|In this diagram a positive test charge +q is situated between two oppositely charged plates. Because of the charge on the plates, the test charge will undergo an electric force from the + plate (directed to the - plate). The hand in the drawing is providing the external force required to move the test charge towards the + plate (neglect gravitational potential energy) because of the electric force (like charges repel).
At locations A and B, the test charge q has electric potential energies. The electric potential difference (V) is the work done per unit charge as a charge is moved between two points in an electric field.
The SI unit of electric potential: joule/coulomb = volt (V).
Note: Electric potential difference uses the variable V as well as the unit volt. Do not refer to electric potential as Volts (even though the units are volts). When you use V in this situation it stands for electric potential.