The electron volt (eV) is the work done in moving one electron through a potential difference of 1 volt.
If 1 Coulomb of charge is moved through a potential difference of 1 volt then 1 Joule of work is done.
Since the charge on the electron is
The erg is an obsolete, non-SI unit for energy. It has the units
It's a very small unit. According to Wiki it's the energy equivalent of a fly doing a push-up.