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Permanent magnetism is caused by the alignment of magnetic moments, and induced magnetism is created when disordered magnetic moments are forced to align in an applied magnetic field. For example, the ordered magnetic moments ( ferromagnetic , Figure 1) change and become disordered ( paramagnetic , Figure 2) at the Curie temperature.
When the temperature rises beyond a certain point, called the Curie temperature, there is a second-order phase transition and the system can no longer maintain a spontaneous magnetization, so its ability to be magnetized or attracted to a magnet disappears, although it still responds paramagnetically to an external field.
These temperature dependencies have also been experimentally observed in NiFe 2/5 Cr 8/5 O 4 [8] and Li 1/2 Fe 5/4 Ce 5/4 O 4. [9] A temperature lower than the Curie temperature, but at which the opposing magnetic moments are equal (resulting in a net magnetic moment of zero) is called a magnetization compensation point. This compensation point ...
The solar dynamo is a physical process that generates the Sun's magnetic field.It is explained with a variant of the dynamo theory.A naturally occurring electric generator in the Sun's interior produces electric currents and a magnetic field, following the laws of Ampère, Faraday and Ohm, as well as the laws of fluid dynamics, which together form the laws of magnetohydrodynamics.
It can be seen from the above discussion that, although on a microscopic scale almost all the magnetic dipoles in a piece of ferromagnetic material are lined up parallel to their neighbors in domains, creating strong local magnetic fields, energy minimization results in a domain structure that minimizes the large-scale magnetic field. In its ...
The coolest of these, 2MASS J10475385+2124234 with a temperature of 800-900 K, retains a magnetic field stronger than 1.7 kG, making it some 3000 times stronger than the Earth's magnetic field. [18] Radio observations also suggest that their magnetic fields periodically change their orientation, similar to the Sun during the solar cycle .
A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. An everyday example is a refrigerator magnet used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic).
The most functional feature of kinematic dynamo theory is that it can be used to test whether a velocity field is or is not capable of dynamo action. By experimentally applying a certain velocity field to a small magnetic field, one can observe whether the magnetic field tends to grow (or not) in response to the applied flow.