|MadSci Network: Physics|
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 firstname.lastname@example.org
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