Conventional value of Josephson constant
ElectromagneticExact
= 483 597.9 × 109 Hz V−1
- Value
- 483 597.9 × 109 Hz V−1
- Standard uncertainty
- exact
- Relative uncertainty
- exact
- Status
- Exact: conventional value adopted in 1990
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
Plain
LaTeX
Python
# conventional value of Josephson constant, CODATA 2022 (NIST)
conventional_value_of_josephson_constant = 4.835979e14 # Hz V^-1, exact
# SciPy: scipy.constants.physical_constants['conventional value of Josephson constant']What it is
From 1990 to 2019 electrical metrology used this agreed value, 483 597.9 GHz/V, instead of the SI value of 2e/h, which was then less precisely known. The practical volt it defined, V₉₀, differed slightly from the SI volt; the 2019 redefinition ended the split.
Equations
- adopted 1990
How the value changed, 1998–2022
| CODATA | Value (uncertainty) | Relative uncertainty | Change from previous |
|---|---|---|---|
| 2022 | 483 597.9 × 109 | exact | exact |
| 2018 | 483 597.9 × 109 | exact | exact |
| 2014 | 483 597.9 × 109 | exact | exact |
| 2010 | 483 597.9 × 109 | exact | exact |
| 2006 | 483 597.9 × 109 | exact | exact |
| 2002 | 483 597.9 × 109 | exact | exact |
| 1998 | 483 597 900 000 000.0 | exact |
“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).