Undergraduate Lecture Notes in Physics978-3-319-21816-8/1.pdf · lowing audiences. First, it could...

Undergraduate Lecture Notes in Physics

Undergraduate Lecture Notes in Physics (ULNP) publishes authoritative texts cov-ering topics throughout pure and applied physics. Each title in the series is suitableas a basis for undergraduate instruction, typically containing practice problems,worked examples, chapter summaries, and suggestions for further reading.

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Kerry Kuehn

A Student’s Guide Throughthe Great Physics TextsVolume III: Electricity, Magnetism and Light

Kerry KuehnWisconsin Lutheran CollegeMilwaukeeWisconsinUSA

ISSN 2192-4791 ISSN 2192-4805 (electronic)Undergraduate Lecture Notes in PhysicsISBN 978-3-319-21815-1 ISBN 978-3-319-21816-8 (eBook)DOI 10.1007/978-3-319-21816-8

Library of Congress Control Number: 2014945636

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For Cindy.

Preface

What is the nature of this book?

This four-volume book grew from a four-semester general physics curriculum whichI developed and taught for the past decade to undergraduate students at WisconsinLutheran College in Milwaukee. The curriculum is designed to encourage a criti-cal and circumspect approach to natural science while at the same time providinga suitable foundation for advanced coursework in physics. This is accomplished byholding before the student some of the best thinking about nature that has been com-mitted to writing. The scientific texts found herein are considered classics preciselybecause they address timeless questions in a particularly honest and convincingmanner. This does not mean that everything they say is true—in fact many clas-sic scientific texts contradict one another—but it is by the careful reading, analysisand discussion of the most reputable observations and opinions that one may beginto discern truth from error.

Who is this book for?

Like fine wine, the classic texts in any discipline can be enjoyed by both the noviceand the connoisseur. For example, Sophocles’ tragic play Antigone can be appreci-ated by the young student who is drawn to the story of the heroine who braves therighteous wrath of King Creon by choosing to illegally bury the corpse of her slainbrother, and also by the seasoned scholar who carefully evaluates the relationshipbetween justice, divine law and the state. Likewise, Galileo’s Dialogues ConcerningTwo New Sciences can be enjoyed by the young student who seeks a clear geomet-rical description of the speed of falling bodies, and also by the seasoned scholar

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who is amused by Galileo’s wit and sarcasm, or who finds in his Dialogues theprogressive Aristotelianism of certain late medieval scholastics.1

Having said this, I believe that this book is particularly suitable for the fol-lowing audiences. First, it could serve as the primary textbook in an introductorydiscussion-based physics course at the university level. It was designed to appeal toa broad constituency of students at small liberal arts colleges which often lack theresources to offer the separate and specialized introductory physics courses foundat many state-funded universities (e.g. Physics for poets, Physics for engineers,Physics for health-care-professionals, Physics of sports, etc.). Indeed, at my institu-tion it is common to have history and fine arts students sitting in the course alongsidebiology and physics majors. Advanced high-school or home-school students willfind in this book a physics curriculum that emphasizes reading comprehension, andwhich can serve as a bridge into college-level work. It might also be adopted as asupplementary text for an advanced placement course in physics, astronomy or thehistory and philosophy of science. Many practicing physicists, especially those atthe beginning of their scientific careers, may not have taken the opportunity to care-fully study some of the foundational texts of physics and astronomy. Perhaps thisis because they have (quite understandably) focused their attention on acquiring astrong technical proficiency in a narrow subfield. Such individuals will find hereina structured review of such foundational texts. This book will also likely appealto humanists, social scientists and motivated lay-readers who seek a thematically-organized anthology of texts which offer insight into the historical development andcultural significance of contemporary scientific theories. Finally, and most impor-tantly, this book is designed for the benefit of the teaching professor. Early inmy career as a faculty member, I was afforded considerable freedom to developa physics curriculum at my institution which would sustain my interest for the fore-seeable future—perhaps until retirement. Indeed, reading and re-reading the classictexts assembled herein has provided me countless hours of enjoyment, reflectionand inspiration.

How is this book unique?

Here I will offer a mild critique of textbooks typically employed in introductoryuniversity physics courses. While what follows is admittedly a bit of a caricature, Ibelieve it to be a quite plausible one. I do this in order to highlight the unique fea-tures and emphases of the present book. In many university-level physics textbooks,the chapter format follows a standard recipe. First, accepted scientific laws are pre-sented in the form of one or more mathematical equations. This is followed by a

1 See Wallace, W. A., The Problem of Causality in Galileo’s Science, The Review of Metaphysics,36(3), 607–632, 1983.

Preface ix

few example problems so the student can learn how to plug numbers into the afore-mentioned equations and how to avoid common conceptual or computational errors.Finally, the student is presented with contemporary applications which illustrate therelevance of these equations for various industrial or diagnostic technologies.

