When two positive charges or two negative charges are got near to each other they repel each other while the positive and negative charge are attracted to each other. Then the charged particle has the ability to do work.
The ability of a charged particle to do work is called an Electric Potential.
“The potential difference between two points is one volt if one joule of work is done displacing one coulomb of charge”
Thus two dissimilar charges have a difference of potential and the unit of potential difference (pd) is called the volt. The volt unit of potential difference named after Alessandro Volta (1745–1827), involves work which is the measure of the amount of work required to move an electric charge which in turn involves force and distance.
The SI unit of work is the joule with unit symbol J, the SI unit of force is the newton with unit symbol N, and the SI unit for distance is the meter with unit symbol m.
W (joules) = N (newtons) x m (meters)
Energy is the capacity to do work. Potential energy which is the energy a body has because of its physical position.
Symbol of Potential Difference
In electronics theory, potential difference is normally referred to as voltage with the symbol V. Sometimes the symbol U or E for emf (electromotive force) is used but the standard voltage symbol V represents potential difference.
This applies either to the voltage generated by a source such as a battery or solar cell or to the voltage dropped across a passive component such as a resistor.
The voltage difference also called potential difference between two points is the work in joules required to move one coulomb of charge from one point to the other. The SI unit of voltage is the volt and is given as:
V (volts)= is the Voltage in Volts
W (joules)= is the Work done
Q (coulombs)= Total Charge passing a fixed point