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!

QM- Why is the separation constant +/-l(l+1) ?

  1. Oct 24, 2011 #1
    This isn't a HW problem, it's more of a general question. I'm reading Griffith's Intro to QM 3rd Edition. On page 134 he uses separation of variables, of which I'm familiar (but by no means an expert). Could someone explain why the separation constant in equations 4.16 and 4.17 changes sign?

    The equations in question : http://imgur.com/8OKqz" [Broken]
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Oct 24, 2011 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    If you look at the equation above those two, you see the terms sum to 0, so if one is positive, the other one is negative.
  4. Oct 24, 2011 #3
    Jeez, that should have been obvious!
    Thanks for your help.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: QM- Why is the separation constant +/-l(l+1) ?