Circuit Theory/Terminology

Basic Terminology

There are a few key terms that need to be understood at the beginning of this book, before we can continue. This is only a partial list of all terms that will be used throughout this book, but these key words are important to know before we begin the main narrative of this text.

Time domain 

The concept of a domain is very important in mathematics, and is also very important in engineering. Depending on what domain you are in, there are different tools and techniques for analyzing circuits. The "Time domain" is simply another way of saying that our circuits change with time, and that the major variable used to describe the system is time. Another name is "Temporal".

Frequency domain

The frequency domain is a very commonly used method of describing the behavior of a circuit as functions of the frequency of the signals within it. Another name is the "Fourier domain". Other domains that an engineer might encounter are the "Laplace domain" (or the "s domain"), and the "Z domain". Sometimes is also indicated with the word "Spectral"

Circuit Response 

Circuits generally have inputs and outputs. In fact, it is safe to say that a circuit isn't useful if it doesn't have one or the other (usually both). The response to a circuit is the relationship between the circuit's input to the circuit's output. The circuit response may be a measure of either current or voltage.

Steady State 

When something changes in a circuit, there is a certain amount of transition period before a circuit "settles down", and reaches its final value. This final value, when all elements have a constant or periodic behaviour, is known as the steady-state value of the circuit. The circuit response at steady state (when things aren't changing) is also known as the "steady state response".

Transient Response 

The response that a circuit has before it settles on its steady-state response is known as the transient response.