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How do fluorescent tubes light up with radio waves?

  1. Feb 29, 2012 #1
    I was reading somewhere that radio waves can actually light up gasses in these tubes. How does this work?
     
  2. jcsd
  3. Feb 29, 2012 #2

    Averagesupernova

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    The gas isn't what actually lights. It is the phosphour coating on the inside of the tube. It works, I've done it.
     
  4. Feb 29, 2012 #3

    sophiecentaur

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    But it is the action of the RF waves on the atoms of the gas that produce the effect. If the peak field strength of the RF wave (alternating field) is enough to ionise the atoms then, when the electrons re-combine with the ions, UV is produced. This UV hits the Phosphor material on the sides of the tube and it fluoresces (glows).

    You can get the same effect with some gases which produce visible light (e.g. the original Neon tubes) but it is coloured light. The phosphors on the side of the tube are a mixture of materials and in the solid state, which means that broad bands of visible light are produced. looking a bit like tungsten or sun light - much more useful.
     
  5. Mar 1, 2012 #4
    How strong does the peak field strength have to be in order for this to occur?
     
  6. Mar 3, 2012 #5
    It's not something that's simple to say since the ionization point of the gas is affected by pressure (refer to Paschen's curve). The small inverters that people commonly use to drive CCFL tubes for lighting effects have a sufficient voltage to capacitively couple through the glass and light a tube.
     
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