# Orbital Angular Momentum Origin

by widderjoos
Tags: angular momentum
 P: 21 We know from classical mechanics that angular momentum $L = r \times p$ depends on your choice of origin. My question is: How does this work quantum mechanically? We know we get certain eigenvalues, but does this apply only in a certain choice of origin? How do we calculate angular momentum at some other point? I had a similar problem concerning torque on a magnetic dipole, $\tau = \mu \times B = r \times F$. About what point do we measure the moment arm? Do we just assume our origin is at the "center" of the orbit? Thanks for the help.
 Quote by widderjoos We know from classical mechanics that angular momentum $L = r \times p$ depends on your choice of origin. My question is: How does this work quantum mechanically? We know we get certain eigenvalues, but does this apply only in a certain choice of origin? How do we calculate angular momentum at some other point? I had a similar problem concerning torque on a magnetic dipole, $\tau = \mu \times B = r \times F$. About what point do we measure the moment arm? Do we just assume our origin is at the "center" of the orbit? Thanks for the help.