Chapter 5 - Electrical Potential Energy and Electrical Potential

Abstract

This chapter illustrates that the electrical force on a charge q leads to electrical potential energy, denoted by U. The amount of electric potential energy equals the product of q and a quantity V called the electrical potential, whose unit is the volt. Just as for gravity, where only differences in the gravitational potential are meaningful, or electricity, only differences in the electrical potential are meaningful. Sometimes electrical potential energy is called merely electrical energy. There are two ways to consider electrical potential. (1) From the action-at-a-distance viewpoint, the electrical potential is obtained as a sum of the contributions from every electric charge, with the potential at infinity conventionally taken to be zero. This requires a complete knowledge of the positions and magnitudes of every charge. To obtain the electrical potential difference between two points thus requires the potential at both points. (2) From the field viewpoint, the electrical potential difference between those two points is obtained as an integral over the electric field along some path between them. The field viewpoint is particularly useful in describing real electrical conductors in equilibrium.