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classes:2009:fall:phys4101.001:q_a_1005

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classes:2009:fall:phys4101.001:q_a_1005 [2009/10/05 10:13] – jbarthelclasses:2009:fall:phys4101.001:q_a_1005 [2009/10/05 20:08] (current) – yk
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 ===Captain America - 10:09- 10/05/09=== ===Captain America - 10:09- 10/05/09===
-I thought the test was okay even though I confused myself over the ladder operators and probably got a 0 on that question as a result.  I'll agree with everyone else that the integrals shouldn't have been expected to be known since I'm pretty sure most of us just looked them up on an integral chart when we had similar ones for the homework.  A hint for the next time they come up though, try switching the sin and cos terms into Euler's formula with <math>e^(i*\theta)</math> terms as they are much more straightforward to integrate than things like sin squared.+I thought the test was okay even though I confused myself over the ladder operators and probably got a 0 on that question as a result.  I'll agree with everyone else that the integrals shouldn't have been expected to be known since I'm pretty sure most of us just looked them up on an integral chart when we had similar ones for the homework.  A hint for the next time they come up though, try switching the sin and cos terms into Euler's formula with <math>e^(i\theta)</math> terms as they are much more straightforward to integrate than things like sin squared.
  
-====Links====+====Cthulhu Food - 10:30- 10/05/09==== 
 +On page 78 Griffiths says that κ is real.  How can κ be real if E is positive?  Can E be negative? 
 + 
 +===Captain America - 10:43- 10/05/09=== 
 + 
 +In the example here we are only considering bound states, which all have a negative E value by the definition of bound states (since the potential is defined as 0 and the bottom of the well is defined as <math>-V_0</math>).  κ is only real in these situations, and for scattering states where the E is positive κ will have an imaginary term I believe. 
 + 
 +==== time to move on ==== 
 + 
 +It's time to move on to the next Q_A: [[Q_A_1007]] 
 + 
 +--------------------------------
 **Return to Q&A main page: [[Q_A]]**\\ **Return to Q&A main page: [[Q_A]]**\\
 **Q&A for the previous lecture: [[Q_A_0930]]**\\ **Q&A for the previous lecture: [[Q_A_0930]]**\\
classes/2009/fall/phys4101.001/q_a_1005.1254755581.txt.gz · Last modified: 2009/10/05 10:13 by jbarthel

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