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Homework Help: Recoil energy and Heisenberg Uncertainty principal

  1. Sep 4, 2005 #1
    I need to prove that the act of measuring exactly the position of an electron would change its orbit.

    change in position x change in momentum = h

    the limit would suggest that knowing the location exactly would set the change in momentum p= h

    What is the formula that relates energy above a quantity with changing orbits? I saw that the Rhydberg formula gives an Ionization energy, I am thinking that if I can prove that the energy change due to measurement is at least equal to this quantity then I have proven a change in orbit. Is this correct? I have found this energy to be in the 10^-18 J range, any ideas on what I can look at to figure this out? I have spent so much time on this and still have nothing more than qualitative answer that is given by the heisenberg principal.

    Any help would be appreciated.
    Thanks,
    -A
     
  2. jcsd
  3. Sep 5, 2005 #2
    Orbits are wavefuction density of electrons in an atom . With each electron is associated a spatial distribution within an atom.So HUP assigns that , at a given instant you can only determine one of the aspects out of position and momentum precisely . For an accurate knowledge of position , you have to sacrifice your knowledge about the associated momentum. Because there are only some premissible values of energy are allowed for an electron , so whenever there is some disturbance in the environment of an electron , it is transmitted and absorbed by the electron , and if that disturbance is ramnant enough to provide the minimum possible energy for an electron to make a transition , it will . So the "act of measuring " the position/momentum will always lead to a disturbance.

    BJ
     
  4. Sep 5, 2005 #3
    "it is transmitted and absorbed by the electron , and if that disturbance is ramnant enough to provide the minimum possible energy for an electron to make a transition , it will ."

    Yes, I think i'm actually getting a little closer to solving this (after hours of trying..) I will update tomorrow. This is interesting stuff, I wish I was better with it (and it will be a detriment to me if I don't become better really quickly!)

    thx.
    -A
     
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