Re: magnetic poles

[Mark Sylvester <msylvest@spin.it>]

> Date: Sat, 14 Feb 1998 04:16:22 -0500
> From: "William J. Larson" <Bill_Larson@compuserve.com>
> To: "INTERNET:phys-l@atlantis.uwf.edu" <phys-l@atlantis.uwf.edu>
> Subject: magnetic poles
> Message-ID: <199802140417_MC2-3343-E8F8@compuserve.com>
>
> Message text written by INTERNET:phys-l@atlantis.uwf.edu
> > Doesn't this all become a non-issue if we say "The Earth's Magnetic Nort=
> h
> Pole is a south-seeking pole"?<
>
> Sure, but as I understand it, for centuries we have been using the
> definition =
>
> that "The north pole of a magnet points north (if it is free to do so)."
> This is actually easier to remember and use unless you are analyzing the =
>
> Earth's field instead of the magnet's.  But more to the point, it's in
> place and =
>
> overturning it with its exact opposite would be very confusing and indeed=
>
> impossible.  I've never actually tried this with a magnet with its ends
> marked
> "N" and "S", but I think it's correct.  If anyone has, especially if they=
>
> have =
>
> found the opposite, please post your observation.
>
> Bill Larson
> Geneva
>
> ------------------------------

I think you misunderstand me - I'm *not* proposing any change of
terminology! Not really. I just thought (optimistically) that it would
eliminate the problem if we emphasised that the N on the magnet means that's
the end that points north (geographical direction), so it's "north-seeking"
or perhaps "north-pointing" is more digestable in modern English. That's the
nature of its northness. 

The Magnetic North Pole, on the other hand, is (for purposes of this
discussion) a point on the Earth, near the Geographical North Pole (sort
of). *Its* northness means "is north" rather than "points north". If we
could hang the Earth up in the field of a much bigger earth, the little
Earth's MNP would point south. It's a south-pointing pole, i.e. the end of
the magnet with the S on it.

While recognising that explaining this is vastly impeded by the double
ambiguity of both "north" and "pole" in "north pole", I'm not sure what the
textbook misconception is supposed to be. 

Mark

Mark Sylvester
United World College of the Adriatic
34013 Duino TS
Italy.
msylvest@spin.it
tel: +39 49 3739 255