While this method often succeeds in preparing students to pass certain stan-dardized tests or to solve fairly straightforward technical problems, it is lackingin important respects. First, it is quite bland. Although memorizing formulas andlearning how to perform numerical calculations is certainly crucial for acquiringa working knowledge of physical theories, it is often the more general questionsabout the assumptions and the methods of science that students find particularlystimulating and enticing. For instance, in his famous Mathematical Principles ofNatural Philosophy, Newton enumerates four general rules for doing philosophy.Now the reader may certainly choose to reject Newton’s rules, but Newton himselfsuggests that they are necessary for the subsequent development of his universaltheory of gravitation. Is he correct? For instance, if one rejects Rules III and IV—which articulate the principle of induction—then in what sense can his theory ofgravity be considered universal? Questions like “is Newton’s theory of gravity cor-rect?” and “how do you know?” can appeal to the innate sense of inquisitivenessand wonder that attracted many students to the study of natural science in the firstplace. Moreover, in seeking a solution to these questions, the student must typicallyacquire a deeper understanding of the technical aspects of the theory. In this way,broadly posed questions can serve as a motivation and a guide to obtaining a detailedunderstanding of physical theories.

Second, and perhaps more importantly, the method employed by most standardtextbooks does not prepare the student to become a practicing scientist preciselybecause it tends to mask the way science is actually done. The science is presentedas an accomplished fact; the prescribed questions revolve largely around techno-logical applications of accepted laws. On the contrary, by carefully studying thefoundational texts themselves the student is exposed to the polemical debates, thetechnical difficulties and the creative inspirations which accompanied the develop-ment of scientific theories. For example, when studying the motion of falling bodiesin Galileo’s Dialogues, the student must consider alternative explanations of theobserved phenomena; must understand the strengths and weaknesses of competingtheories; and must ultimately accept—or reject—Galileo’s proposal on the basis ofevidence and reason. Through this process the student gains a deeper understandingof Galileo’s ideas, their significance, and their limitations.

Moreover, when studying the foundational texts, the student is obliged tothoughtfully address issues of language and terminology—issues which simplydo not arise when learning from standard textbooks. In fact, when scientific the-ories are being developed the scientists themselves are usually struggling to defineterms which capture the essential features of their discoveries. For example, Oerstedcoined a term which is translated as “electric conflict” to describe the effect that anelectrical current has on a nearby magnetic compass needle. He was attempting todistinguish between the properties of stationary and moving charges, but he lackedthe modern concept of the magnetic field which was later introduced by Faraday.

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When students encounter a familiar term such as “magnetic field,” they typicallyaccept it as settled terminology, and thereby presume that they understand the phe-nomenon by virtue of recognizing and memorizing the canonical term. But whenthey encounter an unfamiliar term such as “electric conflict,” as part of the scientificargument from which it derives and wherein it is situated, they are tutored into theoriginal argument and are thus obliged to think scientifically, along with the greatscientist. In other words, when reading the foundational texts, the student is led intodoing science and not merely into memorizing and applying nomenclature.

Generally speaking, this book draws upon two things that we have in common:(i) a shared conversation recorded in the foundational scientific texts, and (ii) aninnate faculty of reason. The careful reading and analysis of the foundational textsis extremely valuable in learning how to think clearly and accurately about naturalscience. It encourages the student to carefully distinguish between observation andspeculation, and finally, between truth and falsehood. The ability to do this is essen-tial when considering the practical and even philosophical implications of variousscientific theories. Indeed, one of the central aims of this book is to help the studentgrow not only as a potential scientist, but as an educated person. More specifically, itwill help the student develop important intellectual virtues (i.e. good habits), whichwill serve him or her in any vocation, whether in the marketplace, in the family, orin society.

How is this book organized?

This book is divided into four separate volumes; volumes I and II were concurrentlypublished in the autumn of 2014, and volumes III and IV are due to be publishedapproximately a year later. Within each volume, the readings are centered on aparticular theme and proceed chronologically. For example, Volume I is entitledThe Heavens and the Earth. It provides an introduction to astronomy and cosmol-ogy beginning with the geocentrism of Aristotle’s On the Heavens and Ptolemy’sAlmagest, proceeding through heliocentrism advanced in Copernicus’ Revolutionsof the Heavenly Spheres and Kepler’s Epitome of Copernican Astronomy, and arriv-ing finally at big bang cosmology with Lemaître’s The Primeval Atom. VolumeII, Space, Time and Motion, provides a careful look at the science of motion andrest. Here, students engage in a detailed analysis of significant portions of Galileo’sDialogues Concerning Two New Sciences, Pascal’s Treatise on the Equilibrium ofFluids and the Weight of the Mass of Air, Newton’s Mathematical Principles ofNatural Philosophy and Einstein’s Relativity.

