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  • General

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  • 地球作为磁石

    A compass with a rotating dial, indicating cardinal directions including N, S, E, and W.

    Did you ever use a compass like the one in this picture? Even if you’ve never used a compass, you probably know that the needle of a compass always points north. That’s because a compass needle is magnetized, so it is attracted by a .
    ::你曾经使用过像这张照片中的指南针那样的指南针吗? 即使你从未使用过指南针,你也可能知道指南针的针针总是指向北方。 这是因为指南针被磁化了,所以它被一个针所吸引。

    Q: What magnet attracts a compass needle?
    ::问:什么磁铁吸引罗盘针?

    A: A compass needle is attracted by magnet Earth. It always points north because Earth acts as a giant magnet.
    ::A:一个罗盘针被磁铁地球吸引。它总是指向北方,因为地球是巨大的磁铁。

    Earth’s Magnetic Poles
    ::地球的磁极

    Imagine a huge bar magnet passing through Earth’s axis, as in the Figure  . This is a good representation of Earth as a magnet. Like a bar magnet, Earth has north and south magnetic poles. A magnetic pole is the north or south end of a magnet, where the magnet exerts the most force.
    ::想象一下巨大的铁块磁铁穿过地球轴线,如图所示。这是地球作为磁铁的好表示。像铁块磁铁一样,地球有北面和南面磁极。磁极是磁铁的北端或南端,磁铁是磁铁的最大动力。

    Earth depicted as a bar magnet, showing magnetic field lines and poles.

    Two North Poles
    ::两个北极

    Although the needle of a compass always points north, it doesn’t point to Earth’s north geographic pole. Find the north geographic pole in the Figure  . As you can see, it is located at 90° north latitude. Where does a compass needle point instead? It points to Earth’s north magnetic pole, which is located at about 80° north latitude. Earth also has two south poles: a south geographic pole and a south magnetic pole.
    ::尽管一个罗盘的针针总是指向北,但它并不指向地球的北极。在图中找到北地极。如你所见,它位于北纬90度。一个针针针点在哪里?它指向位于北纬80度左右的地球北磁极。地球还有两个南极:一个南地极和一个南磁极。

    Earth'S Magnetic And Geographic Poles With Magnetic Field Lines.

    Q: The north end of a compass needle points toward Earth’s north magnetic pole. The like poles of two magnets repel each other, and the opposite poles attract. So why doesn’t the north end of a compass needle point to Earth’s south magnetic pole instead?
    ::问题:一个罗盘针针的北端指向地球的北磁极。 两块磁铁的极相互反射,对面的极吸引人。 那么,为什么一个罗盘针的北端不指向地球的南磁极呢?

    A: The answer may surprise you. The compass needle actually does point to the south pole of magnet Earth. However, it is called the north magnetic pole because it is close to the north geographic pole. This naming convention was adopted a long time ago to avoid confusion.
    ::答: 答案可能会令你吃惊。 指南针实际上指向磁铁地球的南极。 但是, 它被称为北磁极, 因为它靠近北极。 这个命名公约是很久以前通过的, 以避免混乱 。

    Earth’s Magnetic Field
    ::地球磁场

    Like all magnets, Earth has a . Earth’s magnetic field is called the magnetosphere . It is a huge region that extends outward from Earth in all directions. Earth exerts magnetic force over the entire field, but the force is strongest at the poles, where lines of force converge. 
    ::与所有磁铁一样,地球有一个磁场。 地球的磁场被称为磁层。 这是一个从地球向外向外延伸的巨大区域。 地球在整个磁场上施加磁力,但力量最强的是两极,因为两极的力量交汇在一起。

     

     

    Launch the PLIX Interactive below to learn more about how a compass utilizes the Earth’s magnetic field and observe what happens to a compass as you change positions on Earth:
    ::在下面启动 PLIX 交互式互动, 以了解指南针如何利用地球磁场, 并观察指南针在改变地球位置时会发生什么:

     

     

    Summary
    ::摘要

    • Earth acts as a giant magnet with magnetic poles and a magnetic field over which it exerts magnetic force.
      ::地球是具有磁极和磁场的巨型磁铁,对磁场施加磁力。
    • Earth has north and south magnetic poles like a bar magnet. Earth’s magnetic poles are not the same as the geographic poles.
      ::地球有北面和南面磁极,就像铁棒磁铁一样。 地球的磁极与地理极不同。
    • Earth’s magnetic field is called the magnetosphere. It is strongest at the poles.
      ::地球磁场被称为磁层,在极地最强。

    Review
    ::回顾

    1. How does Earth act as a bar magnet?
      ::地球如何发挥酒吧磁铁的作用?
    2. The compass in a car shows that the car is moving north. Does this mean that the car is moving toward 90° north latitude? Why or why not?
      ::汽车的罗盘显示汽车正向北移动。 这是否意味着汽车正向北纬90度方向移动? 为什么不呢?
    3. Describe the magnetosphere.
      ::描述磁层。