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  • 石油下降实验

    How tall are you?  How much do you weigh? Questions like these are easy to answer because we have the tools to make the measurements.  A yard stick or tape measure will suffice to measure height. You can stand on a bathroom scale and determine your .
    ::你有多高?你体重多少?像这样的问题很容易回答,因为我们有测量工具。院子棍或胶带测量器足以测量身高。你可以站在浴室的尺寸上决定自己的大小。

    But it is a very different matter to measure properties of objects that we cannot see with the naked eye.  If we want to measure the size of a germ, we have to use a .  To learn the size of a single molecule, we have to use even more sophisticated instruments.  So how would we measure something even smaller than a molecule, even smaller than an ? 
    ::但是测量我们肉眼看不到的物体的属性是一个非常不同的问题。 如果我们想要测量细菌的大小, 我们必须使用一个 。 要学习一个分子的大小, 我们必须使用更先进的仪器。 那么我们如何测量比一个分子更小、甚至比一个分子更小的东西呢 ?

    Charge and Mass of the Electron
    ::电电的电荷和质量

    The man who measured properties of the was Robert Millikan (1868-1953). He taught himself physics while a student at Oberlin College since there was nobody on the faculty to instruct him in this field.  Millikan completed postgraduate training in the U.S. and in Germany.  His studies on the properties of the proved to be of great value in many areas of physics and chemistry .
    ::米利坎(1868-81953年)在奥伯林学院任教物理,因为学院里没有人教他这个领域的课程。米利坎在美国和德国完成了研究生培训。他关于物理和化学许多领域都具有巨大价值的物理特性的研究证明。

    Black and white portrait of Robert Millikan, physicist known for the oil drop experiment.
    Robert Millikan.

    Oil Drop Experiment
    ::石油下降实验

    Millikan carried out a series of experiments between 1908 and 1917 that allowed him to determine the charge of a single , famously know as the oil drop .
    ::Millikan在1908年至1917年间进行了一系列实验,

    He sprayed tiny drops of oil into a chamber. In his first , he simply measured how fast the drops fell under the force of gravity.  He could then calculate the mass of the individual drops. Then he sprayed oil drops and applied an electrical charge to them by shining up through the bottom of the apparatus.  The X-rays ionized the air, causing electrons to attach to the oil drops. The oil drops picked up static charge and were suspended between two charged plates. Millikan was able to observe the motion of the oil drops with a and found that the drops lined up in a specific way between the plates, based on the number of electric charges they had acquired.
    ::他将微小的油滴喷入一个舱室。第一次,他只测量了水滴落到引力下的速度,然后他可以计算个人滴落的质量。然后,他喷洒油滴,然后通过在设备底部闪耀而对他们施用电荷。X光将空气电离,使电子附着在油滴上。石油滴取出静电荷,在两个充电板之间悬停。Millikan能够用一个电滴看到油滴运动,发现根据获得的电荷数量,在板块之间以特定的方式排成一排。

    Millikan's oil drop experiment, showing oil droplet generation and charged plates.
    Oil drop experiment.

    Millikan used the information to calculate the charge of an . He determined the charge to be 1.5924 × 10 -19  C, where C stands for coulomb , which is one ampere*second. Today the accepted value of the charge of an electron is 1.602176487 × 10 -19  C. Millikan's experimental value proved very accurate; it is within 1% of the currently accepted value. Millikan later used the information from his oil drop experiment to calculate the mass of an electron. The accepted value today is 9.10938215 ×10 -31  kg. The incredibly small mass of the electron was found to be approximately 1/1840 the mass of a hydrogen . Therefore, scientists realized that atoms must contain another particle that carries a positive charge and is far more massive than the electron.
    ::Millikan使用该信息计算了一个电荷。 他确定电量为1.5924 x 10-19 C, C代表库伦, C代表库伦, 是一个安培* 秒。 今天电子电荷的公认值是1.602176487 × 10-19 C. 米利坎的实验值非常准确, 低于目前接受值的1% 。 Millikan后来使用他油滴实验中的信息计算了一个电子的质量 。 今天的公认值是9. 10938215 × 10- 31 公斤。 电子的异常小质量大约为氢质量的1/1840 。 因此, 科学家意识到原子必须含有另一个带有正电荷的粒子, 并且比电量大得多 。

     

     

     

    Summary
    ::摘要

    • The oil drop experiment allowed Millikan to determine the charge on the electron.
      ::油滴实验让Millikan 能够确定电子上的电荷
    • He later used this data to determine the mass of the electron. 
      ::他后来利用这些数据确定电子的质量。

    Review  
    ::回顾

    1. How did Millikan learn physics in college?
      ::米利坎大学怎么学物理的?
    2. What did Millikan use to pick up static charge?
      ::Millikan用什么来接收静态电荷?
    3. Where did the oil drops go to be measured?
      ::石油滴落到哪里去测量?