3 ms·

A light flash is an EMP. Radio waves are light. They also, unless they are very short, pass easily through blue-tack. When they get that short they are basicall

A light flash is an EMP. Radio waves are light. They also, unless they are very short, pass easily through blue-tack. When they get that short they are basically becoming infra-red anyway. Then we have a wide range through the visible spectrum, up through UV, that blue-tack stops, until we start getting towards x-rays and blue-tack starts to become transparent again. This is caused by an electromagnetic pulse, but of one in or close to the visible spectrum, otherwise blue-tack would be useless. edit : The word light is commonly used as shorthand for variously the whole EM band, the near visible EM band and just the visible EM band. If you are talking about the speed of light, it includes radio and gamma. Discussing the colour of light on the other hand and you are referencing the visual system. As soon as you start talking about visible light however, you are widening the definition of light again to include IR and UV and more, otherwise you would not need to clarify with the word visible. edit 2 - darkmighty. I am not talking about the xenon bulb producing an RF EMP from the lamp flashing circuit, I am merely continuing the terminology used elsewhere in this thread, that a flash of visible light is also quite clearly a form of electromagnetic pulse. edit 3 - foobarbecue. Radio as it gets shorter becomes microwave, then IR, then red, through green, past blue, goes to UV, then xrays, then gamma.

krenoten 12y ago
To the downvoters of the above comment: if it's technically incorrect, say so. I don't know if it is or not, but it's certainly not an offensively worded comment. When you downvote rather than respond, you are actually spreading ignorance. A downvote is an effort to mute. A half-muted incorrect technical comment will encourage far more ignorance than a properly corrected, visible one. Don't encourage ignorance.
- deleted 12y ago
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- _almosnow 12y ago
  True that, I always see downvotes without replies as nonsense. If they could argue something reasonable about the statement then they would post it, but since they don't do it then it's probably a downvote "just because I don't like the guy".
darkmighty 12y ago
Ok I think the biggest misconception here is conflating the EMP with the Xenon lamp flash. The EMP is generated by the lamp/flashing circuit, which is essentially acting like a small (but not atomic) dipole antenna excited by a pulse. Therefore it has a distinctive cut-off frequency, probably in the 10s of Mhz range but I'm not sure exactly (something like this: [1]). This pulse is picked up by wires that act as antenna, and you get RF interference. The Xenon flash has also a distinct spectrum, but it's essentially contained in the visible light range (in a log-frequency spectral density plot) [2], which is what you want with a lamp! This emission is absorbed by the semiconductor material by exciting bandgaps: displacing electrons causing voltage spikes. [1] http://www.rfcafe.com/references/electrical/ew-radar-handbook/images/imgw27.gif http://www.rfcafe.com/references/electrical/ew-radar-handboo... [2] http://www.ushio.co.jp/images/en/products/list/lamp/lamp_07_img_02.gif http://www.ushio.co.jp/images/en/products/list/lamp/lamp_07_...
foobarbecue 12y ago
"When they get that short they are basically becoming infra-red anyway." You mean UV. You got your spectrum backwards. You should probably just admit your error here -- it's light, not radio waves, causing the effect. Sure, they're part of a common spectrum, but your statement "radio waves are light" is obviously false. It's a bit like saying "red is blue". Edit: I misread the above, lotsofmangos was talking about wavelengths coming from the radio site of the spectrum rather than light, so he didn't get it backwards. The rest of this post stands.
- deleted 12y ago
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- lotsofmangos 12y ago
  I have been saying all along that it is electromagnetic waves in the visible or near visible spectrum causing the effect, otherwise the bluetack would not work. As to saying that radio is light, if calculating the propagation speed of a radio wave, you don't talk about its speed of radio, you talk about its speed of light. In many technical contexts, light is one of the default terms. Also, there would be no need for the term 'visible light' if light could not be used to describe electromagnetic radiation outside the visible spectrum. Infra-red and ultra-violet are commonly thought of as light and you can even create lensing optics for radio waves and for x-rays. http://www.rozendalassociates.com/Luneberg/index.htm http://www.rozendalassociates.com/Luneberg/index.htm https://www.imt.kit.edu/english/236.php https://www.imt.kit.edu/english/236.php
  - djmips 12y ago
    Agree, not sure why you were downvoted. EMP is photons. They were already considering the non visible spectrum when talking UV. There's a real prejudice and ignorance regarding visible light versus the entire electromagnetic spectrum.

krenoten 12y ago

To the downvoters of the above comment: if it's technically incorrect, say so. I don't know if it is or not, but it's certainly not an offensively worded comment. When you downvote rather than respond, you are actually spreading ignorance. A downvote is an effort to mute. A half-muted incorrect technical comment will encourage far more ignorance than a properly corrected, visible one. Don't encourage ignorance.

deleted 12y ago
[deleted]
_almosnow 12y ago
True that, I always see downvotes without replies as nonsense. If they could argue something reasonable about the statement then they would post it, but since they don't do it then it's probably a downvote "just because I don't like the guy".

darkmighty 12y ago

Ok I think the biggest misconception here is conflating the EMP with the Xenon lamp flash. The EMP is generated by the lamp/flashing circuit, which is essentially acting like a small (but not atomic) dipole antenna excited by a pulse. Therefore it has a distinctive cut-off frequency, probably in the 10s of Mhz range but I'm not sure exactly (something like this: [1]). This pulse is picked up by wires that act as antenna, and you get RF interference. The Xenon flash has also a distinct spectrum, but it's essentially contained in the visible light range (in a log-frequency spectral density plot) [2], which is what you want with a lamp! This emission is absorbed by the semiconductor material by exciting bandgaps: displacing electrons causing voltage spikes. [1] http://www.rfcafe.com/references/electrical/ew-radar-handbook/images/imgw27.gif http://www.rfcafe.com/references/electrical/ew-radar-handboo... [2] http://www.ushio.co.jp/images/en/products/list/lamp/lamp_07_img_02.gif http://www.ushio.co.jp/images/en/products/list/lamp/lamp_07_...

foobarbecue 12y ago

"When they get that short they are basically becoming infra-red anyway." You mean UV. You got your spectrum backwards. You should probably just admit your error here -- it's light, not radio waves, causing the effect. Sure, they're part of a common spectrum, but your statement "radio waves are light" is obviously false. It's a bit like saying "red is blue". Edit: I misread the above, lotsofmangos was talking about wavelengths coming from the radio site of the spectrum rather than light, so he didn't get it backwards. The rest of this post stands.

deleted 12y ago
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lotsofmangos 12y ago
I have been saying all along that it is electromagnetic waves in the visible or near visible spectrum causing the effect, otherwise the bluetack would not work. As to saying that radio is light, if calculating the propagation speed of a radio wave, you don't talk about its speed of radio, you talk about its speed of light. In many technical contexts, light is one of the default terms. Also, there would be no need for the term 'visible light' if light could not be used to describe electromagnetic radiation outside the visible spectrum. Infra-red and ultra-violet are commonly thought of as light and you can even create lensing optics for radio waves and for x-rays. http://www.rozendalassociates.com/Luneberg/index.htm http://www.rozendalassociates.com/Luneberg/index.htm https://www.imt.kit.edu/english/236.php https://www.imt.kit.edu/english/236.php
- djmips 12y ago
  Agree, not sure why you were downvoted. EMP is photons. They were already considering the non visible spectrum when talking UV. There's a real prejudice and ignorance regarding visible light versus the entire electromagnetic spectrum.