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When watching a video by Veritasium about the SI units redefinition (5:29), a claim that the volt and unit of resistance (presumably the ohm) will change by about 1 part in 10 million caught my attention:
[...] I should point out that a volt will actually change by about 1 part in 10 million, and resistance will change by a little bit less than that. And that's because back in 1990, the electrical metrologists decided to stop updating their value of, effectively, plancks constant, and just keep the one they had in 1990. And there was a benefit to that: they didn't have to update their definitions or their instruments. [...] Well, now the electrical metrologists will have to change. But, that's a very tiny change for a very tiny number of people.
Apparently, the reason is that on 20 May, 2019, redefinitions of SI base units are scheduled to come into force. The kilogram will be redefined using the Planck constant, which, presumably, means that any change in value from the previous definition (the International Prototype of the Kilogram) would affect derived units depending on it, including the volt, ohm, farad, henry, siemens, tesla and (formerly) ampere.
- Will the volt or ohm change, as Veritasium seemingly claims?
- Are any other electrical units (listed above) affected?
- If so, exactly how much will they have changed after the redefinition?