# Moving electrons, moving waves **URL:** \ **Category:** Factual Questions\ **Created:** [March 8, 2003, 12:49am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827 "2003-03-08T00:49:36Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Flying\_Monk](https://avatars.discourse-cdn.com/v4/letter/f/48db29/32.png) [@Flying\_Monk](https://boards.straightdope.com/u/Flying_Monk)\ **Post date:** [March 8, 2003, 12:49am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/1 "2003-03-08T00:49:36Z")
I learned in Electricity 101 that a moving electron produces an electromagnetic wave. While this is obvious in something like an antenna, what about something like my arm? There are electrons in my arm…if I wave my arm in the air, is there some electromagnetic trace, no matter how weak, that propagates throughout the universe? ---
**Author:** ![Shade](https://avatars.discourse-cdn.com/v4/letter/s/2bfe46/32.png) [@Shade](https://boards.straightdope.com/u/Shade)\ **Post date:** [March 8, 2003, 12:53am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/2 "2003-03-08T00:53:30Z")
WAG: A moving charge (electron, proton, etc) creates a em wave, and the electrons and protons in your arm cancel each other out. That is, since your arm is not charged overall, it doesn’t wave… Is that something like right? ---
**Author:** ![Flying\_Monk](https://avatars.discourse-cdn.com/v4/letter/f/48db29/32.png) [@Flying\_Monk](https://boards.straightdope.com/u/Flying_Monk)\ **Post date:** [March 8, 2003, 2:45am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/3 "2003-03-08T02:45:13Z")
Ok, so if I rub my feet against the carpet, then wave my arm, what happens? ---
**Author:** ![Trigonal\_Planar](https://avatars.discourse-cdn.com/v4/letter/t/0ea827/32.png) [@Trigonal\_Planar](https://boards.straightdope.com/u/Trigonal_Planar)\ **Post date:** [March 8, 2003, 6:46am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/4 "2003-03-08T06:46:41Z")
Also a WAG, but if that were the case, you would have accumulated static electricity. Static electricity, by deffinition, is non-moving current. Therefore, no wave will be produced. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [March 8, 2003, 7:06am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/5 "2003-03-08T07:06:18Z")
A moving electron doesn’t always emit radiation. If an electron is flying through vacuum in zero gravity, it would continue to do so forever without emitting anything. If it hits something and accelerates (changes direction or reduces speed), it would emit radation. SImilarly, an electron bound in an atom at absolute zero temperature wouldn’t emit any radiation. As for the electrons in your arm, they _do_ emit radiation because they are not at absoluze zero temperature. It’s mostly in the infrared. Moving your arm doesn’t produce any extra radiation because as **Shade** pointed out, your arm is electrically neutral. But if you wave an electrically charged object (say, a rubber balloon which you just rubbed against your sweater) it will produce radiation that propages through space. A very weak radiation, but it’ll be there. ---
**Author:** ![Flying\_Monk](https://avatars.discourse-cdn.com/v4/letter/f/48db29/32.png) [@Flying\_Monk](https://boards.straightdope.com/u/Flying_Monk)\ **Post date:** [April 17, 2003, 9:50pm UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/6 "2003-04-17T21:50:39Z")
I’m not talking about emitting radiation, I’m talking about propagating an electromagnetic wave. Trigonal: how is the static electricity nonmoving if I’m waving my arm? Let me clarify this way: as far as I understand, the Earth’s magnetic field is caused by iron & nickel in the magma, moving in convective currents. Is this correct? If there is iron in my blood, and it’s flowing, wouldn’t a small magnetic field be produced, and if not, why? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 17, 2003, 10:35pm UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/7 "2003-04-17T22:35:03Z")
> [@](#): > > I’m not talking about emitting radiation, I’m talking about propagating an electromagnetic wave. Same thing. The word “radiation” is usually used for things like gamma rays, while “waves” usually refer more to the radio region, but they’re just different parts of the same spectrum, and either can be discussed in either way. And if you rub a ballon on your hair and wave it around, it’ll still be called static electricity, but it is, in fact, moving (and more importantly, accelerating), and will therefore produce electromagnetic waves. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [April 17, 2003, 11:20pm UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/8 "2003-04-17T23:20:54Z")
Iron in your blood is also elctrically neutral. Same deal as your arm. If you have a magnetic personality, you might produce an e/m wave if you jump up and down real fast. ---
