Instead of actually handing in any homework, how about if we have a quiz tomorrow at the beginning of class. Very short; based on HW8 (which has only one problem).
The quiz will ask for a length scale constructed using only e^2 (in Joules-meters), hbar and m (kg). Any quantity with units of length is correct. Assume e^2 has units of Joule-meters (i.e., so that e^2/r has units of energy). Maybe also a K.E. and P.E.. Those are really easy, right?
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This is a bit short of notice.
ReplyDeleteHW 8 actually has 2 problems. Do we need the second problem for this quiz, because i have no access to Liboff's pages 367-380 until after class tomorrow?
ReplyDeleteThis is too short of a notice. I feel this class is loosing its structure to the disadvantage of those of us that do not regularly check our email. I am a very busy person and I set a schedual in the beginning of the quarter based on regulare HW assignments due on thursday. Now that this is changing I feel I am falling behind.
ReplyDeleteI understand and appreciate your point. Maybe a balance between advanced scheduling and flexibility is possible.
ReplyDeleteI do think this will take you less than 1/2 hour and, if you have that time to spare, this will help you get more out of Tuesday's class.
It is actually very easy. There is no calculation, but, at this point, it is very valuable for you to have the concept of a length scale fresh in your mind and to see the connection to 1D QM length scales, esp. for the delta function potential. What is the eqn for k-1 for that? How did (does) it depend on alpha.
P.S. I don't think the class is loosing structure. I think only the HW due date and pattern associated with that is loosing structure.
ReplyDeleteAlso, I did communicate, in writing i think, at the beginning of the quarter that you were expected to have about 4 hours between each class (Th to Tues., Tues. to Thurs.)to do mini-HW assignments.
PS. The quiz is just what it says above. Write down a length scale constructed from e^2, hbar and m.
ReplyDeleteIsn't the answer for the quiz question on page 447 in Liboff?
ReplyDeleteThe answer is: hbar^2/m e^2
ReplyDeleteIn case anyone was confused: -e is the charge of the electron (and +e the charge of the proton).
Thus e^2 is a measure of the strength of the electron-proton interaction.
So, was the quiz worth anything?
ReplyDeleteCan't we leave it at,"a length scale constructed from e^2, hbar, and m is hbar^2/me^2"?
If I had seen this before now, things would be great, but I hadn't so they're not :(