De Broglie wavelength and atom penetration

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Homework Help Overview

The discussion centers around calculating the de Broglie wavelength of an electron with a kinetic energy of 60 GeV and exploring how this relates to the percentage of an atom's diameter that the electron can penetrate.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to calculate the de Broglie wavelength using the kinetic energy of the electron and expresses uncertainty about how to determine the penetration percentage related to an atom's diameter.
  • Some participants question the use of the electron's rest mass in momentum calculations and suggest using relativistic formulas instead.
  • Others mention the potential relevance of the Bohr model for the hydrogen atom's diameter in this context.

Discussion Status

Participants are actively discussing the appropriate methods for calculating momentum in relativistic scenarios and exploring the relationship between the de Broglie wavelength and atomic dimensions. Some guidance has been offered regarding the use of relativistic equations, but no consensus has been reached on the approach to penetration percentage.

Contextual Notes

There is a mention of needing to consider the relativistic effects due to the high kinetic energy of the electron, and the original poster is looking for equations or guidance on how to proceed with the penetration calculation.

Bakery87
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Homework Statement



Calculate the de broglie wavelength (DBW) of an electron with kinetic energy 60 GeV.

What percentage of an atom's diameter can it penetrate?


Homework Equations



DBW = h/p
p=mv


The Attempt at a Solution



Basically I have an electron traveling at the speed of light. I arrived at this from its kinetic energy (60 GeV) and by using the relativistic K-energy equation. So I get it's de broglie wavelength fairly easily (I have this part done).

The part I don't understand is the penetration. I guess I just need some guidance/equations. Any ideas?
 
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Welcome to PF, Barkery87.

For an atom's diameter, they might mean take the diameter of the Bohr model for the hydrogen atom in its ground state. What percentage of that diameter is the deBroglie wavelength?

p.s.
Um, you didn't use the electron's rest mass to calculate p=mv, did you?
 
I used 0.511003 MeV/c^2
 
Momentum is calculated differently for relativistic motion. There should be a formula in your textbook or lecture notes, relating E, p, and m (the rest mass, sometimes called m0)
 
I did find something...

p = K/c

I'm still looking through my notes.
 
Bakery87 said:
p = K/c

Actually, that's a valid approximation for extremely relativistic situations (like this one).
 

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