Electrical Impedance


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Electrical impedance

The measure of the opposition that an electrical circuit presents to the passage of a current when a voltage is applied. In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current (ac) circuit.

A generalized ac circuit may be composed of the interconnection of various types of circuit elements. The impedance of the circuit is given by Z = V/I, where Z is a complex number given by Z = R + jX. R, the real part of the impedance, is the resistance of the circuit, and X, the imaginary part of the impedance, is the reactance of the circuit. The units of impedance are ohms. See Electrical resistance, Reactance

Impedance, Electrical

 

a quantity characterizing the opposition presented by a circuit to an alternating current. Often called simply impedance, it is measured in ohms. In the case of a sinusoidal alternating current, the impedance is expressed by the ratio of the amplitude of the voltage applied to the circuit terminals and the amplitude of the current throught the circuit; here, the impedance is equal to Impedance, Electrical, where r is the resistance and x is the reactance. In the case of a nonsinusoidal alternating current, the impedance is determined separately for each kth har monic component: Impedance, Electrical.

electrical impedance

[i′lek·trə·kəl im′pēd·əns]
Also known as impedance.
(electricity)
The total opposition that a circuit presents to an alternating current, equal to the complex ratio of the voltage to the current in complex notation. Also known as complex impedance.
The ratio of the maximum voltage in an alternating-current circuit to the maximum current; equal to the magnitude of the quantity in the first definition.
References in periodicals archive ?
At Least 5 Of These Channels Must Have Electrical Impedance Spectroscopy Capability (Eis).
"The first technology we developed was the through vial impedance spectroscopy technique - which enables the application of electrical impedance measurements to the product container during the process of freeze-drying - in a development scale freeze-dryer.
* Electrical impedance spectroscopy (EIS), which uses an electrical alternating current to detect the electrical resistance of potentially cancerous tissue, generates a score with a high negative predictive value and a higher positive predictive value as the score increases.
The test stands also allow the capture of the seals' electrical impedance at a wide range of frequencies.
Among their topics are the influence of temperature on the impedance of premium summer diesel fuel measured with the use of impedance spectroscopy, a mixed-level simulation tool for optimizing the design of electrical impedance spectroscopy systems, modeling to improve the performance of non-contacting capacity sensors for detecting aqueous solutions, a carbon-nanotube-enhanced carbon electrode for detecting nitrite and analyzing water, and a method of intra-ventricular bioimpedance spectroscopy to estimate the dynamic volume of the right ventricle.
The electrical impedance for 2% bentonite ultra soft soil reduced from 2.67 k.Ohm to 1.71 k.Ohm when the current frequency was increased from 0.02 kHz to 300 kHz.
On the other hand, after I showed my arrangement for measuring the electrical impedance of biomass under compression to a captain-of-industry friend, he looked at me and said, "I bet there are fifty applications for this.
We noted that the filled composite material exhibited a nonlinear decrease of the electrical impedance as a function of the filler concentration.
"This deal supports our global aspirations of introducing ZedScan and our proprietary Electrical Impedance Spectroscopy (EIS) technology into emerging markets."
On the contrary, electrical impedance spectroscopy (EIS) is a fast, low cost, and nondestructive method which is found to offer insight into plant physiology and physiological dynamics due to environmental impacts.
The volume-averaged electrical impedance of the spatial area sandwiched between the transmitter and receiver wires correlates with the electrical conductivity of this test area.

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