- #1
CAF123
Gold Member
- 2,948
- 88
Homework Statement
The wavefunction of a particle is given as $$u(r,\theta,\phi) = AR(r)f(\theta)\cos(2\phi),$$ where ##f## is an unknown function of ##\theta##. What can be predicted about the results of measuring
a) The z component of angular momentum
b)The square of the angular momentum
Homework Equations
Operators representing ##\hat{L}_z = -i\hbar \frac{\partial}{\partial \phi}## and ##\hat{L}^2 = -\hbar^2 \left(\frac{1}{\sin\theta} \frac{\partial}{\partial \theta} \left(\sin\theta\frac{\partial}{\partial \theta}\right) + \frac{1}{\sin^2\theta} \frac{\partial^2}{\partial \phi^2}\right)##.
The Attempt at a Solution
To obtain these predictions, I thought I could act with the two operators above in turn on ##u##. If ##u## was an eigenfunction of the operators, then I would know for sure the possible outcomes of the measurement. $$a) \hat{L}_z u(r,\theta,\phi) = -i\hbar A R(r)f(\theta) \frac{\partial}{\partial \phi} \left(\frac{e^{i2\phi} + e^{-i2\phi}}{2}\right) = 2\hbar AR(r)f(\theta) \left(\frac{e^{-2i\phi} - e^{2i\phi}}{2}\right) $$and so ##u## is not an eigenfunction of the operator. How do I obtain the possible outcomes then?