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This expression extends to DC by letting tend to 0.. A surge of energy on a finite transmission line will see an impedance of prior to any reflections returning; hence surge impedance is an alternative name for characteristic impedance.
The equivalent voltage V th is the voltage obtained at terminals A–B of the network with terminals A–B open circuited. The equivalent resistance R th is the resistance that the circuit between terminals A and B would have if all ideal voltage sources in the circuit were replaced by a short circuit and all ideal current sources were replaced ...
An equivalent impedance is an equivalent circuit of an electrical network of impedance elements [note 2] which presents the same impedance between all pairs of terminals [note 10] as did the given network. This article describes mathematical transformations between some passive, linear impedance networks commonly found in electronic circuits.
A resistance equal to the slope of the v/i curve at the operating point (called the dynamic resistance), and tangent to the curve. A generator, because this tangent will not, in general, pass through the origin. With more terminals, more complicated equivalent circuits are required.
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]
To find the Norton equivalent of a linear time-invariant circuit, the Norton current I no is calculated as the current flowing at the two terminals A and B of the original circuit that is now short (zero impedance between the terminals). The Norton resistance R no is found by calculating the output voltage V o produced at A and B with no ...
Figure 4. These circuits are equivalent: (A) A resistor at nonzero temperature with internal thermal noise; (B) Its Thévenin equivalent circuit: a noiseless resistor in series with a noise voltage source; (C) Its Norton equivalent circuit: a noiseless resistance in parallel with a noise current source.
where A, B and C are the so-called Steinhart–Hart coefficients. This equation is used to calibrate thermistors. Extrinsic (doped) semiconductors have a far more complicated temperature profile. As temperature increases starting from absolute zero they first decrease steeply in resistance as the carriers leave the donors or acceptors.