What is the unit used to measure the quantity of electric charge?

The quantity of electric charge is measured in coulombs. A coulomb represents a specific amount of electric charge, defined as the charge transported by a constant current of one ampere in one second. This unit is foundational in understanding electric charge and is used to quantify the amount of charge that flows in a circuit.

Understanding coulombs helps in connecting the concepts of current (which is measured in amperes) and time (in seconds) to the total charge. Therefore, when assessing electric interactions or behaviors in circuits, recognizing that a coulomb is the standard measure is crucial for applying further calculations related to electricity, such as those involving current or voltage.

In contrast, a volt is a measure of electric potential, an ampere measures electric current, and a joule is a unit of energy. Each of these other units plays important roles in the study of electricity, but they do not represent electric charge directly.