Introductory physics education has benefitted greatly from pedagogical research over the past three decades, which has demonstrated the importance of short lectures, guided problem solving, and contextual laboratory work. Graduate students, on the other hand, are expected to be already good problem solvers, allowing professors to spend formal class time delivering densely packed lectures.
This textbook, however, is written for the intermediate level student of electricity, magnetism, and optics. Instructors, therefore, have a dilemma. Is it better to spend precious class time lecturing or problem solving? “Hmm,” an instructor might wonder. “Should I deliver a comprehensive lecture with historical context and a rigorous derivation, or work example problems? If I lecture, will my students have enough guidance to do their homework? If I work example problems, will they be able to understand their importance? Either way, I want students to glean from the textbook what I do not cover in class.”
A good popular science book tells a story, much like an engaging lecture. A good instructional manual includes many examples, much like a problem-solving session. And, finally, a good treatise develops a persuasive argument backed by evidence, much like a derivation in class. Our goal is to combine the best practices of all three genres: the story telling of a popular science book, the worked examples of an instructional manual, and the persuasiveness of a treatise. We will let you decide if we have succeeded in this endeavor.
Over the past decade we have finished this textbook many times, after which it was sent it out for peer review. Some of our referees loved our novel approach, while others did not. After each iteration we have tried to make changes to please our skeptical reviewers, while still keeping the spark that makes the text interesting. Thus, this book has become more conformist over time, primarily in the order in which we present the material.
While our drafts have improved greatly with each revision, there are inevitably things that we miss. Every time we edit, we find typographical errors, such as misspellings, missing words, and copy and paste errors (especially in dates and equations). We also have purposely not numbered our equations and figures. Rather all figures are placed in context by hand, but they sometimes move. We apologize in advance for such things, and we would very much appreciate your letting us know via e-mail when you find erros, so we can correct them for future readers. This book is printed on demand, so corrections can be implemented fairly quickly.
Since we have reorganized the presentation of material multiple times, we have had to change in which chapters we introduce something. At times we may assume that something has already been introduced, when this might not be the case. We also may introduce something more than once, having added, or copied, an introduction without deleting the old one. We hope that our comprehensive table of contents, biographical index, and many cross-references helps the reader navigate to the right place. Please let us know about these oversights, or any others, so we can correct them for the second edition.
We have learned much over the past decade, and in the process, we have discovered many holes in our prior knowledge, and even found that we each held some fundamental physical misconceptions. If you believe that anything slipped through the cracks, please let us know. Just keep in mind that we have attempted to present Maxwell’s theory, and the story of its discovery, in a way that should be accessible to students of either physics or engineering. Moreover, different fields of physics and electrical engineering do things differently, and use different terminology. Physicists often make overly simplistic assumptions, especially if it illustrates a fundamental truth (or simplifies the math). Engineers also value toy models, especially if they can be applied to real things when refined with measurable fudge factors. We are both astrophysicists, so we came to electrodynamics with that particular perspective. Over time, we have learned to appreciate other perspectives as well.
This is a long book, but do not be intimidated. The length is designed to add clarity and perspective, not to be encyclopedic. Many texts skip algebra steps, or leave out important context, simply for brevity. We have used the space to explain how concepts actually developed, so that you can make the connections required of a highly educated professional.
Finally, we did not write this textbook to make money, but rather because we are fascinated by the subject. We believe that nobody, least of all a student, should be priced out of reading our book. We also would like for practicing physicists and electrical engineers to keep a copy of our book for reference. For this reason, we have priced the book at the marginal cost of production, without the usual markup that a major publisher would apply.
We also want to thank everyone who helped in the creation of this book. We owe many thanks to Alistair Kwan for his detailed and insightful comments on our draft chapters. Isaac Keohane put in many hours helping with programming on the numerical exercises, and Jacob Keohane was a superb copy editor. We also owe thanks to Michael Brabanski, who took the photograph shown on page 26 and told us about Michelson’s time in Berlin.
We would also like to thank the National Radio Astronomy Observatory for kindly hosting a year of sabbatical, and our two institutions which generously provided support through Hampden-Sydney College Summer Research Funds and the Barrett Honors College Drescher Award.
Finally we would like to thank Joseph Calamia, for all the time he spent finding suitable experts to review our work, and of course the anonymous reviewers themselves, whose frank and insightful comments were invaluable to our ability to produce this book.
Jonathan W. Keohane Joseph P. Foy
Hampden-Sydney College Arizona State University