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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.
elementary charge: 1.602 176 634 × 10 −19 ... molar Planck constant 3.990 312 712 893 4314 ... While the values of the physical constants are independent of the ...
Robert A. Millikan and Harvey Fletcher's oil drop experiment first directly measured the magnitude of the elementary charge in 1909, differing from the modern accepted value by just 0.6%. [4] [5] Under assumptions of the then-disputed atomic theory, the elementary charge had also been indirectly inferred to ~3% accuracy from blackbody spectra ...
This equation is known as the Planck relation. Additionally, using equation f = c/λ, = where E is the photon's energy; λ is the photon's wavelength; c is the speed of light in vacuum; h is the Planck constant; The photon energy at 1 Hz is equal to 6.626 070 15 × 10 −34 J, which is equal to 4.135 667 697 × 10 −15 eV.
with e being the elementary charge, h being the Planck constant, and c being the speed of light in vacuum, each with exactly defined values. The relative uncertainty in the value of ε 0 is therefore the same as that for the dimensionless fine-structure constant, namely 1.6 × 10 −10. [7]
An electronvolt is the amount of energy gained or lost by a single electron when it moves through an electric potential difference of one volt.Hence, it has a value of one volt, which is 1 J/C, multiplied by the elementary charge e = 1.602 176 634 × 10 −19 C. [2]
In particle physics and physical cosmology, the Planck scale is an energy scale around 1.22 × 10 28 eV (the Planck energy, corresponding to the energy equivalent of the Planck mass, 2.176 45 × 10 −8 kg) at which quantum effects of gravity become significant.
where c is the speed of light and h is the Planck constant. [5] The relative uncertainty, 5 × 10 −8 in the 2006 CODATA recommended value, [6] is due entirely to the uncertainty in the value of the Planck constant. With the re-definition of kilogram in 2019, there is no uncertainty by definition left in Planck constant anymore.