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Do charges (static or moving) reflect light?

  1. May 9, 2003 #1
    Do charges (static or moving) reflect light? If no, then how can we see a spark?
  2. jcsd
  3. May 10, 2003 #2


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    A spark emits light, it doesn't have to reflect it to be seen.
  4. May 10, 2003 #3
    Free charges indeed reflect light, and quite well. Look at a mirror - it is free electrons which reflect.

    Charges also emit very well when they move with acceleration. That is why we see a spark, a flame, Sun, etc.
  5. May 11, 2003 #4
    And what makes spark to emit light?
  6. May 11, 2003 #5


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    The spark heats up the air to tremendous temperatures (into a plasma), which then emit their energy as light.
  7. May 11, 2003 #6
    Atoms are electric charges, right? Right. They have electric field around them. When you shake an atom (say, atom is fast thermal motion in a spark), then field begin to shake too. This shaking electric field is what we call "light".
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