Date: Wed, 16 Oct 2002 20:13:54 +0000

Author: "Edward Sabol"

Subject: Re: Candles and Celestial Spheres

Post:

The blue versus yellow and hotness is the lower oxygen level at the yellow
hence incomplete oxidation less energy output I thought.






>From: Jerry DiMarco
>Reply-To: tap-l@listproc.appstate.edu
>To: tap-l@listproc.appstate.edu
>Subject: Re: Candles and Celestial Spheres
>Date: Wed, 16 Oct 2002 13:31:19 -0600
>
>At 11:22 AM10/15/2002, you wrote:
>
>>1. Is the light from a candle flame only from the blackbody emission
>>spectrum? Thus, is the blue part of the flame hotter than the yellow
>>part? (or as a faculty member stumped me-- Is this part of the flame
>>really hotter than our Sun?) Or is there a contribution from emission
>>spectra from electron transitions within given types of atoms? Flame
>>viewed through a spectroscope with the eye appears to be a continuous
>>spectrum. I know that you can use light emission/absorption to
>>fingerprint salts held in the flame, but we're trying to figure out the
>>optical properties of the original flame first.
>
> This is an interesting question I haven't thought about very much.
>But I do know the temperature of a candle flame is well documented. The
>following webpage says it is 1400 C for the blue part and 800 C for the
>yellow part. http://webexhibits.org/causesofcolor/3B.html
>That seems to be in the ballpark as compared to previous experience. That
>page also has an interesting photo of a candle flame in zero gravity.
> The colors in a flame must be due to spectral lines since the above
>temperatures are not enough to cause even a faint blackbody glow in the
>visible part of the spectrum. I don't know all the elements involved in
>combustion but hydrocarbons are rich in carbon, and the standard spectrum
>wall chart shows that the spectral lines for carbon (C2) are at the blue
>end. There is a nice webpage showing spectra of several more elements at:
>http://home.achilles.net/~jtalbot/data/elements/index.html
>
>>2. Our intro astronomy prof would like a 'celestial sphere' that
>>surrounds an Earth globe. We're looking for something of 0.5-1.0 m
>>diameter that could be used in the classroom to show the tilt of the
>>Earth's axis and the positions of stars above. Any suggestions for
>>quality sources of this at reasonable prices?
>
> We have a large (~1/2 m) celestial sphere which I thought we
>purchased from MMI Corp (mmicorporation.com) but I couldn't find the
>record. However, the other big catalog suppliers have them too...
>
> Jerry
>
>
>>Thanks again!
>>
>>bill
>>
>>--
>>*****************************************
>>William W. McNairy, Ph. D.
>>Lecturer
>>Room 104I (919)-660-2689
>>Dept. of Physics, Duke University
>>Box 90305 Durham, NC 27708
>>*****************************************
>
>
><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
>
> Jerry DiMarco
> Manager of Lecture Demonstrations and Instructional Labs
> Montana State Univ., Physics Dept.
> Bozeman, MT
>
>Our Motto: "We don't use anything the way it was meant to be used."


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