Re: Does heat affect the magnetic field patterns in a horseshoe magnet?

Yes, heat does affect the magnetic field of any magnetic material. What we
have, in atomic scale, is a balance between temperature (that measures the
level of motion of the atoms in a solid) and the magnetic domains (the
preference of the spins to align themselves in a determined direction). As
the temperature increases, the percentage of magnetic domains aligned
decrese, so your magnet becomes "weaky". The temperature where no magnetic
domain can exists because the atoms agitation is so high that the spins can
not align in a preferencial direction is called "Curie Temperature" for
magnetic materials, and is about 600-800 degrees Celsius for most of the
materials. Above the Curie temperature, you have no longer a magnet, even
when you dissipate the heat and the material turns to ambient temperature
again.

So, if you want to show this fact, I suggest you to use some metallic
material (a blade, a nail), that you can magnetize by putting it in contact
with your magnet, sliding it many times against it. After the material
becomes magnetic (you can show this putting it to attract some light
metallic material), you can heat it slightly, and try to attract the
material again, heat it again with more intensity, and so on, until you
show that the material became non-magnetic, because you had "broken the
magnetic domain" of the atoms by heat.

You can use your horseshoe magnet to do that, but, at the end of the
experience, you have no longer a magnet, but only a horseshoe (no problem
if you have a horse to give it a gift...).

If you need any further explanation, please feel free to contact me.

Best regards

Eder C. Molina
IAG-USP
Brazil
eder@iag.usp.br