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Thermodynamics - Work done on a paramagnetic material

  1. Apr 16, 2014 #1
    What is the work done on a paramagnetic? I have seen both of the following:

    [itex]\hat{d}[/itex]w = -MdB
    [itex]\hat{d}[/itex]w = -BdM

    Where B is magnetic field and M is magnetisation

    Am I missing something here or are these two completely opposite? My text book says that -MdB is the work done but I am sure I have seen articles where they use HdM as the work done. Could somebody clear this up for me?
  2. jcsd
  3. Apr 16, 2014 #2
    See the paper The Form of Magnetic Work in a Fundamental Thermodynamic Equation for a Paramagnet
    Am. J. Phys. 67, 613 (1999).

    A copy can also be obtained at http://faculty.luther.edu/~macdonal/ .
  4. Apr 17, 2014 #3


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    Gold Member

    Do you know the relationship between B and H?
  5. Apr 19, 2014 #4


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    Science Advisor

    One of the best discussions is given in Landau, Lifshitz, Vol. V, Section 31 and 32.
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