Trying to understand neon lights

  1. Hi,
    I'm trying to understand how neon lights work. I understand that the emitted light comes from excited atoms in the gas, and I know what a neon light consists of. But I'm a little bit confused about one part, how do the atoms get excited? I've seen two different explanations, if I understand them correctly.
    The first one is that when a high enough voltage is applied to the electrodes, electrons move from one electrode to the other, and when these electrons collide with electrons in the atoms, the energy from the collision is absorbed by the atom's electrons and they get excited.
    Another explanation, which I don't really understand, has to do with the atoms getting ionized.
    If anybody could help me with this, I'd appreciate it.
  2. jcsd
  3. phinds

    phinds 8,082
    Gold Member

    ionization is just an extreme form of excitation, where the electrons don't just jump to a higher energy level, they jump entirely off the atom. I don't really know anything about neon bulbs but I would assume that both explanations are reasonable. The excited electrons fall back to the lower state and emit a photon and the ionized atoms, since there are a lot of them, probably exchange electrons (that is, an ionized atom captures a passing electron from another atom and back and forth) and the electron falls to a lower state an emits a photon.
  4. Thanks for the reply.
    I just found the article on gas-discharge lamps on wikipedia. "Gas-discharge lamps are a family of artificial light sources that generate light by sending an electrical discharge through an ionized gas, a plasma. [...] In operation the gas is ionized, and free electrons, accelerated by the electrical field in the tube, collide with gas and metal atoms. Some electrons in the atomic orbitals of these atoms are excited by these collisions to a higher energy state."
    But I still have one question. These free electrons, are they only coming from the ionized gas, or are there also free electrons moving from one electrode to the other? Does "sending an electrical discharge through an ionized gas" mean that the latter is true?
  5. Borek

    Staff: Mentor

  6. phinds

    phinds 8,082
    Gold Member

    If there weren't, what would be creating the energy that is represented by the light you see ? Do you reckon neon bulbs use zero electricity?
  7. Yeah, I didn't really use my brain. Sorry. But to my defense, I'm in high school, we only just recently started studying electricity, and so far it's only been about static electricity. So I'm not very used to this type of thinking. When it comes to physics, I'm mostly self-taught. For instance, people in my class wouldn't know what a photon is, and neither would they know what an excited atom is or that different electron shells have different energy levels.
  8. phinds

    phinds 8,082
    Gold Member

    Nothing to worry about. My posts sometimes seem a bit sarcastic but I was just adding to what Borak said and giving you something to think about. Glad to hear you are interested in physics. I find it fascinating except for the advanced math which just makes my head hurt so at GR and beyond I just stick to the basic concepts without math. Hope you make if farther along since really, without the math a lot of it is not accurately comprehensible so I know my knowledge is superficial. Stick with that math !
    1 person likes this.
  9. I am assuming neon light work when the negative ion discharge creating electricity therefore causing gases to glow within the neon light remember im just assuming
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