Spin, linear momentum and orbital angular momentum

1. Aug 27, 2014

How to prove when electron spin is perpendicular to linear momentum, orbital angular momentum can't be 0.
And when they are paralleled, orbital angular momentum is 0.
Thanks.

2. Aug 27, 2014

Avodyne

Your statements are not true. Orbital angular momentum does not depend on spin direction.

3. Aug 27, 2014

Meir Achuz

I think you are talking abput L_z, and not L^2.