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Cerenkov Radiation/Cerenkov Light

  1. Jul 13, 2005 #1
    I have done a search but found no answers to my question; which is, why; by definition...
    Cerenkov radiation: light emitted by a transparent medium when charged particles pass through it at a speed greater than the speed of light in the medium.
    After I read that, I immediately narrowed my eyes.

    No sites I have been to have addressed the rather strange thing that the particle is defined to be travelling faster than the speed of light. Can anyone explain this to me? I am having trouble understanding how this particle can move faster than the speed of light.

  2. jcsd
  3. Jul 13, 2005 #2
    the particle isn't actually travelling faster than light. the light still moves at c. it just gets absorbed and reemitted by matter which makes it take longer to go a certain length. though the particle can beat the photon from point a to point b, it is not travelling faster.

    iirc, the cerenkov radiation is because the charged particle outruns the photons which make up it's electric field.
  4. Jul 13, 2005 #3
    dear yourdadonapogostick,

    ah, i see... so light is actually moving slower in the medium? so it appears as though the particle is outrunning light, it's not, really, light just got the brakes put on it?
    pleaes confirm that i have understood this correctly

  5. Jul 13, 2005 #4
    that's correct. Remember that no particle can go faster than the speed of light in a vacuum, in a medium where light is slowed down by interactions with matter, it is perfectly acceptable for a particle to move faster than the speed of light, and when this happens, usually in nuclear reactors, the result is Cerenkov Radiation.

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