[time-nuts] Primary Standards...
Dr. David Kirkby
david.kirkby at onetel.net
Wed Feb 24 00:26:33 UTC 2010
David C. Partridge wrote:
> No they cannot be - yet. At the point where (e.g.) the second is re-defined
> in terms of the aluminium quantum clock, then the aluminium quantum clocks
> are then by definition the primary standards of time, and all the Cs clocks
> are now secondary standards as the second is no longer defined in terms of
> the Cs beam clock.
Does that mean that there is no primary standard for the Ampere?
An Ampere is defined as the current which will produce an attractive force of 2
× 10–7 newtons per metre of length between two straight, parallel conductors of
infinite length and negligible circular cross section placed one metre apart in
Since its impossible to build such a system, does that mean there is no primary
standard for an amp?
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