Units for electric potential and fields
Previously, we noted that electric forces are in Newtons (N), electric potential energies are in Joules (J), and charge is measured in Coulombs (C). Since electric fields and potentials are obtained by dividing the force and potential energy, respectively, by the charge they are measured in units of (N/C) and (J/C) respectively. But a "Joule per Coulomb" is also known as a volt (V), and the electric potential can also be referred to as the voltage. The Electric field can also be noted in units of volts per meter (V/m).
Units
Electric field |
V/m |
N/C |
Electric potential |
V |
J/C |
Force |
CV/m |
N |
Potential Energy |
CV |
J |
A convenient unit of electric potential energy is the electron volt (eV). One electron volt is the potential energy change of moving one electron's worth of charge, e, through one volt. One electron volt equals 1.602E-19 (J). This unit is a convenient for describing microscopic physics, such as the energy of an electron in an atom. Related units are keV, MeV, GeV, and TeV, which represent 103, 106, 109, and 1012 eV. These units will be used in nuclear and particle physics later in the semester.