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Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!calvin!johns
From: johns@calvin.EE.CORNELL.EDU (John Sahr)
Newsgroups: sci.electronics,rec.ham-radio,sci.astro,sci.space
Subject: Re: Trying to build a fluxgate magnetometer -- help!
Message-ID: <1425@calvin.EE.CORNELL.EDU>
Date: 30 Oct 89 02:50:40 GMT
References: <1914@sactoh0.UUCP> <28601@buckaroo.mips.COM> <1989Oct29.174631.12960@ux1.cso.uiuc.edu>
Reply-To: johns@calvin.spp.cornell.edu.UUCP (PUT YOUR NAME HERE)
Organization: Cornell Space Plasma Physics Group
Lines: 41

In article <1989Oct29.174631.12960@ux1.cso.uiuc.edu> mcdonald@aries.scs.uiuc.edu (Doug McDonald) writes:
>>>I would like to measure changes at least as small as
>>>10 gammas (.001 Gauss), and if possible, even smaller.
>>?  You mean of course, nanotesla (nT), since 1954.  :-)
>I have been in the science business for over 20 years and have
>never heard anyone refer to magnetic fields in Tesla - everyone
>uses gauss. It is true that people know that someone somewhere
>created a unit of magnetic field called a Tesla, but no one
>remembers how many gauss are in one Tesla, and no one uses it.
>Sometimes it might appear in a textbook (usually directed at
>freshmen or sophmores - more advanced books use gauss).
[]
>Doug McDonald

Whoa, thea, padnuh.  The "Tesla" is alive and well, thank you.  If I walk
over to the High Volt Lab, I find people quite comfortable with kilogauss
or tesla (not the same, of course), as they torture innocent protons.

Engineering textbooks through the graduate level tend to use MKS units,
which include Tesla.  Physics textbooks, on the other hand, tend to use
cgs, which include gauss.  I have several of each brand of text. For
genuine pandemonium, look at plasma physics texts.  In ionospheric physics, 
there is no standard at all, but a pretty free mix of cgs and MKS.  Chen's
plasma physics 1st ed was in cgs: the second is MKS.  You be the judge.

Actually, I prefer cgs all the way, myself, but I'm not dogmatic about it, 
even though it ought to be obvious that cgs units are The One True Units.  On
the other hand, E/B in MKS has units of velocity, which is convenient.  But
on the other hand, E/B in cgs has no units at all, which is also convenient.
On the other hand, my Radio Shack voltmeter insists on giving me MKS units.
On the other hand, Jackson is a nice reference, and uses cgs, so it must be
good.

So, as I said, I don't insist upon cgs, because this is a free planet.

But, come the revolution, the MKSeoisie will be the first with 
their backs against the wall.

-- 
John Sahr,                   | Electrical Engineering - Space Plasma Physics
johns@alfven.spp.cornell.edu | Cornell University,         Ithaca, NY  14853