| MadSci Network: Engineering |
Hi Milton, Thanks for writing to us! The phenomenon you're talking about is called "Induction Heating" or "Magnetic Cooling" and it affects any electrically conductive material to some extent. Induction Heating is when you form a coil of wire and run an alternating current through it. If you put any metallic or conductive object inside the coil, you'll induce localized "eddy" electrical currents in the object. Since the object has a certain amount of electrical resistivity, it will heat up. If you set the Alternating Current at a low frequency, the heat is concentrated in the center of the object. Higher frequencies will heat the surface of the object. Magnetic Cooling is the flip side of Induction heating. When you remove the part from the magnetic field, it will cool. Certain materials are more affected thermally by magnetic fields than others. This "magnetocaloric" property determines how much heat is generated by how much magnetic field. Right now, there is research being conducted on a Gadolinium/Silicon/Germanium alloy that has the best magnetocaloric effect yet discovered. I think this is the material you are referring to. Links: Magnetic Cooling DOE project Magnetism FAQ Ameritherm Inc. (Manufacturer of Induction Heating power supplies) Radyne Corp. (Induction Heater Manufacturer) (You can request literature about the technology from this company) Magnetic Cooler Schematic Web Elements If you also search "Inductive Heating" or "Magnetic Cooling" on an internet search engine, there are lots of sites with additional info. I hope this helps! Jeff Yap Mad Scientist
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