How to break the attraction of magnets?
For all magnetic materials, they are not magnetic at any temperature. Generally, a magnetic material has a critical temperature Tc, at which the arrangement of atomic magnetic moments is disordered due to the intense thermal motion of atoms at high temperatures. Below this temperature, the magnetic moment of the atom is arranged in order, producing spontaneous magnetization, and the object becomes ferromagnetic.
Curie temperature is the temperature at which material can change between a ferromagnet and a magnet. Below the Curie temperature, the substance becomes ferromagnetic, when the magnetic field associated with the material is difficult to change. When the temperature is higher than the Curie temperature, the material becomes a paramagnetic material, and the magnetic field of the magnet changes easily with the change of the surrounding magnetic field. The magnetic susceptibility at this time is about 10 minus 6 times
With this feature, a number of control components have been developed. For example, we use the rice cooker to take advantage of the Curie dot properties of magnetic materials. At the bottom of the rice cooker, a magnet is placed in the center and a magnetic material with a Curie point of 105 degrees. When the pot of water after the dry food, the temperature will rise from 100 degrees. When the temperature reaches about 105 degrees, due to magnetic material of the magnet magnet disappeared, it lost the suction, then the springs between the magnets and magnetic materials to separate them, and drive the power switch is disconnected, stop heating.
