# Electromagnetically Lighting a Fluorescent Bulb **URL:** \ **Category:** Factual Questions\ **Created:** [July 15, 2005, 5:03pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671 "2005-07-15T17:03:48Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![antich](https://avatars.discourse-cdn.com/v4/letter/a/7c8e57/32.png) [@antich](https://boards.straightdope.com/u/antich)\ **Post date:** [July 15, 2005, 5:03pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/1 "2005-07-15T17:03:48Z")
As per [this video](http://emotors.ncku.edu.tw/english/movie/5.mpeg) . If I were to build a simple electromagnet at a distance of ~1/4 inch from the tube: - How strong would it have to be? - What measurement of the electromagnet’s strength should I be concerned with? If this were feasible at a ‘homemade’ level, what would be the recommended solenoid length, number of turns, power input, etc? I’ve only a basic understanding of all things EM, so if I’ve left out any variables, please feel free to fill in the appropriate blanks. Thanks ---
**Author:** ![Snowboarder\_Bo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snowboarder_bo/32/229_2.png) [@Snowboarder\_Bo](https://boards.straightdope.com/u/Snowboarder_Bo)\ **Post date:** [July 15, 2005, 5:31pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/2 "2005-07-15T17:31:22Z")
I played the video but it had no sound. Without that, I have nothing other than a broad idea of what’s happening. Any more info? ---
**Author:** ![antich](https://avatars.discourse-cdn.com/v4/letter/a/7c8e57/32.png) [@antich](https://boards.straightdope.com/u/antich)\ **Post date:** [July 15, 2005, 5:43pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/3 "2005-07-15T17:43:38Z")
> [@Snowboarder Bo](#): > > I played the video but it had no sound. > > Without that, I have nothing other than a broad idea of what’s happening. > > Any more info? Not much more, other than a rudimentary description of what’s happening on the linking page [here](http://emotors.ncku.edu.tw/english/education.htm) . ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [July 15, 2005, 5:57pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/4 "2005-07-15T17:57:43Z")
It’s not exactly an electromagnet, but an induction coil in an induction stove. There’s a coil connected to the contacts on the tube. When that coil/tube assembly is close enough to the coil in the stove, a current is induced in the tube/coil assembly and the tube lights. In general, induction stoves generate eddy currents in the conductive cooking vessels placed on their surfaces. These eddy currents cause the vessel to get hot, thereby heating the food. ---
**Author:** ![Jurph](https://avatars.discourse-cdn.com/v4/letter/j/50afbb/32.png) [@Jurph](https://boards.straightdope.com/u/Jurph)\ **Post date:** [July 15, 2005, 7:39pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/5 "2005-07-15T19:39:00Z")
[This photo](http://www.zen54564.zen.co.uk/r/asset/the%20field2.jpg) shows a giant grid of fluorescent bulbs standing up under a high-tension power line, and being illuminated by the EM field from the wires! The power required to light the bulb by induction is going to far exceed the amount of power required to light it normally. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [July 15, 2005, 7:47pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/6 "2005-07-15T19:47:25Z")
If you’re willing to pore through army surplus stores, you might be able to find an old HF radio. Hold the fluorescent bulb parallel to the antenna and transmit on high power. I got a demonstration of this in 1996 and was suitably impressed, as well as having it permanently branded into my brain not to touch an HF radio antenna while it is transmitting on high power. ---
**Author:** ![antich](https://avatars.discourse-cdn.com/v4/letter/a/7c8e57/32.png) [@antich](https://boards.straightdope.com/u/antich)\ **Post date:** [July 15, 2005, 8:04pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/7 "2005-07-15T20:04:23Z")
> [@Bryan Ekers](#): > > If you’re willing to pore through army surplus stores, you might be able to find an old HF radio. Hold the fluorescent bulb parallel to the antenna and transmit on high power. I got a demonstration of this in 1996 and was suitably impressed, as well as having it permanently branded into my brain not to touch an HF radio antenna while it is transmitting on high power. Interesting. I may have to look into that. I’m basically creating a showpiece that I’d like to glow without wires leading to it. I had originally thought that it would be easiest to do this with an electromagnet, as I’m already using one in the piece. I’m thinking the tube (size/brightness yet to be decided) will be about 1/4” away from the magnet, but if there are other ways of doing this, I’m all for that. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [July 15, 2005, 8:54pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/8 "2005-07-15T20:54:03Z")
> [@antich](#): > > I’m basically creating a showpiece Well, it’s not the _best_ approach for demonstrations, as the radio will have a big noisy generator that spins up when you press the push-to-talk switch. ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [July 15, 2005, 9:26pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/9 "2005-07-15T21:26:04Z")
Tesla coils energize flourescent tubes nicely and, depending on the size of the coil, potentially from quite a distance. ---
**Author:** ![Carnac\_the\_Magnificent](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Carnac\_the\_Magnificent](https://boards.straightdope.com/u/Carnac_the_Magnificent)\ **Post date:** [July 15, 2005, 9:53pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/10 "2005-07-15T21:53:16Z")
> [@Jurph](#): > > [This photo](http://www.zen54564.zen.co.uk/r/asset/the%20field2.jpg) shows a giant grid of fluorescent bulbs standing up under a high-tension power line, and being illuminated by the EM field from the wires! The power required to light the bulb by induction is going to far exceed the amount of power required to light it normally. Is there any danger in holding up a fluorescent tube while standing under a power line? I’m guessing we’re not talking about freak electrical discharge akin to a lightning bolt. Could the tube burst? ---
