College Physics III – Thermodynamics, Electricity, and Magnetism
Definition
An electron-volt (eV) is a unit of energy equal to approximately $1.602 \times 10^{-19}$ joules. It is the amount of kinetic energy gained or lost by an electron when it moves through an electric potential difference of one volt.
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Electron-volts are commonly used in atomic and subatomic processes such as ionization and radiation.
The relationship between electron-volts and voltage is defined by the equation $E = qV$, where $q$ is the charge of the electron and $V$ is the potential difference.
Electron-volts are often used to measure energy levels in atoms, particularly in quantum mechanics.
In particle physics, larger units such as mega-electron volts (MeV) and giga-electron volts (GeV) are frequently used.
Review Questions
What is the equivalent of one electron-volt in joules?
How is energy measured in electron-volts related to electric potential difference?
Why are electron-volts commonly used in atomic and subatomic physics?
A unit of electric potential or electromotive force, defined as the difference in potential that would drive one ampere of current against one ohm resistance.
A derived unit of energy in the International System of Units, equal to the energy transferred when applying a force of one newton over a distance of one meter.