(Of a circuit.) The greatest #0excludeGlossary (effective) difference of potential between any two conductors of the circuit concerned.
- Nominal:Â A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (as 120/240, 480Y/277, 600, et cetera). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment.
- Ground:Â For grounded circuits, the voltage between the given conductor and that point or conductor of the circuit that is grounded; for ungrounded circuits, the greatest voltage between the given conductor and any other conductor of the circuit.
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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. 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).
Voltage | |
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![]() 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 |
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). 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. Since it is the difference in electric potential, it is a physical scalar quantity.
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. 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.
English
Etymology
From volt + -age, ultimately derived from the name of Alessandro Volta, inventor of the modern battery.
Pronunciation
- (UK) IPA(key): /ˈvəʊltɪd͡ʒ/, /ˈvɒltɪd͡ʒ/
- (General American, Canada) IPA(key): /ˈvoʊltɪd͡ʒ/
- (General Australian) IPA(key): /ˈvəʉltɪd͡ʒ/, /ˈvɐʉltɪd͡ʒ/
- Rhymes: -əʊltɪdʒ, -ɒltɪdʒ
- Hyphenation: volt‧age
Noun
voltage (countable and uncountable, plural voltages)
- (electricity