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Homework Help: Uncertainty Principle, Energy and Position

  1. Mar 30, 2010 #1
    1. The problem statement, all variables and given/known data

    Electrons in atoms are known to have energies in the range of a few eV. Show that the uncertainty principle allows electrons of this energy to be confined in a region the size of an atom (0.1 nm)

    2. Relevant equations

    [tex]\Delta[/tex]x[tex]\Delta[/tex]p [tex]\geq[/tex] h bar / 2

    [tex]\Delta[/tex]E[tex]\Delta[/tex]t [tex]\geq[/tex] h bar / 2

    3. The attempt at a solution

    h bar = 6.58 x 10^-16 eV * s
    [tex]\Delta[/tex]x = .1 nm

    I know that if there was an uncertainty relationship between Energy and displacement I could set h bar and [tex]\Delta[/tex]x to the values given and show that this is possible, but I can't figure out how to find an energy position uncertainty relation.
  2. jcsd
  3. Mar 31, 2010 #2
    1/2mv^2 and mv look an awful lot a like...
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