This is the universal constant for electron volt
In physics, the electron volt (symbol eV; also written electronvolt) is a unit of energy equal to approximately `1.6×10^−19` joule (symbol J). By definition, it is the amount of energy gained (or lost) by the charge of a single electron moved across an electric potential difference of one volt. Thus it is 1 volt (1 joule per coulomb, 1 J/C) multiplied by the elementary charge `(e, or 1.602176565(35)×10^−19 C)`.