magnets is in compasses. Since the earth is a giant magnet, the south pole of a compass needle is always attracted to the North Pole of the earth.
Beside compasses, magnetism is at work all around us. Other daily examples include electric fans and speakers. In these electrical appliances, there is a type of magnetic field which is produced by electricity.
■English highway
Be at work
is an idiom which means 'to be working' or 'to be having an effect'.
e.g. They are at work on the new project.
■Glossary
force (n) 力量
end (n) 末端
repel (v) 相斥
appliance (n) 器械
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[Smarties' Power English 第363期]