The unit for potential energy per unit charge, or voltage, is the volt, which has the symbol "V." It takes its name from the Italian physicist Alessandro Volta, credited with inventing one of the first electric batteries.Voltage refers to the work that would be necessary for each unit charge against the existing electric field to move a charge from Point A to Point B. One volt is the equivalent of multiplying one ampere (a unit of current) by one ohm (a unit of resistance). To get the power in terms of watts, it is necessary to multiply the voltage by the current in amps.