电子信息工程专业英语翻译清华出版社English for IT and EE-03

电子信息工程专业英语翻译清华出版社

信息科学与电子工程专业英语

Technical EnglishFor Information Science and Electronic Engineering

电子信息工程专业英语翻译清华出版社

信息科学与电子工程专业英语

Unit 3EM Fields, Antenna and Microwaves

电子信息工程专业英语翻译清华出版社

信息科学与电子工程专业英语

Part IElectromagnetic Field

电子信息工程专业英语翻译清华出版社

New Wordsvicinity 邻近，附近 邻近， charge 电荷 photon 光子 atom 原子 catastrophe 大灾难，大祸 大灾难， emission 发射，散发 发射， incident 入射的 electrodynamics 电动力学 gravitational 重力的 stationary 静止的，不变的 静止的， quantum 量子 oscillate 振荡 ultraviolet 紫外线的 photoelectric effect 光电效应 metallic 金属的 eject 喷射，强制离开 喷射， dynamics 动力学 entity 实体3

电子信息工程专业英语翻译清华出版社

1The electromagnetic field is a physical field produced by electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the electromagnetic interaction. It is one of the four fundamental forces in the nature (the others are gravitation, the weak interaction, and the strong interaction) 电磁场在空间无限延伸， 电磁场在空间无限延伸， 并描述电磁相互作用。 并描述电磁相互作用。4

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2The field can be viewed as the combination of an electric field and a magnetic field. The electric field is produced by stationary charges, and the magnetic field by moving charges (currents); these two are often described as the sources of the field. The way in which charges and currents interact with the electromagnetic field is described by Maxwell’s equations and the Lorentz force law. 电荷和电流与电磁场相互作用 的方式由麦克斯韦方程组和洛 伦兹力定律所描述。 伦兹力定律所描述。5

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3From a classical point of view, the electromagnetic field can be regarded as a smooth, continuous field, propagated in a wavelike manner, whereas from a quantum mechanical point of view, the field can be viewed as being composed of photons.

从经典的角度，电磁场可认为是光滑、连 从经典的角度，电磁场可认为是光滑、 续的场，以波动方式传播； 续的场，以波动方式传播；而从量子力学 的角度，场可看作是由光子组成的。 的角度，场可看作是由光子组成的。

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4 Structure of the electromagnetic fieldThe electromagnetic field may be viewed in two distinct ways. Continuous structure: Classically, electric and magnetic fields are thought of as being produced by smooth motions of charged objects. For example, oscillating charges produce electric and magnetic fields that may be viewed in a “smooth”, continuous, wavelike manner.

例如，振荡电荷产生电场和磁场，可 例如，振荡电荷产生电场和磁场， 看成平滑的、连续的波动方式。 看成平滑的、连续的波动方式。

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5In this case, energy is viewed as being transferred continuously through the

electromagnetic field between any two locations. For instance, the metal atoms in a radio transmitter appear to transfer energy continuously. This view is useful to a certain extent (radiation of low frequency), but problems are found at high frequencies (see ultraviolet catastrophe). This problem leads to another view. The ultraviolet catastrophe, also called the Rayleigh-Jeans catastrophe, was a prediction of early 20th century classical physics that an ideal black body at thermal equilibrium will emit radiation with infinite power.8

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6Discrete structure: The electromagnetic field may be thought of in a more “coarse” way. Experiments reveal that electromagnetic energy transfer is better described as being carried away in photons with a fixed frequency. Planck’s relation links the energy E of a photon to its frequency ν through the equation: E = h ν 普朗克的关系式将光子的能量E 普朗克的关系式将光子的能量E及其 频率ν 通过下式联系起来

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6where h is Planck’s constant, named in honor of Max Planck, and ν is the frequency of the photon. For example, in the photoelectric effect – the emission of electrons from metallic surfaces by electromagnetic radiation – it is found that increasing the intensity of the incident radiation has no effect, and that only the frequency of the radiation is relevant in ejecting electrons.1 例如在光电效应中， 例如在光电效应中，即因电磁辐射而从金属表面 发射电子的现象， 发射电子的现象，我们发现增加入射辐射的强度 并无影响，只有辐射频率与发射的电子有关。 并无影响，只有辐射频率与发射的电子有关。10

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7This quantum picture of the electromagnetic field has proved very successful, giving rise to quantum electrodynamics, a quantum field theory describing the interaction of electromagnetic radiation with charged matter.

已经证明电磁场的量子描述是非常成 功的，引出了量子电动力学， 功的，引出了量子电动力学，一种描 述电磁辐射与带电物体之间的相互作 用的量子场理论。 用的 …… 此处隐藏：3774字，全部文档内容请下载后查看。喜欢就下载吧 ……