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  • 磁石

    A maglev train floats above a guideway, demonstrating magnetic levitation technology.

    Some countries are using powerful electromagnets to develop high- trains, called maglev, or magnetic levitation , trains. These trains use the repulsive force of magnets to float over a guide way, removing the of steel wheels and train tracks. Reducing this friction allows the trains to travel at much higher speeds.
    ::有些国家正在使用强大的电磁铁来开发高列火车,称为磁力悬浮或磁性悬浮列车。 这些列车使用磁力在向导上漂浮,去除钢轮和铁轨。 减少这种摩擦可以让列车以更高速度行驶。

    Properties of Magnets
    ::Magnet 的属性

    Any magnet , regardless of its shape, has two ends called poles where the magnetic effect is strongest. If a magnet is suspended by a fine thread, it is found that one pole of the magnet will always point toward the north. This fact has been made use of in navigation since the eleventh century. The pole of the magnet that seeks the north pole is called the north pole of the magnet, while the opposite side is the south pole.
    ::任何磁铁,不管其形状如何,都有两端称为磁效应最强的极。 如果磁铁用细线悬浮, 就会发现磁铁的一极总是指向北方。 这一事实自十一世纪以来一直用于导航。 寻求北极的磁铁的极被称为磁铁的北极, 而相反的则指向南极。

    It is a familiar fact that when two magnets are brought near one another, the magnets exert a force on each other.  The magnetic force can be either attractive or repulsive. If two north poles or two south poles are brought near each other, the force will be repulsive. If a north pole is brought near a south pole, the force will be attractive.
    ::众所周知的事实是,当两块磁铁相互靠近时,磁铁会相互产生一种力量。磁力可以是吸引的,也可以是令人厌恶的。 如果两根北极或两根南极相靠近,那么这种力量就会令人厌恶。 如果一个北极接近南极,那么这种力量就会具有吸引力。

    Earth'S Magnetic Poles And Geographic Poles With Labels For North And South.

    The Earth's geographic north pole (which is close to, but not exactly at the magnetic pole) attracts the north poles of magnets. We know, therefore, that this pole is actually the Earth's magnetic south pole. This can be seen in the image above; the geographic north and south poles are labeled with barber shop poles, and the Earth's magnetic poles are indicated with the double-headed arrow. 
    ::地球地理上的北极(靠近但并不完全位于磁极)吸引了磁铁的北极。 因此,我们知道,这个极实际上是地球的磁性南极。 从上面的图像中可以看到这一点;地理上的北极和南极的标签是理发店的极,地球的磁极则用双头箭标出。

    Only iron and few other materials such as cobalt, nickel, and gadolinium show strong magnetic effects. These materials are said to be ferromagnetic . Other materials show some slight magnetic effect but it is extremely small and can be detected only with delicate instruments.
    ::只有铁和很少的其他材料,如钴、镍和等,具有强烈的磁效应,据说这些材料是铁磁效应,其他材料的磁效应微乎其微,但微小,只能用微妙的仪器探测出来。

    Ferromagnetic Domains
    ::热磁域

    Microscopic examination reveals that a magnet is actually made up of tiny regions known as  magnetic domains , which are about one millimeter in length and width. Each domain acts like a tiny magnet with a north and south pole.
    ::微观检查显示,磁铁实际上由微小的磁场组成,这些磁场的长度和宽度约为1毫米。每个磁场都像一个小磁铁,有北面和南面。

    Aligned And Random Orientations Of Magnetic Domains In Materials.

    If  an  object remains a magnet even when removed from the other it is called a  permanent magnet . If alignment is made in the presence of a permanent magnetic field, the object is  a  temporary magnet .  If the material is not magnetized in the presence of another magnetic field because the domains are randomly organized so that the north and south poles do not line up and often cancel each other it is non-magnetic .
    ::如果一个物体即使从另一个物体上移除,也仍然是磁铁。如果对齐是在永久磁场上进行的,则该物体是暂时的磁铁。如果该物质在另一个磁场上没有磁化,因为区域是随机排列的,因此北极和南极不会排队,常常相互取消,而是非磁性。

    When a  ferrous material is placed in a magnetic field, the domains line up with the magnetic field so that the north poles are all pointed in the same direction and the south poles are all pointed in the opposite direction. In this way, the ferrous material has become a magnet. In many cases, the domains will remain aligned only while the ferrous material is in a strong magnetic field; when the material is removed from the field, the domains return to their previous random organization and the ferrous material loses any magnetic properties. These temporary magnets have magnetic properties while in the field of another magnet but lose the magnetic properties when removed from the field.
    ::当有色材料放置在磁场中, 域与磁场相排, 使北极都指向同一方向, 南极都指向相反方向。 这样, 有色材料就变成了磁铁。 在许多情况下, 域将保持对齐, 只有当有色材料处于强烈磁场中; 当材料从场中移除时, 域将返回到先前的随机组织中, 带色材料会失去任何磁性特性。 这些临时磁铁具有磁性, 在另一个磁铁场中具有磁性, 但从场中移除时会失去磁性 。

