electronvolt (eV)
1 electronvolt = 1.602177e-19 joules
What is electronvolt?
An electronvolt is a unit of energy equal to the work done on an electron by a potential difference of one volt, approximately 1.602 × 10⁻¹⁹ joules. It is used in atomic physics, particle physics, and quantum mechanics.
Notes: Atomic-scale energy
Real-world uses
The electronvolt is the standard energy unit in particle physics, atomic physics, and semiconductor science. X-ray photon energies are measured in keV; visible light photons in eV (about 1.8–3.1 eV); nuclear reactions in MeV; and particle accelerator energies in GeV or TeV.
History
The electronvolt came into use in the early 20th century with the development of quantum mechanics and experimental atomic physics. As physicists began measuring energies of electrons and photons, the eV provided a convenient unit far smaller than the joule but appropriate for subatomic-scale phenomena.
Common mistakes
Confusing the electronvolt with a unit of voltage—it is a unit of energy equal to the kinetic energy gained by one electron accelerated through a potential difference of one volt (1 eV = 1.602 × 10⁻¹⁹ J). Also mixing up the scale prefixes (keV, MeV, GeV, TeV) when discussing different physical phenomena.
When is this conversion used?
Electricity bills use kilowatt-hours while physics calculations use joules. Converting between them is essential for energy audits, comparing appliance efficiency, and understanding power consumption.
How to convert electronvolt to joule
To convert electronvolt to joule, multiply the value by 1.602177e-19.
Conversion formula (from base unit)
x * 1.602176634e-19
Measurement standards
The joule is the SI derived unit of energy, defined as one kilogram-metre-squared per second-squared (kg·m²/s²). The kilowatt-hour, equal to exactly 3.6 megajoules, is accepted for use with the SI by the BIPM for practical electricity metering.
Did you know?
A single bolt of lightning releases roughly 1 to 5 gigajoules of energy, yet only a small fraction reaches the ground as electrical current. Most of the energy dissipates as light, heat, and the thunder shockwave.
| electronvolts | joules |
|---|---|
| 0.1 | 1.602177e-20 |
| 0.5 | 8.010883e-20 |
| 1 | 1.602177e-19 |
| 2 | 3.204353e-19 |
| 5 | 8.010883e-19 |
| 10 | 1.602177e-18 |
| 25 | 4.005442e-18 |
| 50 | 8.010883e-18 |
| 100 | 1.602177e-17 |
| 250 | 4.005442e-17 |
| 500 | 8.010883e-17 |
| 1,000 | 1.602177e-16 |
Common values
| electronvolts | joules | |
|---|---|---|
| A food calorie (1 kcal) | 2.611447e+22 electronvolts | 4,184 joules |
| A AA battery | 5.842052e+22 electronvolts | 9,360 joules |
| Boiling a kettle | 2.621434e+24 electronvolts | 420,000 joules |
| Daily human diet (2000 kcal) | 5.222895e+25 electronvolts | 8,368,000 joules |
| 1 gallon of gasoline | 8.223812e+26 electronvolts | 131,760,000 joules |
Full electronvolt conversion table
| Unit | Value | Factor |
|---|---|---|
| joule | 1 eV = 1.602177e-19 J | × 1.602177e-19 |
| kilojoule | 1 eV = 1.602177e-22 kJ | × 1.602177e-22 |
| kilowatt hour | 1 eV = 4.450491e-26 kWh | × 4.450491e-26 |
| calorie (thermochemical) | 1 eV = 3.829294e-20 cal | × 3.829294e-20 |
| kilocalorie (dietary) | 1 eV = 3.829294e-23 kcal | × 3.829294e-23 |
| watt hour | 1 eV = 4.450491e-23 Wh | × 4.450491e-23 |
| megajoule | 1 eV = 1.602177e-25 MJ | × 1.602177e-25 |
| British thermal unit | 1 eV = 1.518570e-22 BTU | × 1.518570e-22 |
| therm (US) | 1 eV = 1.518933e-27 therm | × 1.518933e-27 |