What is voltage defined as?

Voltage is defined as a force that causes current to flow through a conductor. It represents the potential difference between two points in an electrical circuit, which drives the movement of electric charge. When there is a difference in voltage, it creates an electric field that pushes electrons from the negative terminal to the positive terminal, resulting in a flow of current. This is analogous to water pressure in a plumbing system; just as higher pressure pushes water through pipes, higher voltage pushes electric charge through a circuit.

The other options do not accurately represent the definition of voltage. For instance, a measure of current flow pertains to current itself, while electrical resistance refers to the opposition to the flow of current. Circuit protection relates to devices designed to safeguard electrical systems from overload or faults, but it doesn't define what voltage is. Thus, understanding voltage as a driving force in an electrical system is crucial for grasping the foundations of electricity and circuit design.