Question about cherenkov radiation

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    Cherenkov Radiation
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Discussion Overview

The discussion centers around the conditions under which Cherenkov radiation is emitted by two charged slabs moving at relativistic speeds, particularly focusing on the role of the medium and the relative velocities of the slabs. Participants explore theoretical scenarios and clarify concepts related to electric fields and radiation emission.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions whether both slabs would emit Cherenkov radiation if they are moving together at relativistic speeds, suggesting that in their respective rest frames, each slab approaches the other faster than the group velocity of light in its material.
  • Another participant asserts that Cherenkov radiation occurs only if each slab is moving faster than c/n in the medium, emphasizing the importance of the medium's speed.
  • A participant clarifies that they are not suggesting anything travels faster than c, but questions whether Cherenkov radiation occurs in both slabs or just one, noting the role of electric fields.
  • One participant asks for clarification on what medium the slabs are moving through and reiterates that they would emit Cherenkov radiation if moving faster than c/n.
  • A participant specifies that the slabs are moving through free space and discusses the interaction of their electric fields, questioning if one or both slabs emit radiation.
  • Another participant emphasizes that only the charge's velocity relative to the medium matters for radiation emission, reiterating that any slab moving faster than c/n will radiate.
  • One participant reiterates that the slabs are not in a medium and discusses the concept of electric fields causing radiation as they pass each other.
  • A final participant states that without a medium, there can be no Cherenkov radiation, as it is defined as radiation produced by a charged particle moving faster than light in that medium.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of a medium for Cherenkov radiation and the conditions under which it occurs. There is no consensus on whether both slabs would emit radiation or just one, and the discussion remains unresolved.

Contextual Notes

Participants reference the concept of electric fields and their propagation, but there is uncertainty regarding the definitions and implications of these concepts in the context of Cherenkov radiation. The discussion also highlights the dependence on the presence of a medium and the relative velocities of the slabs.

cragar
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If I had 2 charged slabs that were moving together at relativistic speeds would both slabs
emit cherenkov radiation. In each of the rest frames of the slabs the other slab is approaching it at a speed that is faster than the group velocity of light in its material.
 
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Only if each one is moving faster than c/n in the medium. The medium's speed matters in this case.
 
okay I am not saying anything travels faster than c.
Cerenkov radiation occurs when an E field is being forced through a material
faster than light in that material. so we are talking about speed lass than c.
Does Cherenkov radiation happen in both dielectric slabs or just one.
I was typing this up the same time vandium posted.
 
What are both slabs moving through? If they are moving through a medium at a velocity higher than c/n (the speed of light divided by the refractive index of the medium), then they would emit cherenkov radiation.

And what do you mean when you say that an E field is being forced through a material. Electric fields have no "speed", they simply exist. Changes in the field propagate at c however.
 
the slabs are moving through free space but they are moving by each other and their E fields exist in each others slab. I know its c/n but we are dealing with relative speed here.
in slab A's frame its at rest and slab B is moving towards it and vice versa for the other slab. So is their Cerenkov radiation in one slab or both? I know E fields don't travel, but in a sense the slab is outrunning its E field that is being setup in the other slab.
kind of like retarded potentials
 
The only thing that matters is the charge's velocity relative to the medium. Any slab moving faster than c/n will radiate.
 
Vanadium 50 said:
The only thing that matters is the charge's velocity relative to the medium. Any slab moving faster than c/n will radiate.

The slabs are not in a medium, he's talking about the electric field from each slab somehow causing radiation to be emitted as they pass by each other.
 
If there's no medium, there is no Cerenkov radiation, since the definition of Cerenkov radiation is the radiation produced by a charged particle moving faster than light in that medium.
 

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