This is the course blog for Semester 1, 2011 at the University of Queensland
5/26/11
question
i am confused about the physical meaning of j(j+1),s(s+1),and l(l+1) in paramagnetism and diamagnetism in chapter 31 in Ashcroft and Mermin please can any one explain it ?
It's basically one of the differences between quantum and classical physics. If you consider the result, classically vec(J)^2 = |J|^2. However here in the quantum case, vec(J)^2 = |J|^2 + |J|, i.e. there is a quantum correction to the result. Also, remember in the above two equations you're dealing with the result when you act the vector operators on kets.
In their use in the chapter, its really nothing more than stating that acting J^2 on |J> will give you the eigenvalue J(J+1) and similiar for L and S.
It's basically one of the differences between quantum and classical physics. If you consider the result, classically vec(J)^2 = |J|^2. However here in the quantum case, vec(J)^2 = |J|^2 + |J|, i.e. there is a quantum correction to the result. Also, remember in the above two equations you're dealing with the result when you act the vector operators on kets.
ReplyDeleteIn their use in the chapter, its really nothing more than stating that acting J^2 on |J> will give you the eigenvalue J(J+1) and similiar for L and S.
thank you so much Robert for a clear explanation.
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