# Components for the angular momentum operator L

#### QMquestions

1. The problem statement, all variables and given/known data

Consider wavefunction psi (subscript "nlm") describing the electron in the stationary state for the hydrogen atom with quantum numbers n,l,m and the third component L3 for the orbital angular momentum operator L. What is the expectation value of L3 and of L3^2 for the state described by psi?

2. Relevant equations

3. The attempt at a solution

L = sqrt(l(l+1)*hbar).

And I think L3 is the same as Lz
Lz = m*hbar
but I don't know what stationary state implies in terms of quantum numbers.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

#### QMquestions

To add to my attempt at a solution:

<L3> = <Lz> = integral(-inf to inf of(psi* x L3operator x psi dz)

L3 operator = (-i x hbar) x (partial / partial x phi)

#### malawi_glenn

Homework Helper
stationary means that it does not depend on time, no time dependence.

#### QMquestions

does that have implications on the orbital angular momentum operator?

#### malawi_glenn

Homework Helper
no, hint: write the solutions in terms of spherical harmonics and use the property of L_z operator on those.

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