Proposal for the direct comparison of the standards of, capacitance and inductance to ac QHR

The representation of the ohm by the quantum Hall effect permits the reproduction of the farad unit by tracing capacitance to dc resistance. Many R–C bridge’s types are used in these determinations. In effect a chain of some bridges must be used.The proposed “direct comparison method” (DCM) is based on the definition of impedance and admittance and performs the detection of the equality of the rms value of voltage drops and currents.By DCM, at maximum operating frequency of 3 kHz, capacitance and inductance standards in the rage from 2 nF to 2 μF and from 30 mH to 1 H can be directly compared to ac QHR.These comparisons by DCM can be performed within few parts in 109 and a frequency measurement currently performable within one part in 109–1010 and the detection of the ratio of resistances and conductances performable within few parts in.