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Re: Magnetic Field in a Flat Spiral



Original poster: "Paul Nicholson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <paul-at-abelian.demon.co.uk>

David Thomson wrote:
> NIB magnet in various positions around the coil.

That's a really neat experiment - what a nice demonstration of the
shape of the field around a coil, every school physics lab should
have some of those NIB magnets, not to mention a TC or two!

Your description of the shape of the field as determined by the
magnet's vibration is very clear and spot on.

Beats the heck out of iron filings any day!  Nice one.

FYI,
It's quite easy to plot the magnetic field around an air cored coil,
just apply Biot and Savart's law to lots of points in a plane
containing the axis of the coil.  Work in cylindrical coordinates so
that you only have to sum components in the r and z directions, then
plot a little arrow at each point.  An easy and worthwhile
programming exercise - an hour or two, tops.  A little more of a
challenge if you want to plot field lines.

BTW, what's an NIB disk magnet, and where do I get one from?
--
Paul Nicholson
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