Volume III traces the theoretical and experimental development of the electro-magnetic theory of light using texts by William Gilbert, Benjamin Franklin, CharlesCoulomb, André Marie Ampère, Christiaan Huygens, James Clerk Maxwell, Hein-rich Hertz, Albert Michelson, and others. Volume IV provides an exploration ofmodern physics, focusing on the mechanical theory of heat, radio-activity andthe development of modern quantum theory. Selections are taken from works by

Preface xi

Joseph Fourier, William Thomson, Rudolph Clausius, Joseph Thomson, JamesClerk Maxwell, Ernest Rutherford, Max Planck, James Chadwick, Niels Bohr,Erwin Schrödinger and Werner Heisenberg.

While the four volumes of the book are arranged around distinct themes, thereadings themselves are not strictly constrained in this way. For example, in hisTreatise on Light, Huygens is primarily interested in demonstrating that light can bebest understood as a wave propagating through an aethereal medium comprised oftiny, hard elastic particles. In so doing, he spends some time discussing the speedof light measurements performed earlier by Ole Rømer. These measurements, inturn, relied upon an understanding of the motion of the moons of Jupiter which hadrecently been reported by Galileo in his Sidereal Messenger. So here, in this Treatiseon Light, we find references to a variety of inter-related topics. Huygens does notartificially restrict his discussion to a narrow topic—nor does Galileo, or Newton orthe other great thinkers. Instead, the reader will find in this book recurring conceptsand problems which cut across different themes and which are naturally addressedin a historical context with increasing levels of sophistication and care. Science is aconversation which stretches backwards in time to antiquity.

How might this book be used?

This book is designed for college classrooms, small-group discussions and individ-ual study. Each of the four volumes of the book contains roughly 30 chapters, pro-viding more than enough material for a one-semester undergraduate-level physicscourse; this is the context in which this book was originally implemented. In sucha setting, one or two 50-min classroom sessions should be devoted to analyzingand discussing each chapter. This assumes that the student has read the assignedtext before coming to class. When teaching such a course, I typically improvise—leaving out a chapter here or there (in the interest of time) and occasionally addinga reading selection from another source that would be particularly interesting orappropriate.

Each chapter of each volume has five main components. First, at the beginningof each chapter, I include a short introduction to the reading. If this is the firstencounter with a particular author, the introduction includes a biographical sketchof the author and some historical context. The introduction will often contain asummary of some important concepts from the previous chapter and will concludewith a few provocative questions to sharpen the reader’s attention while reading theupcoming text.

Next comes the reading selection. There are two basic criteria which I used forselecting each text: it must be significant in the development of physical theory, andit must be appropriate for beginning undergraduate students. Balancing these crite-ria was very difficult. Over the past decade, I have continually refined the selectionsso that they might comprise the most critical contribution of each scientist, while atthe same time not overwhelming the students by virtue of their length, language or

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complexity. The readings are not easy, so the student should not feel overwhelmedif he or she does not grasp everything on the first (or second, or third. . . ) reading.Nobody does. Rather—like classic literature—these texts must be “grown into” (soto speak) by returning to them time and again.

I have found that the most effective way to help students successfully engagefoundational texts is to carefully prepare questions which help them identify andunderstand key concepts. So as the third component of each chapter, I have prepareda study guide in the form of a set of questions which can be used to direct eitherclassroom discussion or individual reading. After the source texts themselves, thestudy guide is perhaps the most important component of each chapter, so I willspend a bit more time here explaining it.

The study guide typically consists of a few general discussion questions aboutkey topics contained in the text. Each of these general questions is followed byseveral sub-questions which aid the student by focusing his or her attention on theauthor’s definitions, methods, analysis and conclusions. For example, when studentsare reading a selection from Albert Michelson’s book Light Waves and their Uses, Iwill often initiate classroom discussion with a general question such as “Is it possi-ble to measure the absolute speed of the earth?” This question gets students thinkingabout the issues addressed in the text in a broad and intuitive way. If the students getstuck, or the discussion falters, I will then prompt them with more detailed follow-up questions such as: “What is meant by the term absolute speed?” “How, exactly,did Michelson attempt to measure the absolute speed of the earth?” “What tech-nical difficulties did Michelson encounter while doing his experiments?” “To whatconclusion(s) was Michelson led by his results?” and finally “Are Michelson’s con-clusions then justified?” After answering such simpler questions, the students areusually more confident and better prepared to address the general question whichwas initially posed.

