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Light and Conservation of Energy

  1. Jun 5, 2014 #1
    Sorry if this is posted in the wrong place, I'm new to this forum.

    If an object in negatively charged and it is in oscillating motion is produces light waves which have energy. Does this mean that if I had a negatively charged pendulum in a vacuum (no friction/air resistance) it would eventually slow down where as a neutrally charged pendulum wouldn't?

    Thanks in advance for a response.
  2. jcsd
  3. Jun 5, 2014 #2


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    Staff: Mentor

    Yes, the pendulum would decrease its amplitude, somewhat as if there were air resistance.
  4. Jun 5, 2014 #3
  5. Jun 5, 2014 #4


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    Science Advisor
    Gold Member

    And as an interesting side note: the binary neutron stars, PSR B1913+16, discovered in 1974, were shown to be losing energy as a system ... and the calculation showed that the gravitational radiation predicted by Einstein's General Relativity predicted the energy loss with great accuracy:

    So yes, mechanical systems can lose energy by means of radiation: electromagnetic or gravitational.
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