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EM Spectrum's Official EM Ranges

  1. Feb 11, 2004 #1


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    Different sources show different ranges for the electromagnetic spectrum. Some sources say X-rays range from 10 nm to .01 nm and other sources say that it ranges from 1 nm to .001 nm for instance. I know that it's all really abritrary, but I would like to use numbers that are official or at least the most widely used in the scientific community.

    I wanted to know for the list below.

    Code (Text):

    TEMP(K)       PEAK WAVE(nm)    RANGE NAME

    500000000     0.006            Gamma Rays
    400000000     0.0075           Gamma Rays
    300000000     0.01             ?NAME CHANGE
    200000000     0.015            X-rays
    100000000     0.03             X-rays

    50000000      0.06             X-rays
    40000000      0.075            X-rays
    30000000      0.1              X-rays
    20000000      0.15             X-rays
    10000000      0.3              X-rays

    5000000       0.6              X-rays
    4000000       0.75             X-rays
    3000000       1               *NAME CHANGE
    2000000       1.5              Ultraviolet
    1000000       3                Ultraviolet

    500000        6                Ultraviolet
    400000        7.5              Ultraviolet
    300000        10               Ultraviolet
    200000        15               Ultraviolet
    100000        30               Ultraviolet

    50000         60               Ultraviolet
    40000         75               Ultraviolet
    30000         100              Ultraviolet
    20000         150              Ultraviolet
    10000         300              Ultraviolet

    9000          333.3            Ultraviolet
    8000          375              Ultraviolet
    7000          428.5            Blue-violet
    6000          500              Blue-green

    5000          600              Infrared
    4000          750              Infrared
    3000          1000             Infrared
    2000          1500             Infrared
    1000          3000             Infrared

    500           6000             Infrared
    400           7500             Infrared
    300           10000            Infrared
    200           15000            Infrared
    100           30000            Infrared

    50            60000            Infrared
    40            75000            Infrared
    30            100000           *NAME CHANGE
    20            150000           Microwaves
    10            300000           Microwaves

    5             600000           Microwaves
    4             750000           Microwaves
    3             1000000          Microwaves
    2             1500000          Microwaves
    1             3000000          Microwaves

    0.5           6000000          Microwaves
    0.4           7500000          Microwaves
    0.3           10000000         Microwaves
    0.2           15000000         Microwaves
    0.1           30000000         Microwaves

    0.05          60000000         Microwaves
    0.04          75000000         Microwaves
    0.03          100000000        Microwaves
    0.02          150000000        Microwaves
    0.01          300000000        *NAME CHANGE

    0.005         600000000        Radio Waves
    0.004         750000000        Radio Waves
    0.003         1000000000       Radio Waves
    0.002         1500000000       Radio Waves
    0.001         3000000000       Radio Waves
    Last edited: Feb 12, 2004
  2. jcsd
  3. Feb 12, 2004 #2


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    I just remembered another thing that I was wondering about. The new Blu-ray HD-DVD technology says that it uses a blue laser, more specifically, a 405 nm laser. A lot of sources list 400 nm as the smallest wavelength of the visible spectrum, some others say 390 nm is. Wouldn't something that close to ultraviolet be violet and not blue? Another website said that 400 nm was a deep blue, that doesn't leave much room for violet. And a lot of other sources list... I think violet as getting up to 450 nm! Although a couple websites have said that Blu-ray uses a blue-violet laser, which still doesn't mesh well with some of the other numbers that I've seen.
  4. Feb 12, 2004 #3


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    I'm not sure why you're so fixated on these boundary numbers; they're inexact for a reason.

    Every human being is going to have a slightly different frequency range. Some people can't detect 390 nm light, others easily can. Some people would call 405 nm light "blue," while others will see it as "violet."

    As far as the rest of the EM spectrum, most people's concern with frequency is the different technologies required to work with those frequencies. The electronic techniques to build microwave equipment is quite different than to build lower-frequency radio equipment. The technology ranges overlap, hower -- you can make a pretty good low-frequency microwave device using simple radio-frequency techniques, and vice versa.

