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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 by an open circuit (i.e., the sources are set to provide zero voltages and currents).
The total resistance of this parallel arrangement is expressed by the following equation: 1/R total = 1/R a + 1/R b + ... + 1/R n. R a, R b, and R n are the resistances of the renal, hepatic, and other arteries respectively. The total resistance is less than the resistance of any of the individual arteries. [3]
A general formula for the current I X in a resistor R X that is in parallel with a combination of other resistors of total resistance R T (see Figure 1) is [1] = +, where I T is the total current entering the combined network of R X in parallel with R T.
Summarizing, for any truly ohmic device having resistance R, V/I = ΔV/ΔI = R for any applied voltage or current or for the difference between any set of applied voltages or currents. The I–V curves of four devices: Two resistors, a diode, and a battery. The two resistors follow Ohm's law: The plot is a straight line through the origin.
The Norton resistance R no is found by calculating the output voltage V o produced at A and B with no resistance or load connected to, then R no = V o / I no; equivalently, this is the resistance between the terminals with all (independent) voltage sources short-circuited and independent current sources open-circuited (i.e., each independent ...
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.
Source transformations are easy to compute using Ohm's law.If there is a voltage source in series with an impedance, it is possible to find the value of the equivalent current source in parallel with the impedance by dividing the value of the voltage source by the value of the impedance.
The best-known bridge circuit, the Wheatstone bridge, was invented by Samuel Hunter Christie and popularized by Charles Wheatstone, and is used for measuring resistance. It is constructed from four resistors, two of known values R 1 and R 3 (see diagram), one whose resistance is to be determined R x, and one which is variable and calibrated R 2.