Beatrice Lang
The volt (V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). In other words, it is the potential difference between two points that will impart one joule of energy per coulomb of charge that passes through it. The volt is named after the Italian physicist Alessandro Volta, who invented the voltaic pile, a forerunner of the battery. Voltage, also known as electric pressure, is the difference in electric potential between two points. It is often used interchangeably with the term potential difference. The greater the voltage in a circuit, the greater its ability to push more electrons and do work.
| Characteristics | Values |
|---|---|
| Full Form | Volt |
| Symbol | V |
| Unit of | Electric potential, electric potential difference (voltage), and electromotive force |
| Definition | Electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points |
| SI Base Units | m, kg, s, and A |
| SI Base Units Expression | 1 V = 1 kg times m2 times s-3 times A-1 (kilogram meter squared per second cubed per ampere) |
| Other Names | Electrical tension, electric pressure, electromotive force |
| Volt Named After | Italian physicist Alessandro Volta |
| Examples | Household AA alkaline battery (1.5 V), Typical household electrical outlets (120 V) |
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What You'll Learn
The volt (V) is the unit of electric potential
In 1881, the International Electrical Congress, now the International Electrotechnical Commission (IEC), approved the volt as the unit for electromotive force. They chose a ratio of 108 cgs units of voltage for one volt because the cgs unit of voltage is inconveniently small. One volt is approximately the emf of a Daniell cell, the standard source of voltage in the telegraph systems of the time.
A volt can be defined as the electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points. It can be expressed in terms of SI base units (m, kg, s, and A) as:
> {\displaystyle {\text{V}}={\frac {\text{power}}{\text{electric current}}}={\frac {\text{W}}{\text{A}}}={\frac {{\text{kg}}{\cdot }{\text{m}}^{2}{\cdot }{\text{s}}^{-3}}{\text{A}}}={\text{kg}}{\cdot }{\text{m}}^{2}{\cdot }{\text{s}}^{-3}{\cdot }{{\text{A}}^{-1}}.}
Equivalently, it is the potential difference between two points that will impart one joule of energy per coulomb of charge that passes through it. Voltage is the pressure from an electrical circuit's power source that pushes charged electrons (current) through a conducting loop, enabling them to do work such as illuminating a light. 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.
The volt is also used to measure reactive power, which is the power needed in capacitors and inductors to create electric and magnetic fields.
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Voltage is the pressure from an electrical circuit
Voltage, also known as electric potential difference, electric pressure, or electric tension, is the pressure from an electrical circuit that pushes charged electrons (current) through a conducting loop, enabling them to do work. It 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 one point to another. Voltage is measured in volts (V), which is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI).
The volt is named in honour of the Italian physicist Alessandro Volta (1745-1827), who invented the voltaic pile, possibly the first chemical battery. In 1861, Latimer Clark and Sir Charles Bright coined the term "volt" for the unit of resistance. By 1873, the British Association for the Advancement of Science had defined the volt, ohm, and farad. In 1881, the International Electrotechnical Commission (IEC) approved the volt as the unit for electromotive force.
The voltage produced by each electrochemical cell in a battery is determined by the chemistry of that cell. Cells can be combined in series for multiples of that voltage, or additional circuitry can be added to adjust the voltage to a different level. Voltage can be compared to water stored in a tank. The larger the tank, and the greater its height (and thus its potential velocity), the greater the water's capacity to create an impact when a valve is opened and the water (like electrons) can flow. Similarly, the greater the voltage in a circuit, the greater its ability to "push" more electrons and do work.
A simple analogy for an electric circuit is water flowing in a closed circuit of pipework, driven by a mechanical pump. This can be called a "water circuit". The potential difference between two points corresponds to the pressure difference between two points. If the pump creates a pressure difference between two points, then water flowing from one point to the other will be able to do work, such as driving a turbine.
In the water-flow analogy, voltage (difference in electric potential) is likened to the difference in water pressure, while current is proportional to the diameter of the pipe or the amount of water flowing at that pressure.
