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1.2 Voltage (V) and Electric Field (E) 3 1.2 Voltage (V) and Electric Field (E) Most Electronic Engineers are familiar with voltages and with the way they are used to represent the behaviour of AC and DC electrical circuits. One should not forget however that Voltage is also called Electric Potential and it represents the potential energy (per unit charge) associated with electric forces. The Electric Potential Energy is analogous to the Gravitational Potential Energy. This is illustrated by the example below Figure 1.2-1 Water analogy Just as the pumping of water to a higher level results in energy being stored, "pumping" electrons to create an electric charge imbalance results in a certain amount of energy being stored in that imbalance. And, just as providing a way for water to flow back down from the heights of the reservoir results in a release of that stored energy, providing a way for electrons to flow back to their original "levels" results in a release of stored energy. When the electrons are poised in that static condition (up in the reservoir), the energy stored there is called potential energy, because it has the possibility (potential) to be released and do some work. This potential energy, stored in the form of an electric charge imbalance and capable of provoking electrons to flow through a conductor, is often expressed in terms of voltage, which is a measure of potential energy per unit charge of electrons. We cannot assess the amount of stored energy in a water reservoir simply by measuring the volume of water, we must also consider how far it will drop from its initial height. Likewise, the potential energy available for moving electrons from one point to another is relative to those two points. Therefore, voltage is always expressed as a quantity between two points. The analogy of a mass potentially "dropping" from one height to another is why the voltage between two points is sometimes called a voltage drop. Such a voltage drop ΔV may be expressed mathematically as shown by equation (1.2-1) Conquer Radio Frequency 3 www.cadence.com/go/awr

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