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Entropy concept

  1. Jun 13, 2014 #1
    I'm having trouble getting my head around entropy. In an isolated system, entropy can only remain the same or increase. Is this the same for a thermodynamics cycle? What I mean is, if I drew a cycle on a PV diagram, would the entropy keep increasing? I can't see how that would work, that would mean I would have infinite entropy if I run the cycle an infinite number of times
  2. jcsd
  3. Jun 14, 2014 #2

    Jano L.

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    Gold Member

    Thermodynamic entropy is a function of state. Cyclic process returns system into the same state all over again. So the value of entropy returns to the initial value as well.
  4. Jun 14, 2014 #3

    The entropy of the system undergoing the cycle would be the same after every cycle. If you have work dissipation or heat transfer between finite temperature differences then the entropy of the universe increases. So yeah the law of entropy applies perfectly to cycles.
    That being said, what's the problem with the entropy increasing without bound if you run the cycle many times? entropy increases or remains the same, there's no upper limit to the amount of entropy that can be created in the universe.
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