Physics Principles And Applications PDF
Preview Physics Principles And Applications
PHYSICS PRINCIPLES AND APPLICATIONS PHYSICS PRINCIPLES AND APPLICATIONS HENRY MARGENAU Eugene Higgins Professor of Physics and Natural Philosophy, Yale University ,vILLIAM W. WATSON Professor of Physics and Chairman of the Department, Yale University C. G. MONTGOMERY Late Associate Professor of Physics Yale University SECOND EDITION NEW YORK TORONTO LONDON lVIcGRAW-HILL BOOK COMPANY, INC. 1953 PHYSICS-PRINCIPLES AND APPLICATIONS Copyright, 1949, 1953, by the McGraw-Hill Book Company, Inc. Printed in the United States of America. All rights reserved. This book, or parts there of, may not be reproduced in any form without permission of the publishers. Library of Congress Catalog Card Number: 53-5171 THE MAPLE PRESS COMPANY, YORK, PA. PREFACE TO THE SECOND EDITION In preparing the second edition we have utilized our experience with the first edition and the comments, both critical and constructive, of numer ous users of the book. Principal changes are the foltowing. 1. Since we felt that the book was, on the whole, a little too rigorous, we have omitted some of the most difficult portions, particularly in the subjects of electricity and magnetism. No attempt has been made to pare the material down to the precise contents of a year's course. There is still a sufficient variety of subjects to provide continuity for an ele mentary course; but the choice is left to the instructor. 2. Stars have been removed from the text, but the device of using small print for the less important and the more difficult sections has been retained as a guide for possible omissions. Our own one-year course which meets four hours per week, exclusive of laboratory, takes up approximately 75 per cent of the subject matter in the book. Problems based on text material in fine print are still starred. 3. Most old problems have been changed and many new ones are added. The additions contain a good measure of drill problems which can be used as alt~rnates for others illustrating the same principle. 4. Crucial sections of the book have been completely rewritten, mainly with an eye upon simplifications. While all systems of units are mentioned, greater emphasis is placed upon mks units in the subject of mechanics in order to prepare the student more fully for the use of prac tical electromagnetic ·units later. The three constants, k, k', and k", which designate different unit systems, have in our opinion proved satisfactory pedagogical tools and we have added to their explanation. 5. The swift movement of physical discoveries permits us to add, after only four years, a number of novel subjects. Among them are the cosmotron, the Schmidt camera, the transistor, and the hydrogen bomb. Older topics absent from the first but included in the second edition are the magnetic circuit, electric motors, special relativity. We record with utmost sorrow the death of our colleague and collabor ator, Carol Gray Montgomery, whose help we have sorely missed in this rev1s1on. HENRY MARGENAU WILLIAM W. WATSON NEW HAVEN, CONN. March, 1953 v PREFACE TO THE FIRST EDITION This book has grown out of a collaboration of the authors in a sophomore course in physics at Yale University, a course which is aimed to equip engineering students and majors in the natural sciences with sufficient basic knowledge of physics to serve as a foundation for further work in the various exact sciences and technologies. We have been conscious of the need for a book that presents in a single volume an account of the subject which is at once rigorous, vital, and modern, and we have endeavored to fill that need. The problem of how to use the calculus in an introductory physics course on the college level has given us serious concern over the whole period in which this course was taught. The students' knowledge of that discipline is still in the formative stage and amounts to a set of newly acquired skills rather than understanding. Yet physics requires the understanding as well as the skill. On the other hand, a use of the calculus is so clearly advantageous and so obviously desirable that its renunciation, in this day and age, is an unwarranted sacrifice. For the saying that calculus is the language of physics is true as well as trite, and continuity of training demands that a student should, even in his early work, be confronted with those methods of analysis which form the major tools of his later thinking. Altogether too many students have to con fess, at the end of their senior year, that their introductory physics course was nearly useless because it did not acquaint them with the "elegant" methods of the calculus. And the fact that the physics course provides opportune applications for a student's fresh mathematical acquisitions is not to be overlooked. The fact remains, however, that few students can "take it" when the calculus is employed as freely as these considerations suggest. Hence, in composing this book, we have adopted a device which is neither new nor ingenious: We have allowed the student to catch his breath by treating subjects not requiring the use of this form of mathematics in the first four chapters and then exposing him to it increasingly, but in easy stages and with full explanation. Toward the end of the book the stu dent is expected to take elementary integrations in his stride. Our treatment i~ suited to the level of attainment of readers who have had an introduction to the calculus and are taking a more solid course concurrently. Students often complain that a course like the one for which this book may serve as a text is very difficult, and they invariably, though some what confusedly, blame the "emphasis on mathematics" for their dis vii viii PREFACE TO THE FIRST EDITION satisfaction. In our experience this diagnosis has often been in error: What has created difficulty is not the mathematics but the volume of novelties that is being pushed out to the students. The wise teacher, when using a book like the present, will select his topics with care and limit his selection with pedagogical foresight. For that reason, we have put in the book rather a plenum of material for selection. It is our guess that coverage of all items presented will require three full semesters' work. In our own course, which meets four times a week (exclusive of laboratory exercises) for two semesters, we have succeeded in covering about three-fourths of the subject matter without incurring accusations of having idled. This was done by omitting many of the starred sections. To make possible this selective procedure without prescribing what ought to be left to every teacher's judgment, we have divided the book into starred and unstarred sections. The unstarred sections, which can be covered in leisurely fashion in a two-semester course meeting three hours per week, form a basic and coherent matrix of work and are understandable by themselves. In only a few places will it be found necessary to take for granted a result derived in a starred section. In a similar way some of the problems at the end of each chapter are distinguished by stars. Unstarred problems go with the unstarred material. Worked examples are employed very freely everywhere in the text. They represent a simple pedagogic device for concrete understanding, a device which the authors have found very useful in their teaching. Our outlook, we believe, is fairly modern. In electromagnetism the exposition recognizes that the forces between charges, at rest and in motion, are fundamental, and hence magnetic poles take on minor significance in this book. We have shunned the sensational for its own sake. Rather have we endeavored to broaden the treatment and to make contact with the students' general studies by inserting historical references, by explaining the etymology of important technical terms, and by an occasional com ment in a philosophic vein. The proper treatment of units in physics is a subject for controversy, often heated, and we have tried to adopt a more moderate viewpoint. In the first chapters, the familiar British units are most often employed, but as the subject is developed, emphasis is shifted to the metric systems in both the cgs and the mks forms. In the study of electricity, where three or four metric systems are in common use today, the attempt has been made to minimize troubles by employing three constants that have different values and dimensions in the different systems. All the funda mental equations are written, therefore, in terms that are independent PREFACE TO THE FIRST EDITION ix of the units except for these constant factors. Although this device may not lessen the difficulties, it is hoped that it will help the student to understand more clearly the distinctions between arbitrary conventions and physical principles. HENRY MARGENAU WILLIAM W. WATSON c. G. MONTGOMERY NEW HAVEN, CONN. January, 1949
The list of books you might like
