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!

Particles unit of volume

  1. Mar 25, 2014 #1
    1. The problem statement, all variables and given/known data

    Show that for an ideal gas:

    n(E)dE=2πn/(kπT)3/2 *E1/2 exp(-E/kT) dE

    where n(E) is the number of particles for each element of volume whose energy is between E and E+dE

    2. Relevant equations

    3. The attempt at a solution
    Really don't know where to start from :frown:
  2. jcsd
  3. Mar 25, 2014 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    Start by reviewing your recent coursework concerning density of states and distributions.
    Is the gas confined to some sort of container? What sort? Do you have notes about energy levels and so on?
    That stuff.
  4. Mar 25, 2014 #3
    I have to start from
    E=1/2 mv²
    dE=mv dv

    I found an expression on the internet n(E)dE=N/z exp(-E/kt) * g(E)
    But how can I prove that to use it ?
  5. Mar 25, 2014 #4

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    I'm sorry - what is the course you are doing and what level?
    I'd have expected you to start from some potential - i.e. "particles in a box".
  6. Mar 26, 2014 #5

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    You should have a text book and lecture notes then.
    1st cycle = undergraduate: is this a first-year paper or course?

    Basically I cannot help you without giving you a couple of lectures on thermodynamics.
    These are things you should already have had - so you have lecture notes for those.
    You need to review your notes and give it your best shot.
    If there is something you don't understand in your notes, I could help with that.

    I have a crash-course review:
    http://home.comcast.net/~szemengtan/ [Broken] see: Statistical Mechanics.
    particularly ch1 and ch4.
    ... but it may be more advanced than you need.

    What you should not be doing is looking for equations online.
    They won't help you. You need to understand the physics behind the equations.

    ... reads like:
    $$n(E)dE = \frac{2\pi n}{(k\pi T)^{\frac{3}{2}}}\frac{E}{e^{-E/kT}} $$
    ... seems funny: is this verbatim for how it was given to you?
    ... do you know what all the symbols mean?
    ... is the n(E) on the LHS the same as the n on the RHS?
    Last edited by a moderator: May 6, 2017
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted