Electrodynamics related question

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Discussion Overview

The discussion revolves around the Bremsstrahlung effect and the emission of photons by accelerated electrons, particularly in the context of X-ray production and radio frequency radiation. Participants explore the conditions under which electrons radiate photons when accelerated by a potential difference.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant describes the process of generating X-rays through the Bremsstrahlung effect, questioning whether electrons radiate photons when accelerated by a potential difference.
  • Another participant draws a parallel between the acceleration of electrons and the functioning of radio transmitter antennas, suggesting that similar principles apply to the emission of radio waves.
  • A later reply confirms that electrons do emit radiation when accelerated, noting that the emitted radiation's bandwidth is lower than that of X-rays and that the emission rate is reduced due to slower acceleration compared to the braking mechanism. The Larmor formula is mentioned as a means to calculate the power of the emitted radiation.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the emission of radiation by accelerated electrons, with some clarifications provided. However, there is no explicit consensus on the details of the mechanisms involved or the comparative rates of emission.

Contextual Notes

Participants reference the Larmor formula and Jackson's textbook for further details, indicating that the discussion may depend on specific definitions and assumptions related to radiation emission and acceleration rates.

fluidistic
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I've "learned" how to make X-Rays with the Bremsstrahlung effect. That is, we accelerate electrons (that we get by a current passing through a resistance) through a difference of potential and we put a material (generally metallic) so that electrons get "decelerated" very quickly and they emit photons, X-rays.
My question is: when we accelerate the electrons with the difference of potential, don't they radiate photons?
 
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fluidistic said:
I've "learned" how to make X-Rays with the Bremsstrahlung effect. That is, we accelerate electrons (that we get by a current passing through a resistance) through a difference of potential and we put a material (generally metallic) so that electrons get "decelerated" very quickly and they emit photons, X-rays.
My question is: when we accelerate the electrons with the difference of potential, don't they radiate photons?
For regular RF frequencies it is called a radio transmitter antenna. In this case the radio antenna (usually 1/2 or 1/4 wavelength long) radiates a coherent RF wave (photons) with wavelengths of a few centimeters to ~300 meters. Microwave antennas are slightly different in that the radio waves are often emitted directly from waveguides without physical antennas.

Bob S
 
fluidistic said:
I've "learned" how to make X-Rays with the Bremsstrahlung effect. That is, we accelerate electrons (that we get by a current passing through a resistance) through a difference of potential and we put a material (generally metallic) so that electrons get "decelerated" very quickly and they emit photons, X-rays.
My question is: when we accelerate the electrons with the difference of potential, don't they radiate photons?

Yes, but the bandwidth of the emitted radiation is much lower than X-rays and the rate of emmission is lower due to the much slower acceleration when compared to the braking mechanism. You can actually calculate the power of the emited radiation using the Larmor formula. Jackson gives a detailed treatment of such problems in his textbook.
 
Ok thank you guys, really awesome explanations. I get it.
 

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