tailieunhanh - Electric Circuits, 9th Edition P4

Electric Circuits, 9th Edition P4. Designed for use in a one or two-semester Introductory Circuit Analysis or Circuit Theory Course taught in Electrical or Computer Engineering Departments. Electric Circuits 9/e is the most widely used introductory circuits textbook of the past 25 years. As this book has evolved over the years to meet the changing learning styles of students, importantly, the underlying teaching approaches and philosophies remain unchanged. | 6 Circuit Variables engineering a challenging and exciting profession. The emphasis in engineering is on making things work so an engineer is free to acquire and use any technique from any field that helps to get the job done. Circuit Theory In a field as diverse as electrical engineering you might well ask whether all of its branches have anything in common. The answer is yes electric circuits. An electric circuit is a mathematical model that approximates the behavior of an actual electrical system. As such it provides an important foundation for learning in your later courses and as a practicing engineer the details of how to design and operate systems such as those just described. The models the mathematical techniques and the language of circuit theory will form the intellectual framework for your future engineering endeavors. Note that the term electric circuit is commonly used to refer to an actual electrical system as well as to the model that represents it. In this text when we talk about an electric circuit we always mean a model unless otherwise stated. It is the modeling aspect of circuit theory that has broad applications across engineering disciplines. Circuit theory is a special case of electromagnetic field theory the study of static and moving electric charges. Although generalized field theory might seem to be an appropriate starting point for investigating electric signals its application is not only cumbersome but also requires the use of advanced mathematics. Consequently a course in electromagnetic field theory is not a prerequisite to understanding the material in this book. We do however assume that you have had an introductory physics course in which electrical and magnetic phenomena were discussed. Three basic assumptions permit us to use circuit theory rather than electromagnetic field theory to study a physical system represented by an electric circuit. These assumptions are as follows 1. Electrical effects happen instantaneously .