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Copyright: 1996 - 2024
Webmaster:
Kirt Blattenberger,
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
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and text used on the RF Cafe website are hereby acknowledged.
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AirplanesAndRockets.com
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IEEE: Redefining the Kilogram - RF Cafe Forums
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Kirt Blattenberger
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Post subject: IEEE: Redefining the Kilogram
Posted: Fri May 18, 2012 8:33 am
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Joined: Sun Aug 03, 2003
2:02 pm
Posts: 476
Location: Erie, PA
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Greetings: The May 2012 edition of IEEE's
Spectrum
magazine has an interesting article discussing the
frustrating effort to establish a new method for
determining the standard kilogram. For 125 years,
the master standard has been a platinum-iridium
alloy cylinder about the size of a plumb. It is
stored in a vault, under three concentric Bell jars.
Every three years, the master standard is cleaned,
and every decade or so, the standard is compared
to other country's identical standards to determine
whether they all still measure the same mass. The
problem is that aside from the need to maintain
a physical block, the cumbersome process of comparative
measurement introduces perturbations and errors
in the results. The master standard has apparently
lost 55 micrograms since the first measurements,
and nobody knows where they went. That is not a
lot of mass compared to a kilogram, but with the
precision of measurements made by laboratory and
even commercial instruments and products, an uncertainty
in the eighth decimal point can be a serious handicap.
The article is only four pages long, but it
covers a lot of ground, including the current proposals
for the new master standard that does not involve
storing a specific mass.
The Kilogram, Reinvented
http://spectrum.ieee.org/consumer-electronics/standards/the-kilogram-reinvented/0
_________________ - Kirt Blattenberger
RF Cafe Progenitor & Webmaster
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Posted 11/12/2012
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