Electron Volt to Joules Converter
Precise energy conversion between eV and J for physics calculations
Quick Conversions
Conversion Result
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Conversion Formula
From Electron Volts to Joules:
From Joules to Electron Volts:
The electron volt represents the amount of kinetic energy gained by a single electron when accelerated through an electric potential difference of one volt in vacuum [web:1][web:7]. The precise conversion factor, 1.602176634 × 10-19, is derived from the elementary charge constant and is officially defined by NIST [web:8][web:10].
Conversion Steps
Determine the energy value you want to convert (e.g., 5 eV).
Use the constant 1.602176634 × 10-19 to convert to joules.
Perform the multiplication: 5 eV × 1.602176634 × 10-19 = 8.01088317 × 10-19 J.
For very small values, scientific notation provides clarity and precision.
Quick Reference Table
| Electron Volts (eV) | Joules (J) | Scientific Notation |
|---|---|---|
| 1 eV | 0.0000000000000000001602 J | 1.602 × 10-19 J |
| 10 eV | 0.000000000000000001602 J | 1.602 × 10-18 J |
| 100 eV | 0.00000000000000001602 J | 1.602 × 10-17 J |
| 1 keV (1,000 eV) | 0.0000000000000001602 J | 1.602 × 10-16 J |
| 10 keV | 0.000000000000001602 J | 1.602 × 10-15 J |
| 100 keV | 0.00000000000001602 J | 1.602 × 10-14 J |
| 1 MeV (1,000,000 eV) | 0.0000000000001602 J | 1.602 × 10-13 J |
| 10 MeV | 0.000000000001602 J | 1.602 × 10-12 J |
| 100 MeV | 0.00000000001602 J | 1.602 × 10-11 J |
| 1 GeV (1,000,000,000 eV) | 0.0000000001602 J | 1.602 × 10-10 J |
Common Energy Values
These common energy values in atomic and nuclear physics demonstrate why electron volts are preferred over joules [web:3][web:5]. The numbers are more manageable when expressed in eV rather than the extremely small joule equivalents.
Real-World Applications
Atomic Physics
Electron volts measure atomic electron binding energies and ionization potentials. The hydrogen ground state electron has an energy of -13.6 eV.
Particle Accelerators
Large Hadron Collider operates at 13 TeV (13 trillion eV), accelerating protons to near light speed for collision experiments.
Semiconductor Physics
Band gaps in semiconductors are measured in eV. Silicon has a band gap of 1.1 eV, determining its electronic properties.
Medical Imaging
X-ray and CT scan energies range from 20-150 keV, providing the penetration needed for medical diagnostics.
Photovoltaics
Solar cell efficiency depends on matching photon energies (measured in eV) to semiconductor band gaps for optimal conversion.
Spectroscopy
Photon energies in spectroscopy are expressed in eV to analyze atomic transitions and molecular structures.
Why Use Electron Volts?
The electron volt emerged as a preferred energy unit in atomic and subatomic physics because it provides practical numerical values [web:6]. When working with individual particles and quantum phenomena, energies expressed in joules become inconveniently small, requiring negative exponents of 19 or greater.
Scale Comparison
Consider the ionization energy of hydrogen: 13.6 eV versus 2.18 × 10-18 joules. The eV value is immediately comprehensible, while the joule value requires scientific notation and careful tracking of decimal places. This practical advantage makes eV the standard unit in particle physics, atomic physics, and related fields [web:4][web:5].
Multiple Unit Conversions
| Unit Name | Symbol | Equivalent in eV | Equivalent in J |
|---|---|---|---|
| Electron Volt | eV | 1 | 1.602 × 10-19 |
| Kiloelectron Volt | keV | 1,000 | 1.602 × 10-16 |
| Megaelectron Volt | MeV | 1,000,000 | 1.602 × 10-13 |
| Gigaelectron Volt | GeV | 1,000,000,000 | 1.602 × 10-10 |
| Teraelectron Volt | TeV | 1,000,000,000,000 | 1.602 × 10-7 |
Frequently Asked Questions
What is an electron volt?
An electron volt is the amount of kinetic energy gained or lost by a single electron accelerating through an electric potential difference of one volt. It equals 1.602176634 × 10-19 joules and is the standard energy unit in atomic and particle physics.
How do you convert eV to joules?
Multiply the electron volt value by 1.602176634 × 10-19. For example, 5 eV × 1.602176634 × 10-19 = 8.01088317 × 10-19 joules. This conversion factor comes from the elementary charge constant.
Why is eV smaller than joule?
The electron volt is designed for atomic-scale measurements where energies are extremely small. One eV equals approximately 0.0000000000000000001602 joules. This makes eV more practical for expressing energies of individual particles and photons.
When should I use eV instead of joules?
Use eV when working with atomic physics, nuclear physics, particle physics, or quantum mechanics. Use joules for macroscopic energy measurements, mechanical systems, thermodynamics, and general physics calculations where SI units are standard.
What is the relationship between voltage and eV?
One electron volt is the energy change when an electron moves through a potential difference of exactly one volt. The relationship is: Energy (eV) = Charge (in elementary charges) × Potential Difference (V). For one electron, the charge equals 1 elementary charge.
How accurate is the conversion factor?
The conversion factor 1.602176634 × 10-19 J/eV is exact by definition as of the 2019 SI redefinition. The elementary charge was fixed at this value, making all eV to joule conversions precisely determinable.
What are keV, MeV, and GeV?
These are multiples of electron volts: keV (kiloelectron volt) = 1,000 eV, MeV (megaelectron volt) = 1,000,000 eV, and GeV (gigaelectron volt) = 1,000,000,000 eV. They are used for higher-energy phenomena like X-rays (keV), nuclear reactions (MeV), and particle accelerators (GeV).
Can photons be measured in electron volts?
Yes, photon energies are commonly expressed in eV. The relationship is E = hf, where h is Planck’s constant and f is frequency. Visible light photons range from 1.8-3.1 eV, while X-ray photons range from 1-100 keV.
References
1. BYJU’S. “Relation Between eV and Joule.” Physics Education Resources.
2. RapidTables. “Electron-volts to Joules Conversion.” Energy Conversion Reference.
3. Testbook. “eV to Joule – Definition, Conversion Formula & Real-Life Applications.” Physics Reference Guide, 2022.
4. Einstein Online. “Electron Volt.” Physics Dictionary, Max Planck Institute for Gravitational Physics, 2015.
5. National Institute of Standards and Technology (NIST). “Fundamental Physical Constants – Complete Listing.” Physics Laboratory, 2024.
6. Britannica, The Editors of Encyclopaedia. “Electron Volt.” Encyclopedia Britannica, 1998.