De Broglie Wavelength/Electron momentum

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Homework Help Overview

The discussion revolves around the de Broglie wavelength and electron momentum within the context of quantum physics. Participants explore the relationship between momentum and kinetic energy, particularly in relation to electrons and their behavior in quantum mechanics.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants question the distinction between linear and angular momentum in the context of electrons. There is a discussion about the applicability of classical equations for kinetic energy in relativistic scenarios. Some participants express confusion regarding unit conversions and the meaning of electronvolts (eV) in SI units.

Discussion Status

The discussion is active, with participants providing insights into the nature of momentum and kinetic energy. There is an ongoing exploration of unit conversions and the implications of relativistic effects on calculations. Some guidance has been offered regarding the relationship between kinetic energy and momentum.

Contextual Notes

Participants are navigating the complexities of quantum mechanics and its equations, with specific attention to the relevance of relativistic effects and unit conversions in their calculations.

DiamondV
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Homework Statement


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Homework Equations


Einsteins photon momentum: p=h/wavelength (rearrange to get de broglie wavelength)

The Attempt at a Solution


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I am quite new to all this quantum physics stuff. First of all where is the momentum of the electron referring to its angular momentum when it is orbiting? Can anyone explain this further to me. I think I need an equation here that relates the momentum to kinetic energy, I can't find anything like that.
 
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DiamondV said:
First of all where is the momentum of the electron referring to its angular momentum when it is orbiting?
No, this is linear momentum. You can simply imagine an electron traveling in a straight line.

DiamondV said:
I think I need an equation here that relates the momentum to kinetic energy, I can't find anything like that.
The relation is the same as in classical physics.
 
DrClaude said:
No, this is linear momentum. You can simply imagine an electron traveling in a straight line.The relation is the same as in classical physics.

Doesn't Einsteins relativity apply with electrons kinetic energy? I mean I don't think we can use KE=(1/2)mv^2
 
DrClaude said:
No, this is linear momentum. You can simply imagine an electron traveling in a straight line.The relation is the same as in classical physics.

Okay. I seem to have gotten somewhere further now. But my answer is incorrect, not too sure what to do with units. What is eV actually equal to in SI units?
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DiamondV said:
Doesn't Einsteins relativity apply with electrons kinetic energy? I mean I don't think we can use KE=(1/2)mv^2
What is the velocity corresponding to the momentum you calculated? Is it relativistic?
DiamondV said:
Okay. I seem to have gotten somewhere further now. But my answer is incorrect, not too sure what to do with units.
First, you should write the units in the calculation you made, to make sure everything is correct.

DiamondV said:
What is eV actually equal to in SI units?
1 eV = 1.60218×10-19 (that wasn't hard to find with Google :wink:)

By the way, you should commit to memory that ##E_K = p^2/(2m)##. It comes up all the time in quantum mechanics (and classical mechanics, for that matter).
 
DrClaude said:
What is the velocity corresponding to the momentum you calculated? Is it relativistic?
First, you should write the units in the calculation you made, to make sure everything is correct.1 eV = 1.60218×10-19 (that wasn't hard to find with Google :wink:)

By the way, you should commit to memory that ##E_K = p^2/(2m)##. It comes up all the time in quantum mechanics (and classical mechanics, for that matter).

Alright. So I checked the units it and I am getting Joules for my kinetic energy which seems correct. My answer is wrong though not sure why?

EDIT: I just realized its asking for answer in microeV, so ill just convert it. thanks for the help
 

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