Planck's constant

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Related to Planck's constant: Reduced planck's constant


The basic unit of radiant energy defined by the equation
E = hν
where h is Planck's constant (6.62 ✕ 10−34 joule ✕ second), ν the frequency of the light and E the energy difference carried away by the emission of a single photon of light. The term photon usually refers to visible light whereas the term quantum refers to other electromagnetic radiations. See quantum theory; wave theory; troland.
References in periodicals archive ?
The new measurements have such low uncertainty that they exceed the international requirements for redefining the kilogram in terms of Planck's constant.
The watt balance and atom-counting techniques now give nearly identical values of Planck's constant, with an uncertainty of less than 20 parts in a billion, says metrologist Ian Robinson of the National Physical Laboratory in Teddington, England.
where M is the mass of the system, c is the speed of light, [??] is Planck's constant, and H is the Hubble constant.
But then, we are not working with Planck's constant. TABLE 1 THE AVERAGE DURATION ON POOR RELIEF IN THE UNITED STATES IS CONSTANT, 1820s-1990s Average Duration on Years Data Description Relief (in Months) 1820s New York City and State 5-9 (public relief) 1850s-60s Six representative states 4-11.6 (urban) (public relief) 8-11.3 (rural) 1880s-90s Charity Organization Society, 9.4-15.7 Indianapolis (private charity) 1910s New York City and Brooklyn 9-15 (private charity) 1970s Negative Income Tax 13.3 Experiment, Seattle and Denver (AFDC) 1980s-90s United States means-tested 6.3-7.8 (natives) programs (AFDC, food 6.7-9.5 (immigrants) stamps, Medicaid) NOTE: The studies are, or are roughly comparable with, random samples from the "flow" of month-to-month activity.
The amount of such energy must be a whole-number multiple of h (Planck's constant: 6.55 X [10.sup.-27] erg-seconds).
Planck's constant represented, so to speak, the graininess of the Universe.
Instruments based on the technique could soon be capable of reproducing the international ampere to the required accuracy, which may also pave the way to a new definition of the kilogramme, via Planck's constant. The famous but gently-corroding platinum-iridium brick held near Paris will then be retired, the last basic unit to be defined by reference to an artifact.
(C/mol) Faraday constant L/A Flux density [L=luminosity; A=area] G -9.81 (m/(s^2)) Gravitational constant -32 (ft/(s^2)) Gravitational constant [PI]/(dh)=(MRT)/(dh) Gravitational constant [j=osmotic pressure; d=density; h=height; M=concentration (molarity) of solution; R=ideal gas constant; T=temperature in Kelvins] w/m Gravitational constant [w=weight; m=mass] H E+PV Enthalpy [E=energy; P=pressure; V=volume] E/v Planck's constant [E=energy; v=frequency] E/f Planck's constant [E=energy; f=frequency] (E[lambda])/c Planck's constant [E=energy; [lambda]=wavelength; c=speed of light] mv[lambda] Planck's constant [m=mass; v=velocity; [lambda]=wavelength] [lambda][rho] Planck's constant [[lambda]=wavelength; [rho]=momentum] 6.62607 ...
Producing a number with a plausible length for the atomic spoke was possible only by combining the key quantity in quantum theory, Planck's constant, with the electric charges and masses of the electron and nucleus.
Combining the speed of light, the electric charge of an electron, and Planck's constant, alpha has always been measured on Earth to have the same value, approximately 1/137.
They could only occupy states, called "shells" by Bohr , that were proportional to the angular corollary of Planck's constant. The allowed orbits were calculated by Bohr from the mountain of data accumulated from years of spectroscopic investigations.
(In the preceding equation, h is Planck's constant and c, the speed of light.) If the photon is absorbed by a grain of dust, that grain picks up its energy, warming in the process and radiating in the infrared.