# Thermodynamics - Work done on a paramagnetic material

 P: 5 What is the work done on a paramagnetic? I have seen both of the following: $\hat{d}$w = -MdB $\hat{d}$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?