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Volts can be expressed in SI base units
The volt (with the symbol V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). One volt is defined as the electric potential between two points of a conducting wire when an electric current of one ampere (a constant current) dissipates one watt of power between those points.
> {\displaystyle {\text{V}}={\frac {\text{power}}{\text{electric current}}}={\frac {\text{W}}{\text{A}}}={\frac {{\text{kg}}{\cdot }{\text{m}}^{2}{\cdot }{\text{s}}^{-3}}{\text{A}}}={\text{kg}}{\cdot }{\text{m}}^{2}{\cdot }{\text{s}}^{-3}{\cdot }{{\text{A}}^{-1}}.}
This can be understood as one volt being equal to one kilogram metre squared per second cubed per ampere. In other words, it is the potential difference between two points that will impart one joule of energy per coulomb of charge that passes through it.
Volts can also be expressed as amperes times ohms (current times resistance, as per Ohm's law), webers per second (magnetic flux per time), watts per ampere (power per current), or joules per coulomb (energy per charge).
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The volt is named after Alessandro Volta
The volt, represented by the letter V, is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after Alessandro Giuseppe Antonio Anastasio Volta, an Italian physicist and chemist who lived from 1745 to 1827.
Volta is known for his pioneering work in electricity and power, including the invention of the electric battery and the discovery of methane. He invented the voltaic pile, the first electric battery, in 1799, and his experiments proved that electricity could be generated chemically, debunking the previous theory that electricity was generated only by living beings.
The volt, as a unit of measurement, was coined in 1861 by Latimer Clark and Sir Charles Bright, and it was defined by the British Association for the Advancement of Science in 1873. In 1881, the International Electrical Congress, now the International Electrotechnical Commission (IEC), approved the volt as the unit for electromotive force.
The volt is defined as the electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points. In other words, it is the potential difference between two points that will impart one joule of energy per coulomb of charge passing through it. This definition is based on the work of Volta, who studied electrical potential difference (V) and charge (Q), discovering that they are proportional for a given object. This discovery, known as Volta's Law of Capacitance, contributed to the development of the field of electrochemistry.
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Voltage is the difference in electric potential between two points
Voltage, also known as electric potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In simpler terms, it is the pressure from an electrical circuit's power source that pushes charged electrons (current) through a conducting loop, enabling them to do work, such as illuminating a light. The higher the voltage in a circuit, the greater its ability to push more electrons and do work.
The volt (V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). One volt is defined as the electric potential between two points of a conducting wire when an electric current of one ampere (a constant current) dissipates one watt of power between those points. In other words, a potential of one volt appears across a resistance of one ohm when a current of one ampere flows through that resistance. Volts can be expressed in SI base units as 1 V = 1 kg x m^2 x s^-3 x A^-1 (kilogram meter squared per second cubed per ampere).
The term electromotive force was first used by Alessandro Volta in a letter to Giovanni Aldini in 1798, and it first appeared in a published paper in 1801. In 1861, Latimer Clark and Sir Charles Bright coined the name "volt" for the unit of resistance. By 1873, the British Association for the Advancement of Science had formally defined the volt, along with the ohm and farad. In 1881, the International Electrical Congress, now the International Electrotechnical Commission (IEC), approved the volt as the unit for electromotive force.
Voltage is commonly produced by utilities via generators, where mechanical energy is converted to electrical energy. The voltage supplied to homes and businesses varies by nation. For example, the primary voltage supply in the United States is 120 volts, while some antique vehicles use "6 V" 3-cell batteries. Voltage can be measured using a voltmeter, and it is often used interchangeably with the term "potential difference."
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Frequently asked questions
V is the symbol for volt, the unit of electric potential, electric potential difference (voltage), and electromotive force.
Voltage is the difference in electric potential between two points. It is often referred to as electric pressure or electric tension. Voltage is measured in volts.
A volt is the electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points. It is named after the Italian physicist Alessandro Volta, who invented the voltaic pile, considered the forerunner of today's household battery.
