An electronvolt (eV) is a unit of energy commonly used in atomic, nuclear, and particle physics to measure the energy carried by individual particles and electromagnetic radiation. It’s a convenient unit because the energies involved in these fields are much smaller than those we encounter in everyday life.
- Electronvolts can be used to measure the energy of elementary particles, including photons, which are the smallest units of electromagnetic radiation (quanta of the electromagnetic field).
- One electronvolt is equal to the energy gained by a single electron when it is accelerated across a potential difference of 1 volt.
- Photons (quanta of light) travelling through this same potential difference would also gain 1 eV of energy.
- The electronvolt is not part of the SI unit system. The SI unit for energy is the joule (J). However, joules are too large for many particle-level interactions.
- 1 electronvolt (eV) is equivalent to approximately 1.602 x 10^-19 joules (J).