[time-nuts] Primary Standards...

Dr. David Kirkby david.kirkby at onetel.net
Wed Feb 24 01:11:50 UTC 2010

Tom Holmes, N8ZM wrote:
> My recollection of the definition of an Ampere is 6.02 x 10^23 electrons per second (Avogadro's Number, I believe) passing a point in a conductor. To this day, I wonder how they managed to count all those electrons. But it does suggest that the silver deposit approach might be a better method of building a standard. Seems, though, like you'd have to make a darned high resolution weight measurement.

That certainly was not the definition I learned during my EE degree, and neither 
is it the one given on Wikipedia - not that I'd call Wikipedia a standard.

My recollection is the same as Wikipedia's - though I could not remeber the bit 
about it needing to be a vacuum. But if you stuffed mu-metal between the wires, 
it would tend to reduce the force, so I can well believe its defined in a vacuum.

I think as someone else said, this depends on one's definition of a "standard". 
There's no one standard definition of a standard (pun intended).


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