Re: Teaching Magnetism

[Herbert H Gottlieb <herbgottlieb@JUNO.COM>]

Also, it is easy to make a re-magnetiser
to recharge weak permanent magnets or to
make new magnets from bars of iron, steel,
or alnico.

One can be made in a few minutes using
a long length of insulated wire, a
tiny piece of aluminum foil and
an ordinary electric plug that can be
inserted into your wall socket.

Herb Gottlieb from New York City
(Where these magnet rechargers were
used by hundreds of our physics teachers)

On Sun, 06 Jul 2003 16:22:02 -0400 Larry Cartwright
<exit60@CABLESPEED.COM> writes:
> John Clement wrote:
> > The other problem that I see is that my bar magnets are very weak,
> but
> > with the disk magnets it is harder to see where the poles are
> located.
> > Also my bar magnets already have labels N on one end.
>
> Anyone who uses old iron-alloy magnets (bars, horseshoes, etc) in
> their
> instructional program should consider investing in a re-magnetizing
> coil.  Those alloy bars probably didn't have much of a field when
> they
> were new, and they get worse with time.  A re-magnetizer removes a
> lot
> of the frustration which comes from trying to conduct experiments
> with
> "magnets" that are not magnetic.
>
> The "N"'s can be cut off or ground off some of the bars if you want
> an
> unlabelled set.  If you have a re-magnetizer, you can make your own
> custom unlabelled magnets from steel bar stock.
>
> Best wishes,
>
> Larry
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Larry Cartwright                    Retired Physics Teacher
> <exit60@cablespeed.com>              Charlotte MI 48813 USA
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> - Good judgment comes from experience,
>   and a lot of that comes from bad judgment.
> - If you're leadin' the herd, take a look back
>   now and then to make sure it's still there.
> - A good time to keep your mouth shut is when
>   you're in deep water.
> - If you're lookin' for permanent employment,
>   scratch a dog.
> - Learn from the mistakes of others.  You ain't gonna live
>   long enough to make 'em all yourself.
>                         -- The Cowboys' Guide To Life
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


Herb Gottlieb from New York City
A nice friendly  place to visit