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In the SI system of units, the value of the elementary charge is exactly defined as = 1.602 176 634 × 10 −19 coulombs, or 160.2176634 zeptocoulombs (zC). [3] Since the 2019 revision of the SI, the seven SI base units are defined in terms of seven fundamental physical constants, of which the elementary charge is one.
The coulomb (symbol: C) is the unit of electric charge in the International System of Units (SI). [1] [2] It is equal to the electric charge delivered by a 1 ampere current in 1 second and is defined in terms of the elementary charge e, at about 6.241 509 × 10 18 e. [2] [1]
The SI system after 1983, but before the 2019 revision: Dependence of base unit definitions on other base units (for example, the metre is defined as the distance travelled by light in a specific fraction of a second), with the constants of nature and artefacts used to define them (such as the mass of the IPK for the kilogram).
Related to the Faraday constant is the "faraday", a unit of electrical charge. Its use is much less common than of the coulomb, but is sometimes used in electrochemistry. [4] One faraday of charge is the charge of one mole of elementary charges (or of negative one mole of electrons), that is, 1 faraday = F × 1 mol = 9.648 533 212 331 001 84 × ...
The Avogadro constant, commonly denoted N A [1] or L, [2] is an SI defining constant with an exact value of 6.022 140 76 × 10 23 mol −1 (reciprocal moles). [3] [4] It is this defined number of constituent particles (usually molecules, atoms, ions, or ion pairs—in general, entities) per mole and used as a normalization factor in relating the amount of substance, n(X), in a sample of a ...
It is common in particle physics, where units of mass and energy are often interchanged, to express mass in units of eV/c 2, where c is the speed of light in vacuum (from E = mc 2). It is common to informally express mass in terms of eV as a unit of mass, effectively using a system of natural units with c set to 1. [3] The kilogram equivalent ...
While not an SI-unit, the litre may be used with SI units. It is equivalent to (10 cm) 3 = (1 dm) 3 = 10 −3 m 3. Many non-SI units continue to be used in the scientific, technical, and commercial literature. Some units are deeply embedded in history and culture, and their use has not been entirely replaced by their SI alternatives.
The SI unit of temperature is the kelvin (K), but using the above relation the electron temperature is often expressed in terms of the energy unit electronvolt (eV). Each kelvin (1 K) corresponds to 8.617 333 262 ... × 10 −5 eV ; this factor is the ratio of the Boltzmann constant to the elementary charge . [ 6 ]