is perturbed by the potential $\mathrm{V}'=\mathrm{cx}\,\mathrm{eV}$, where c is a constant. The 1st order correction to the 1st excited state of the system is ____ $\times \mathrm{c\,eV}$.
Answer
SELF-PRACTICE — the source book printed no answer.
Nothing is invented here, so this question has no answer on record.