Elementary charge: Difference between revisions
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{{ | {{DISPLAYTITLE:Elementary Charge}} | ||
{{Infobox physical quantity | |||
| name = Elementary charge | |||
| symbol = e | |||
| dimension = [[Electric charge|Q]] | |||
| value = 1.602176634 × 10⁻¹⁹ [[Coulomb|C]] | |||
| uncertainty = exact | |||
| unit = [[Coulomb|C]] | |||
}} | |||
The '''elementary charge''', denoted as '''e''', is a fundamental physical constant that represents the smallest unit of electric charge that is considered indivisible in the context of [[quantum mechanics]]. It is a key component in the study of [[electromagnetism]], [[particle physics]], and [[quantum field theory]]. | |||
==Definition== | |||
The elementary charge is defined as the magnitude of the electric charge carried by a single [[proton]], or equivalently, the negative of the charge carried by a single [[electron]]. It is a fundamental constant of nature and is used as a basic unit of charge in the [[International System of Units|SI]] system. | |||
==Value== | |||
The value of the elementary charge is exactly 1.602176634 × 10⁻¹⁹ [[Coulomb|C]]. This value is fixed by the definition of the [[coulomb]], which is based on the elementary charge itself. The elementary charge is a dimensionless quantity in the context of [[natural units]], where it is often set to 1 for simplification in theoretical physics. | |||
==Historical Context== | |||
The concept of the elementary charge was first introduced by [[George Johnstone Stoney]] in 1874, who coined the term "electron" to describe this fundamental unit of charge. The measurement of the elementary charge was significantly refined by [[Robert A. Millikan]] in his famous oil-drop experiment in 1909, which provided the first accurate determination of the charge of the electron. | |||
==Role in Physics== | |||
The elementary charge plays a crucial role in the [[Standard Model]] of particle physics, where it is a fundamental parameter in the [[electromagnetic force]], one of the four fundamental forces of nature. It is also a key component in the [[quantum electrodynamics]] (QED) theory, which describes how light and matter interact. | |||
In [[atomic physics]], the elementary charge is essential for understanding the structure of [[atoms]], as it determines the electrostatic forces between [[protons]] and [[electrons]]. In [[solid-state physics]], it is important for the study of [[semiconductors]] and [[superconductors]], where the movement of charge carriers is a fundamental process. | |||
==Applications== | |||
The elementary charge is used in various applications across different fields of science and technology. In [[electronics]], it is fundamental to the operation of [[transistors]], [[diodes]], and other semiconductor devices. In [[chemistry]], it is crucial for understanding [[ionic bonds]] and [[electrochemical reactions]]. | |||
In [[metrology]], the elementary charge is used in the definition of the [[ampere]], which is one of the seven base units in the SI system. The ampere is defined by taking the fixed numerical value of the elementary charge to be 1.602176634 × 10⁻¹⁹ when expressed in the unit [[Coulomb|C]], which is equal to [[A]]·s, where the second is defined in terms of the [[cesium]] frequency. | |||
==See Also== | |||
* [[Electron]] | |||
* [[Proton]] | |||
* [[Coulomb]] | |||
* [[Quantum mechanics]] | |||
* [[Electromagnetism]] | |||
* [[Standard Model]] | |||
==External Links== | |||
* [Elementary Charge on NIST](https://physics.nist.gov/cgi-bin/cuu/Value?e) | |||
* [Elementary Charge on CODATA](https://physics.nist.gov/cuu/Constants/index.html) | |||
[[Category:Physical constants]] | |||
[[Category:Electromagnetism]] | |||
[[Category:Particle physics]] | |||
[[Category:Quantum mechanics]] | |||
Latest revision as of 21:23, 1 January 2025
The elementary charge, denoted as e, is a fundamental physical constant that represents the smallest unit of electric charge that is considered indivisible in the context of quantum mechanics. It is a key component in the study of electromagnetism, particle physics, and quantum field theory.
Definition[edit]
The elementary charge is defined as the magnitude of the electric charge carried by a single proton, or equivalently, the negative of the charge carried by a single electron. It is a fundamental constant of nature and is used as a basic unit of charge in the SI system.
Value[edit]
The value of the elementary charge is exactly 1.602176634 × 10⁻¹⁹ C. This value is fixed by the definition of the coulomb, which is based on the elementary charge itself. The elementary charge is a dimensionless quantity in the context of natural units, where it is often set to 1 for simplification in theoretical physics.
Historical Context[edit]
The concept of the elementary charge was first introduced by George Johnstone Stoney in 1874, who coined the term "electron" to describe this fundamental unit of charge. The measurement of the elementary charge was significantly refined by Robert A. Millikan in his famous oil-drop experiment in 1909, which provided the first accurate determination of the charge of the electron.
Role in Physics[edit]
The elementary charge plays a crucial role in the Standard Model of particle physics, where it is a fundamental parameter in the electromagnetic force, one of the four fundamental forces of nature. It is also a key component in the quantum electrodynamics (QED) theory, which describes how light and matter interact.
In atomic physics, the elementary charge is essential for understanding the structure of atoms, as it determines the electrostatic forces between protons and electrons. In solid-state physics, it is important for the study of semiconductors and superconductors, where the movement of charge carriers is a fundamental process.
Applications[edit]
The elementary charge is used in various applications across different fields of science and technology. In electronics, it is fundamental to the operation of transistors, diodes, and other semiconductor devices. In chemistry, it is crucial for understanding ionic bonds and electrochemical reactions.
In metrology, the elementary charge is used in the definition of the ampere, which is one of the seven base units in the SI system. The ampere is defined by taking the fixed numerical value of the elementary charge to be 1.602176634 × 10⁻¹⁹ when expressed in the unit C, which is equal to A·s, where the second is defined in terms of the cesium frequency.
See Also[edit]
External Links[edit]
- [Elementary Charge on NIST](https://physics.nist.gov/cgi-bin/cuu/Value?e)
- [Elementary Charge on CODATA](https://physics.nist.gov/cuu/Constants/index.html)
