Final report on key comparison EUROMET.EM-K4 of 10 pF and 100 pF capacitance standards

This report describes a comparison of 10 pF and 100 pF capacitance standards organized within the framework of EUROMET Project No. 345 between 1995 and 1998. Piloted by the National Physical Laboratory (NPL, UK), the comparison involved sixteen national metrology institutes (NMIs), several of which are members of other regional metrology organizations, and the Bureau International des Poids et Mesures. The results show that there are significant differences between representations of the farad by some NMIs. However, the agreement demonstrated by the comparison gives confidence in maintaining traceability for the farad via either a calculable capacitor or a quantum Hall reference standard and the consensus value of the von Klitzing constant, R_K-90.