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What experiment best demonstrates electron radiation?

  1. Oct 18, 2012 #1
    1.) When and how did idea about radiating electrons come about, atomic theory and orbitals?

    2.) Is this phenomena considered purely QM, or inter-related with some other branch of physics like SR maybe? Or perhaps it can also be defined independently using some theories and equations other than QM?

    3.) What experiment best demonstrates electron radiation, most recent such experiment?

    4.) If electron is indivisible smallest amount of matter, then what is the explanation as to where those radiated photons are supposed to come from?
  2. jcsd
  3. Oct 18, 2012 #2
    1 , 2) This is in fact a classical idea which follows from Maxwell's equations. (Just to make sure - we're talking about electric charges emitting EM radiation when they accelerate)

    3) That's how radio waves are emitted from an antenna. That's where synchrotron radiation is produced in charged particle accelerators. Also check out Bremsstrahlung.

    4) But remember that whenever the radiation is produced by an accelerating electron, this electron is accelerated by something, e.g. an external electric field - so it interacts with some other system - and in Quantum field theory these interactions are described as exchanging photons. Now honestly I don't entirely understand exactly how an accelation of an electron is described this way, but you see that it's not just an electron emitting photons. It's also interacting with external photons.
  4. Oct 18, 2012 #3
    Ok, thank you.

    Do you know if there is any other interpretation that can successfully predict those same observations beside that one where attraction/repulsion is defined by "exchange of (virtual) particles"?
  5. Oct 19, 2012 #4
    The emission of EM waves by an accelerating charge can be understood just from classical electromagnetism:

    But this description doesn't apply always - e.g. it doesn't work for an electron bounded in an atom, accelerating cetripetally as it moves around the nucleus.
    Last edited by a moderator: Sep 25, 2014
  6. Oct 19, 2012 #5


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    It has been known since the mid 1800's or so that an accelerating charge emits EM radiation. Atomic theory was developed in the early 1900's. There are plenty of sites online dealing with both of these subjects, including wikipedia.

    That depends on exactly what you mean by "electron radiation".

    Photons are the quantum of the electromagnetic field. This means that when you send out an EM wave it interacts in little packets of energy we label as photons. They don't come from the electron itself, but rather the EM wave it generates when it is accelerated.
  7. Oct 20, 2012 #6
    Ok, cheers.
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