Potential energy is indeed measured in joules, but for electrical potential energy is usually given in joules per-unit charge, or joules per coulomb which are volts. This gives additional meaning to the potential energy, as it is based on a specific amount of charge. If we have a charge of 1 coulomb (1C) at a potential of 5V, then it has 5J of energy. But if we have 2C of charge at a potential of 5V, then that charge has 10J of energy. The energy relation is given by
