Editing Electrical element (section)

==Types==
Circuit elements can be classified into different categories. One is how many terminals they have to connect them to other components:
* '''''One-port elements'''''{{snd}} represent the simplest components, with only two terminals to connect to. Examples are 
** [[Electrical resistance and conductance|resistances]], 
** [[capacitance]]s, 
** [[inductance]]s, 
** and [[diode]]s.
* '''''Two-port elements'''''{{snd}} are the most common multiport elements with four terminals consisting of two ports.
* '''''Multiport elements'''''{{snd}}these have more than two terminals.  They connect to the external circuit through multiple pairs of terminals called [[port (circuit theory)|port]]s. For example, 
** a [[transformer]] with three separate windings has six terminals and could be idealized as a three-port element; the ends of each winding are connected to a pair of terminals representing a port.

Elements can also be divided into active and passive:

* '''''Passive elements'''''{{snd}}These elements do not have a source of energy; examples are 
** diodes, 
** resistances, 
** capacitances, 
** and inductances.

* '''''Active elements''''' or '''''sources'''''{{snd}}these are elements which can source electrical [[Electric power|power]]. They can be used to represent ideal [[battery (electricity)|batteries]] and [[power supply|power supplies]]; examples are 
** [[voltage source]]s 
** and [[current source]]s. 
*** '''''Dependent sources'''''{{snd}}These are two-port elements with a voltage or current source proportional to the [[voltage]] or [[Electric current|current]] at a second pair of terminals. These are used in the modelling of [[amplifier|amplifying]] components such as
**** [[transistor]]s, 
**** [[vacuum tube]]s, 
**** and [[op-amp]]s.

Another distinction is between linear and nonlinear:
* '''''Linear elements'''''{{snd}}these are elements in which the constituent relation, the relation between voltage and current, is a [[linear function]]. They obey the [[superposition principle]]. Examples of linear elements are resistances, capacitances, inductances, and linear-[[dependent source]]s. [[Electrical network|Circuits]] with only linear elements, [[linear circuit]]s, do not cause [[intermodulation distortion]] and can be easily analysed with powerful mathematical techniques such as the [[Laplace transform]].
* '''''Nonlinear elements'''''{{snd}}these are elements in which the relation between voltage and current is a [[nonlinear function]]. An example is a [[diode]], where the current is an [[exponential function]] of the voltage. Circuits with nonlinear elements are harder to analyse and design, often requiring [[circuit simulation]] computer programs such as [[SPICE]].