Resolution 2 of the 19th CGPM (1991)

The Josephson and quantum-Hall effects

The 19th Conférence Générale des Poids et Mesures,


  • that worldwide uniformity and long-term stability of the national representations of electrical units are of great importance for science, industry and commerce for both technical and economic reasons,
  • that many national laboratories now use the Josephson and quantum-Hall effects for the conservation of their representations of the volt and the ohm respectively, a practice giving complete security in terms of long-term stability,
  • that the values attributed to their representations should be in as close as possible agreement with the SI,

recalling Resolution 6 of the 18th Conférence Générale concerning adjustments then foreseen in representations of the volt and the ohm,

noting the decisions made by the Comité International des Poids et Mesures in 1988, during its 77th Meeting concerning these adjustments, in particular the conventional values KJ-90 (equal to 483 597,9 GHz/V) and RK-90 (equal to 25 812,807 Ω) attributed to the Josephson constant KJ and the von Klitzing constant RK used in representations of the volt and the ohm respectively,


  • that national laboratories continue their efforts to reduce the uncertainty in the knowledge of the ratios KJ-90/KJ and RK-90/RK,
  • that research be continued into the basic theory of the Josephson and quantum-Hall effects.

DOI : 10.59161/CGPM1991RES2E

The reader should note that the official version of this Resolution is the French text

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