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Why accelerated charge emits electromagnetic radiation

  1. Oct 31, 2009 #1
    Its well known that an accelerated charge emits electromagnetic radiation. Then why the orbiting electrons in atom merge in nucleus after some time.
     
  2. jcsd
  3. Oct 31, 2009 #2
    Uhhhh they dont?
    They will continue to orbit or they will be ejected completely
    Electrons don't fall into the nucleus of an atom
     
  4. Oct 31, 2009 #3
    Electrons in the lowest bound states of atomic orbits cannot radiate, because of energy conservation. The electrons cannot transition to lower energy states. But in certain atoms, like beryllium-7 (lifetime 53.25 days), the proton can "absorb" an electron in the 1s state and decay to a bound neutron (in lithium-7).
    Bob S
     
    Last edited: Oct 31, 2009
  5. Oct 31, 2009 #4

    jtbell

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    Atomic electrons don't "orbit" in the classical sense.
     
  6. Oct 31, 2009 #5
    This was the question that made people realize that Rutherford's idea of the atom as a little solar system was an imperfect model - that the electrons couldn't radiate waves without long energy and having their orbits decay and spiral into the nucleus. Bohr suggested to Rutherford fixing the model by saying that electrons don't radiate waves as long as they stay in certain stable orbits. Bohr's idea established the "n" quantum number.
     
  7. Oct 31, 2009 #6

    Andrew Mason

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  8. Oct 31, 2009 #7
    Panofsky and Phillips "Classical Electricity and Magnetism" First edition, page 301 eqn(19-19) shows that a uniformly accelerating charge radiates. It is proportional to (dv/dt)2.
    Bob S
     
  9. Oct 31, 2009 #8
    :confused:

    According to the Maxwell, electromagnetic field equations it radiates for sure.

    Another thing is how to take this fact into account in the electron, mechanical equations. There have been many attempts, all unsuccessful except mine.
     
    Last edited: Oct 31, 2009
  10. Oct 31, 2009 #9

    jtbell

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    The acceleration in a circular orbit (which is what people were thinking in terms of, in Bohr's day) is not uniform acceleration.
     
  11. Oct 31, 2009 #10
    It nearly merges - the neutral atom is so small that is invisible with an eye. It is invisible even in a microscope. :wink:
     
    Last edited: Oct 31, 2009
  12. Nov 1, 2009 #11

    Andrew Mason

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    Well, a charge that accelerates uniformly due to its interaction with an electro-magnetic field will radiate. But is that caused by the interactions of the charge with the field or is it caused by the acceleration?

    If it was the acceleration, then acceleration due to gravity should also produce radiation. And, since gravitational acceleration is locally equivalent to moving at uniform speed in a gravitational field, a stationary charge in a gravitational field should radiate. But neither does.

    AM
     
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