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Candle Light

  1. Jun 9, 2009 #1
    Imagine you're lighting a candle, and it emits yellow light. Because the candle flame is hot, the light is probably thermal (not atomic) in origin. Right?
    If you made a spectrum of the candle light, it would appear to be continuous, and that would confirm experimentally that the light was thermal in origin, or so my teacher tells me. But I have no idea why.

    I think I get the gist of atomic light. The way I understand, electrons in a certain type of atom absorb light of certain frequencies and then rerelease light of the same frequencies. (eg: neon burns red)
    But what's thermal light??
    This whole concept drives me crazy.
  2. jcsd
  3. Jun 9, 2009 #2
    Everything your teacher has told you is correct. "Atomic" light is the name for photons that are released when an electron undergoes a quantum leap between orbitals which are quantized and thus you only see specific discrete wavelengths emitted. "Thermal" light is photons that come from the blackbody radiation of an object (http://en.wikipedia.org/wiki/Blackbody_radiation)
  4. Jun 9, 2009 #3
    Thank you, that link was helpful.
  5. Jun 9, 2009 #4
    Yellow candle light, red neon light, and yellow sodium light (actually a doublet) are characteristic atomic emission lines of the specific atoms in question. For real thermal emission spectrum, heat a piece of steel with a torch to a red glow, or look at the filament of an incadescent light bulb as a function of input current.
  6. Jun 9, 2009 #5
    OK I'm not sure that's true, but thanks for the input.
  7. Jun 9, 2009 #6
    I'm pretty sure most of the light from a candle is going to be entirely blackbody. Evidenced by the fact that flashlights (which use a heated metal element) and candles give off the same kind of light and furthermore that candles can be made of a number of differnet substances
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