In the classroom, I always emphasize that it is critical for participants to carefullyread the assigned selections before engaging in discussion. This will help them tomake relevant comments and to cite textual evidence to support or contradict asser-tions made during the course of the discussion. In this way, many assertions will berevealed as problematic—in which case they may then be refined or rejected alto-gether. Incidentally, this is precisely the method used by scientists themselves inorder to discover and evaluate competing ideas or theories. During our discussion,students are encouraged to speak with complete freedom; I stipulate only one class-room rule: any comment or question must be stated publicly so that all others canhear and respond. Many students are initially apprehensive about engaging in publicdiscourse, especially about science. If this becomes a problem, I like to emphasizethat students do not need to make an elaborate point in order to engage in classroomdiscussion. Often, a short question will suffice. For example, the student might say“I am unclear what the author means by the term inertia. Can someone please clar-ify?” Starting like this, I have found that students soon join gamely in classroomdiscussion.

Fourth, I have prepared a set of exercises which test the student’s understand-ing of the text and his or her ability to apply key concepts in unfamiliar situations.

Preface xiii

Some of these are accompanied by a brief explanation of related concepts or formu-las. Most of them are numerical exercises, but some are provocative essay prompts.In addition, some of the chapters contain suggested laboratory exercises, a few ofwhich are in fact field exercises which require several days (or even months) ofobservations. For example, in Chap. 3 of Volume I, there is an astronomy field exer-cise which involves charting the progression of a planet through the zodiac over thecourse of a few months. So if this book is being used in a semester-long collegeor university setting, the instructor may wish to skim through the exercises at theend of each chapter so he or she can identify and assign the longer ones as ongoingexercises early in the semester.

Finally, I have included at the end of each chapter a list of vocabulary wordswhich are drawn from the text and with which the student should becomeacquainted. Expanding his or her vocabulary will aid the student not only in theircomprehension of subsequent texts, but also on many standardized college anduniversity admissions exams.

What mathematics preparation is required?

It is sometime said that mathematics is the “language of science.” This sentimentappropriately inspires and encourages the serious study of mathematics. Of course ifit were taken literally then many seminal works in physics—and much of biology—would have to be considered either unintelligible or unscientific, since they containlittle or no mathematics. Moreover, if mathematics is the only language of science,then physics instructors should be stunned whenever students are enlightened byverbal explanations which lack mathematical form. To be sure, mathematics offersa refined and sophisticated language for describing observed phenomena, but manyof our most significant observations about nature may be expressed using everydayimages, terms and concepts: heavy and light, hot and cold, strong and weak, straightand curved, same and different, before and after, cause and effect, form and function,one and many. So it should come as no surprise that, when studying physics viathe reading and analysis of foundational texts, one enjoys a considerable degree offlexibility in terms of the mathematical rigor required.

For instance, Faraday’s Experimental Researches in Electricity are almostentirely devoid of mathematics. Rather, they consist of detailed qualitative descrip-tions of his observations, such as the relationship between the relative motionof magnets and conductors on the one hand, and the direction and intensity ofinduced electrical currents on the other hand. So when studying Faraday’s work,it is quite natural for the student to aim for a conceptual, as opposed to a quan-titative, understanding of electromagnetic induction. Alternatively, the student cancertainly attempt to connect Faraday’s qualitative descriptions with the mathemati-cal methods which are often used today to describe electromagnetic induction (i.e.vector calculus and differential equations). The former method has the advantage

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of demonstrating the conceptual framework in which the science was actually con-ceived and developed; the latter method has the advantage of allowing the student tomake a more seamless transition to upper-level undergraduate or graduate courseswhich typically employ sophisticated mathematical methods.

In this book, I approach the issue of mathematical proficiency in the followingmanner. Each reading selection is followed by both study questions and homeworkexercises. In the study questions, I do not attempt to force anachronistic concepts ormethods into the student’s understanding of the text. They are designed to encour-age the student to approach the text in the same spirit as the author, insofar as thisis possible. In the homework exercises, on the other hand, I often ask the studentto employ mathematical methods which go beyond those included in the readingselection itself. For example, one homework exercise associated with a selectionfrom Hertz’s book Electric Waves requires the student to prove that two counter-propagating waves superimpose to form a standing wave. Although Hertz casuallymentions that a standing wave is formed in this way, the problem itself requires thatthe student use trigonometric identities which are not described in Hertz’s text. Incases such as this, a note in the text suggests the mathematical methods which arerequired. I have found this to work quite well, especially in light of the easy accesswhich today’s students have to excellent print and online mathematical resources.

