De borgie relation and photon energy

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Discussion Overview

The discussion revolves around the relationship between the de Broglie relation, photon energy, and the application of these concepts to electrons. Participants explore the validity of using certain equations to derive the wavelength of an electron and the implications of their findings.

Discussion Character

  • Exploratory
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant presents an equation derived from the de Broglie relation and attempts to calculate the wavelength of an electron, questioning why their professor dismissed the method as circular reasoning.
  • Another participant suggests that the first participant might be using the de Broglie relation in a different way, implying that the approach is not entirely invalid.
  • Some participants argue that the equation for photon energy (e = hc/l) is specifically relevant to photons and not applicable to electrons, raising concerns about the differences between photon energy and electron kinetic energy.
  • There is a suggestion that the energy of any particle could potentially be defined using its wavelength, although this is presented with caution.
  • A later reply emphasizes that momentum is related to wavelength through the equation P = h/λ, which may imply a different perspective on the relationship between energy and wavelength.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of the photon energy equation to electrons and whether the initial approach is valid. There is no consensus on the correctness of the method or the interpretation of the results.

Contextual Notes

Participants highlight the distinction between photon energy and electron kinetic energy, indicating potential limitations in the application of certain equations. The discussion also reflects uncertainty regarding the definitions and relationships between energy, momentum, and wavelength.

Who May Find This Useful

Individuals interested in quantum mechanics, wave-particle duality, and the mathematical relationships between energy and wavelength in different contexts may find this discussion relevant.

siromar
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I was playing around with equations last night while waiting on a friend, when I thought I stumbled on something strange.

I came up with the equation energy(e) = mass(m) x speed of light(c) x velocity(v) from the de Borgie relation wavelength(l)= plank's constant (h)/mv and the formula for the photon's electromagnetic energy e= hc/l. I tried plugging in numbers to see if I can solve for the wavelength of an electron without using the de Borgie relation, and it worked.

If the electron travels at 3.65 x 10^6 and using the invariant mass of the electron, e= mcv would give 7.24 x 10^-16

Plugging in that number in e = hc/l would give the correct answer of 2.74 x 10^-10 even though, according to my professor, the photon energy is completely unrelated to the electron.

Upon showing it to the professor to inquire as why such method would give a correct answer, he quickly dismissed me and said I got the correct answer because I went in a circle.

Can someone explain to me how what I did was going in a circle?
 
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Aren't you simply using the de broglie relation in a different way?
 
Drakkith said:
Aren't you simply using the de broglie relation in a different way?

Wouldn't that be true only if e= hc/l is relevant for the electron? I have been told that the equation can only be used for the energy of a photon, and that the electron kinetic energy is something completely different.
 
siromar said:
Wouldn't that be true only if e= hc/l is relevant for the electron? I have been told that the equation can only be used for the energy of a photon, and that the electron kinetic energy is something completely different.

I believe the energy of any particle can be defined by using the wavelength. But don't quote me on that.
 
It's the momentum that's related to wavelength.
P=h/λ
 

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