If voltage is defined as energy per charge, how is it quantified?

Voltage, also known as electric potential difference, is quantified as the amount of energy transferred per unit of charge. This is expressed in terms of joules per coulomb, which is the definition of a volt. When we say that voltage is the energy transfer per charge, it means that for every coulomb of charge that moves through an electrical potential difference of one volt, one joule of energy is transferred.

This understanding is essential in electrical circuits, where voltage drives the flow of current (the movement of charge) and determines how much energy each coulomb carries. Thus, the correct quantification of voltage directly relates to how many joules are transferred for each coulomb of charge, which corresponds precisely to the correct choice.