i joule is equal to how many ev
In physics, the electronvolt (symbol eV, also written electron-volt and electron volt) is a unit of energy equal to approximately 1.6 × 10 joules (symbol J). By definition, it is the amount of energy gained (or lost) by the charge of a single electron moving 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 6981160217662079999 ♠ 1.602 176 6208 (98) × 10 C). Therefore, one electronvolt is equal to 6981160217662079999 ♠ 1.602 176 6208 (98) × 10 J. Historically, the electronvolt was devised as a standard unit of measure through its usefulness in electrostatic particle accelerator sciences because a particle with charge q has an energy E = qV after passing through the potential V; if q is quoted in integer units of the elementary charge and the terminal bias in volts, one gets an energy in eV.