The electron volt (eV) is a unit of energy commonly used in atomic and nuclear physics. It is defined as the kinetic energy gained or lost by an electron when it moves through an electric potential difference of one volt.

1. Definition: $1 \text{ eV} = 1.602 \times 10^{-19} \text{ J}$ .
2. Comparison:

• Charge: Unit is Coulomb (C).
• Potential Difference: Unit is Volt (V).
• Momentum: Unit is $kg \cdot m/s$.
• Energy: Unit is Joule (J), Erg, Calorie, or Electron volt (eV) .