What is scattering by a potential and how does it affect a passing particle?

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    Potential Scattering
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Discussion Overview

The discussion centers on the concept of scattering by a potential, particularly in the context of unbound particles interacting with potential wells. Participants explore the implications of scattering in one, two, and three dimensions, as well as the physical interpretation of potential wells in classical and quantum mechanics.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants propose that scattering involves a probability of reflection or transmission of a particle when interacting with a potential well.
  • Others clarify that in one dimension, a particle can either be transmitted (continuing in the same direction) or reflected (changing direction), depending on its interaction with the potential.
  • A participant questions the physical meaning of transmission and reflection, particularly in the context of electrons approaching an attractive square potential.
  • Another participant explains that in classical mechanics, a passing electron can be deflected by the electric field produced by a proton, suggesting a similar framework applies in quantum mechanics where the electron moves in an electric potential set up by the proton.
  • There is an expressed uncertainty regarding the physical representation of potential wells and how they influence the path of particles.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the physical interpretation of potential wells or the mechanics of scattering, indicating multiple competing views and ongoing uncertainty.

Contextual Notes

Limitations include the need for clearer definitions of terms like "transmitted" and "reflected," as well as the physical implications of potential wells in both classical and quantum contexts.

Shaybay92
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"Scattering" by a potential

When we have an unbound particle traveling past a potential well, what does it mean when it is said that the potential well will "scatter" the particle?
 
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In the one-dimensional case, it means that there is some probability that the particle will be reflected instead of transmitted.

In the two- or three-dimensional case, it means that there is some probability that the particle will emerge in a different direction than it entered.
 


What do you mean when you say transmitted/reflected? If we are talking about a beam of electrons moving towards an attractive square potential (-ve well), what is meant by whether it is transmitted or not..? (In 1D)
 


Suppose the particle is coming in from the -x direction, that is, it is traveling in the +x direction. Then:

Transmitted = after interacting with the barrier, it is traveling in the +x direction.

Reflected = after interacting with the barrier, it is traveling in the -x direction.
 


Ok, but how physically does this make sense? How does the fact it goes past a potential change its path? I suppose I still don't fully understand what potential wells represent physically.
 


In classical mechanics a proton, say, produces an electric field, and a passing electron can be deflected ("scattered") by this electric field. You can also write the problem in terms of the electron moving in an electric potential set up by the proton. This is how you have to do the problem in quantum mechanics.
 

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