电磁学（英文影印版）

　　本书是在美国大学使用比较广泛的一本为本科生编写的电磁学教材。虽然在总体上，该教材仍然是一本比较传统的教材，但作者仍然在如何能帮助学生更好的学习电磁学课程做了不少努力。例如，提供不少和实际联系比较紧密的例子，讲解详细的例题以及提供了不少使用计算机解决问题的算例。这些内容对于学生理解电磁学内容，应用所学知识都有很好的帮助。另外，该教材的习题难度适中，并有不少提示，对于巩固学习内容也有很好的帮助。.
　　 本书的难度和国内教学要求比较接近，可作为物理类专业电磁学课程的教材，尤其适合开展双语教学的学校，对于有志出国深造的人员也是一本必不可少的参考书。...

1 history and perspective . 1
1.1 brief history of the science of electromagnetism 1
1.2 electromagnetism in the standard model 5
2 vector calculus
2.1 vector algebra 10
2.2 vector differential operators 18
2.3 integral theorems 25
2.4 curvilinear coordinates 30
2.5 the helmholtz theorem 37
3 basic principles of electrostatics 44
3.1 coulomb's law 44
3.2 the electric field 46
3.3 curl and divergence of e 54
3.4 the integral form of gauss's law 57
3.5 green's function and the dirac delta function 62
3.6 the electric potential 65
3.7 energy of the electric field 72
3.8 the multipole expansion 75
3.9 applications 82
3.10 chapter summary 83

