International General Certificate of Secondary Education (IGCSE) Physics Practice Exam

One volt is defined as one joule per coulomb. This definition arises from the relationship between electrical potential difference, energy, and charge. In practical terms, it means that if one joule of energy is used to move one coulomb of electric charge between two points, the potential difference between those points is one volt. This definition is fundamental in understanding how electrical circuits operate, including the concepts of energy transfer and electric potential.

In circuits, when a device uses energy, this energy is quantified in joules and related to the amount of charge (in coulombs) that the device works with, establishing the voltage that drives the current through the circuit. Understanding this definition is essential for interpreting how voltage influences current flow and energy use in electrical systems.