Several teams are using different techniques to zero in on the
Planck constant (SN: 9/5/15, p.
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, Phys.
where [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] is the momentum operator and h is the reduced
Planck constant, can be expressed using (2) as