# Physics H133: Problem Set #8

Here are some hints, suggestions, and comments on the problem set.
## Two-Minute Problems

Remember to give a **good** explanation, no longer than
two sentences.

- Q8T.7: In which states will the quantons sit if they are bosons
(fermions)? Add up the corresponding energy eigenvalues.
- Q9T.6:
Look at the answers to Exercises Q9X.7 and Q9X.8
(page 173) for example explanations.

## Chapter Q8 and Q9 Problems

- Q8S.7: (a) How should you modify Eq.(Q8.7) for helium to account
for the modifications in a_0 and E_n? (Don't forget the
ke
^{2} part.) (b) Check
that n_i=infty produces visible light for n_f=5, and then
lower n_i until you reach the edge of the visible spectrum.
(c) Try other values of n_f, starting from n_f=1. For each n_f,
bring your modified version of Eq.(Q8.7) into a form
that allows you to quickly check whether there are any
possible n_i-values *at all* that will produce
visible light. If the answer is yes, identify these n_i.
- Q8S.9: Protons and neutrons are commonly called "nucleons". Use
the Pauli principle to fill up the box states with either
only neutrons or with neutrons and protons until all 12
nucleons are placed in the lowest possible energy eigenstates.
Add up the energy eigenvalues for each case and compare.
- Q9S.4: Look up xenon (Xe) in the periodic table on the back inside cover
of Unit Q. What is the ground state configuration of its
filled electron orbitals? Use Table Q9.3 to explore the
possible excited states for one of the 5p electrons and
whether any of them are metastable.
- Q9S.7: Draw "before and after" pictures for the emission and
absorption processes and consider in each case the constraints
from energy and momentum conservation. Convince yourself that
in either case the atom suffers
*recoil*, i.e. it ends
up with kinetic energy even if before the emission or absorption
process it was at rest. Work out the effects of this recoil
energy on the energy balance and photon energy.
- Q8R.1: Consider the
*ratio* of the two longest wavelengths
in each case. How do they compare with the ratio of the
given numbers?

Your comments and
suggestions are appreciated.

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**Physics H133: Hints for Problem Set 8.**

Last modified: 05:19 pm, April 15, 2012.

furnstahl.1@osu.edu