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3.1: Prelude to Electric Potential
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Two terms commonly used to describe electricity are its energy and voltage, which we show in this chapter is directly related to the potential energy in a system. We know, for example, that great amounts of electrical energy can be stored in batteries, are transmitted cross-country via currents through power lines, and may jump from clouds to explode the sap of trees. In a similar manner, at the molecular level, ions cross cell membranes and transfer information.
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3.2: Electric Potential Energy
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When a free positive charge q is accelerated by an electric field, it is given kinetic energy (Figure). The process is analogous to an object being accelerated by a gravitational field, as if the charge were going down an electrical hill where its electric potential energy is converted into kinetic energy, although of course the sources of the forces are very different.
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3.3: Electric Potential and Potential Difference
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Electric potential is potential energy per unit charge. The potential difference between points A and B, VB−VA, that is, the change in potential of a charge q moved from A to B, is equal to the change in potential energy divided by the charge. Potential difference is commonly called voltage, represented by the symbol ΔV.