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The 52 pages that link to Planck constant, each with the reason it gives.

• Electromagnetic radiationRelated: It sets the proportionality between radiation frequency and energy per photon.

• Niels BohrRelated: Bohr used Planck’s quantum of action to set allowed atomic energies.

• Thermal radiationRelated: It sets the energy scale in Planck's quantized account of radiation.

• Metric systemBroader topic: Its fixed value defines the kilogram in the modern system.

• Bohr modelRelated: Quantum restrictions in Bohr’s model are expressed using this constant.

• Max PlanckBroader topic: Planck’s constant sets the size of the energy elements in his radiation theory.

• Planck's lawRelated: It sets the energy spacing that shapes Planck's spectrum.

• Boltzmann constantCompared with: It sets quantum action scales, whereas k sets thermal energy scales.

• KilogramRelated: Its fixed numerical value anchors the kilogram’s present definition.

• Energy levelRelated: It converts transition frequencies into energy differences through the relation E = hν.

• International Bureau of Weights and MeasuresRelated: Its fixed numerical value now defines the kilogram in the SI.

• Old quantum theoryRelated: Quantization rules in this framework used Planck’s constant to restrict allowed motions.

• Reduced Planck constantRelated: ℏ is defined by dividing this constant by 2π.

• Fine-structure constantRelated: It sets the quantum scale in the denominator of the fine-structure constant.

• Ultraviolet catastropheRelated: Its role in quantized energy makes high-frequency modes harder to excite.

• 2019 redefinition of SI base unitsRelated: Its fixed value now defines the kilogram through quantum mechanical measurements.

• ElectronvoltRelated: Together with electronvolts, it links energy measurements to frequencies used in quantum physics.

• Faraday constantCompared with: It is another fixed SI-defining constant, but links energy and frequency rather than charge and amount.

• Louis de BroglieRelated: It links a particle’s momentum to its proposed matter-wave wavelength.

• Canonical commutation relationRelated: Its reduced form ℏ appears as the commutator's proportionality constant.

• General Conference on Weights and MeasuresRelated: Fixing its value made the kilogram independent of the international prototype.

• Rayleigh–Jeans lawRelated: Its appearance in Planck’s law suppresses high-frequency radiation absent from the classical formula.

• Natural unitsRelated: Setting it to one removes explicit quantum-action factors from equations.

• Wien's displacement lawRelated: It enters Planck’s radiation law and therefore helps set the displacement constant.

• De Broglie wavelengthRelated: Its value converts momentum into the associated wavelength.

• Action (physics)Related: It sets the scale against which action determines quantum phase.

• Matter waveRelated: It converts momentum into wavelength in the de Broglie relation.

• Planck unitsRelated: Planck's original natural units used h; modern conventions commonly use ℏ.

• Classical limitRelated: The classical limit is often expressed as action becoming large compared with this constant.

• Compton wavelengthRelated: It supplies the quantum scale in the numerator of the Compton-wavelength formula.

• Atomic mass unitRelated: Its exact SI value helps define the kilogram, while the atomic mass unit remains tied to carbon-12.

• Correspondence principleRelated: Classical behavior often emerges when relevant actions greatly exceed its scale.

• Integer quantum Hall effectRelated: Its value helps define the universal conductance unit.

• Eyring equationRelated: Its appearance in the prefactor gives the equation its characteristic frequency scale.

• Gas constantCompared with: Unlike R, it sets a quantum scale independent of temperature and amount of substance.

• International Prototype of the KilogramRelated: Its fixed numerical value now anchors the kilogram’s definition.

• Physical constantBroader topic: It sets the scale at which quantum effects become significant.

• Bohr radiusRelated: It enters the Bohr radius squared in the numerator.

• Photon momentumRelated: It converts a photon’s wavelength into momentum through the de Broglie relation.

• Robert MillikanRelated: The slope of Millikan’s photoelectric measurements yielded its value.

• Arthur ComptonRelated: It appears in the wavelength-shift formula Compton derived from photon energy and momentum.

• Constant (mathematics)Related: It sets the scale connecting energy and frequency in quantum physics.

• Electron massRelated: Modern precision measurements connect electron mass to the fixed Planck constant.

• Magnetic flux quantumRelated: It supplies the quantum of action in the numerator of the flux quantum.

• Planck relationBroader topic: It is the proportionality constant that converts frequency into energy.

• Modern physicsBroader topic: It marks the scale at which classical descriptions give way to quantum behavior.

• History of the metric systemRelated: Fixing its value made the kilogram definition independent of any single physical artifact.

• Stefan–Boltzmann constantRelated: Its cube appears in the fundamental expression for σ.

• De Broglie equationRelated: Its value converts a particle’s momentum into its associated wavelength.

• Joule-secondRelated: Its SI unit is the joule-second.