The Planck constant, or Planck's constant, denoted by ,[1] is a fundamental physical constant[1] of foundational importance in quantum mechanics: a photon's energy is equal to its frequency multiplied by the Planck constant, and the wavelength of a matter wave equals the Planck constant divided by the associated particle momentum.
The constant was postulated by Max Planck in 1900 as a proportionality constant needed to explain experimental black-body radiation.[2] Planck later referred to the constant as the "quantum of action".[3] In 1905, Albert Einstein associated the "quantum" or minimal element of the energy to the electromagnetic wave itself. Max Planck received the 1918 Nobel Prize in Physics "in recognition of the services he rendered to the advancement of Physics by his discovery of energy quanta".
In metrology, the Planck constant is used, together with other constants, to define the kilogram, the SI unit of mass.[4] The SI units are defined in such a way that, when the Planck constant is expressed in SI units, it has the exact value = 6.62607015×10−34 J⋅Hz−1.[5][6] It is often used with units of electronvolt (eV), which corresponds to the SI unit per elementary charge.
^ ab"Planck constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. Archived from the original on 2022-05-27. Retrieved 2023-09-03.
^Cite error: The named reference Planck01 was invoked but never defined (see the help page).
^"Max Planck Nobel Lecture". Archived from the original on 2023-07-14. Retrieved 2023-07-14.
^Le Système international d’unités [The International System of Units] (PDF) (in French and English) (9th ed.), International Bureau of Weights and Measures, 2019, p. 131, ISBN 978-92-822-2272-0
^"2018 CODATA Value: Planck constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. Retrieved 2021-04-28.
^"Resolutions of the 26th CGPM" (PDF). BIPM. 2018-11-16. Archived from the original (PDF) on 2018-11-19. Retrieved 2018-11-20.
The Planckconstant, or Planck'sconstant, denoted by h {\textstyle h} , is a fundamental physical constant of foundational importance in quantum mechanics:...
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c, the gravitational constant G, the Planckconstant h, the electric constant ε0, and the elementary charge e. Physical constants can take many dimensional...
for Planck'sconstant, which is of foundational importance for quantum physics, and which he used to derive a set of units, today called Planck units...
on Constants, Units, and Uncertainty. NIST. 20 May 2019. Retrieved 2019-05-20. "2018 CODATA Value: Planckconstant". The NIST Reference on Constants, Units...
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defined in terms of the Planckconstant, the second, and the metre, both of which are based on fundamental physical constants. This allows a properly...
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h {\displaystyle h} is the Planckconstant, and c {\displaystyle c} is the speed of light in vacuum. The Rydberg constant for hydrogen may be calculated...
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maximum. The solar "constant" is not a physical constant in the modern CODATA scientific sense; that is, it is not like the Planckconstant or the speed of...
constantPlanck postulate Planck's law of black body radiation Planck-taper window Planck–Bessel window Planck–Einstein relation Planck units Planck energy...
{\displaystyle a_{0}} , and of h / 2 π {\displaystyle h/2\pi } is the reduced Planckconstant ℏ {\displaystyle \hbar } . Hartree's expressions that contain e {\displaystyle...
equilibrium (that is, at a constant temperature) emits electromagnetic black-body radiation. The radiation is emitted according to Planck's law, meaning that it...
energy of a photon, via the Planck relation E = hν, where E is the photon's energy, ν is its frequency, and h is the Planckconstant. The hertz is equivalent...
{\displaystyle h} is the Planckconstant f {\displaystyle f} is frequency (typically in hertz) This equation is known as the Planck–Einstein relation. Additionally...
inferred to ~3% accuracy from blackbody spectra by Max Planck in 1901 and (through the Faraday constant) at order-of-magnitude accuracy by Johann Loschmidt's...
fundamental constants, namely the Planckconstant (h), the elementary charge (e), the Boltzmann constant (k), and the Avogadro constant (NA). This approach...
frequency of caesium ΔνCs, the Planckconstant h, the elementary charge e, the Boltzmann constant k, the Avogadro constant NA, and the luminous efficacy...
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