　　This is an intermediate-level textbook on electricity and magnetism. It is intended to be used for a two- or one-semester course for students of physics, engineering, mathematics, and other sciences, who have already had a one-year introductory physics course with calculus. .
　　The book is flexible enough to be used in several ways: (1) The traditional two-semester course would cover electrostatics and magnetostatics in the first semester using Chapters 1-8; and then magnetic materials and time-dependent fields in the second semester using Chapters 9-15. (2) An instructor teaching a one-semester course could cover all the basic principles of electromagnetism by using Chapters 1-3 and 6-11; there might also be time for a few examples from Chapters 4 and 5. (3) An interesting alternative approach in a two-semester course would be to go over the basic principles of Chapters 1-3 and 6-11 in the first semester, and then applications and advanced topics in the second semester based on Chapters 4,5, and 12-15.
　　The total material in the book is more than could be realistically covered by any instructor, even in two semesters. Instructors are encouraged to pick and choose based on their own judgment of what is important. Electricity and magnetism is a wonderfully interesting subject, but to students at the intermediate level its physical concepts are non-intuitive, and the associated mathematical techniques are new and challenging. Therefore it's important in teaching this subject to avoid the kind of heroic pace which will tire out all but the strongest students and instructors. The general principle that in teaching it's better to uncover a little than to cover a lot, applies to this subject of course.
　　The order of presentation of subjects is the traditional one: electrostatics first, then magnetism, electrodynamics and Maxwell's equations, relativity, and radiation. Chapter 2 is an introductory treatment of vector calculus, which should help students acquire the necessary mathematical armamentarium. Our experience in teaching this subject is that at the outset of the course most students do not know vector calculus well enough to study electromagnetic field theory, so it's important to help them gain the necessary mastery. Chapter 2 is sophisticated in places, and it is not necessary to comprehend all of it before starting on Chapter 3; the student can return to Chapter 2 when additional mathematical skill is needed. Students might also read a specialized book on vector calculus (e.g., one of the two references at the end of Chapter 2) while studying Chapter 2.
　　We have given an extensive treatment of electrostatics, in Chapters 3-6. The topics treated later in the book are more interesting than electrostatics to many students and instructors, so there's a tendency to hurry into them. But our experience is that time invested studying electrostatics pays dividends later on, because students acquire in electrostatics mathematical skills and confidence that are needed for other areas of electromagnetism.
　　Many good textbooks have been written on electromagnetism, and thousands of students have learned the subject from them. The two authors have taught this subject to hundreds of students over several decades, using some of those earlier books. It was from those many interactions with students, as well as with our colleagues and teachers, all remembered with pleasure, that we were led to write this book.
　　What is special about this book? For the most part it is a traditional, even conventional, exposition of electromagnetism, but we have also done three things we believe are important, and not stressed quite enough in other textbooks. First, we have tried to show how the mathematical principles that students are studying are used in modern technology--i.e., in real applications that students encounter in science and everyday life--applications such as cellular phones, optical fibers, magnetic resonance imaging, and charged particle accelerators and detectors. How is Faraday's Law related to the electricity in a wall socket? How can we calculate the interaction between radio waves and the ionosphere? Although it is necessary to study highly idealized, academic examples in field theory--e.g., the magnetic field of an infinitely long wire carrying a constant current, or the electric field in a spherical capacitor--students should also learn that the theory describes real physical phenomena and devices. The ideal cases are not the whole story. ..
　　Second, we have included in the text many worked-out mathematical examples in each area, including some examples that go beyond the elementary, exactly solvable, ones, and other examples that require multi-step analysis such as the use of the superposition principle. This book is based on a two-semester course that we have taught at Michigan State University. The course is taken by senior undergraduate students, and some first-year graduate students who are not yet enrolled in the graduate-level course. Our experience is that for students to master the intermediate level they must study more than just the simplest cases. Even to "uncover a little" requires that the instructor show a variety of examples. Each chapter starts at an elementary level, with topics the student is likely to know from an introductory physics course. The discussion then leads into the junior/senior-level material which is the heart of the book. At the end of several chapters we've introduced an interesting, more advanced, subject; we hope this will inspire students to future further study of the subject by indicating what lies beyond the horizon.
　　Third, we have included a number of computer calculations, both in the text and in the end of chapter exercises. Computer software that integrates analysis, numerical calculation, and graphics, e.g., Mathematica, Maple, Mathcad, Matlab, Excel, etc., can be used for these calculations. Students who are comfortable with Fortran or other computer languages can do the exercises by writing their own programs. Much of current physics, both experimental and theoretical, is done with computers, so today's students need this experience. On the other hand, the computer cannot replace the understanding of theoretical principles. We regard the computer exercises as an important, but not dominant, part of the book.
　　An essential part of this subject is learning how to do problems. There is a tendency (maybe it's even a tradition) for some textbooks on this subject--Smythe's book being the most dramatic example--to give many very difficult problems, on which the student spends uncounted and often frustrating hours. Many practicing physicists, the authors included, have been brought up in this draconian school. We believe however that the principle of "all things in moderation" should be applied to E&M problems. At the end of each chapter we have given a number of exercises of various degrees of difficulty, but mostly of only moderate difficulty, which are intended to help students understand the subject. Hints and answers are given in many of the exercises.
　　In writing Electromagnetism we had in mind the learning needs of present-day students, who are in some ways ready for a deeper understanding of the subject than we, their instructors, were at their age. They have had sophisticated courses in mathematics, even if they are still learning to apply this mathematics; we therefore use advanced mathematics freely, but also give generous explanations, so that students can exercise these valuable, newly acquired, skills. Mastering the subject at the intermediate level is not easy, and we encourage students to discuss what they are learning with other students and with their instructors at every opportunity. 1 Learning and doing physics has a social component. One learns much more from such discussions than by reading a textbook alone.
　　We believe it is especially important to meet the needs of those students who will go on to further study of electrodynamics, for example in graduate school in physics or electrical engineering, or who will use these principles in industry or engineering. Among these are the men and women who will write the next generation of books on this and related subjects, invent and develop new applications and (who knows?) discover new principles. To this end we try to extend the students' knowledge to a high enough level that they will be adequately prepared for working in J. D. Jackson's Classical Electrodynamics, or similar advanced books.
　　We would like to thank our students for listening to so many of our lectures on electromagnetism. We also owe a great debt to our own teachers of this subject, among them, R. P. Feynman, M. Firebaugh, R. C. Garth, D. L. Huber, F. E. Low, W. Mais, and W. R. Smythe. ...