What is the sum of the difference in potential of all charges in an electrostatic field called?

The sum of the difference in potential of all charges in an electrostatic field is referred to as electromotive force (EMF). This term specifically describes the potential difference generated by a source such as a battery or generator that can cause an electric current to flow in a circuit.

Electromotive force is typically measured in volts and encapsulates the energy per unit charge provided by the source to move charges through a circuit. It represents the work done by the electrical energy source to create a difference in potential.

The other options, while related to electricity, point to different concepts. For instance, current refers to the flow rate of electric charge and resistance describes how much a device opposes the flow of current. Voltage, on the other hand, measures the potential difference between two points but does not account for the overall work done by the source in establishing the electric field. Thus, understanding EMF is key to grasping how energy is imparted to charges in the context of electric circuits.