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Electron volt
Beginner
Energy gained by an electron across one volt.
1 eV = 1.6×10⁻¹⁹ J1 eV is the energy gained by an electron moving through 1 V: 1.602×10⁻¹⁹ J. Convenient for atomic and particle physics.
Visible photons have 1.8–3.1 eV; a hydrogen ionisation is 13.6 eV.
It's an energy unit, not a voltage.
In more detail
An electron volt is the energy gained by an electron moving through a potential difference of one volt, about 1.6 × 10⁻¹⁹ J. It is a convenient unit for atomic and particle energies.
Real-world uses
- Particle accelerators quote energies in electron volts, such as GeV.
- Semiconductor band gaps are given in electron volts.
- Physicists use the electron volt as a convenient energy unit for atoms, electrons and particle accelerators.
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Frequently asked questions
How many joules are in an electron volt?
About 1.6 × 10⁻¹⁹ joules.
Why not use joules?
Atomic energies are tiny in joules, so electron volts give more convenient numbers.
How many joules are in an electron volt?
About 1.6 times ten to the power minus 19 joules, the energy gained by an electron across one volt.
Related topics in Electrostatics
Potential difference · Equipotential surfaces · Relation of E and V · Potential energy of charges · Capacitor · Parallel-plate capacitor