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Radial postion - momentum uncertain for 2s Hydrogen

  1. Apr 8, 2013 #1
    1. The problem statement, all variables and given/known data
    I'm trying to calculate delta r * delta p for the Hydrogen atom in the 2s state

    2. Relevant equations
    ψ(r) = (1/ 2√π) (1 / 2a)^(3/2) (2 - (r/a)) e^(-r/2a)
    where a is the bohr radius

    3. The attempt at a solution
    I figured out that <r> = 6a, but I'm at a loss as to how to figure out <r2> or <p>.

    Using E = (-ke2 / 2a)(1/n2), and p2 = 2mE, i found <p2> = (m/2)(-ke2 / 2a), but im not 100% sure this is right

    EDIT: would <p> = 0 since Hydrogen 2s is spherically symmetric?
    Last edited: Apr 8, 2013
  2. jcsd
  3. Apr 8, 2013 #2


    User Avatar

    Staff: Mentor

    How did you calculate ##\langle r \rangle##?

    What is ##k##?

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