Electron volt is defined as the amount of energy one electron gains by moving through a potential difference of one volt. Hence, one electron volt is equal to elementary charge (1.60217657 × 10^{-19 }coulombs (C)) multiplied by one volt. It can be written as

ev = (1.60217657 × 10^{-19} C) (1V)

**Therefore, 1ev = 1.60217657 × 10**^{-19} J.