大学英文版电磁学讲义1-2

Chapter 1 History and Perspective 历史与前景
The electromagnetic interaction(电磁相互作用) is one of the fundamental interactions(基本相互作用) of the physical world. Interaction: atoms and molecules. Phenomenon: sunshine, lightning, rainbows. Technology: communication with NASA's planetary probes(行星探测器), electromagnetic medical imaging(医学成象), computer electronics.
Additi i A y B y j A z B z k
Multiplication: 乘法
Chapter 1 History and Perspective 历史与前景 Modern theory of gravity: Einstein's general relativity(广义相对论).
Elementary Charges, Photons, and QED 基本电荷, 光子和量子电动力学
1.1 Brief history of the science of electromagnetism 电磁科学简史
Electric and magnetic phenomena have been known for millenia. Ancient Greece. Amber(琥珀) rubbed with animal fur can attract small bits of matter. The force between natural magnets(磁铁), ferromagnetism(铁磁性). Early part of the scientific revolution in 1600. Gilbert. an important book.
2.1 Vector Algebra 矢量代数 2.1.1 Definitions 定义
position vector 位置矢量
In Cartesian coordinates(笛卡尔坐标系), the position of a point P is 4
Chapter 2 Vector Calculus 矢量分析
The Classical Limit 经典极限
Classical electromagnetism is the science of electromagnetic phenomena in macroscopic(宏观的) system, is the limit of QED for large systems. Only electromagnetism has both quantum and classical realms accessible to experiment.
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Chapter 2 Vector Calculus 矢量分析
Chapter 2 Vector Calculus 矢量分析
Notation
Table 2.1 Quantity vector vector unit vector vector component vector component vector magnitude scalar Notation Examples boldface x, E xi , E i suffix notation hat i , r plainface and subscript E x , B subscript with vector in ( ) E x , B ∣E∣= E plainface or vector in | | plainface t, U
The Electromagnetic Field 电磁场
Faraday, the concept of field, "the line of force". Maxwell, in 1864, "the electromagnetic field", — guided by fluid mechanics(液体力 学) and elasticity(弹性力学), — "aether"(以太); displacement current(位移电流) — electromagnetic wave(电磁波).
Unification of Electricity and Magnetism 电学与磁学的统一
Oersted, in 1820, discovered that electric current produces magnetic field(磁场) — electricity and magnetism are related. Biot and Savart, found that the strength of the magnetic field varies inversely with the distance from the wire(与距离的平方成反比), and the magnetic field curls(环 绕) around the current. Ampere, discovered the action of one current element on another(电流元对电流元 的作用). Faraday, in 1831, discovered electromagnetic induction(电磁感应).
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2.1 Vector Algebra 矢量代数
A = Ax i Ay j A z k

A' x Ax A ' y =R Ay A' z Az Ex. electric and magnetic fields E and B.
(2.10)
2.1.2 Addition and Multiplication of Vectors 矢量的加法和乘法
. x= x i y jz k are unit direction vectors(单位方向矢量). Figure 2.1 i , j,k
(2.1)
r ≡∣x∣
Transformation of coordinates 坐标变换
If the coordinate axes are rotated(转动), but the point P is left fixed, → ' , the coordinates of P (x, y, z) →( x', y', z'). i , j,k i' , j' , k . Figure 2.2 Rotation of coordinate axis by angle about axis k cos sin 0 matrix(矩阵) R = −sin cos 0 0 0 1
Conservation of Charge 电荷守恒
The net charge(净电荷) of an isolated system(孤立系统) is constant. — based on experimental observation. If the charge of any sample(样品) of matter changes by Δq, then the charge of matter in contact with the sample must change by − Δq.
1.2 Electromagnetism in the Standard Model 标准模型中的电磁学
Four basic interactions(四种基本相互作用): electromagnetic and weak(弱的和电的), chromodynamic(色动力学的), and gravity(引力). Electroweak interaction(弱电相互作用): unified theory for weak interaction and electromagnetism. Chromodynamics(色动力学): or quantum(量子) chromodynamics (QCD), the theory of the interaction between quarks(夸克) and gluons(胶子). 2
Elementary charge in matter: electron has negative charge -e. Quarks have charge 2e/3 and -e/3. Proton has charge +e. Neutron(中子) has charge 0. QED: Quantum electrodynamics. Charge is a property of the elementary particles(基本粒子) of matter. Charge is quantized(量子化的). The electromagnetic field is also quantized. — photon.
Chapter 1 History and Perspective 历史与前景
Electromagnetism 电磁学
教材：Electromagnetism, by Gerald L. Pollack & Daniel R. Stump, Higher Eduction Press, Addison Wesley
1.1 Brief history of the science of electromagnetism 电磁科学简史 electrons and protons(质子). Coulomb, in 1785, the force between charges. Volta and Galvani, development of battery(电池), source of continuous current(电 流).
Static Electricity and Current Electricity 静电与电流
18th century, significant progress in electricity; two technical advances, electrostatic devices(静电器), electrochemical cells(化学电池). DuFay, two kinds of static electricity(静电), —negative and positive charge(电荷). Franklin, theoretical models. fluid models(流体模型), one-fluid model. Thomson, Discovery of electron(电子) in 1897. Charge is a property of matter, — 1


(2.9)

x' x y ' =R y z' z
Scalar(标量): A quantity that does not change under rotation of coordinates. Ex. charge density x Vector(矢量): a quantity with three components(分量) that transform under rotation in the same way as the position vector.