Generally speaking, there is an increasing level of mathematical sophisticationrequired as the student progresses through the curriculum. In Volume I students needlittle more than a basic understanding of geometry. Euclidean geometry is sufficientin understanding Ptolemy’s epicyclic theory of planetary motion and Galileo’s cal-culation of the altitude of lunar mountains. The student will be introduced to somebasic ideas of non-Euclidean geometry toward the end of Volume I when studyingmodern cosmology through the works of Einstein, Hubble and Lemaître, but thisis not pushed too hard. In Volume II students will make extensive use of geomet-rical methods and proofs, especially when analyzing Galileo’s work on projectilemotion and the application of Newton’s laws of motion. Although Newton devel-ops his theory of gravity in the Principia using geometrical proofs, the homeworkproblems often require the student to make connections with the methods of cal-culus. The selections on Einstein’s special theory of relativity demand only the useof algebra and geometry. In Volume III, mathematical methods will, for the mostpart, be limited to geometry and algebra. More sophisticated mathematical methodswill be required, however, in solving some of the problems dealing with Maxwell’selectromagnetic theory of light. This is because Maxwell’s equations are most suc-cinctly presented using vector calculus and differential equations. Finally, in VolumeIV, the student will be aided by a working knowledge of calculus, as well as somefamiliarity with the use of differential equations.

It is my feeling that in a general physics course, such as the one being presented inthis book, the extensive use of advanced mathematical methods (beyond geometry,algebra and elementary calculus) is not absolutely necessary. Students who plan tomajor in physics or engineering will presumably learn more advanced mathematicalmethods (e.g. vector calculus and differential equations) in their collateral mathe-matics courses, and they will learn to apply these methods in upper-division (junior

Preface xv

and senior-level) physics courses. Students who do not plan to major in physics willtypically not appreciate the extensive use of such advanced mathematical methods.And it will tend to obscure, rather than clarify, important physical concepts. In anycase, I have attempted to provide guidance for the instructor, or for the self-directedstudent, so that he or she can incorporate an appropriate level of mathematical rigor.

Figures, formulas, and footnotes

One of the difficulties in assembling readings from different sources and publishersinto an anthology such as this is how to deal with footnotes, references, formulasand other issues of annotation. For example, for any given text selection, there maybe footnotes supplied by the author, the translator and the anthologist. So I haveappended a [K.K.] marking to indicate when the footnote is my own; I have notincluded this marking when there is no danger of confusion, for example in myfootnotes appearing in the introduction, study questions and homework exercises ofeach chapter.

For the sake of clarity and consistency, I have added (or sometimes changed the)numbering for figures appearing in the texts. For example, Fig. 16.3 is the thirdfigure in Chap. 16 of this volume I; this is not necessarily how Kepler or his trans-lator numbered this figure when it appeared in an earlier publication of his EpitomeAstronomae Copernicanae. For ease of reference, I have also added (or sometimeschanged the) numbering of equations appearing in the texts. For example, Eqs. 31.1and 31.2 are the equations of the Lorentz and Galilei transformations appearing inthe reading in Chap. 31 of Volume II, extracted from Einstein’s book Relativity. Thisis not necessarily how Einstein numbered them.

In several cases, the translator or editor has included references to page numbersin a previous publication. For example, the translators of Galileo’s Dialogues haveindicated, within their 1914 English translation, the locations of page breaks in theItalian text published in 1638. A similar situation occurs with Faith Wallis’s 1999translation of Bede’s The Reckoning of Time. For consistency, I have rendered suchpage numbering in bold type surrounded by slashes. So /50/ refers to page 50 insome earlier “canonical” publication.

Acknowledgements

I suppose that it is common for a teacher to eventually mull over the idea ofcompiling his or her thoughts on teaching into a coherent and transmittable form.Committing this curriculum to writing was particularly difficult because I am keenlyaware how my own thinking about teaching physics has changed significantly sincemy first days in front of the classroom—and how it is quite likely to continue toevolve. So this book should be understood as a snapshot, so to speak, of how I amteaching my courses at the time of writing. I would like to add, however, that Ibelieve the evolution of my teaching has reflected a maturing in thought, rather thana mere drifting in opinion. After all, the classic texts themselves are formative: howcan a person, whether student or teacher, not become better informed when learningfrom the best thinkers?

