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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 ...
The reactance and susceptance are only reciprocals in the absence of either resistance or conductance (only if either R = 0 or G = 0, either of which implies the other, as long as Z ≠ 0, or equivalently as long as Y ≠ 0).
In practice, capacitors deviate from the ideal capacitor equation in several aspects. Some of these, such as leakage current and parasitic effects are linear, or can be analyzed as nearly linear, and can be accounted for by adding virtual components to form an equivalent circuit. The usual methods of network analysis can then be applied. [34]
where C is the capacitance of the capacitor. Solving this equation for V yields the formula for exponential decay: =, where V 0 is the capacitor voltage at time t = 0. The time required for the voltage to fall to V 0 / e is called the RC time constant and is given by, [1]
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]
Reactance is the imaginary part of the complex electrical impedance.Both capacitors and inductors possess reactance (but of opposite sign) and are frequency dependent. The specification that the network must be passive and lossless implies that there are no resistors (lossless), or amplifiers or energy sources (passive) in the network.
The two-element LC circuit described above is the simplest type of inductor-capacitor network (or LC network). It is also referred to as a second order LC circuit [ 1 ] [ 2 ] to distinguish it from more complicated (higher order) LC networks with more inductors and capacitors.
By changing the value of the example in the diagram by a capacitor with a value of 330 nF, a current of approximately 20 mA can be provided, as the reactance of the 330 nF capacitor at 50 Hz calculates to = and applying Ohm's law, that limits the current to . This way up to 48 white LEDs in series can be powered (for example, 3.1 V/20 mA/20000 ...