Which equation is used to calculate the momentum of an electron?

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    Electron Momentum
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Discussion Overview

The discussion revolves around the appropriate equations for calculating the momentum of an electron, considering different contexts such as classical and quantum mechanics. Participants explore the implications of using either p=mγv or p=h/λ, and the relevance of each in various scenarios.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants question whether to use p=mγv or p=h/λ for calculating the momentum of an electron, emphasizing the need for context.
  • One participant notes that the momentum of an electron in a material differs from that in a particle accelerator, suggesting that the context determines the appropriate equation.
  • Another participant distinguishes between free particle momentum, which can be described by classical physics, and momentum in quantum mechanical situations.
  • It is proposed that p=mγv applies in any context, while λ=h/p relates to the wave function of an electron.
  • One participant argues that the Hamiltonian of the system influences the electron's momentum, and that momentum eigenstates do not exist in reality due to normalization issues.
  • There is a mention that the electron's momentum is dependent on the potential it is in, and that one can only calculate a probability distribution rather than a definitive momentum eigenstate.

Areas of Agreement / Disagreement

Participants express differing views on the appropriate equations to use for calculating electron momentum, indicating that multiple competing perspectives remain unresolved.

Contextual Notes

The discussion highlights limitations related to the context of the problem, the definitions of momentum in different frameworks, and the complexities of quantum mechanics that affect the calculation of momentum.

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When finding the momentum of an electron, would you use p=mγv or p=h/λ? It is a massive particle, so which one would you use?
 
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DownQuark said:
When finding the momentum of an electron, would you use p=mγv or p=h/λ? It is a massive particle, so which one would you use?

This cannot be answered without context. The momentum for electron in a material is different than finding it in a particle accelerator. So which one do you want?

Zz.
 
Well what is the difference? And, which equation is for which case?
 
One is a free particle and can be accurately described by classical physics. The other is a quantum mechanical situation.

Zz.
 
[tex]p=mv\gamma[/tex] in any context. [tex]\lambda=h/p[/tex] for the wave function of an electron.
 
Delends on the hamiltonian of the system, and there really exist no momentum eigenstates in reality, since they cannot be normalized.

If the above made no sense to you, the electron's momentum depends on the potential it is in, and even then you can only calculate the probability distribution, a momentum eigen state is not a physical state
 

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