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Measurable quantites vs Base units

by elegysix
Tags: base, measurable, quantites, units
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f95toli
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Jul11-14, 05:34 AM
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Quote Quote by elegysix View Post
Can't current be 'measured' by the number of charge carriers which pass a point in a specific time?
That's just an amount, and a time.
Yes it can, and it is likely that this is how the Ampere will be re-defined in a few years. The realization will then by some sort of electron pump that send electrons one at a time and the current will be I=e*f where e is the electron charge and f the pump frequency. e would then be defined to have an exact value. These devices already exist, but at the moment they are not quite accurate enough (they need to improve by about a factor of 5).

However, this would not in any way change the fact that the Ampere is a base unit in the SI; only the definition(and realization) will change.


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