# Difference between expectation values of $L^2$, $L_z$ and measuring $L^2$, $L_z$

I was given with this hydrogen radial wavefunction

$$R_{21} =\left(\sqrt{\frac{1}{3}}Y^0_1 + \sqrt{\frac{2}{3}}Y^1_1\right)$$

a) What are the expectation values of the $L^2$, and $L_z$?
b) If you measured the orbital angular momentum squared $L^2$, what values might you get? Do the same for $L_z$.
My answer for $L^2$ is: $$L^2 \psi = l(l+1)h^2 \psi \\ = 2h^2 \psi$$ hence the expectation value for $L^2$ is $2h^2$, now what should be my answer for b)?
If $R_{21}$ is an eigenfunction of $L_z$ then all measurements of this quantity when the wavefunction is in such a state will yield the same value always. So, in that case, the answers to a) and b) will be the same. I am currently learning QM as well so someone correct me if this is incorrect. Your wavefunction is conveniently expressed in terms of the eigenstates of both $L^2$ and $L_z$ so by acting with these operators onto the eigenstates gives the possible values immediately. –  CAF Mar 17 at 20:59
your own lecture notes work out this exact problem on page 5, under "class excercise", but correctly distinguish the wavefunction $\psi$, the radial function R and the spherical harmonic Y. physics.udel.edu/~msafrono/626/Lecture%201.pdf –  DavePhD Mar 17 at 21:22