Re: borrowing from tomorrow

[jmclean@chem.ucsd.edu (James Mclean)]

kowalskil@alpha.montclair.edu says:
> It is not "logical coninuity" that forces us to borrow from tomorrow. It is
> the practice of defining Coulomb before defining Ampere. Do you agree that SI
> is not compatible with the sequence we use to teach electricity? People who
> introduced SI created a problem which we should recognize. Using 4*Pi*eps
> (or 9*10^9, for that matter) is antipedagogical.

Why is it necessary to teach the SI definition of Coulomb in order to teach
E&M?  The meter doesn't have to be justified; you just present it and say
"here's our prefered unit of length".  Why not do the same thing with the
Coulmb, and leave the details of the SI definition for later in the course?
The 4*pi*eps can just be treated as a conversion factor.

On re-reading my note, I should probably make my question more specific
than "why not?".  If the above approach is used, what conceptual
difficulties to you find students to have, and why do you prefer to deal
with those difficulties at a different time in the course?

-- 
--James McLean
jmclean@chem.ucsd.edu
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