Re: DBowman's Def 4

[Jim Green <JMGreen@SISNA.COM>]

John, I don't doubt that this is quite true, but in my weakness  I am
unable to calculate the S of such a system in the same manner that I am the
standard cylinder --  and show that dS=0.  See the sketch on my web
page.  -- I have already tried what you suggest, but.... .  If you can post
such a derivation, you would have even greater admiration from me.

Jim

> For instance, take a thermally isolated paramagnetic substance and
> change the magnetic field slowly. Doing so alters the energy
> levels of the spin states without altering their occupation
> numbers and is, therefore, "pure" work. This is the basis of the
> adiabatic demagnetizaion refrigerator. It is closely analogous to
> the way that moving the piston slowly while thermally isolating
> the gas alters the translational kinetic energy levels of the gas
> without altering their occupation numbers. Again, "pure" work.
>
> John Mallinckrodt     mailto:ajm@csupomona.edu
> Cal Poly Pomona         http://www.csupomona.edu/~ajm

Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen