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classes:2009:fall:phys4101.001:q_a_1007 [2009/10/07 19:05] – kuehlerclasses:2009:fall:phys4101.001:q_a_1007 [2009/10/13 16:53] (current) – x500_kroh0054
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 ====Zeno 10/7 11AM==== ====Zeno 10/7 11AM====
 One more conceptual question: I understand how particles can penetrate potential barriers, reflecting and transmitting the incident wave, but I don't understand the reflection by a potential //well//. The delta function well in Fig 2.15 has me wondering how a well reflects part of a wave instead of "trapping" it in a bound state or transmitting it. I feel like there's something simple conceptually that I'm missing, so a little help with interpretation would be much appreciated. One more conceptual question: I understand how particles can penetrate potential barriers, reflecting and transmitting the incident wave, but I don't understand the reflection by a potential //well//. The delta function well in Fig 2.15 has me wondering how a well reflects part of a wave instead of "trapping" it in a bound state or transmitting it. I feel like there's something simple conceptually that I'm missing, so a little help with interpretation would be much appreciated.
 +
 +===chavez 10/8 6PM===
 +It makes sense (to me) if you divide the space under consideration into regions associated with specific potentials. There will then be a discontinuity in the potential energy between each region of space. It is a general property of waves to scatter when a discontinuity in potential is encountered.
  
 ===Pluto 4ever 10/7 7PM=== ===Pluto 4ever 10/7 7PM===
 Essentially, what I get from this is that this deals with the probability of a particle being able to get out of a well. The more energetic a particle is the greater the probability it has of escaping from the well. So if a particle does not have the energy to make it through the barrier then it will be reflected back into the well (trapped). Of course, that is not to say it will never be able to get out. Although, it energy is less than the barrier it can still escape by means of tunneling. Essentially, what I get from this is that this deals with the probability of a particle being able to get out of a well. The more energetic a particle is the greater the probability it has of escaping from the well. So if a particle does not have the energy to make it through the barrier then it will be reflected back into the well (trapped). Of course, that is not to say it will never be able to get out. Although, it energy is less than the barrier it can still escape by means of tunneling.
  
 +===Dark Helmet 10/08===
 +I think of it like waves on a string of different materials.  Any time the wave changes medium there will be both reflection and transmission.  If you think of the potential well as just a part of the string that is less dense and a wall as part that is more dense, it makes sense.  Anytime the wave changes potentials, it's like the string changing mediums.  At least that's how i think of it, but i could be missing something too. 
 +===spillane===
 +Are there other resources that explain the delta function and the associated limit of a sequence. 
  
 +====Dagny====
 +When we have a delta-function barrier, why do we no longer have a bound state?
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classes/2009/fall/phys4101.001/q_a_1007.1254960306.txt.gz · Last modified: 2009/10/07 19:05 by kuehler

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