# Physics H133: Problem Set #6

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.

- Q6T.5: What determines the probability of finding the quanton
at a given position?
- Q6T.9: For a free particle with well-defined momentum (or wave length),
what can we say about the probability to find the particle at
a given point? Are there any positions more likely than others?
So if we measure a definite position (i.e. the quanton's state
collapses to a position eigenstate), can the momentum be still
well-defined?

## Chapter Q6 Problems

- Q6S.5: (a) What is the expression for the probability of collapse of
either |psi> or |psi'> to |psi_f>? Now simply work it out.
(b) You can use Eq. (Q5.7).
- Q6S.9: (a) Just use the normalization condition with the
result for the integral in (Q6.31).
(b) You need to do an integral over the region near the origin.
If x is always small in this interval, you can do a Taylor
expansion of the integrand (how many terms should you keep),
leaving an integral you can do in
your head.
- Q6S.11: (a) Is there
* experimental * evidence suggesting that the die has
settled down before we look? (b) Is there * experimental *
evidence which is * in contradiction * with the assumption
that the quanton has a definite position before we measure it (e.g.
in the two-slit experiment)?
- Q6R.2: Write down a general normalized 2-component complex state
|psi> and translate the statements given in the problem into
conditions for these complex components. Which rule provides these
conditions? After you have written them down, solve these conditions.
There is more than one solution, but you need to find only one.
- Q6A.1: Simply follow the logic given in the problem statement.
Write down general expressions for the desired pairs of 2-component
vectors which satisfy the additional special properties stated in
parts (a) and (b), respectively, and translate the expected 50
percent "overlap" probabilities into conditions for the unknown vector
components. Solve them together with the conditions for orthogonality
and normalization. The reasons why we can demand the special properties
of the vector components (real, positive, etc.) given in parts (a) and
(b) are explained in the Comment at the end of the problem -- this
is not part of the problem to be solved by you (you did this part
already in Q6S.5).

Your comments and
suggestions are appreciated.

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**Physics H133: Hints for Problem Set 6.**

Last modified: 08:17 pm, April 11, 2012.

furnstahl.1@osu.edu