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B Gravity and radiation from charge

  1. May 11, 2018 #1
    Reading a thread in relativity I would like to know more precisely about radiation from charge.

    I put a charge on the table of my house. Gravity and table reaction force work on the charge.
    They cancel so net force does not work on the charge, thus no-force no-velocity cause no radiation. Am I right ?
    A charge is put on the Earth that rotates around the Sun. Does synchrotron radiation by rotation motion take place ? Does it takes place but in non measurable tiny amount ?
    Say a charge is free falling attracted by gravity of an electrically neutral planet, radiation takes place from a charge due to acceleration motion. But in co-moving local frame of reference with the charge, nothing particular including radiation would take place. How do we conciliate these views?
  2. jcsd
  3. May 11, 2018 #2


    Staff: Mentor

    You simply recognize that radiation is frame dependent. What is invariant is not whether or not there is radiation, but whether or not a given detector detects a fluctuating voltage/current.
  4. May 11, 2018 #3
    I have thought something running with speed c, radiated electromagnetic wave, is commonly recognized to all the frames. I will do practice with your teaching. Thanks.
  5. May 11, 2018 #4


    Staff: Mentor

    All inertial frames, yes. Not non inertial frames.
  6. May 11, 2018 #5


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    Science Advisor

  7. May 17, 2018 #6
    Thanks for your teaching. I will read PDF to get it.
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