电磁场与电磁波(英文版)ppt课件

Electrostatic field and steady magnetic field are independent of each other,
and may be investigated separately.静电场与恒定磁场相互无关、彼此独立，
可以分别进行研究
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Entity 物质属性
Electromagnetic Fields and Waves
Rugui Yang
Higher Education Press Higher Education Electronic and
Video Press
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The physical understanding is emphasized instead of the mathematical derivation.
The magnetic fields unchanging with time are called steady magnetic
fields. 不随时间变化的磁场称为恒定磁场。
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Electromagnetic Wave电磁波
If the charge and the current vary with time, the electric field and magnetic field they produce will be functions of time.如果电荷及电流均随时间改变，它 们产生的电场及磁场也是随时变化的
Time-varying electric field and magnetic field must co-exist and have definite relation to each other, leading to a time-varying electromagnetic field. 时变的电场与时变的磁场可以相互转化，两者不可分割，它们构成统一的时 变电磁场
Steady current fields 3
Guided EM waves 8
Steady mag radiation 8
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Preface 前言
Electric Field & Magnetic Field 电场和磁场
The fields produced by the static charges behaves as the function of the force acting on the charge, and it is called the electric fields. 静止电荷产生的场表现为对于带电体有力的作用，这种场称为电场
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Class hour distribution
（Class hours 64：Lecture 60，Spare:4）
Vector analysis 4
EM induction 3
Electrostatic fields 7
Time-varying EM fields 7
Boundary-value problems 4 Plane EM waves 10
The interaction between time-varying electric field and time-varying magnetic field results in an electromagnetic wave in space.时变电场与时变磁 场之间的相互转化作用，在空间形成了电磁波
Forces and energy are the most important.
The existence and transmission of electromagnetic waves need not rely on any medium. Specifically, when an electromagnetic wave travels through a vacuum, it is said to propagate in “free space”.
Electromagnetic fields and waves are invisible (except for visible light), their existence can be inferred from the energy and momentum they carry.
电磁场与电磁波虽然不能亲眼所见，但是客观存在的一种物质，因为它具 有物质的两种重要属性：能量和质量。但是，电磁场与电磁波的质量极其微小， 因此，通常仅研究电磁场与电磁波的能量特性。
The electricfields unchanging with time are called electrostatic fields. 不随 时间变化的电场称为静电场
The fields produced by the moving charges or the electric currents behaves as the function of the force acting on the magnet and the conductor carrying currents are called magnetic fields. 运动电荷或电流产生的场表现为对于磁铁和载流导体有力的作用，这种物质 称为磁场
电磁场与电磁波是一种物质，它的存在和传播无需依赖于任何媒质。在 没有物质存在的真空环境中，电磁场与电磁波的存在和传播会感到更加“自
由”。因此对于电磁场与电磁波来说，真空环境通常被称为“自由空间”。
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Field & Matter 场与媒质
In the presence of matter, an electromagnetic field gives rise to polarization and magnetization, and they in turn lead to secondary fields which will modify the original field distribution. This is the interaction between the field and matters.