Electrical element

To model the nonideal behavior of a real circuit component may require a combination of multiple ideal electrical elements to approximate its function.

One is how many terminals they have to connect them to other components: Elements can also be divided into active and passive: Another distinction is between linear and nonlinear: Only nine types of element (memristor not included), five passive and four active, are required to model any electrical component or circuit.

[2] Each element is defined by a relation between the state variables of the network: current,

In reality, all circuit components are non-linear and can only be approximated as linear over a certain range.

To describe the passive elements more precisely, their constitutive relation is used instead of simple proportionality.

This is the case for all linear elements, but also, for example, an ideal diode, which in circuit theory terms is a non-linear resistor, has a constitutive relation of the form

[3] The fourth passive element, the memristor, was proposed by Leon Chua in a 1971 paper, but a physical component demonstrating memristance was not created until thirty-seven years later.

It was reported on April 30, 2008, that a working memristor had been developed by a team at HP Labs led by scientist R. Stanley Williams.

Two lossless, passive, linear two-port elements are typically introduced into network analysis.

Networks built from just the basic linear elements are necessarily reciprocal, so they cannot be used by themselves to represent a non-reciprocal system.

However, transformer, capacitance, and inductance are normally retained in analysis because they are the ideal properties of the basic physical components transformer, inductor, and capacitor, whereas a practical gyrator must be constructed as an active circuit.