**Author:** ![toadspittle](https://avatars.discourse-cdn.com/v4/letter/t/c0e974/32.png) [@toadspittle](https://boards.straightdope.com/u/toadspittle)\ **Post date:** [July 15, 2005, 10:51pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/11 "2005-07-15T22:51:59Z")
> [@Jurph](#): > > [This photo](http://www.zen54564.zen.co.uk/r/asset/the%20field2.jpg) shows a giant grid of fluorescent bulbs standing up under a high-tension power line, and being illuminated by the EM field from the wires! The power required to light the bulb by induction is going to far exceed the amount of power required to light it normally. A question: Is this EM field energy lost from such lines on a regular basis? Or are the fluorescents stealing extra energy? ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [July 16, 2005, 1:17am UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/12 "2005-07-16T01:17:25Z")
> [@toadspittle](#): > > A question: Is this EM field energy lost from such lines on a regular basis? Or are the fluorescents stealing extra energy? Any time and anywhere there is a conductor carrying an AC or DC current there is an electric field associated with the conductor. The fluorescents are merely utilizing a very small amount of this energy and procucing light in their own way. ---
**Author:** ![antich](https://avatars.discourse-cdn.com/v4/letter/a/7c8e57/32.png) [@antich](https://boards.straightdope.com/u/antich)\ **Post date:** [July 16, 2005, 3:55am UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/13 "2005-07-16T03:55:28Z")
> [@spingears](#): > > Any time and anywhere there is a conductor carrying an AC or DC current there is an electric field associated with the conductor. That raises another very good question. I was originally running a DC coil for another part of this, but should I be using an AC to light up the bulb? ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [July 16, 2005, 7:14am UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/14 "2005-07-16T07:14:16Z")
> [@Carnac the Magnificent!](#): > > Is there any danger in holding up a fluorescent tube while standing under a power line? I’m guessing we’re not talking about freak electrical discharge akin to a lightning bolt. Could the tube burst? I honestly do not know but if anecdotal evidence counts my experience is no…they will not burst. I’ve done this myself and the flourescent buld did not glow all that brightly but it definitely glowed. This was under serious power lines along the lines of those shown in the linked picture but I cannot say how powerful those were and if something more powerful exists to bust the bulb. My guess is no as these power lines seem to be the heaviest duty I am familiar with and I cannot imagine what it would take to overload one but take it FWIW. ---
**Author:** ![Mac\_Guffin](https://avatars.discourse-cdn.com/v4/letter/m/2bfe46/32.png) [@Mac\_Guffin](https://boards.straightdope.com/u/Mac_Guffin)\ **Post date:** [July 16, 2005, 8:30am UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/15 "2005-07-16T08:30:33Z")
I have one of those plasma disks that you can buy at any Walmart, or Spencers. The round, flat disks that discharge filiments of plasma within. If I place that thing anywhere near a flourecent light tube, either in a fixture or out, it lights up. I am certian the plasma balls will do this as well. They are cheap, plentiful, and less dangerous than a HF radio or Tesla coil. You might pick one up and use that for your demo… ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [July 16, 2005, 11:04am UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/16 "2005-07-16T11:04:23Z")
I’m pretty sure this is how Nicola Tesla wanted to light homes and transport power - via EM waves. ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [July 16, 2005, 12:58pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/17 "2005-07-16T12:58:30Z")
> [@Bryan Ekers](#): > > If you’re willing to pore through army surplus stores, you might be able to find an old HF radio. Hold the fluorescent bulb parallel to the antenna and transmit on high power. **FYI It is illegal to operate a HF radio transmitter without a license in the US!** ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [July 16, 2005, 5:39pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/18 "2005-07-16T17:39:19Z")
> [@spingears](#): > > **FYI It is illegal to operate a HF radio transmitter without a license in the US!** Good thing I’m Canadian. ---
**Author:** ![Carnac\_the\_Magnificent](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Carnac\_the\_Magnificent](https://boards.straightdope.com/u/Carnac_the_Magnificent)\ **Post date:** [July 16, 2005, 7:04pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/19 "2005-07-16T19:04:05Z")
> [@Bryan Ekers](#): > > Good thing I’m Canadian. Not for long. Not for long… ---
**Author:** ![toadspittle](https://avatars.discourse-cdn.com/v4/letter/t/c0e974/32.png) [@toadspittle](https://boards.straightdope.com/u/toadspittle)\ **Post date:** [July 16, 2005, 7:43pm UTC](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671/20 "2005-07-16T19:43:59Z")
> [@spingears](#): > > Any time and anywhere there is a conductor carrying an AC or DC current there is an electric field associated with the conductor. > The fluorescents are merely utilizing a very small amount of this energy and procucing light in their own way. Yes, but. If I’m working for the power company, and I look at our meters before and during the time someone sets up these tubes (or, say, several thousand of them), will the meters read a power drain? Or is this just waste EM that is lost all the time, and already accounted for? [Next page](https://boards.straightdope.com/t/electromagnetically-lighting-a-fluorescent-bulb/312671.md?page=2)