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# Vacuum permittivity

The physical constant (pronounced as "epsilon nought"), commonly called the vacuum permittivity, permittivity of free space or electric constant, is an ideal, (baseline) physical constant, which is the value of the absolute dielectric permittivity of classical vacuum. 

## Ampère's force law

In magnetostatics, the force of attraction or repulsion between two current-carrying wires (see first figure below) is often called Ampère's force law.

## Ampere

The ampere (symbol: A), often shortened to "amp",SI supports only the use of symbols and deprecates the use of abbreviations for units.

## Casimir effect

In quantum field theory, the Casimir effect and the Casimir–Polder force are physical forces arising from a quantized field.

## Charles-Augustin de Coulomb

Charles-Augustin de Coulomb (14 June 1736 – 23 August 1806) was a French military engineer and physicist.

## Coulomb

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

## Coulomb's constant

Coulomb's constant, the electric force constant, or the electrostatic constant (denoted) is a proportionality constant in electrodynamics equations.

## Coulomb's law

Coulomb's law, or Coulomb's inverse-square law, is a law of physics for quantifying the amount of force with which stationary electrically charged particles repel or attract each other.

## Dyne

The dyne (symbol dyn, from Greek δύναμις, dynamis, meaning power, force) is a derived unit of force specified in the centimetre–gram–second (CGS) system of units, a predecessor of the modern SI.

## Electric charge

Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field.

## Electric displacement field

In physics, the electric displacement field, denoted by D, is a vector field that appears in Maxwell's equations.

## Electric field

An electric field is a vector field surrounding an electric charge that exerts force on other charges, attracting or repelling them.

In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space-time, carrying electromagnetic radiant energy.

## Electromagnetic wave equation

The electromagnetic wave equation is a second-order partial differential equation that describes the propagation of electromagnetic waves through a medium or in a vacuum.

## Elementary charge

The elementary charge, usually denoted as or sometimes, is the electric charge carried by a single proton, or equivalently, the magnitude of the electric charge carried by a single electron, which has charge.

## Epsilon

Epsilon (uppercase Ε, lowercase ε or lunate ϵ; έψιλον) is the fifth letter of the Greek alphabet, corresponding phonetically to a mid<!-- not close-mid, see Arvanti (1999) - Illustrations of the IPA: Modern Greek. --> front unrounded vowel.

The farad (symbol: F) is the SI derived unit of electrical capacitance, the ability of a body to store an electrical charge.

## Fine-structure constant

In physics, the fine-structure constant, also known as Sommerfeld's constant, commonly denoted (the Greek letter ''alpha''), is a fundamental physical constant characterizing the strength of the electromagnetic interaction between elementary charged particles.

## Free University of Berlin

The Free University of Berlin (Freie Universität Berlin, often abbreviated as FU Berlin or simply FU) is a research university located in Berlin, Germany.

## Glyph

In typography, a glyph is an elemental symbol within an agreed set of symbols, intended to represent a readable character for the purposes of writing.

## Henry (unit)

The henry (symbol: H) is the SI derived unit of electrical inductance.

## Institute of Electrical and Electronics Engineers

The Institute of Electrical and Electronics Engineers (IEEE) is a professional association with its corporate office in New York City and its operations center in Piscataway, New Jersey.

## International Bureau of Weights and Measures

The International Bureau of Weights and Measures (Bureau international des poids et mesures) is an intergovernmental organization established by the Metre Convention, through which Member States act together on matters related to measurement science and measurement standards.

## International System of Units

The International System of Units (SI, abbreviated from the French Système international (d'unités)) is the modern form of the metric system, and is the most widely used system of measurement.

## International Union of Pure and Applied Chemistry

The International Union of Pure and Applied Chemistry (IUPAC) is an international federation of National Adhering Organizations that represents chemists in individual countries.

## ISO 31-5

ISO 31-5 is the part of international standard ISO 31 that defines names and symbols for quantities and units related to electricity and magnetism.

## Kilogram

The kilogram or kilogramme (symbol: kg) is the base unit of mass in the International System of Units (SI), and is defined as being equal to the mass of the International Prototype of the Kilogram (IPK, also known as "Le Grand K" or "Big K"), a cylinder of platinum-iridium alloy stored by the International Bureau of Weights and Measures at Saint-Cloud, France.

## Magnetic field

A magnetic field is a vector field that describes the magnetic influence of electrical currents and magnetized materials.

## Mathematical descriptions of the electromagnetic field

There are various mathematical descriptions of the electromagnetic field that are used in the study of electromagnetism, one of the four fundamental interactions of nature.

## Maxwell's equations

Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, and electric circuits.

## Metre

The metre (British spelling and BIPM spelling) or meter (American spelling) (from the French unit mètre, from the Greek noun μέτρον, "measure") is the base unit of length in some metric systems, including the International System of Units (SI).

## MKS system of units

The MKS system of units is a physical system of units that expresses any given measurement using base units of the metre, kilogram, and/or second (MKS).

## Newton (unit)

The newton (symbol: N) is the International System of Units (SI) derived unit of force.

## Permittivity

In electromagnetism, absolute permittivity, often simply called permittivity, usually denoted by the Greek letter ε (epsilon), is the measure of resistance that is encountered when forming an electric field in a particular medium.

## Physical constant

A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that is generally believed to be both universal in nature and have constant value in time.

## Planck constant

The Planck constant (denoted, also called Planck's constant) is a physical constant that is the quantum of action, central in quantum mechanics.

## Polarization density

In classical electromagnetism, polarization density (or electric polarization, or simply polarization) is the vector field that expresses the density of permanent or induced electric dipole moments in a dielectric material.

## Relative permittivity

The relative permittivity of a material is its (absolute) permittivity expressed as a ratio relative to the permittivity of vacuum.

## Second

The second is the SI base unit of time, commonly understood and historically defined as 1/86,400 of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each.

## SI base unit

The International System of Units (SI) defines seven units of measure as a basic set from which all other SI units can be derived.

## Sinusoidal plane-wave solutions of the electromagnetic wave equation

Sinusoidal plane-wave solutions are particular solutions to the electromagnetic wave equation.

## Speed of light

The speed of light in vacuum, commonly denoted, is a universal physical constant important in many areas of physics.

## Statcoulomb

The statcoulomb (statC) or franklin (Fr) or electrostatic unit of charge (esu) is the physical unit for electrical charge used in the esu-cgs (centimetre–gram–second system of units) and Gaussian units.

## Vacuum

Vacuum is space devoid of matter.

## Vacuum permeability

The physical constant μ0, (pronounced "mu naught" or "mu zero"), commonly called the vacuum permeability, permeability of free space, permeability of vacuum, or magnetic constant, is an ideal, (baseline) physical constant, which is the value of magnetic permeability in a classical vacuum.

## Volt

The volt (symbol: V) is the derived unit for electric potential, electric potential difference (voltage), and electromotive force.

## Wave impedance

The wave impedance of an electromagnetic wave is the ratio of the transverse components of the electric and magnetic fields (the transverse components being those at right angles to the direction of propagation).

## References

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