What is the volt, in electrical terms?

• A. The unit of electrical resistance
• B. A measurement of current
• C. The unit of electrical potential
• D. The symbol for power

Answer: (C)

The volt is the unit of electric potential difference, the “pressure” that pushes charges through a circuit. One volt means that each coulomb of charge would gain or lose one joule of energy as it moves between two points with that potential difference. In circuits, this potential difference drives current through conductors, and how much current flows depends on the resistance: I = V / R. So the volt measures energy per charge, while current is the flow of charge and resistance is what resists that flow. The volt is symbolized by V. For example, a 5-volt source across a 2-ohm resistor would push 2.5 amperes of current (I = V/R = 5/2). This distinguishes it from the unit of resistance (ohm), the unit of current (ampere), and power (watt).