[geocentrism] Re: SI units.
- From: "philip madsen" <pma15027@xxxxxxxxxxxxxx>
- To: <geocentrism@xxxxxxxxxxxxx>
- Date: Tue, 27 Feb 2007 06:42:46 +1000
Most of us would find it more logical to define the Coulomb in terms of a
integral number of charge carriers (e.g., electrons) and make the Ampere a
derived unit defined from that quantity of charge carriers passing through a
fixed region within one second of time,..... What can I say? Martin.
I say absolutely. er, its an absolute unit. But how can we derive an exact
second, and be certain of its duration?? (evil grin)
Philip.
----- Original Message -----
From: Martin Selbrede
To: geocentrism@xxxxxxxxxxxxx
Sent: Monday, February 26, 2007 3:37 PM
Subject: [geocentrism] Re: SI units.
Let's be careful here: the "four times pi" factor in the following
expression, , is based on the number of steradians in a sphere: the E field is
integrated over an entire sphere. This accounts for the presence of the "four
times pi" factor in the denominator or numerator of other equations governing
electromagnetism.
Moreover, you could derive this from the electrical permittivity with equal
ease, given the algebraic relationship of the magnetic permeability and
electrical permittivity of free space to the speed of light in a vacuum.
Finally, it should be noted that in the SI system, the Ampere is a
fundamental unit and not a derived unit (which makes the Coulomb a derived
unit, namely, an Ampere-Second). Most of us would find it more logical to
define the Coulomb in terms of a integral number of charge carriers (e.g.,
electrons) and make the Ampere a derived unit defined from that quantity of
charge carriers passing through a fixed region within one second of time, but
the SI Committee, well.... What can I say?
Martin
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