Chapter 6.4, Problem 6.13P

(a)

To determine

To show that if the electron is in the ground state, then $\langle {\text{p}}_{\text{e}}\rangle =0$.

(b)

To determine

To give an example of wave function that has an energy level of $n=2$ that has non-vanishing expectation value $\langle {\text{p}}_{\text{e}}\rangle$, and compute the expectation value $\langle {\text{p}}_{\text{e}}\rangle$ for this state.