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On Jan 24, 2007, at 3:31 PM, Bernard Cleyet wrote:
I doubt a $10 IR thermometer. is that sophisticated *, even in this
21st. cent. They likely make use of the T^4 relation,
What is proportional to T^4 is the total intercepted intensity. But that intensity is also proportional to 1/r^2, where r is the distance from the source. Therefore, the reading, for a given T, would change with r. Does the indicated T change when r is changed?
The only things that do not change with r are the location of the maximum and ratios of partial intensities at two different wavelengths. My guess is that T is determined from a ratio of two partial intensities. Some kind of a filter, and two detectors, would make this possible, at least in principle.
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Ludwik Kowalski, a retired physicist
5 Horizon Road, apt. 2702, Fort Lee, NJ, 07024, USA
Also an amateur journalist at http://blake.montclair.edu/~kowalskil/cf/
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