Josephson junction array chip developed by NIST as a standard volt.

The volt (symbol: V) is the SI derived unit of electric potential difference or electromotive force. SI derived units are part of the SI system of measurement units and are derived from the seven SI base units They are derived from SI basic units/defined In Physics, the potential difference or pd between two points is the difference of the points' Scalar potential, equivalent to the line integral Electromotive force ( emf, \mathcal{E} is a term used to characterize electrical devices such as Voltaic cells thermoelectric devices electrical [1][2] It is named in honor of the Lombard physicist Alessandro Volta (1745–1827), who invented the voltaic pile, the first modern chemical battery. The Lombards ( Latin Langobardi, whence the alternative names Langobards and Longobards) were a Germanic people originally from A physicist is a Scientist who studies or practices Physics. Physicists study a wide range of physical phenomena in many branches of physics spanning Count Alessandro Giuseppe Antonio Anastasio Volta was a Lombard physicist known especially for the development of the first electric cell in A voltaic pile is a set of individual Voltaic cells placed in series In electronics a battery is a combination of two or more Electrochemical cells which store chemical Energy which can be converted into electrical energy

## Definition

The volt is defined as the potential difference across a conductor when a current of one ampere dissipates one watt of power. In Physics, the potential difference or pd between two points is the difference of the points' Scalar potential, equivalent to the line integral Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. The ampere, in practice often shortened to amp, (symbol A is a unit of Electric current, or amount of Electric charge per second The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. In Physics, power (symbol P) is the rate at which work is performed or energy is transmitted or the amount of energy required or expended for [3] Hence, it is the base SI representation m2 · kg · s-3 · A-1, which can be equally represented as one joule of energy per coulomb of charge, J/C. The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International The second ( SI symbol s) sometimes abbreviated sec, is the name of a unit of Time, and is the International System of Units The ampere, in practice often shortened to amp, (symbol A is a unit of Electric current, or amount of Electric charge per second The joule (written in lower case ˈdʒuːl or /ˈdʒaʊl/ (symbol J) is the SI unit of Energy measuring heat, Electricity In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός The coulomb (symbol C) is the SI unit of Electric charge. It is named after Charles-Augustin de Coulomb.

$\mbox{V} = \dfrac{\mbox{W}}{\mbox{A}} = \dfrac{\mbox{W} \cdot \mbox{s}}{\mbox{A} \cdot \mbox{s}} = \dfrac{\mbox{J}}{\mbox{C}} = \dfrac{\mbox{N} \cdot \mbox{m} }{\mbox{A} \cdot \mbox{s}} = \dfrac{\mbox{kg} \cdot \mbox{m}^2}{\mbox{A} \cdot \mbox{s}^{3}}$

### Josephson junction definition

Since 1990 the volt is maintained internationally for practical measurement using the Josephson effect, where a conventional value is used for the Josephson constant, fixed by the 18th General Conference on Weights and Measures as

K{J-90} = 0. The Josephson effect is the phenomenon of current flow across two weakly coupled Superconductors, separated by a very thin insulating barrier The magnetic flux quantum Φ0 is the Quantum of Magnetic flux passing through a Superconductor. The General Conference on Weights and Measures is the English name of the Conférence générale des poids et mesures ( CGPM, never GCWM 4835979 GHz/µV.

## Hydraulic analogy

In the hydraulic analogy sometimes used to explain electric circuits by comparing them to water-filled pipes, voltage is likened to water pressure – it determines how fast the electrons will travel through the circuit. The electronic&ndash hydraulic analogy (derisively referred to as the drain-pipe theory by Oliver Heaviside) is the most widely used analogy for "electron fluid" Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface Current (in amperes), in the same analogy, is a measure of the volume of water that flows past a given point per unit time (volumetric flow rate). The volumetric flow rate in Fluid dynamics and Hydrometry, (also known as volume flow rate or rate of fluid flow) is the volume of fluid which The flow rate is determined by the width of the pipe (analogous to electrical resistance) and the pressure difference between the front end of the pipe and the exit (potential difference or voltage). Electrical resistance is a ratio of the degree to which an object opposes an Electric current through it measured in Ohms Its reciprocal quantity is In Physics, the potential difference or pd between two points is the difference of the points' Scalar potential, equivalent to the line integral Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical The analogy extends to power dissipation: the power given up by the water flow is equal to flow rate times pressure, just as the power dissipated in a resistor is equal to current times the voltage drop across the resistor (amperes x volts = watts).

The relationship between voltage and current (in ohmic devices) is defined by Ohm's Law. Ohm's law applies to Electrical circuits it states that the current through a conductor between two points is directly proportional to the

## Common voltages

A multimeter can be used to measure the voltage between two points
1. A multimeter or a multitester, also known as a volt/ohm meter or VOM, is an electronic Measuring instrument that combines several 5 V C-cell batteries

Nominal voltages of familiar sources:

