Several teams are using different techniques to zero in on the Planck constant
(SN: 9/5/15, p.
Fundamental particles have "inherent" number of spin, equal to integral or half-integral number (in Planck constant
units), which never changes.
These are the ground state hyperfine splitting frequency of the cesium 133 atom [DELTA]v[([.sup.133]Cs).sub.hfs]; the speed of light in vacuum c; the Planck constant
h; the elementary charge e (charge of a proton); the Boltzmann constant k; the Avogadro constant [N.sub.A], and the luminous efficacy [K.sub.cd] of monochromatic radiation of frequency 540 x [10.sup.12] hertz.
21 PHYSICAL REVIEW LETTERS, the NIST group gives a new value for the Planck constant
of 6.62606891 X [10.sup.-34] Joule-seconds, with an uncertainty of 87 parts per billion, less than half the uncertainty of prior measurements.
The electron's angular momentum is always equal to the reduced Planck constant
. This implies that the electron's mass has to increase [gamma] times in order to compensate for the decrease in its rotational velocity:
The energy values and the neutron wave functions in such a system depend on m, g, on the Planck constant
and on the quantum number n only.
Kibble at England's National Physical Laboratory, this method offers a precise value of the Planck constant
, from which one derives Avogadro's number.
Table 1 shows the basic set of electron and proton units that can be considered as a fundamental metrology (c is the speed of light in a vacuum, [??] is the Planck constant
, [k.sub.B] is the Boltzmann constant).
The National Institute of Standards and Technology (NIST) watt balance experiment completed a determination of Planck constant
in 1998 with a relative standard uncertainty of 87 X [10.sup.-9] (k = 1), concurrently with an upper limit on the drift rate of the SI kilogram mass standard.
Olsen, Accurate measurement of the Planck constant
where [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] is the momentum operator and h is the reduced Planck constant
, can be expressed using (2) as