The Electron Volt (eV) is a unit of Energy. It is a very small unit specifically designed for measuring energies at the atomic and subatomic level, where using Joules would result in inconveniently tiny numbers.
The electron volt is NOT an SI unit. The official SI unit of energy is the Joule (J). However, eV is a widely accepted and universally used unit in atomic, nuclear, and particle physics.
1 Electron Volt is defined as the amount of kinetic energy gained by a single electron when it is accelerated through a potential difference of 1 Volt in a vacuum.
Conversion to Joules:
1 eV = 1.6 × 10⁻¹⁹ Joules
This is an extremely small amount of energy by everyday standards, but it is perfect for describing energies in atoms, photons, and nuclear reactions.
In atomic and nuclear physics, energies are incredibly tiny. For example, the energy of a visible light photon is about 2-3 eV, which equals roughly 3-5 × 10⁻¹⁹ Joules — a horribly inconvenient number to write. Using eV simplifies calculations immensely.
Common multiples:
No. Despite having 'electron' in its name, the electron volt is a unit of **energy**, not charge. The unit of charge is the Coulomb (C).
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