# Circuits Fundamentals: Definitions, Graph Properties, Current & Voltage, Power & Energy

This is EE44 Circuits & Systems, and we are going to be discussing the fundamentals of mathematical concepts that we’ll use in electrical engineering and the relationship with physical phenomena. In this class, we will attempt to create that link. The topics that will be covered today will give you a quick overview of what the topics are and what we’ll do later on, so we’ll start with some fundamentals of circuit theory and system theory. We will talk about circuit theory, circuit elements such as linear and nonlinear circuits, and then we will talk about network diagrams, node and mesh analysis, and then we will move onto time domain analysis, while we will use that to develop the system theory.

The systems have inputs and outputs, and how to represent this behavior will be done by using responses like impulse response, step response, and different types of response of sinusoidal signals. In the end, we’ll see that the reason we’ll perform those tasks is not because they are important in themselves, but rather, because they serve as a basis to analyze all possible inputs and provide any possible output.

Our discussion will revolve around a bit about operator theory and operator analysis. Using the concept of frequency we will transition from time domain to frequency domain in an organic manner. We will also discuss the transfer function poles and zeros. The laplace transform and fourier transform, and their applications, will be discussed. At the end of the class, we’ll talk about time and transform constants.

The main point of this is to understand the relationship and mathematical model that describes the physical world and how it applies? Right? Even with this additional constraint, if you are merely a mathematician, you can make any structure you want so long as it is self-consistent. Physics has its own constraints on those structures that have to be met to meet the experimental results.