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In electrical engineering, impedance is the opposition to alternating current presented by the combined effect of resistance and reactance in a circuit. [1]Quantitatively, the impedance of a two-terminal circuit element is the ratio of the complex representation of the sinusoidal voltage between its terminals, to the complex representation of the current flowing through it. [2]
In the special case of entirely zero admittance or exactly zero impedance, the relations are encumbered by infinities. However, for purely-reactive impedances (which are purely-susceptive admittances), the susceptance is equal to the negative reciprocal of the reactance, except when either is zero. In mathematical notation:
In electrical circuits, reactance is the opposition presented to alternating current by inductance and capacitance. [1] Along with resistance, it is one of two elements of impedance; however, while both elements involve transfer of electrical energy, no dissipation of electrical energy as heat occurs in reactance; instead, the reactance stores energy until a quarter-cycle later when the energy ...
When a parallel-plate capacitor is filled with a dielectric, the measurement of dielectric properties of the medium is based upon the relation: = ′ ″ = = (), where a single prime denotes the real part and a double prime the imaginary part, Z(ω) is the complex impedance with the dielectric present, C cmplx (ω) is the so-called complex ...
The stub is made capacitive or inductive according to whether the main line presents an inductive or capacitive impedance, respectively. This is not the same as the actual impedance of the load since the reactive part of the load impedance will be subject to impedance transformer action and the resistive part.
For a generic multi-port network definition, it is assumed that each of the ports is allocated an integer n ranging from 1 to N, where N is the total number of ports. For port n , the associated Z-parameter definition is in terms of the port current and port voltage, I n {\displaystyle I_{n}\,} and V n {\displaystyle V_{n}\,} respectively.
In electrochemistry, faradaic impedance [1] [2] is the resistance and capacitance acting jointly at the surface of an electrode of an electrochemical cell.The cell may be operating as either a galvanic cell generating an electric current or inversely as an electrolytic cell using an electric current to drive a chemical reaction.
The complex generalization of resistance is impedance, usually denoted Z; it can be shown that for an inductor, = and for a capacitor, =. We can now write, V = Z I {\displaystyle V=Z\,I} where V and I are the complex scalars in the voltage and current respectively and Z is the complex impedance.