UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > General Vintage Technology Discussions

Notices

General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc.

Closed Thread
 
Thread Tools
Old 19th Nov 2009, 10:21 pm   #1
Lee de Forest
Retired Dormant Member
 
Join Date: Sep 2008
Location: Harrogate, North Yorkshire, UK.
Posts: 352
Default The Watt balance and the search for the kilogram

It is refreshing to read that one of the most advanced state of the art experimental machines for providing an accurate definition of the kilogram uses current-carrying coils and Faraday's law of induction.
Vintage electronics is alive and well.
http://en.wikipedia.org/wiki/Watt_balance
Lee de Forest is offline  
Old 19th Nov 2009, 11:46 pm   #2
SPCh
Rest in Peace
 
SPCh's Avatar
 
Join Date: Nov 2004
Location: Antwerp, Belgium
Posts: 345
Default Re: The Watt balance and the search for the kilogram

There was once a lump of platinum-iridium alloy in France which we all believed in.
No problem with "progress", but don't anyone get carried away ....!
SPCh is offline  
Old 20th Nov 2009, 11:42 am   #3
julie_m
Dekatron
 
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
Default Re: The Watt balance and the search for the kilogram

But surely this depends on the value of g being the same all along the balance beam? Even my school teachers couldn't agree on g ..... we would use 9.8 in maths (where we were using 22/7 for π and no calculators) or 10 in physics and CDT (where we were using calculators, and they already had a button for π. I remember my own calculator had several other fundamental constants, but g was not among them).

I always thought they were going to redefine the kilogram in terms of Avogadro's constant. I can just see some hapless lab technician having to count out 602 300 000 000 000 000 000 000 individual atoms of carbon-12 ..... and making sure there's no carbon-14 in there .....
__________________
If I have seen further than others, it is because I was standing on a pile of failed experiments.
julie_m is offline  
Old 20th Nov 2009, 7:11 pm   #4
Lee de Forest
Retired Dormant Member
 
Join Date: Sep 2008
Location: Harrogate, North Yorkshire, UK.
Posts: 352
Default Re: The Watt balance and the search for the kilogram

The British engineering breakthrough that establishes exactly how much mass there is in a kilogram has been sold to Canada.
http://www.eurekamagazine.co.uk/arti...e-problem.aspx
according to the article the uncertainty is enough to put a space probe off course (I don't think that this is going to be a problem to most of us seeing that I can't remember the last time that I plotted the flight path of a space ship).
The machine was first designed to define the amp in terms of the metre, kilogram and second. I assume that the amp can now be defined in terms of Planck's constant(?), the second and metre can be defined to high degrees of accuracy which working backwards allows you to calculate the kg.
It would be interesting to create some of the early vintage instruments.
Lee de Forest is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 12:34 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.