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Radiowaves and potential harm? Intensity?

  1. Dec 23, 2015 #1
    I understand that radio waves have very low frequency, which means it is not ionizing as gamma and ultraviolet are, but while browsing the web, it seems that there are mixed point of views on its potential hazard to human health.

    Hmm, if it is dangerous, why? Does it have to do with intensity? What does intensity really mean? Does Intensity mean there are many radio waves focused at a single point?

    Can we impose light waves onto each other?

    Sorry for the bombardment of questions and thank you in advance PhysicsForums Community!!!
     
  2. jcsd
  3. Dec 23, 2015 #2
    Yes, radio waves are electromagnetic radiation at the low frequency end of the whole range of EM and yes it is not ionizing radiation.
    Above the radio range are microwave, infrared, and visible light, also none of which pose any radiation hazard.
    UV just above visible light (UVA) also is not a hazard, but the higher frequencies are a risk, (UVB is fairly low risk unless exposure is prolonged, UVC a higher risk).
    Above that are X rays and gamma rays which can be seriously hazardous, although X-rays are of course used routinely for medical diagnosis.
    While the risk is there, the exposure is almost instantaneous and is not long enough for serious damage to be likely.
    Gamma rays you do not want to be anywhere near, (like near a nuclear detonation for example).

    While lower frequency EM is non-ionizing, a powerful source nearby can heat things up.
    Standing too close to a fire (red/infra red) could burn you, but would not induce the kind of symptoms associated with 'radiation sickness'

    There is a special case for microwaves at the frequency used for ovens.
    These still are not ionizing, but are very efficient at heating up anything containing water.
    Because of that they are well shielded and there is also a safety mechanism which prevent it from operating when the door is open and somebody could put their hands in.
    However that risk is still just down to burning/scalding injury..
     
    Last edited: Dec 23, 2015
  4. Dec 24, 2015 #3

    davenn

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    just so the OP @jlyu002@ucr.e doesn't have any misunderstandings
    Microwave EM is/are still radio waves


    Dave
     
  5. Dec 24, 2015 #4

    davenn

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    I have a bunch of good gamma emitters at home ...... makes the Geiger counter click really well :wink:


    Dave
     
  6. Dec 25, 2015 #5

    mfb

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    We are exposed to natural gamma radiation all the time. It's a matter of dose, nuclear explosions lead to a huge dose while the natural background radiation does not.
    You cannot focus waves to regions significantly smaller than their wavelengths (there are a few exceptions but those are not relevant here). Focusing waves to a smaller region increases their intensity, yes.
    Unless you are directly next to a powerful radio emitter (like climbing up the antenna), they won't heat anything in dangerous ways.
     
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