# Physics H133: Problem Set #9

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.

1. Q10T.2: How are kinetic energy and wavelength related? de Broglie!
2. Q10T.4: Check the derivation in Section Q10.3 (the summary in the chapter overview at the beginning may be clearest!).

## Chapter Q9 and Q10 Problems

• Q10S.4 and Q10S.5: Follow the usual step -- take two derivatives, plug everything into the Schrodinger equation and check whether the ansatz solves the equation. In one case it does, in one it doesn't.
• Q10S.8: (a) Where does a cosine "crest"? (b,c) Straightforward if you use some graph paper. (d) Remember how to compute the local wavelength (see Section Q10.2).
• Q10R.1: Parts (a), (b), and (d) are straightforward. For (c), check how the kinetic energy is found at each x and how this relates to the local momentum and thus wavelength. Figure Q10.1 may be helpful. For (e), guess some power of n (not necessarily an integer!).
• Q9A.1: Just follow the instructions (and hint) in each part.

Your comments and suggestions are appreciated.
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Physics H133: Hints for Problem Set 9.
Last modified: 05:20 pm, April 15, 2012.
furnstahl.1@osu.edu