1、信息科学与电子工程专业英语Technical EnglishFor Information Science and Electronic Engineering信息科学与电子工程专业英语Unit 3EM Fields, Antenna and Microwaves信息科学与电子工程专业英语Part IElectromagnetic Field 4New Wordsvicinity 邻近，附近邻近，附近 stationary 静止的，不变的静止的，不变的charge 电荷电荷 quantum 量子量子photon 光子光子 oscillate 振荡振荡atom 原子原子 ultraviolet
2、紫外线的紫外线的catastrophe 大灾难，大祸大灾难，大祸 photoelectric effect 光电效应光电效应emission 发射，散发发射，散发 metallic 金属的金属的incident 入射的入射的 eject 喷射，强制离开喷射，强制离开 electrodynamics 电动力学电动力学 dynamics 动力学动力学gravitational 重力的重力的 entity 实体实体51The electromagnetic field is a physical field produced by electrically charged objects. It a
3、ffects 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
4、 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。62The 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 t
5、he field. The way in which charges and currents interact with the electromagnetic field is described by Maxwells equations and the Lorentz force law. 电荷和电流与电磁场相互作用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。73From a classical point of view, the electromagnetic field can be regarded as a
6、 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、连续的场，以波动方式传播；而从量子力学续的场，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。 84 Structure of the electromagne
7、tic 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 “
8、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，可看成平滑的、连续的波动方式。看成平滑的、连续的波动方式。 95 In 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
9、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
10、20th century classical physics that an ideal black body at thermal equilibrium will emit radiation with infinite power. 106 Discrete 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. Plancks relation links the energy E of a photon to its frequency n through the equation: E = h n普朗克的关系式将光子的能量普朗克的关系式将光子的能量 E及其及其频率频率 n 通过下式联系起来通过下式联系起来