This being said, I would like to offer my apologies to those students who suf-fered through the birth pains, as it were, of the curriculum presented in this book.The countless corrections and suggestions that they offered are greatly appreciated;any and all remaining errors in the text are my own fault. Many of the readingselections included herein were carefully scanned, edited and typeset by undergrad-uate students who served as research and editorial assistants on this project: JaymeeMartin-Schnell, Dylan Applin, Samuel Wiepking, Timothy Kriewall, StephanieKriewall, Cody Morse, Michaela Otterstatter, and Ethan Jahns deserve specialthanks. My home institution, Wisconsin Lutheran College, provided me with con-siderable time and freedom to develop this book, including a year-long sabbaticalleave, for which I am very grateful. During this sabbatical, I received support andencouragement from my trusty colleagues in the Department of Mathematical andPhysical Sciences. Also, the Higher Education Initiatives Program of the Wiscon-sin Space Grant Consortium provided generous funding for this project, as did theFaculty Development Committee of Wisconsin Lutheran College. Greg Schulz hasbeen an invaluable intellectual resource throughout this project. Aaron Jensen con-scientiously translated selections of the Almagest, included in Volume I of this book,from Heiberg’s edition of Ptolemy’s Greek manuscript. And Glen Thompson wasinstrumental in getting this translation project initiated. Starla Siegmann and Jenny

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xviii Acknowledgements

Baker, librarians at the Marvin M. Schwan Library of Wisconsin Lutheran Col-lege, were always up to the challenge of speedily procuring obscure resources fromremote libraries. I would also like to thank the following individuals who facili-tated the complex task of acquiring permissions to reprint the texts included in thisbook: Jenny Howard at the Liverpool University Press, Elizabeth Sandler, EmilieDavid and Norma Rosado-Blake at the American Association for the Advancementof Science, Chris Erdmann at the Harvard College Observatory’s Wolbach Library,Carmen Pagán at Encyclopædia Britannica, and Michael Fisher, McKenzie Carna-han and and Scarlett Huffman at the Harvard University Press. Cornelia Mutel andKathryn Hodson very kindly provided digital images for inclusion with the Galileoand Pascal selections from the History of Hydraulics Rare Book Collection at theUniversity of Iowa’s IIHR-Hydroscience and Engineering. Also, I would like tothank Jeanine Burke, the acquisition editor at Springer who originally agreed to takeon this project with me, and Robert Korec, Tom Spicer and Catherine Rice, who allpatiently saw it through to publication. Shortly after submitting my book proposalto Springer, I received very encouraging and helpful comments from several anony-mous reviewers, for whom I am thankful. I received similar suggestions from theeditors of Springer’s Undergraduate Lecture Notes in Physics series for which I amlikewise grateful. Finally, I would especially like to thank my wife, Cindy, who hasprovided unwavering encouragement and support for my work from the very start.

Milwaukee, 2015 Kerry Kuehn

Contents

1 Iron, Loadstones and Terrestrial Magnetism . . . . . . . . . . . . . . . . . . . . . . 11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Reading: Gilbert, On the Loadstone and Magnetic Bodies and on

the Great Magnet the Earth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2.1 Chapter I: Of Direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2.2 Chapter II: Directive (or Versorial) Force, Which We Call

Verticity: What It Is; How It Resides in the Loadstone; andHow It Is Acquired When Not Naturally Produced . . . . . . . . 5

1.2.3 Chapter III: How Iron Acquires Verticity from theLoadstone, and How This Verticity Is Lost or Altered . . . . . . 9

1.2.4 Chapter IV: Why Magnetized Iron Takes OppositeVerticity; and Why Iron Touched by the True North Sideof the Stone Moves to the Earth’s North, and WhenTouched by the True South Side to the Earth’s South:Iron Rubbed with the North Point of the Stone Does NotTurn to the South, Nor Vice Versa, as All Writers on theLoadstone Have Erroneously Thought . . . . . . . . . . . . . . . . . . . 10

1.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2 The Life and Death of a Magnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192.2 Reading: Gilbert, On the Loadstone and Magnetic Bodies and on

the Great Magnet the Earth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192.2.1 Chapter V: Of Magnetizing Stones of Different Shapes . . . . . 202.2.2 Chapter VI: What Seems to be a Contrary Movement

of Magnetic Bodies is the Regular Tendence to Union . . . . . 202.2.3 Chapter VII: A Determinate Verticity and a Directive

Power Make Magnetic Bodies Accord, and not anAttractional or a Repulsative Force, Nor Strong CoitionAlone or Unition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

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2.2.4 Chapter VIII: Of Disagreements Between Pieces of Ironon the Same Pole of a Loadstone; How They May ComeTogether and be Conjoined . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2.2.5 Chapter IX: Directional Figures Showing the Varietiesof Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.2.6 Chapter X: Of the Mutation of Verticity and MagneticProperties, or of the Alteration of the Force Awakenedby the Loadstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

