Voltage

Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to move a test charge between the two points. In the International System of Units, the derived unit for voltage is named volt.[1]:166

Voltage
Batteries are sources of voltage in many electric circuits.
Common symbols
V , V , U , U
SI unitvolt
In SI base unitskg⋅m2⋅s−3⋅A−1
Derivations from
other quantities
Voltage = Energy / charge
DimensionM L2 T−3 I−1

The voltage between points can be caused by the build-up of electric charge (e.g., a capacitor), and from an electromotive force (e.g., electromagnetic induction in generator, inductors, and transformers).[2][3] On a macroscopic scale, a potential difference can be caused by electrochemical processes (e.g., cells and batteries), the pressure-induced piezoelectric effect, and the thermoelectric effect.

A voltmeter can be used to measure the voltage between two points in a system. Often a common reference potential such as the ground of the system is used as one of the points. A voltage can represent either a source of energy or the loss, dissipation, or storage of energy.