Conventional value of von Klitzing constant
ElectromagneticExact
= 25 812.807 Ω
- Value
- 25 812.807 Ω
- 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 von Klitzing constant, CODATA 2022 (NIST)
conventional_value_of_von_klitzing_const = 2.5812807e4 # ohm, exact
# SciPy: scipy.constants.physical_constants['conventional value of von Klitzing constant']What it is
The agreed value 25 812.807 Ω used for resistance standards from 1990 to 2019. The practical ohm it defined, Ω₉₀, differs from the SI ohm by the small amount shown on the ohm-90 page.
Equations
- adopted 1990
How the value changed, 1998–2022
| CODATA | Value (uncertainty) | Relative uncertainty | Change from previous |
|---|---|---|---|
| 2022 | 25 812.807 | exact | exact |
| 2018 | 25 812.807 | exact | exact |
| 2014 | 25 812.807 | exact | exact |
| 2010 | 25 812.807 | 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).