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Voltage
Batteries are sources of voltage in many electric circuits.
Common symbols	V , ∆V , U , ∆U
SI unit	volt
In SI base units	kg⋅m2⋅s−3⋅A−1
Derivations from other quantities	Voltage = Energy / charge
Dimension	${\displaystyle {\mathsf {M}}{\mathsf {L}}^{2}{\mathsf {T}}^{-3}{\mathsf {I}}^{-1}}$

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Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points.^[1][2] In a static electric field, it corresponds to the work needed per unit of charge to move a positive test charge from the first point to the second point. In the International System of Units (SI), the derived unit for voltage is the volt (V).^[3][4][5]

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 a generator).^[6][7] On a macroscopic scale, a potential difference can be caused by electrochemical processes (e.g., cells and batteries), the pressure-induced piezoelectric effect, photovoltaic effect, and the thermoelectric effect. Since it is the difference in electric potential, it is a physical scalar quantity.^[8]

A voltmeter can be used to measure the voltage between two points in a system.^[9] Often a common reference potential such as the ground of the system is used as one of the points. In this case, voltage is often mentioned at a point without completely mentioning the other measurement point. A voltage can be associated with either a source of energy or the loss, dissipation, or storage of energy.