Electrical circuits are systems that have many dynamic response characteristics in common with mechanical systems. But electrical variables (voltage, current, charge) and circuits are quite different physically than mechanical variables and systems, and the physical laws and methods for deriving ordinary differential equations that describe behaviors of electrical circuits also are entirely different. This chapter is an introduction to the theory of electrical circuits and basic analog electronics, and to some common but simple practical applications of the theory. The material presented here provides the basis for many examples of system dynamic behavior in later chapters.
Many engineering students in fields other than electrical engineering are exposed to electrical theory only in a required introductory physics course. This presentation is designed for such engineers who, nevertheless, have applications for simple circuits and electronics. For example, almost every engineer who works with electromechanical systems will at some time require at least the background in circuits and electronics that is presented in this chapter. The same is true for almost every engineer who uses sensors of any kind, or is involved with testing of prototypes or products in the laboratory or in the field. Even the process of logically evaluating for possible purchase the capabilities and specifications of modern electronic instrumentation requires more sophistication with circuits and electronics than a student can acquire from an introductory physics course.