    The formation of temporary magnets allows a magnet to attract a non-magnetized piece of iron. You have most likely seen a magnet pick up a paper clip. The presence of the magnet aligns the domains in the iron paper clip and it becomes a temporary magnet. Whichever pole of the magnet is brought near the paper clip will induce magnetic properties in the paper clip that remain as long as the magnet is near.
    ::临时磁铁的形成使得磁铁能够吸引非磁铁块。 您最有可能看到磁铁捡起一个纸片。 磁铁的存在将铁纸片中的域对齐, 并成为暂时磁铁。 不管磁铁的哪个极被带近纸片, 都会在纸片中诱发磁性, 只要磁铁离它不近, 纸片中的磁性就会一直存在。

    Permanent magnets lose their magnetic properties when the domains are dislodged from their organized positions and returned to a random jumble. This can occur if the magnet is hammered on or if it is heated strongly.
    ::永久磁铁在将域从其组织位置移开并返回随机跳动时会失去磁性。 如果磁铁被敲碎或加热强度强, 则会发生这种情况 。

    Magnetic Fields
    ::磁场

    When we were dealing with electrical effects, it was very useful to speak of an electric field that surrounded an electric charge. In the same way, we can imagine a magnetic field surrounding a magnetic pole . The force that one magnet exerts on another can be described as the interaction between one magnet and the magnetic field of the other magnet. Magnetic field lines go from the north magnetic pole to the south magnetic pole. We define the magnetic field at any point as a vector (represented by the letter B ) whose direction is from north to south magnetic poles.
    ::当我们处理电效应时,说一个电场环绕电荷是非常有用的。同样,我们可以想象一个磁场环绕一个磁极。一个磁力对另一个磁力施加于另一个磁力的力可以描述为一个磁力和另一个磁力的磁场之间的相互作用。磁力场线从北磁极到南磁极。我们把任何一点的磁场定义为向北向南磁极的矢量(用字母B表示)。

    Launch the Field Lines simulation below to help you visualize the invisible magnetic field that surrounds the Earth. You can also travel to different planets in the solar system and measure the properties of their magnetic fields. Can you determine which planet has the largest magnetic field? Which planet has no field? Then, try to develop a hypothesis about why this might be.
    ::启动下面的实地线模拟, 帮助您看到环绕地球的隐形磁场。 您也可以前往太阳系的不同行星, 测量其磁场的特性。 您能够确定哪个星球有最大的磁场吗? 哪个星球没有磁场? 那么, 尝试制定一个假设, 说明为什么会有磁场 。

    Further Reading
    ::继续阅读

    • Ferromagnetic Material
      ::热磁材料

    Summary
    ::摘要

    • Any magnet has two ends called poles where the magnetic effect is strongest.
      ::任何磁铁都有两端 叫做电磁效应最强的极
    • The magnetic pole found at the north geographical pole of the earth is a south magnetic pole.
      ::在地球的北地极发现的磁极是南地磁极。
    • The force that one magnet exerts on another can be described as the interaction between one magnet and the magnetic field of the other magnet.
      ::一种磁力对另一种磁力施加于另一种磁力的力量可被描述为一种磁力与另一磁力磁场之间的相互作用。
    • Magnetic field lines go from the north magnetic pole to the south magnetic pole.
      ::磁场线从北磁极到南磁极。

    Review
    ::回顾

    1. The earth’s magnetic field
      1. has a north magnetic pole at exactly the same spot as the geographical north pole.
        ::北磁极与北极的地理位置完全相同。
      2. is what causes compasses to work.
        ::是什么导致罗盘工作。
      3. is what causes electromagnets to work.
        ::是什么导致电磁网起作用。
      4. all of these are true.
        ::所有这些都是真实的。
      5. none of these are true.
        ::这些都不是真实的。

      ::地球磁场的北磁极与北极的位置完全相同。 引致罗盘工作的原因就是指南针。 电磁场是导致电磁网工作的原因。 所有这些都是真实的。 这些都不是真实的。
    2. A material that can be permanently magnetized is generally said to be
      1. magnetic.
        ::磁力。
      2. electromagnetic.
        ::电磁
      3. ferromagnetic.
        ::铁磁学
      4. none of these are true.
        ::这些都不是真实的。

      ::一般说来,可以永久磁化的材料是磁性材料。 电磁、铁磁性材料,其中没有一个是真实的。
    3. The force between like magnetic poles will be
      1. repulsive.
        ::令人反感。
      2. attractive.
        ::很有吸引力。
      3. could be repulsive or attractive.
        ::可能是令人厌恶或有吸引力的。

      ::磁极之间的力量会令人厌恶 吸引人 可能令人厌恶 也可能吸引人
    4. Why is a magnet able to attract a non-magnetic piece of iron?
      ::为什么磁铁能吸引非地磁铁?
    5. If you had two iron rods and noticed that they attract each other, how could you determine if both were magnets or only one was a magnet?
      ::如果你有两根铁棒 并且注意到它们互相吸引, 你怎么能确定两者是磁铁还是只有一块是磁铁?

    Explore More
    ::探索更多

    Use this resource to answer the question that follows.
    ::使用此资源回答以下问题 。

    1. In the video, one object rests on top of the magnetic field of another. Compare the friction between these two objects to the friction between a saucer and a table the saucer rests on.
      ::在视频中, 一个天体位于另一个磁场的顶部。 比较这两个天体之间的摩擦与碟子和碟子所依赖的桌子之间的摩擦 。