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The coulomb was originally defined, using the latter definition of the ampere, as 1 A × 1 s. [4] 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.
As of the 2019 revision of the SI, the ampere is defined by fixing the elementary charge e to be exactly 1.602 176 634 × 10 −19 C, [6] [9] which means an ampere is an electric current equivalent to 10 19 elementary charges moving every 1.602 176 634 seconds or 6.241 509 074 × 10 18 elementary charges moving in a second.
Symbol [1] Name of quantity Unit name Symbol Base units E energy: joule: J = C⋅V = W⋅s kg⋅m 2 ⋅s −2: Q electric charge: coulomb: C A⋅s I electric current: ampere
The henry (symbol: H) is the unit of electrical inductance in the International System of Units (SI). [1] If a current of 1 ampere flowing through a coil produces flux linkage of 1 weber turn, that coil has a self-inductance of 1 henry. The unit is named after Joseph Henry (1797–1878), the American scientist who discovered electromagnetic induction independently of and at about the same ...
The electronvolt is divided by the Boltzmann constant to convert to the Kelvin scale: / = = , where k B is the Boltzmann constant. The k B is assumed when using the electronvolt to express temperature, for example, a typical magnetic confinement fusion plasma is 15 keV (kiloelectronvolt), which is equal to 174 MK (megakelvin).
where Ω is ohm, C is coulomb, J is joule, and N is newton. The weber is named after Wilhelm Eduard Weber . As with every SI unit named for a person, its symbol starts with an upper case letter (Wb), but when written in full, it follows the rules for capitalisation of a common noun ; i.e., weber becomes capitalised at the beginning of a ...
In the International System of Units (SI), electric current is expressed in units of ampere (sometimes called an "amp", symbol A), which is equivalent to one coulomb per second. The ampere is an SI base unit and electric current is a base quantity in the International System of Quantities (ISQ).
The ampere may be expressed directly in terms of the defining constants as: 1 A = e Δν Cs / (1.602 176 634 × 10 −19)(9 192 631 770) For illustration, this is equivalent to defining one coulomb to be an exact specified multiple of the elementary charge. 1 C = e / 1.602 176 634 × 10 −19