Which electromagnetic waves does a source emit?

  • #1
If a source emits high frequency electromagnetic wave, for example gamma rays, does it imply that it also emits all the waves of lesser frequency?
 

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  • #2
ZapperZ
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If a source emits high frequency electromagnetic wave, for example gamma rays, does it imply that it also emits all the waves of lesser frequency?

Think about it. Does a blue laser or LED light also emit red light?

Zz
 
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  • #3
sophiecentaur
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If a source emits high frequency electromagnetic wave, for example gamma rays, does it imply that it also emits all the waves of lesser frequency?

There is no general rule here. It’s true for some sources and not true for others. A hot body will emit a wide range of frequencies (a continuous spectrum), due to the random thermal activity inside. Gamma photons are produced by individual nuclei (or two nuclei in the case of fusion). Many nuclear decay events can occur in isolation and just one gamma photon may be emitted but other situations can involve high temperature thermal radiation as well.
What was the context of your question?
 
  • #4
There is no general rule here. It’s true for some sources and not true for others. A hot body will emit a wide range of frequencies (a continuous spectrum), due to the random thermal activity inside. Gamma photons are produced by individual nuclei (or two nuclei in the case of fusion). Many nuclear decay events can occur in isolation and just one gamma photon may be emitted but other situations can involve high temperature thermal radiation as well.
What was the context of your question?
I was asking in a general sense. I am taking an introductory class to astronomy and understood that the Sun emits a wide range of electromagnetic waves, that led me to question about whether any thermal source emits a wide range of electromagnetic waves that are smaller (in frequency) than its max frequency wave. Though if you would place a prism after a blue light I would assume to see the rest of the colors in the rainbow with lower frequency than blue light, therefore we could see red in the refracted blue light... correct?? (Edit: also thank you for your answer)
 
  • #5
DaveE
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Each photon of light is created by a single event and has a single wavelength (=color). Usually the event is an energy state change of an electron in an atom, but, more generally, many particle interactions can create a photon. So, your question is really about a collection of photons created by a collection of associated particle energy transitions. This question won't have a general answer as the objects that create photons can vary widely. For example, CW lasers, hot (thermal) objects, and elementary particle collisions all create photons, but are vary different in their statistical nature. I think your question isn't as much about the photons as the different types of objects that create multiple photons. The colors of light created by such objects is a powerful and commonly used method of understanding how they are constructed and what they are doing.
To learn more check out these Wikipedia pages:
https://en.wikipedia.org/wiki/Black-body_radiation
https://en.wikipedia.org/wiki/Laser
https://en.wikipedia.org/wiki/Spectroscopy
 
  • #6
Each photon of light is created by a single event and has a single wavelength (=color). Usually the event is an energy state change of an electron in an atom, but, more generally, many particle interactions can create a photon. So, your question is really about a collection of photons created by a collection of associated particle energy transitions. This question won't have a general answer as the objects that create photons can vary widely. For example, CW lasers, hot (thermal) objects, and elementary particle collisions all create photons, but are vary different in there statistical nature. I think your question isn't as much about the photons as the different types of objects that create multiple photons. The colors of light created by such objects is a powerful and commonly used method of understanding how they are constructed and what they are doing.
To learn more check out these Wikipedia pages:
https://en.wikipedia.org/wiki/Black-body_radiation
https://en.wikipedia.org/wiki/Laser
https://en.wikipedia.org/wiki/Spectroscopy
Thank you DaveE!
 
  • #7
ZapperZ
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I was asking in a general sense. I am taking an introductory class to astronomy and understood that the Sun emits a wide range of electromagnetic waves, that led me to question about whether any thermal source emits a wide range of electromagnetic waves that are smaller (in frequency) than its max frequency wave. Though if you would place a prism after a blue light I would assume to see the rest of the colors in the rainbow with lower frequency than blue light, therefore we could see red in the refracted blue light... correct?? (Edit: also thank you for your answer)

In the future, you need to post THIS, i.e. the context of your question, rather than just putting out something vague as in your first post.

I gave you one scenario out of many, trying to see what you will respond to. A "light source" can be of numerous type. A laser or LED has a smaller band of frequency than, say, an incandescent light bulb. Without you elaborating what you are really looking for, anyone can give you any answer that will be correct without the context of that answer, but may not be within your context, or valid in general.

If a question is vague enough, as Ethel Mermin used to sang, you will get "anything the traffic will allow".

Zz.
 
  • #8
In the future, you need to post THIS, i.e. the context of your question, rather than just putting out something vague as in your first post.

I gave you one scenario out of many, trying to see what you will respond to. A "light source" can be of numerous type. A laser or LED has a smaller band of frequency than, say, an incandescent light bulb. Without you elaborating what you are really looking for, anyone can give you any answer that will be correct without the context of that answer, but may not be within your context, or valid in general.

If a question is vague enough, as Ethel Mermin used to sang, you will get "anything the traffic will allow".

Zz.
Got it, thanks for the feedback
 
  • #9
sophiecentaur
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a single wavelength (=color).
Please don't equate colour with wavelength. It opens up a whole can of worms. If you think it may help the uninitiated then I suggest that it could cause more problems than it solves.
 
  • #10
Please don't equate colour with wavelength. It opens up a whole can of worms. If you think it may help the uninitiated then I suggest that it could cause more problems than it solves.
It didn't open any cans here, I know that wavelength that are smaller or bigger than the visible light range are waves that are not visible
 
  • #11
DaveE
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Please don't equate colour with wavelength. It opens up a whole can of worms. If you think it may help the uninitiated then I suggest that it could cause more problems than it solves.
Yes, you are absolutely correct. Sorry, I was being sloppy. I hope by inadvertently allowing retinas and visual cortices into the discussion I didn't confuse anyone about physics.
 
  • #12
davenn
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Though if you would place a prism after a blue light I would assume to see the rest of the colors in the rainbow with lower frequency than blue light, therefore we could see red in the refracted blue light... correct??


incorrect .... try it, you sill still get just the single colour
 
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  • #13
sophiecentaur
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It didn't open any cans here, I know that wavelength that are smaller or bigger than the visible light range are waves that are not visible
Ah well it did open a can. I could give you a combination of red and green coloured spectral light and produce a Yellow that could couldn't distinguish (visually) from spectral yellow. Would that Yellow fit in with the statement about a "single wavelength"? There is really no point in including the word "colour" in a general discussion about spectra. It is pointless and singles out just one octave of the EM spectrum for a different measurement / description rule. It's like using "shoe size" for descriptions of lengths between 80mm and 300mm. It doesn't increase the information content in any way of a statement about EM spectra.
 

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