[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.
> 
> Dave

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 
a vacuum.

Since its impossible to build such a system, does that mean there is no primary 
standard for an amp?



Dave





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