By Paul Dohrman, Updated Mar 24, 2022
Image credit: Eric Tischler/iStock/GettyImages
Magnetic heating, or magnetic hysteresis loss, occurs when a ferromagnetic material is exposed to a rapidly alternating magnetic field. The field forces the material’s magnetic domains to flip, producing frictional heat that can be harnessed for various applications—from industrial furnaces to targeted cancer therapy. This article demonstrates how a standard household AC outlet can generate such a field using a simple lamp cord and an iron or steel bolt.
Unplug an old lamp that you no longer use. Carefully cut the cord about two feet from the plug. If you prefer, you can purchase a replacement lamp plug or cord from an electronics store such as Radio Shack.
Use scissors or a knife to cut the two conductors all the way down to a few inches from the plug. Be sure not to expose the bare wire by cutting through the plastic insulation.
Wrap one of the conductors tightly around a large iron or steel bolt. Aim for 40 or more turns, keeping the layers to no more than three or four to maintain a compact coil. The metal core is essential because only ferromagnetic materials reverse polarity in an alternating magnetic field.
Trim about an inch of insulation from the ends of both wires. Connect the exposed ends together, securing them with electrical tape for insulation and safety.
Insert the plug into a wall outlet. The alternating current will create a magnetic field that forces the domains in the bolt to flip, generating heat. Gently touch the bolt to feel the temperature rise.
Remove the plug immediately if you detect any burning odor or if the bolt becomes excessively hot. The coil’s resistance may be insufficient to prevent a high current draw, potentially overloading your circuit.
