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Re: Teaching Magnetism



On Sunday, Jul 6, 2003, at 10:10 US/Eastern, John Clement wrote:

>. . . There is an allied problem to the N, S problem for magnets
> vs. geography. That is the +, - problem for charges. Again
> students tend to confuse this terminology with the usage of +
> and - in math. The fact that they do not really understand the
> number line and proper usage of + or - compounds this problem.
> Ben Franklin could very well have labeled the charges fur and
> silk. The idea that - is the absence of something is a very big
> problem for students . . .

On Sunday, Jul 6, 2003, at 10:54 US/Eastern, Marc Kossover wrote:

>>A few years ago, when I decided to get serious about teaching
magnetism,
>> I finally figured out a problem that many of my students had. They
thought
>> that the "North" side of a magnet was the side of the magnet that
was on
>> the north -- geographically -- side of the magnetic. . . .

The problem of renaming physics words has been addressed
here many times. At one time I started avoiding the word "heat"
but then I stopped doing this. I simply started to emphasize
possible misconceptions. Instead of referring to magnetic poles
as N/S, or +/-, one can say up/down, good/evil, black/white,
top/bottom, gold/silver, male/female or another similar pair of
word; even fur/silk, if you like. That is not a big issue for me.

The real issue has to do with the model itself. We know that
electromagnetism can be described without a reference to
magnetic poles. But does it mean that using them "as if they
were as real as electric charges" is desirable in introductory
courses? I think so. Likewise, I think that geometrical optics
should not be avoided "to make more room for" physical or
e&m optics. Models of limited validity, even the caloric model
of energy, are useful. But we must emphasize that many
aspects of reality are not accounted for in our conceptual
tools (models).
Ludwik Kowalski