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Homework Help: Expectation value of 1s state of hydrogen driving me absolutely nuts

  1. Oct 15, 2006 #1
    My question says:

    "Evaluate the expectation value <1/r> of the 1s state of hydrogen. How does this result compare to the result found using the Bohr theory?"

    Firstly, I have been told that <1/r> does not mean <1/r> but rather that it means 1/<r>. Having made it this far I now do the 1/<r> and get about 12 times the bohr radius which is obviously wrong. Apparently the answer is 3/2 the bohr radius.
    But also, I thought that doing <r> was supposed to give you 3/2 bohr radius, so what is this 1/<r> for?
    Basically, what the hell is going on, in simple, clear terms???
    Thank you for any help,
  2. jcsd
  3. Oct 15, 2006 #2

    Meir Achuz

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    1/<r> is wrong. It should be <1/r>.
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