2.2.7 Chapter XI: Of Friction of Iron with the Mid Parts ofa Loadstone Between the Poles, and at the EquinoctialCircle of a Terrella . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

2.2.8 Chapter XII: How Verticity Exists in All Smelted Ironnot Excited by the Loadstone . . . . . . . . . . . . . . . . . . . . . . . . . . 27


3 Conservation of Electrical Charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333.2 Reading: Franklin, Experiments and Observations on Electricity . . . 35

3.2.1 Extract of Letter I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353.2.2 Letter II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35


4 Müschenbroek’s Wonderful Bottle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434.2 Reading: Franklin, Experiments and Observations on Electricity . . . 44

4.2.1 Letter III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444.2.2 Experiments Confirming the Above . . . . . . . . . . . . . . . . . . . . . 464.2.3 Letter IV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504.2.4 Letter XXXVIII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51


5 Thunder and Lightning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 615.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 615.2 Reading: Franklin, Experiments and Observations on Electricity . . . 61

5.2.1 Letter XI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625.2.2 Letter XLVIII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625.2.3 Letter LIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

5.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 665.4 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Contents xxi

6 Coulomb’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 676.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 676.2 Reading: Coulomb, Law of Electric Force and the Fundamental

Law of Electricity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 686.2.1 Law of Electric Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 686.2.2 Fundamental Law of Electricity . . . . . . . . . . . . . . . . . . . . . . . . 71

6.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 726.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

7 The Dawn of Electro-Magnetism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 757.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 757.2 Reading: Oersted, Experiments on the Effect of a Current of

Electricity on the Magnetic Needle . . . . . . . . . . . . . . . . . . . . . . . . . . . . 767.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 807.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 807.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

8 Electric Currents, Magnetic Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 838.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 838.2 Reading: Ampère, Actions Between Currents . . . . . . . . . . . . . . . . . . . 84

8.2.1 New Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 848.2.2 Actions Between Currents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84


9 Work and Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 999.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 999.2 Reading: Helmholtz, On the Conservation of Force . . . . . . . . . . . . . . 101

9.2.1 Introduction to a Series of Lectures Delivered at Carlsruhein the Winter of 1862–1863 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

9.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1109.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1109.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

10 Kinetic and Potential Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11310.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11310.2 Reading: Helmholtz, On the Conservation of Force . . . . . . . . . . . . . . 11310.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11910.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12010.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

xxii Contents

11 Conservation of Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12311.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12311.2 Reading: Helmholtz, On the Conservation of Force . . . . . . . . . . . . . . 12411.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13611.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13711.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

12 Geometric Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13912.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13912.2 Reading: Newton, Opticks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

12.2.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14012.2.2 Axioms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141


13 The Wave Theory of Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15713.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15713.2 Reading: Huygens, Treatise on Light . . . . . . . . . . . . . . . . . . . . . . . . . . 158

13.2.1 Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15813.2.2 Chapter I: On Rays Propagated in Straight Lines . . . . . . . . . . 159


14 Huygens’ Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16914.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16914.2 Reading: Huygens, Treatise on Light . . . . . . . . . . . . . . . . . . . . . . . . . . 169

14.2.1 Chapter I: On Rays Propagated in Straight Lines, Continued 16914.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17514.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17614.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179

15 Reflection of Light Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18115.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18115.2 Reading: Huygens, Treatise on Light . . . . . . . . . . . . . . . . . . . . . . . . . . 182

15.2.1 Chapter II: On Reflexion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18215.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18515.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18515.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186

16 Opacity, Transparency and Snell’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . 18916.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18916.2 Reading: Huygens, Treatise on Light . . . . . . . . . . . . . . . . . . . . . . . . . . 189

16.2.1 Chapter III: On Refraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

Contents xxiii


17 Atmospheric Refraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20317.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20317.2 Reading: Huygens, Treatise on Light . . . . . . . . . . . . . . . . . . . . . . . . . . 203

17.2.1 Chapter IV: On the Refraction of the Air . . . . . . . . . . . . . . . . . 20417.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20817.4 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

18 The Particle Theory of Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20918.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20918.2 Reading: Newton, Opticks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21018.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21918.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22118.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222

19 Passive Laws and Active Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22319.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22319.2 Reading: Newton, Opticks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224

19.2.1 Excerpts From Qu. 31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22419.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23019.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23119.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

20 Measuring Light’s Wavelength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23320.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23320.2 Reading: Young, On the Nature of Light and Colours . . . . . . . . . . . . 23420.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24420.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24420.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248

21 Films, Bubbles and Rainbows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24921.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24921.2 Reading: Young, On the Nature of Light and Colours . . . . . . . . . . . . 24921.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25421.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25421.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256

