Proofs with current density and wavefunctions

[Mary]

Homework Statement

So I was able to find a problem that was kind of similar to a homework problem that I am working on. Unfortunately, I'm not quite sure what is going on partially within the problem.

In the problem they state that \phi=\phi*, but it does not state why. I was wondering if someone could explain this to me?

Also, later on in the problem e^{-i\phi}e^{i\phi}+e^{i\phi}e^{-i\phi} cancels out along with the 1/2i. I'm not quite sure how this happened either. I have tried to review the euler's equation to understand where this comes from because I'm supposing it is being canceled out based on its properties.

I have attached the proof to this forum.


I would greatly appreciate some help because the problem I am working on involves proving that the integral of the current density over a surface is equal to the momentum operator/m. I understand conceptually what this means but I need a push in the write direction with the math behind it.

 

[MisterX]

You seem to be missing a factor of i when you plug back in. The i factors come from the \frac{\partial}{\partial x}.

Also,

e^{i\phi}e^{-i\phi} = e^{0} = 1.

This comes from the properties of exponentials, but you can show this using Euler's formula as well. Note \left(a + ib\right)\left(a-ib\right) = a^2 + b^2, and \sin\left(-\phi\right) = -\sin\phi.