Pyromagnetism

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Pyromagnetism (from the Greek πῦρ pȳr : fire) is a largely obsolete technical term in physics and electrical engineering that describes various interactions between heat and magnetism . The term was used in scientific publications until the beginning of the 20th century. With a few exceptions, the term is not used in modern physics.

In modern scientific literature, the term pyromagnetism is used in the following meanings.

  • As an abbreviation for temperature-dependent ferromagnetism .
  • As an analogy to pyroelectricity . Hence the property of an originally non-magnetic material to generate a macroscopic magnetic field when the temperature changes.
  • In patent law for the classification of thermodynamic machines that have magnetic components.

So-called pyromagnetic motors have a low level of efficiency and are only used in physical toys or as demonstration objects.

Historical

Up until the beginning of the 20th century, the physics of ferromagnetism in solids could not be theoretically explained, so the thermodynamics of the effect could not be calculated. There have been numerous attempts, including by Nikola Tesla , to construct a pyromagnetic motor or pyromagnetic generator based on temperature-dependent ferromagnetism or exceeding the Curie temperature . The efficiency and power density of such pyromagnetic motors and generators is low, so that no practical application has been made.

The term pyromagnetism was never exactly defined and disappeared from the literature with the discovery of the Curie effect and the quantum mechanical description of para- and diamagnetism.

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  • Margaret Cheney "Nikola Tesla"

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