# Coulomb

**CPicoCoulomBExacoulombGigacoulombMegacoulombmicrocoulombMillicoulombpCPetacoulombTeracoulomb**

The coulomb (symbol: C) is the International System of Units (SI) unit of electric charge.wikipedia

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### Electric charge

**chargeelectrical chargecharged**

The coulomb (symbol: C) is the International System of Units (SI) unit of electric charge.

The SI derived unit of electric charge is the coulomb (C) named after French physicist Charles-Augustin de Coulomb.

### Ampere

**AmAamp**

It is the charge (symbol: Q or q) transported by a constant current of one ampere in one second: The SI system defines the coulomb in terms of the ampere and second: 1 C = 1 A × 1 s. The 2019 redefinition of the ampere and other SI base units fixed the numerical value of the elementary charge when expressed in coulombs, and therefore fixed the value of the coulomb when expressed as a multiple of the fundamental charge (the numerical values of those quantities are the multiplicative inverses of each other).

The ampere was then defined as one coulomb of charge per second.

### Farad

**microfaradFpF**

Thus, it is also the amount of excess charge on a capacitor of one farad charged to a potential difference of one volt:

One farad is defined as the capacitance across which, when charged with one coulomb, there is a potential difference of one volt.

### Volt

**VkVvolts**

Thus, it is also the amount of excess charge on a capacitor of one farad charged to a potential difference of one volt:

It is also equal to the potential difference between two parallel, infinite planes spaced 1 meter apart that create an electric field of 1 newton per coulomb.

### Capacitor

**capacitorscapacitivecondenser**

Thus, it is also the amount of excess charge on a capacitor of one farad charged to a potential difference of one volt:

:A capacitance of one farad (F) means that one coulomb of charge on each conductor causes a voltage of one volt across the device.

### Elementary charge

**eelectron chargecharge**

Under the 2019 redefinition of the SI base units, which took effect on 20 May 2019, the elementary charge (the charge of the proton) is exactly 1.602176634 coulombs. The SI system defines the coulomb in terms of the ampere and second: 1 C = 1 A × 1 s. The 2019 redefinition of the ampere and other SI base units fixed the numerical value of the elementary charge when expressed in coulombs, and therefore fixed the value of the coulomb when expressed as a multiple of the fundamental charge (the numerical values of those quantities are the multiplicative inverses of each other).

From the 2019 redefinition of SI base units, that took effect on 20 May 2019, its value is exactly by definition of the coulomb.

### International System of Units

**SISI unitsSI unit**

The coulomb (symbol: C) is the International System of Units (SI) unit of electric charge. The SI system defines the coulomb in terms of the ampere and second: 1 C = 1 A × 1 s. The 2019 redefinition of the ampere and other SI base units fixed the numerical value of the elementary charge when expressed in coulombs, and therefore fixed the value of the coulomb when expressed as a multiple of the fundamental charge (the numerical values of those quantities are the multiplicative inverses of each other).

### Electron

**electronse − electron mass**

The same number of electrons has the same magnitude but opposite sign of charge, that is, a charge of −1 C.

Electrons have an electric charge of -1.602176634 coulombs, which is used as a standard unit of charge for subatomic particles, and is also called the elementary charge.

### 2019 redefinition of the SI base units

**2019 redefinition of SI base unitsredefinitionredefinition of the SI base units**

Under the 2019 redefinition of the SI base units, which took effect on 20 May 2019, the elementary charge (the charge of the proton) is exactly 1.602176634 coulombs. The SI system defines the coulomb in terms of the ampere and second: 1 C = 1 A × 1 s. The 2019 redefinition of the ampere and other SI base units fixed the numerical value of the elementary charge when expressed in coulombs, and therefore fixed the value of the coulomb when expressed as a multiple of the fundamental charge (the numerical values of those quantities are the multiplicative inverses of each other).