**Author:** ![Flying\_Monk](https://avatars.discourse-cdn.com/v4/letter/f/48db29/32.png) [@Flying\_Monk](https://boards.straightdope.com/u/Flying_Monk)\ **Post date:** [April 22, 2003, 1:18am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/9 "2003-04-22T01:18:05Z")
So the iron and nickel in the magma isn’t electrically nuetral? Chronos: If you read this “A moving electron doesn’t always emit radiation. If an electron is flying through vacuum in zero gravity, it would continue to do so forever without emitting anything. If it hits something and accelerates (changes direction or reduces speed), it would emit radation.” , I think you’ll see it’s not the same thing. He’s talking about electrons emitting photons, not EM waves. Yes, I understand infrared light, like all light, is EM…but I’m talking about low-frequency radio waves. As I understand it, an electron moving through vacuum in zero gravity would create an EM wave, though, wouldn’t it? ---
**Author:** ![bbeaty](https://avatars.discourse-cdn.com/v4/letter/b/c0e974/32.png) [@bbeaty](https://boards.straightdope.com/u/bbeaty)\ **Post date:** [April 22, 2003, 11:09am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/10 "2003-04-22T11:09:58Z")
> [@](#): > > \*Originally posted by Flying\_Monk \* > \*\*I learned in Electricity 101 that a moving electron produces an electromagnetic wave. While this is obvious in something like an antenna, what about something like my arm? There are electrons in my arm…if I wave my arm in the air, is there some electromagnetic trace, no matter how weak, that propagates throughout the universe? \*\* Not a moving electron, an accelerating one. And it only works if the electron is alone (not accompanied by an equal and opposite charged particle.) If you wiggle a single electron, the electron emits radiation composed of EM waves. Here’s an analogy that shows charges visually: [http://amasci.com/redgreen.html](http://amasci.com/redgreen.html) Matter is made of “red plastic” overlayed with “green plastic.” Wiggle the red while holding the green still, that creates EM waves. Or wiggle the green while holding the red still. Same thing. Or wiggle both in different directions. It makes EM waves. But glue them together and wiggle them as a unit, and no waves are generated. And about static electricity? STATIC ELECTRICITY IS NOT ELECTRICITY WHICH IS STATIC [http://amasci.com/emotor/stmiscon.html#one](http://amasci.com/emotor/stmiscon.html#one) [http://amasci.com/miscon/eleca.html#static](http://amasci.com/miscon/eleca.html#static) [http://amasci.com/miscon/eleca.html#statcur](http://amasci.com/miscon/eleca.html#statcur) ---
**Author:** ![Flying\_Monk](https://avatars.discourse-cdn.com/v4/letter/f/48db29/32.png) [@Flying\_Monk](https://boards.straightdope.com/u/Flying_Monk)\ **Post date:** [April 22, 2003, 11:24am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/11 "2003-04-22T11:24:12Z")
Thank you bbeaty! So can I say with absolute accuracy that an accelerating charged particle creates an EM wave? What about the iron & nickel in the magma? Are they charged? ---
**Author:** ![bbeaty](https://avatars.discourse-cdn.com/v4/letter/b/c0e974/32.png) [@bbeaty](https://boards.straightdope.com/u/bbeaty)\ **Post date:** [April 23, 2003, 2:39am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/12 "2003-04-23T02:39:07Z")
> [@](#): > > \*Originally posted by Flying\_Monk \* > \*\*Thank you bbeaty! > > So can I say with absolute accuracy that an accelerating charged particle creates an EM wave? What about the iron & nickel in the magma? Are they charged? \*\* The Earth’s core? I think any net imbalance of charge would quickly migrate to the surface. Then the question becomes, does the whole Earth behave as a charged object? As the earth revolves, does it send out a .000000032 Hz radio wave? (That’s one cycle per year.) On the other hand, there are some feeble charges associated with the Earth’s core because the core is acting like an electric generator. It might be sending out some very low frequency waves, especially if the currents in the core can be “twanged” by sudden changes in the solar wind hitting the Earth. ---
**Author:** ![Flying\_Monk](https://avatars.discourse-cdn.com/v4/letter/f/48db29/32.png) [@Flying\_Monk](https://boards.straightdope.com/u/Flying_Monk)\ **Post date:** [April 23, 2003, 4:38am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/13 "2003-04-23T04:38:41Z")
So what is the exact process which causes the Earth to have a magnetic field? ---
**Author:** ![Trigonal\_Planar](https://avatars.discourse-cdn.com/v4/letter/t/0ea827/32.png) [@Trigonal\_Planar](https://boards.straightdope.com/u/Trigonal_Planar)\ **Post date:** [April 23, 2003, 5:24am UTC](https://boards.straightdope.com/t/moving-electrons-moving-waves/159827/14 "2003-04-23T05:24:43Z")
I believe this is still under investigation. But is it not conceivable that the moving currents of magma are sufficient to generate a magnetic field? If the magma is moving in a non-uniform manner, than parts will be accelerating and other parts deccelerating. Perhaps there is a sufficient net imbalance to generate a field?