Final answer:
Electric potential energy per unit charge is called potential difference or voltage, measured in volts (V), which is equivalent to joules per coulomb (J/C).
Step-by-step explanation:
The electric potential energy per unit charge, measured in joules per coulomb (J/C), is known as potential difference or voltage. This concept is analogous to gravitational potential energy, where it represents the potential that charges have to do work due to their positions relative to each other. Electric potential, voltage, and electric potential difference all refer to the same concept; the term used may depend on the context.
The unit for electric potential is the volt (V), named after the Italian physicist Alessandro Volta. A potential difference (also known as voltage) of 1 volt implies that 1 joule of work is done when moving a charge of 1 coulomb from one point to another in an electric field. The formula for the electric potential difference between points A and B is VB - VA, which represents the change in potential energy (ΔUE) of a charge q moved from point A to point B, divided by the charge.