The seven definitions above are rewritten below with the derived units (joule, coulomb, hertz, lumen, and watt) expressed in terms of the seven base units; second, metre, kilogram, ampere, kelvin, mole, and candela, according to the 9th SI Brochure.

### International Electrical Congress

**Congrès internationale des électricienselectrical congressesExposition internationale d'Électricité de Paris**

In 1881, the International Electrical Congress, now the International Electrotechnical Commission (IEC), approved the volt as the unit for electromotive force, the ampere as the unit for electric current, and the coulomb as the unit of electric charge.

The Congress resolved to endorse the 1873 British Association for the Advancement of Science proposal for defining the ohm and the volt as practical units, and also made resolutions to define ampere, coulomb and farad, as units for current, quantity, and capacity respectively, to complete the practical system.

### Ampere hour

**mAhAhampere-hour**

An ampere hour or amp hour (symbol: A⋅h or A h; sometimes also unofficially denoted as Ah) is a unit of electric charge, having dimensions of electric current multiplied by time, equal to the charge transferred by a steady current of one ampere flowing for one hour, or 3,600 coulombs.

### Faraday constant

**Faraday's constantfaradayFaraday (unit)**

One can divide the amount of charge in coulombs by the Faraday constant in order to find the amount (in moles) of the element that has been oxidized.

### Lightning

**lightning boltlightning strikelightning strikes**

An average bolt of negative lightning carries an electric current of 30,000 amperes (30 kA), and transfers 15 coulombs of electric charge and 1 gigajoule of energy.

### Abcoulomb

**abC**

One abcoulomb is equal to ten coulombs.

### Electrostatics

**electrostaticelectrostatic repulsionelectrostatic interactions**

If r is the distance (in meters) between two charges, then the force (in newtons) between two point charges q and Q (in coulombs) is:

### Statcoulomb

**esufranklinelectrostatic unit**

### Charles-Augustin de Coulomb

**CoulombCharles CoulombCharles Augustin de Coulomb**

The SI unit of electric charge, the coulomb, was named in his honor in 1908.

### Coulomb's law

**Coulomb forceelectrostatic forceCoulomb interaction**

When the electromagnetic theory is expressed in the International System of Units, force is measured in newtons, charge in coulombs, and distance in meters.

### SI derived unit

**derived unitderived unitsJ/kg**

### Centimetre–gram–second system of units

**CGScgs unitsCGS unit**

As well as the volt and amp, the farad (capacitance), ohm (resistance), coulomb (electric charge), and henry are consequently also used in the practical system and are the same as the SI units.

### Second

**ssecmegasecond**

It is the charge (symbol: Q or q) transported by a constant current of one ampere in one second: The SI system defines the coulomb in terms of the ampere and second: 1 C = 1 A × 1 s. The 2019 redefinition of the ampere and other SI base units fixed the numerical value of the elementary charge when expressed in coulombs, and therefore fixed the value of the coulomb when expressed as a multiple of the fundamental charge (the numerical values of those quantities are the multiplicative inverses of each other).

### Proton

**protonsH + p**

Under the 2019 redefinition of the SI base units, which took effect on 20 May 2019, the elementary charge (the charge of the proton) is exactly 1.602176634 coulombs.

### Mole (unit)

**molemolmoles**

Thus the coulomb is exactly the charge of 1/(1.602176634) protons, which is approximately 6.2415090744 protons (1.036 mol).

### Multiplicative inverse

**reciprocalinversereciprocals**

The SI system defines the coulomb in terms of the ampere and second: 1 C = 1 A × 1 s. The 2019 redefinition of the ampere and other SI base units fixed the numerical value of the elementary charge when expressed in coulombs, and therefore fixed the value of the coulomb when expressed as a multiple of the fundamental charge (the numerical values of those quantities are the multiplicative inverses of each other).

### British Science Association

**British Association for the Advancement of ScienceBritish AssociationBritish Science Festival**

By 1873, the British Association for the Advancement of Science had defined the volt, ohm, and farad, but not the coulomb.