No abstract

The precise measurement of Planck Constant h to establish a kind of quantum mass standard is an important but very difficult work. The Joule Balance method, for the same purpose but different from Watt Balance method, is going on in NIM for three years. The principle and progress are described.

The Joule Balance method, for the same purpose but different from the Watt Balance method, is going on at NIM for several years. The first measurement result of the Planck constant h is 6.6261(5)×10 −34 Js with a measurement uncertainty of 7.7 × 10 −5 . The further plan for improvement is discussed.

No abstract

Traditionally, the most precise way to get the mutual inductance value is by a calculable mutual inductor. Here a new approach of measuring the mutual inductance at low frequency with compensation method is described. The mutual inductance is traced to the value of the frequency and resistance directly. The measurement uncertainty is 0.1ppm and could be improved further.