章节大纲

  • A red Tesla sports car parked near wind turbines against a mountainous backdrop.

    One of the most famous electric car companies is Tesla , named after Nikola Tesla. These electric cars, and all others, require an electromagnet to run the engine.
    ::最有名的电动汽车公司之一是以尼古拉·特斯拉命名的特斯拉。 这些电动汽车和其他汽车都需要电磁系统来操作引擎。

    Electromagnets
    ::电磁

    A long coil of wire consisting of many loops of wire and making a complete is called a . The within a solenoid can be quite large since it is the sum of the fields due to the current in each individual loop.
    ::长长的电线圈,由许多电线圈组成,并制造一个完整的电线圈,称为“ ” 。 溶质内部的电线圈可能相当大, 因为它是字段的总和, 因为每个电线圈中都有电流。

    A Solenoid With Current Flow And Magnetic Field Direction Indicated.

    The magnetic field around the wire is determined by a hand rule. Since this description doesn’t mention electron flow, we must assume that the current indicated by I is conventional current (positive). Therefore, we would use a right hand rule . We grasp a section of wire with our right hand pointing the thumb in the direction of the current flow and our fingers will curl around the wire in the direction of the magnetic field. Therefore, the field points down the cavity in these loops from right to left as shown in the sketch.
    ::电线周围的磁场是由手法决定的。 由于这个描述没有提及电子流, 我们必须假设我所说的电流是传统流( 积极的 ) 。 因此, 我们将使用右手法。 我们用右手抓住一根线条, 用右手将拇指指向电流的方向, 我们的手指会绕着电线向磁场的方向弯曲。 因此, 球线指向这些圆圈从右到左的空洞, 正如草图所示 。

    If a piece of iron is placed inside the coil of wire, the magnetic field is greatly increased because the domains of the iron are aligned by the magnetic field of the current. The resulting magnetic field is hundreds of time stronger than the field from the current alone. This arrangement is called an electromagnet . The picture below shows an electromagnet with an iron bar inside a coil.
    ::如果铁块放置在铁线圈内,磁场就会大增, 因为铁的域与电流的磁场对齐。 由此产生的磁场比电磁场本身的磁场强数百年。 这种安排被称为电磁网。 下面的图示显示一个电磁网, 圆圈内有铁条。

    A coil of wire wrapped around an iron core, illustrating an electromagnet's construction.

    Our knowledge of electromagnets developed from a series of observations. In 1820, Hans Oersted discovered that a current-carrying wire produced a magnetic field. Later in the same year, André-Marie Ampere discovered that a coil of wire acted like a permanent magnet and François Arago found that an iron bar could be magnetized by putting it inside of a coil of current-carrying wire. Finally, William Sturgeon found that leaving the iron bar inside the coil greatly increased the magnetic field.
    ::1820年,汉斯·奥斯特德(Hans Oersted)发现带电磁铁的电磁铁丝会产生磁场。 同年晚些时候,安德列-马里·安佩尔(André-Marie Ampere)发现,铁丝圈的动作就像永久磁铁一样,弗朗索瓦·阿拉戈发现,将铁条放在带电电电电铁铁铁丝圈内可以使铁条磁化。 最后,威廉·斯特金(William Sturgeon)发现,将铁条留在圆圈内会大大增加磁场。

    Two major advantages of electromagnets are that they are extremely strong magnetic fields, and that the magnetic field can be turned on and off. When the current flows through the coil, it is a powerful , but when the current is turned off, the magnetic field essentially disappears.
    ::电磁网的两个主要优点是它们具有极强的磁场,磁场可以开关。当电磁场通过电圈时,电磁场是强大的,但当电磁场关闭时,磁场基本上就消失了。

    A telegraph is one example of a device that utilizes an electromagnet and its ability to be turned on and off to transmit information very long distances. When the electromagnet is on, it creates a click. When it is off, there is no click. We translate the language of clicks and no-clicks into alphabet characters, known as Morse Code. Launch the Telegraph simulation below and click on a letter in the Morse code chart. Then, press play to hear how the telegraph communicates this letter using electromagnets:
    ::电报是利用电磁网及其开关和关闭能力来传送非常长距离信息的装置的一个例子。 当电磁网打开时, 它会创建一个点击。 当它关闭时, 没有点击。 我们将点击和不点击的语言翻译成字母字符, 称为 Morse 代码。 在下面启动电报模拟, 并在 Morse 代码图表中点击一个字母 。 然后按下播放, 以听听电磁网如何传递此信件 :

     

    Electromagnets find use in many practical applications. Electromagnets are used to lift large masses of magnetic materials such as scrap iron, rolls of steel, and auto parts.
    ::电磁网在许多实际应用中都有用。 电磁网被用来提升大量磁材料,如废铁、钢卷和汽车部件。

    A yellow lifting electromagnet on a crane, moving steel pipes in an industrial setting.

    The overhead portion of this (painted yellow) is a lifting electromagnet. It is lowered to the deck where steel pipe is stored and picks up a length of pipe and moves it to another machine where it is set upright and lowered into an oil well drill hole.
    ::其上方部分(油漆黄色)是升起式电磁铁,降至钢管储存的甲板上,取出一段钢管,然后移到另一台机器上,在那里架立直立,降入油井钻孔。

    Electromagnets are essential to the design of the electric and and are also employed in  breakers, television receivers, loudspeakers, electric dead bolts, car starters, clothes washers, atomic particle accelerators, and electromagnetic brakes and clutches. Electromagnets are commonly used as switches in electrical machines or even a simple doorbell. Launch the Doorbell simulation below to learn more:
    ::电磁网对电动设计至关重要,也用于断路器、电视接收器、扬声器、电动断线机、汽车起动器、洗衣机、原子粒子加速器以及电磁刹车和离合器。

     

    Further Reading
    ::继续阅读

    • Discovery of Magnetism
      ::发现磁权主义

    Summary
    ::摘要

    • A solenoid is a long coil of wire consisting of many loops of wire that makes a complete circuit.
      ::溶胶是一条长长的线圈,由许多铁丝环组成,形成完整的电路。
    • An electromagnet is a piece of iron inside a solenoid.
      ::电磁网是溶液里面的铁块
    • While the magnetic field of a solenoid may be quite large, an electromagnet has a significantly larger magnetic field.
      ::虽然溶质的磁场可能很大,但电磁网的磁场要大得多。
    • Electromagnets' magnetic fields can be easily turned off by just halting the current.
      ::电磁铁磁场的磁场 只需停止电流就可以轻易关闭

    Review
    ::回顾

    1. Magnetism is always present when electric charges ___________.
      ::当电费收费时,总是存在磁政。
    2. What happens to the strength of an electromagnet if the number of loops of wire is increased?
      ::电磁网的强度会怎么样? 如果电磁铁环的频率增加呢?
    3. What happens to the strength of an electromagnet if the current in the wire is increased?
      ::如果电磁铁的电流增加 电磁铁的强度会怎样?
    4. Which direction does the magnetic field point in the solenoid sketched here?
      ::磁场指向什么方向?

     

    Electron Flow In A Wire, Related To Electromagnetism Concepts.

     

     

    Explore More
    ::探索更多

    Use this resource to answer the questions that follow.
    ::使用此资源回答下面的问题 。

    1. What components are needed to make a homemade electromagnet?
      ::制造自制电磁铁需要哪些部件?
    2. What objects were attracted by the electromagnet in the video?
      ::视频中的电磁铁吸引了什么物体?