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Practical impedance-matching devices will generally provide best results over a specified frequency band. The concept of impedance matching is widespread in electrical engineering, but is relevant in other applications in which a form of energy, not necessarily electrical, is transferred between a source and a load, such as in acoustics or optics.
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]
The transformation ratio is the ratio of the input and output impedances of the impedance matching network. The series-parallel transformation allows the input impedance to be dropped down to lower impedances while sustaining a voltage across the circuit. This system works in reverse as well.
Equivalent unbalanced and balanced networks. The impedance of the series elements in the balanced version is half the corresponding impedance of the unbalanced version. Fig. 3. To be balanced, a network must have the same impedance in each "leg" of the circuit. A 3-terminal network can also be used as a 2-port.
On the other hand, it might merely change the form into one in which the components can be reduced in a later operation. For instance, one might transform a voltage generator into a current generator using Norton's theorem in order to be able to later combine the internal resistance of the generator with a parallel impedance load.
Dual Miller theorem actually expresses the fact that connecting a second current source producing proportional current = in parallel with the main input source and the impedance element changes the current flowing through it, the voltage and accordingly, the circuit impedance seen from the side of the input 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.
If the light bulbs are connected in parallel, the currents through the light bulbs combine to form the current in the battery, while the voltage drop is 12 volts across each bulb and they all glow. In a series circuit, every device must function for the circuit to be complete. If one bulb burns out in a series circuit, the entire circuit is broken.