Please note that the volt and voltage are two different things. The volt is a unit by which we measure something. Both electric potential and voltage are things we measure and the volt is the unit of measure for both. Yes, a little confusing, but that is the way it is. The symbol for the unit volt is written with a V (9 volts or 9 V). When voltage is used in a formula the symbol for voltage is a lowercase v. ( e.g. voltage = current x resistance or v = ir) This distinguishes the difference between volts (V) and voltage (v) when there is only a single letter symbol to go by. Electrical engineers use the symbol 'e' for voltage (e.g. e=ir) to distinguish the difference more clearly.