22 Producing and Detecting Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25722.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25722.2 Reading: Tyndall, Six Lectures on Light . . . . . . . . . . . . . . . . . . . . . . . . 258

22.2.1 Double Refraction of Light Explained by the UndulatoryTheory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

22.2.2 Polarization of Light Explained by the Undulatory Theory . . 260

xxiv Contents


23 Crystal Symmetry and Light Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26923.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26923.2 Reading: Tyndall, Six Lectures on Light . . . . . . . . . . . . . . . . . . . . . . . . 269

23.2.1 Action of Crystals on Polarized Light: The Nicol Prism . . . . 27023.2.2 Colours of Films of Selenite in Polarized Light . . . . . . . . . . . 27123.2.3 Colours of Crystals in Polarized Light Explained

by the Undulatory Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27223.2.4 Colours Produced by Strain and Pressure . . . . . . . . . . . . . . . . 27623.2.5 Colours of Unannealed Glass . . . . . . . . . . . . . . . . . . . . . . . . . . 27823.2.6 Circular Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27923.2.7 Complementary Colours of Bi-refracting Spar

in Circularly Polarized Light. Proof that Yellowand Blue Are Complementary . . . . . . . . . . . . . . . . . . . . . . . . . . 281

23.2.8 The Magnetization of Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28223.2.9 Iris-Rings Surrounding the Axes of Crystals . . . . . . . . . . . . . . 283


24 Light Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28924.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28924.2 Reading: Tyndall, Six Lectures on Light . . . . . . . . . . . . . . . . . . . . . . . . 289

24.2.1 Power of the Undulatory Theory . . . . . . . . . . . . . . . . . . . . . . . 28924.2.2 The Blue of the Sky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29124.2.3 Artificial Sky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29224.2.4 Polarization of Sky-Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293


25 Induction of Electrical Currents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29925.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29925.2 Reading: Faraday, Experimental Researches in Electricity . . . . . . . . . 301

25.2.1 On the Induction of Electric Currents . . . . . . . . . . . . . . . . . . . 30225.2.2 Evolution of Electricity from Magnetism . . . . . . . . . . . . . . . . 305


Contents xxv

26 Arago’s Mysterious Wheel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31926.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31926.2 Reading: Faraday, Experimental Researches in Electricity . . . . . . . . . 320

26.2.1 Explication of Arago’s Magnetic Phenomena . . . . . . . . . . . . . 32026.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32926.4 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

27 Faraday’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33127.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33127.2 Reading: Faraday, Experimental Researches in Electricity . . . . . . . . . 33127.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34027.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34027.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344

28 The Magnetic Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34528.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34528.2 Reading: Faraday, On the Physical Character of the Lines of

Magnetic Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34628.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35928.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36128.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362

29 Paramagnetism and Diamagnetism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36329.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36329.2 Reading: Faraday, On the Physical Character of the Lines of

Magnetic Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36429.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37629.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37829.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378

30 Action-at-a-Distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37930.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37930.2 Reading: Maxwell, On Action at a Distance . . . . . . . . . . . . . . . . . . . . 380

30.2.1 Experiment on Lines of Force . . . . . . . . . . . . . . . . . . . . . . . . . . 38730.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39030.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39030.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392

31 Maxwell’s Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39331.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39331.2 Reading: Maxwell, A Dynamical Theory of the Electromagnetic

Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39331.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40231.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40231.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409

xxvi Contents

32 Propagating Electromagnetic Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41132.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41132.2 Reading: Heaviside, Electromagnetic Theory . . . . . . . . . . . . . . . . . . . 414

32.2.1 Adagio. Andante. Allegro moderato . . . . . . . . . . . . . . . . . . . . . 41432.2.2 Simple Proof of Fundamental Property of a Plane Wave . . . . 41532.2.3 The General Plane Wave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416


33 Circuits, Antennae and Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42333.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42333.2 Reading: Hertz, On Electric Radiation . . . . . . . . . . . . . . . . . . . . . . . . . 424

33.2.1 The Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42533.2.2 The Production of the Ray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42633.2.3 Rectilinear Propagation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42733.2.4 Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42833.2.5 Reflection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42933.2.6 Refraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43133.2.7 Explanation of the Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432


34 The Michelson-Morley Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44134.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44134.2 Reading: Michelson, The Ether . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44234.3 Study Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45334.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45534.5 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 456

Vector Algebra and Vector Calculus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457A.1 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467

Undergraduate Lecture Notes in Physics978-3-319-21816-8/1.pdf · lowing audiences. First, it could...

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Transcript of Undergraduate Lecture Notes in Physics978-3-319-21816-8/1.pdf · lowing audiences. First, it could...