Talk:Incandescence

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spectral graphs[edit]

We need graphs/curves of the spectral emissions.-69.87.203.220 19:54, 25 May 2007 (UTC)

I recently edited this page, removing the incorrect "atomic orbital excitation". This is because incandescence is purely related to black body radiation which produces a continuous spectrum of radiation and has nothing to do with atomic orbital excitation which produces descrete radiation consistent with the specific energy diffenrences in the orbitals. However after making this change, Robin David Saunders reverted the entry back to include this error. I suggest when an expert on this subject reviews this article that they confirm this. - 194.130.163.67 17.31, 07 september 2007(GMT).

Definitions[edit]

Defs on the web, other than the one from wikipedia, are all about visible light, as are the ones in books that I've looked at. So I changed it. Dicklyon (talk) 21:23, 26 May 2008 (UTC)

Dubious caption to Incandescence.jpg[edit]

I'm not sure if the caption for Image:Incandescence.jpg is correct, or at least it might be misleading and a poor example. IIRC, many metals' colors in flame (sodium, etc., and their ions) are due to electron excitation. It's more common to use the color of metals in flame as an example of excitation and energy levels. It's confusing to discuss the colors of "metal embers", since this other factor comes into play. —AySz88\^-^ 02:42, 8 June 2008 (UTC)

Is there some way that light is emitted other than via electron excitation/de-excitation? I don't think so. The difference that's relevant here is between the solid bits (the embers) and the gas. In the gas, electron energy states are pretty discrete, but in solids the distribution is pretty continuous; that's why solids act sort of like black bodies, and gases don't. I'm not sure it's appropriate to say the gas is not incandescent; do we have a definition that implies that? Dicklyon (talk) 07:42, 8 June 2008 (UTC)
Some gases glow by high temperatures alone -- such as the hydrogen in our Sun; that is incandescence.
Other gases glow by some other process -- such as the light from sodium vapor lamp; that is luminescence.
The difference is usually obvious when looking at the spectrum -- with incandescence, the spectrum looks more or less like the black body spectrum, with a peak wavelength more or less predicted by the Wien's displacement law from the temperature of the gas.
(I wish the spectrum were shown on the Bunsen burner article -- hold on a second while I drop a request on Talk:Bunsen_burner).
While I agree that technically "many metals' colors in flame (sodium, etc., and their ions) are due to electron excitation.", that only applies when the metal is vaporized into a gas or plasma, which I don't see in this picture. Larger pieces of liquid or solid metal (such as sparks, forks, spoons, liquid droplets, etc.) exhibit black-body incandescence.
I see 2 things in this photograph; perhaps it would be less confusing if they were in 2 completely different photographs:
  • little white-hot blobs of liquid metal from the spark generator, glowing with incandescence that spectrally looks similar to all black bodies at that temperature. Sparks look about the same even with the gas turned off.
  • the blue glow of the Bunsen burner flame. While starving the burner of air produces an incandescent yellow light, and while it is reasonable to suspect that the temperature shift and color shift caused by adding air may be an illustration of Wien's displacement law to "blue-hot" incandescence, most of the light comes from luminescence. (ref: "If sun is hotter than bunsen burner then why is it yellow and the burner gives blue flame?"). The flame article and Swan bands article implies that conclusion.
Rather than implying things, I wish these articles would state the wp:obvious.
--68.0.124.33 (talk) 17:34, 19 July 2008 (UTC)

I did not know sun looks yellow. The peak of spectrum of the sunlight is in UV. The blue color of the Bunsen burner has been explained.

That the sun looks red during sunrise and yellow immediately afterwards, is due to atmospheric effects and also Raleigh scattering in the upper atmosphere. These effects are minimum at noon.Ck.mitra (talk) 16:34, 25 July 2009 (UTC)

"Luminescence is radiation emitted from relatively cool bodies" - Spectrochemical Analysis by Ingle and Crouch. "Luminescence - the low-temperature emission of light" Merriam Webster's online dictionary. Atomic and molecular emission in a flame is not luminescence. —Preceding unsigned comment added by 130.64.102.240 (talk) 13:58, 21 October 2008 (UTC)

Threshold[edit]

I added the info that incandescence becomes visible only around 400°C in the dark. I think it is important to give that as a rule of the thumb. I don't know if a reference is needed; I don't think the issue is very controversial. (I found this reference that says 390°C.) I wrote “most bodies” rather than “all” because a white body doesn't glow at all. Perhaps that could be better worded. David Olivier (talk) 16:09, 8 June 2009 (UTC) I wish to mention that a "white body", like a "black body" is an idealisation. At a sufficiently high temperature, all "bodies" get closer to "black body" - and an ideal white body does not emit at any temperature.

If we "fit" the emission from a fluorescent lamp to the black body radiation, we get what is called the color temperature and is often printed on the fluorescent tube (often loosely called cool, warm, daylight etc). The fit to the black body radiation os often poor and causes serious problem in photography (too much of green in fluorescent light, mostly due to mercury).Ck.mitra (talk) 16:34, 25 July 2009 (UTC)

Practical[edit]

I don't understand the meaning of this sentence "While higher temperatures can increase efficiency, there are currently no materials able to withstand such temperatures which would be appropriate for use in fluorescent lamps."

Should that be "incandescent lamps" at the end of the sentence? Bj norge (talk) 10:39, 4 February 2010 (UTC)

Minor question[edit]

How is this different from thermoluminiscence? --200.59.188.242 (talk) 19:43, 23 September 2010 (UTC)

Merge with thermal radiation?[edit]

Please discuss at Talk:Thermal radiation#Merge with Incandescence? Thanks! --Steve (talk) 19:32, 16 December 2011 (UTC)

Incandescence[edit]

Incandescence — Preceding unsigned comment added by RaySys (talkcontribs) 12:11, 10 October 2013 (UTC)

There is no reason for this to be a JPEG or GIF. It can be generated with HTML, which would allow the spelling of Temperature to be corrected. — Preceding unsigned comment added by 137.54.2.208 (talk) 22:45, 10 March 2014 (UTC)

I'm very much doubt that this chart has much relationship to reality (compare the one in the colour temperature article) and suggest it be deleted. Has anyone for example seen an incandescent object glowing a little green, like that shown for 1200 deg.?
By the way, the spelling of 'temperature' in the caption would appear to be a mangled transliteration from the Russian температура (thanks to Google translate!). The letter that looks like a 'p' is pronounced like an r in Russian (cf. the Greek 'rho', written ρ, which also looks like a 'p' and is pronounced like an r. --Brian Josephson (talk) 21:30, 22 November 2014 (UTC)