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dgruss23
2005-Feb-25, 04:18 PM
Anybody want to take a stab at this one. The New York State Physics Reference tables for students taking the state exam in physics are here (http://www.nysedregents.org/testing/reftable/archreftable/phyreftab02.pdf) (pdf).

On page 2 they show overlap of X-rays with the Gamma and U-V range and overlap of the microwaves with IR and Radio waves. Is this an error or is there disagreement as to the wavelengths/frequencies at which microwaves and X-rays begin and end? They have done the same thing in the NYS Earth Science Reference Tables. I haven't found any textbook or web source that has such overlaps.

TravisM
2005-Feb-25, 04:24 PM
I've seen them overlap before, in my electronics days at vocational school (fancy highschool) we had a gigantic chart like this. All fancy with color and what-not. But, it showed the same overlaps. I never did question it, but it does beg the question now.

At any rate, that's a great PDF file. I saved a copy for myself, thanks dgruss23! =D>

A Thousand Pardons
2005-Feb-25, 04:31 PM
On page 2 they show overlap of X-rays with the Gamma and U-V range and overlap of the microwaves with IR and Radio waves. Is this an error or is there disagreement as to the wavelengths/frequencies at which microwaves and X-rays begin and end?
Those various bands are defined by their characteristics--and those characteristics don't suddenly stop at a specific frequency. In the overlap regions, the distinctions (if there are any) are blurred. It's like, when does yellow stop and green start?

ngc3314
2005-Feb-25, 04:34 PM
Anybody want to take a stab at this one. The New York State Physics Reference tables for students taking the state exam in physics are here (http://www.nysedregents.org/testing/reftable/archreftable/phyreftab02.pdf) (pdf).

On page 2 they show overlap of X-rays with the Gamma and U-V range and overlap of the microwaves with IR and Radio waves. Is this an error or is there disagreement as to the wavelengths/frequencies at which microwaves and X-rays begin and end? They have done the same thing in the NYS Earth Science Reference Tables. I haven't found any textbook or web source that has such overlaps.

Certainly in astronomical use most of these ranges don't have formal definitions. Is 1.0 micron far red or near-IR? Is there a distinct submillimeter range, or is that the far end of the IR? Microwaves may or may not get a seat at the table. And the boundaries between far-UV and X-rays, and between X- and gamma rays, depend on whose detector is being sold at the moment. And it gets worse when someone pops up claiming that gamma rays must arise from nuclear transitions (yeah, like we'd know that when picking up emission from an unknown source - which is why I don't think that is at all useful as a definition!).

I see this table as simply reflecting the fuzziness of contemporary usage.

papageno
2005-Feb-25, 05:02 PM
I think that labelling ranges in the elecromagnetic spectrum depends on the origin of the radiation.
For example, the visible range has its name form the fact that we can see radiation in that range, gamma radiation has a nuclear origin, etc.
The ranges obtained this way can, of course, overlap.

EDIT to add: In the end, labelling the ranges is a matter of convention.

tlbs101
2005-Feb-25, 06:25 PM
The place I worked in the 1980's dealt with "hard" X-rays, "soft" X-rays, and Gamma. The classification of the energy level was made by the looking at the peak of the black-body spectrum, as measured during the tests. Hard X-rays would cause pair production in the instrumentation cables (for which we had to take action against), just as if they were Gamma radiation.

"Hard" Ultraviolet sources can cause ionization -- that's how melanomas are thought to be started.

Recently Terahertz waves have been generated in "the lab" using transistors (I am sorry I don't have a reference, but I read it somewhere a few months ago). These would be considered "Microwaves" coexisting in the far infared spectrum.

dgruss23
2005-Feb-25, 06:44 PM
Thanks for the comments. That all seems quite reasonable. You have to understand that when it comes to New York State Regents anything - something that doesn't seem right often isn't. For example, a few years ago they had a question about electronegativity that had density units on the electronegativity column of the data table! #-o

George
2005-Feb-25, 08:36 PM
Overlapping bands? Shucks, try to pin down the angstroms for colors in the visible spectrum. I have found no two web sites that give the same answers. :-? [ However, with LED's and lasers of many different specific wavelengths, more light will likely be shed on this colorful issue. ]