    The reason the scientific community has not agreed upon a set of boundaries between microwave and radio, and so on, is simply because that just wouldn't be useful to anyone. The spectrum is continuous, after all, and drawing a line in the sand just isn't necessary. No one needs that kind of standardization.

    - Warren
  5. Feb 12, 2004 #4

    Chi Meson

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    As I understand it, the overlap between x-rays and gamma rays is so extensive, that they are distinguished only in how they are created: a photon would be an X-ray if it was created by a high speed electron hitting a metal surface while an identical photon would be a gamma ray if it was created through a nuclear process.

    There is a similar overlap between microwaves and radiowaves. I've got an older textbook that depicts microwaves as a subset entirely within radiowaves. THere used to also be "cosmic rays." Whatever happened to cosmic rays? Its a very mushy spectrum.

    I totally agree with Warren that it doesn't do anyone any good to make definite barriers between segments. THe names are indicative of the ways the various ranges are used. Recently there has been a breakthrough in the creation of "T-waves." This is light with frequencies in the tetrahertz range. THis is right in the microwave/infra-red overlap. If we develop enough uses that are specific to "T-waves," we might as well start calling it another region unto itself.
  6. Feb 12, 2004 #5


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    Yup... kinda silly. :smile:
    Cosmic rays are not necessarily EM -- they can be charged particles too, like protons and electrons. Some cosmic rays are gamma photons, though. The term "cosmic rays" refers to basically anything, particle or photon, coming in from space.

    - Warren
  7. Feb 12, 2004 #6


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    Instead of having things inexact, I think a better way would be to just have more than one standard way of organizing the frequencies that each have a purpose for a certain application, which would make the numbers more meaningful. Their could be a wireless/broadcast scheme, biology scheme, source scheme, and basic scheme, for example. Their kind of is in a way, but it's a bit sloppy.

    And I wouldn't say I am fixated on them. I wanted to use the numbers that were at least the most commonly used, so as not to be as confusing. But if there is no such thing, then I'll just choose what I think is best. And the 405 nm laser confused me. I've never, not even once, seen violet listed between 400-390 nm, and many times see it end (not begin) at 400 nm, which is almost 405 nm. That's almost the same as saying a 400 nm laser is blue, when the spectrum is shown many times as ending at 400 nm (where did purple go?).

    If I had a 405 nm laser, would some people really see it as blue while others see it as violet or blue-violet? If so, I figure the wavelength should be labeled by whatever color that most people see it as. And I assumed that most people would see violet, especially if some people can't even see frequencies beyond 400 nm.

    I came across a couple websites yesterday that had microwaves listed as part of radio waves. A lot of times microwaves are refered to as "high frequency radio waves".
  8. Feb 12, 2004 #7


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    Well, that would be extremely complicated, and basically pointless.
    The eye does not see violet directly. It sees violet as an equal excitation of both the red and blue photodetectors. If you shine high-end violet light into someone's eye, their blue receptor may fire, but not their red -- thus, they'll see it as blue.

    Color is not very scientific -- it's a perception, not a sensation.

    - Warren
  9. Feb 12, 2004 #8


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    While there may be differences in perception of color, you have 500 listed as red. That is bluish-green. Anybody seeing this as red would be considered rare enough to have some sort of condition.

    Now, it may have something to do with labelling -Range name and peak wave etc. I suppose if all visible light is considered red or violet, that extends the range a bit.

  10. Feb 12, 2004 #9


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    Good catch Njorl. I always thought red was roughly 700 nm.

    - Warren
  11. Feb 12, 2004 #10


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    How would it be complicated? I know that for me personally, it wouldn't be complicated at all. And this is something that is done for a lot of things to make them simpler. One thing that comes to mind is the network protocol models. And how is assigning different frequencies a range and scheme that gives them meaning pointless? People have already assigned certain ranges, the only thing they haven't done is clearly seperate their interpretation from other peoples interpretation. I just think that it's a good idea to have a basic layout of things and for any alteration of that layout to be made clear by giving it a name. You don't see alterations of the OSI model for protocols for instance, any alterations that are made are given a name such as the DoD model. There is more than one way to catagorize animals too, but these different ways/schemes are given different names instead of using inexact labeling under one name.

    Thanks for pointing that out.
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