>From: Spike Jones <spike66@ibm.net> Fri, 03 Mar 2000
>
>> ... express velocities in horseturds per fortnight... {8^D spike
>
>> Michael S. Lorrey wrote:
>> Due to the predominantly US membership, I made it in Her
>> Majesties Royal units,
>> though I admit that even when I was in school in the 80's
>> (high school physics),
>> english units were used at least half the time.
>
>Mike someone asked me the other day what was 7.4 meters in
>English units. I said very loudly "English schmingliiiish! Think metric!"
How about cgs? (centimeter-gram-sec)
Those are the astronomers' units. Unfortunately, cgs *electrodynamics*
calculations are not as easy to use, (and I find those units really
weird) and it's easy to forget a 1/c or (4 pi eps_0) or some such thing.
But plasmas are everywhere in the Universe, so we are faced with
cgs electrodynamics equations sometimes.
elementary charge = e = 4.8E-10 statCoulomb
current = 1 statC/sec = (1/3)E-9 ampere
Potential is statC/cm, which doesn't grok with me at all,
so I have to make a conversion:
==> e(SI)/e(cgs)=3.335E-10C. Then to convert potential from cgs-SI,
I must multiply (3.335E-10/(4 pi eps_0) *10^2 (in meter)
= 299.7, final units in Volts
Maybe horseturds per fortnight makes sense to me now. :{
Amara
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Amara Graps | Max-Planck-Institut fuer Kernphysik
Interplanetary Dust Group | Saupfercheckweg 1
+49-6221-516-543 | 69117 Heidelberg, GERMANY
Amara.Graps@mpi-hd.mpg.de * http://galileo.mpi-hd.mpg.de/~graps
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