• Nerve cell action potential: around 75 mV[4]
• Single-cell, rechargeable NiMH or NiCd battery: 1. Neurons (ˈnjuːɹɒn also known as neurones and nerve cells) are responsive cells in the Nervous system that process and transmit information In Neurophysiology, the action potential is a self-regenerating Wave of Electrochemical activity that allows Nerve cells to carry a signal A nickel-metal hydride battery, abbreviated NiMH, is a type of Rechargeable battery similar to a nickel-cadmium ( Ni[[Cadmium Cd]] battery The nickel-cadmium battery (commonly abbreviated NiCd and ˈnɑɪˌkæd "nye-cad" is a type of Rechargeable battery using Nickel oxide hydroxide 2 V
• Mercury battery: 1. A mercury battery (also called mercuric oxide battery, or mercury cell) is a non-rechargeable electrochemical battery, a Primary cell. 355 V
• Single-cell, non-rechargeable alkaline battery (e. Alkaline batteries are a type of disposable battery dependent upon the reaction between Zinc and Manganese (IV oxide ( Zn / Mn[[Oxygen g. AAA, AA, C and D cells): 1. In electronics a battery is a combination of two or more Electrochemical cells which store chemical Energy which can be converted into electrical energy 5 V
• Lithium polymer rechargeable battery: 3. Lithium-ion polymer batteries, polymer lithium ion, or more commonly lithium polymer batteries (abbreviated Li-poly Li-Pol LiPo LIP PLI or LiP are 75 V
• Transistor-transistor logic/CMOS (TTL) power supply: 5 V
• PP3 battery: 9 V
• Automobile electrical system: "12 V", about 11. Transistor–transistor logic ( TTL) is a class of Digital circuits built from Bipolar junction transistors (BJT and Resistors It is called Complementary metal–oxide–semiconductor ( CMOS) (pronounced "see-moss" siːmɔːs ˈsiːmɒs is a major class of Integrated circuits CMOS technology A PP3 battery, commonly referred to simply as a "nine-volt battery" is shaped as a rounded rectangular prism and has a nominal output of nine Volts 8 V discharged, 12. 8 V charged, and 13. 8-14. 4 V while charging (vehicle running).
• Household mains electricity: 240 V RMS in Australia, 230 V RMS in Europe, Asia and Africa, 120 V RMS in North America, 100 V RMS in Japan (see List of countries with mains power plugs, voltages and frequencies)
• Rapid transit third rail: 600 to 750 V (see List of current systems for electric rail traction)
• High speed train overhead power lines: 25 kV RMS at 50 Hz, but see the list of current systems for electric rail traction for exceptions. Mains is the general-purpose Alternating current (AC Electric power supply (as in "I've connected the appliance to the mains" This article includes a list of countries and territories with the plugs voltages and frequencies they use for providing electrical power to Small appliances A rapid transit, underground, subway, elevated railway or metro(politan system is an electric passenger railway A third rail is a method of providing Electricity to power a railway through a continuous rigid conductor alongside the railway track or between the rails This a list of the voltages used or have been used for tramway and Railway electrification systems Note the voltages are nominal and vary depending on load and distance from the substation This a list of the voltages used or have been used for tramway and Railway electrification systems Note the voltages are nominal and vary depending on load and distance from the substation
• High voltage electric power transmission lines: 110 kV RMS and up (1150 kV RMS was the record as of 2005)
• Lightning: Varies greatly, often around 100 MV. Electric power transmission, a process in the delivery of Electricity to consumers is the bulk transfer of electrical power Lightning is an atmospheric discharge of Electricity, which typically occurs during Thunderstorms and sometimes during volcanic eruptions or

Note: Where 'RMS' (root mean square) is stated above, the peak voltage is $\sqrt{2}$ times greater than the RMS voltage for a sinusoidal signal centered around zero voltage. In Mathematics, the root mean square (abbreviated RMS or rms) also known as the quadratic mean, is a statistical measure of the

## History of the volt

In 1800, as the result of a professional disagreement over the galvanic response advocated by Luigi Galvani, Alessandro Volta developed the so-called Voltaic pile, a forerunner of the battery, which produced a steady electric current. Luigi Galvani was an Italian Physician and Physicist who lived and died in Bologna. A voltaic pile is a set of individual Voltaic cells placed in series In electronics a battery is a combination of two or more Electrochemical cells which store chemical Energy which can be converted into electrical energy Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and silver. Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen In the 1880s, the International Electrical Congress, now the International Electrotechnical Commission (IEC), approved the volt for electromotive force. The International Electrotechnical Commission ( IEC) is a not-for-profit, non-governmental international Standards organization that prepares and publishes At that time, the volt was defined as the potential difference across a conductor when a current of one ampere dissipates one watt of power. The ampere, in practice often shortened to amp, (symbol A is a unit of Electric current, or amount of Electric charge per second The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second.

Prior to the development of the Josephson junction voltage standard, the volt was maintained in national laboratories using specially constructed batteries called standard cells. The Weston cell, invented by Edward Weston in 1893 is a wet-chemical cell that produces a highly stable Voltage suitable as a laboratory standard The United States used a design called the Weston cell from 1905 to 1972. The Weston cell, invented by Edward Weston in 1893 is a wet-chemical cell that produces a highly stable Voltage suitable as a laboratory standard

 This SI unit is named after Alessandro Volta. Count Alessandro Giuseppe Antonio Anastasio Volta was a Lombard physicist known especially for the development of the first electric cell in As with every SI unit whose name is derived from the proper name of a person, the first letter of its symbol is uppercase (V). The musical instrument is spelled Cymbal. A symbol is something --- such as an object, Picture, written word a sound a piece Capital letters or majuscules pronunciation /məˈdʒʌskyuls ˈmædʒəˌskyuls/ in the Roman alphabet A, B, C, D, When an SI unit is spelled out in English, it should always begin with a lowercase letter (volt), except where any word would be capitalized, such as at the beginning of a sentence or in capitalized material such as a title. Lower case (also lower-case or lowercase) minuscule, or small letters are the smaller form of letters as opposed to upper Note that "degree Celsius" conforms to this rule because the "d" is lowercase. The Celsius Temperature scale was previously known as the centigrade scale. — Based on The International System of Units, section 5. 2.