1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Another question about Entropy

  1. May 8, 2009 #1
    First I apologize if this has been asked before; however, did a google search of the archives and could not find anything talking directly about my question about entropy of light and the entropy of sound. Also, it been bothering me for quite some time:

    1. Is there a quantitative or formulaic relationship between the measured properites of sound wave and the change in entropy of a system? If so can you give a common example?
    2. Is there a quantitative or formulaic relationship between the measured properties of a light wave and the change in entropy of a system? If so can you give a common example?
  2. jcsd
  3. May 8, 2009 #2


    User Avatar
    Homework Helper
    Gold Member

    Entropy of what system?
  4. Jun 14, 2009 #3
    First thanks for the fast response, ^_^. I honestly thought it was going to take longer XD. Unfortunately, I personally don't know what system either, although I would assume that it would be somewhat isolated. Maybe a better way would be to talk about what really sparked this train of thought....

    About ... 3 maybe 3.5 years ago I found a certain article written in 2000 by Seth Putterman and K. R. Weninger called "http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.fluid.32.1.445" [Broken]" I found the very article interesting (so interesting I decide to go as a major in physics); however, to get to the point, one of the things that struck me odd about this article was the following quote on page 447:

    "The local heating, which is 15 orders of
    magnitude greater than follows from Kirchoff’s law for the attenuation of sound,
    is strong enough to lyse cells. In fact this device is regularly used for the surgical
    procedure called ultrasonically assisted liposuction (Weninger et al 1999a). In
    that case a small hole up the center of the probe is used to remove the emulsified
    fatty tissue." pg. 447

    What I found odd was not the magnitude of heat at all, rather the simple fact that a formula called "Kirchoff's Law" (see footnote 1) existed that related sound to heating and vis versa for a certain set of conditions. (I don't know this law so I am not really sure what those conditions are ><; ) This made be wonder.... if we can draw a relationship between the properties of sound wave and heat transfer in a system then is it possible to go deeper ..... and draw a relationship between sound and entropy of that same system? Is there an academic example in physics relating the sound emitted on and entropy of a system? I am really not sure so that why I asked the questions I did.

    Then Beyond that I remember that http://en.wikipedia.org/wiki/Planck%27s_law" [Broken] for black body radiation related the temperature of a black body to the intensity of light. In the same manner, I wonder if its possible can one derive a relationship between the intensity of light and the entropy of the black body? Unfortunately I wasn't sure what would be a valid method of showing such a relationship.

    footnote 1: When I searched for the term "Kirchoff's law for the attenuation of sound", found it was Helmholtz-Kirchhof formula for the attenuation of sound not just Kirchhoff
    Last edited by a moderator: May 4, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook