Re: Earth's Magnetic Field

[Maurice Barnhill <mvb@UDEL.EDU>]

Larry Smith wrote:
> > The whole business is easy if you recognize that the magnetic pole of
> > the Earth which is located in the northern part of the planet is a
> > *south*-seeking pole. It therefore attracts the opposite poles of
> > compasses, the north-seeking poles.  This way the north poles of
> > compasses point roughly north and navigators go in the right direction.
>
> I'm confused by your "seeking" suffix.  I would agree with your whole
> paragraph if you left out the "seeking" everywhere.  To me, the end of a
> bar magnet or a compass needle (both labeled with the same convention, in
> my opinion, contrary to the magnetizer instructions) with an "N" on it
> should point to the arctic, geographic North pole (magnetic south pole) of
> the earth.
>
> The "seeking" part seems to confuse the issue.


The "seeking" label is an old terminology and perhaps deserved to be
discarded.  I think the point was simply to have a way of emphasizing
the distinction between the compass-pole labelling and the
geomagnetic-pole labelling.  [Notince that even in that last sentance
where I wanted to avoid the terminology I had to invent a new one --
"compass-pole".]

> > The convention with respect to the direction of flux, out of
> > north-seeking poles and into south-seeking poles, also works with the
> > Earth's poles; *provided that you recognize that the south-seeking pole
> > is the one in Canada.*  In the northern (magnetic) hemisphere, the
> > Earth's magnetic field point northward and *down*.
>
> Field lines go from N to S _outside_ the magnet, but from S to N inside the
> magnet.  At least that is the "convention" I've been teaching.

Of course.  Sorry I wasn't clear about meaning the lines outside the
dipole.
> Cheers,
> Larry Smith

--
Maurice Barnhill, mvb@udel.edu
http://www.physics.udel.edu/~barnhill/
Physics Dept., University of Delaware, Newark, DE 19716