Science in the Microwave

Sunda666 writes "I have just hit this site which describes in detail how to build an one-atmosphere plasmoid using ordinary stuff and a microwave oven. Interesting thing, i'll try it as soon as I get a spherical glass vessel like that ;-)"

You don't need a "vessel" and this is old news

[a3d0a3m]

This has been done before, and posted to slashdot before. You can do it without the glass vessel. There's an old quickies here [slashdot.org] that shows how to do it without the vessel.

Adam

Seen this before, be carefull!

[j3110]

I was going to try this a year ago, but decided that I didn't really need a darwin award :) You can do it with any glass bowl and anything that burns in any microwave that you feel safe doing it in :) The brown gas you see, NO2, is toxic and is found in cigarette smoke. Be careful, it's arguably the most harmful substance in cigarettes. Not good for the atmosphere either :) I really don't think there is that much in cigarettes, and I would urge anyone foolish enough to do this (like me after a few drinks) to NOT breath the funky air! :)

You have been warned! :)
http://www.epa.gov/oar/aqtrnd95/no2.html
bad stuff really :) when it dissolves in your lungs, it's likely to make nitric acid, which is like to make your lungs liquid if you breath too much.

Re:You don't need a "vessel" and this is old news

[garglblaster]

Here is another page which has been around for a few years now:

the "funny things to do with your microwave oven" [utwente.nl] page

I like the one with the CDs !!

More microwave experiments

[eram]

Some other potentially dangerous experiments with CD:s, light bulbs and other objects in microwave owens can be found here [utwente.nl]. Looks interesting, but I personally wouldn't do that in my own kitchen.

Marshmallows: poor man's plasma

[Oink.NET]

For an even quicker thrill, try putting marshmallows in the microwave.

For those too lazy to actually get up, find marshmallows and find microwave, use this applet [colorado.edu] to cook them virtually, or check out this time lapse video [angelfire.com].

For those craving more of an intellectual thrill, find the speed of light with marshmallows [bowlesphysics.com] using a microwave.

Re:You don't need a "vessel" and this is old news

[BlueUnderwear]

You can do it without the glass vessel.

Yes, but without a glass vessel, the ball lightning will be too short-lived. Indeed, due to higher temperature, it raises up, and as soon as it reaches the metal ceiling of the nuker, it collapses. The glass vessel makes sure that it can get to the metal, and hence it will stay longer (contact with glass doesn't make the plasmoid collapse, because glass doesn't conduct electricity).

I just wonder whether the shape is important, or whether an inverted drinking glass would also do the job.

Re:GDP thruster?

[Anonymous Coward]

...though I'd be afraid to put anything other than food in my own microwave.

Who said you had to use your own? 7-11's, university canteen's, your workplace, etc. all have "public access" microwave ovens which are perfect for this purpose...

Other items of interest:

• eggs (you said you were only concerned about putting non-food items inside...)
• pencils: they'll burn pretty quickly
• pencil mines: they get so hot that they can melt glass...
• soap: if you try this, make sure your microwave oven is very big (or only use a rather small filing of soap
• the newest MSDN CD's from work (perfect for doing in the office kitchen!). Those make great office ornaments, but it's probably best if your boss and/or colleagues don't see them... Microsofties are known for their lack of sense of humor, and might not appreciate it...
• chocolate, bread (again, if you're concerned about putting non-food items inside...)

Re:What if you DON'T heed the warnings...

[BlueUnderwear]

If you do and it melts the glass, will it attack the ceiling of the microwave itself next? =)

No. Actually, as soon as the plasmoid touches a conductive (metal) surface, it shorts out and just collapses. The purpose of the glass vessel is not to protected the ceiling of the microvave oven, but rather to protect the plasmoid ;-)

Re:Umm

[Alsee]

explaining to me what the hell this is?

When air gets hot enough it turns into a plasma which is conductive. This means it adsorbs microwaves which drives up the temperature and keeps it in the conductive plasma state. You get a ball of plasma, as long as you keep pumping in microwave energy.

The flame itself is nowhere near hot enough to create plasma to get the process started, but after a few seconds the flame, microwaves, and I think the burning object (conductive carbon) combine to trigger a little high temperature spark which can get the process going.

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Re:what exactly is 'plasma'

[Ozan]

Often gas that is emitting light is being falsely named plasma, but the atoms are only being stimulated by heat or light and emit light. A real plasma is a gas which is stimulated so high that the atoms are ionized and free electrons are floating between them.

The "humming" explained

[Alsee]

If you look deeper into the website you'll see that the author goes into detail analyzing the sound produced. The humming sound is simply the frequency of the microwave electronics. The plasma itself would normally be silent. It is acting as a "speaker" based on the varying energy it gets from the microwave oven. If you take a look here [google.com] you'll see projects that use the plasma effect as an extremely high quality tweeter.

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Just tried it out...

[BlueUnderwear]

Having no suitable sperical vessel ready, I used a sawed-off plastic mineral water bottle. Having no tooth-picks ready either, I just stuck the match itself into the cork. As recommended in a previous Slashdot story about the subject, I removed the revolving plate, and put a glass of water into the back.

First attempt: the match always went out before it could produce any plasma ball. D'oh

Second attempt: rather than using a match, I stuck a long pencil mine into the cork, and set the oven to thirty seconds. 29 seconds of nothing. Then a loud whizz, and the time ran out before it could get any more interesting (should've set it to a minute). However, this one second of action was enough to fill the bottle with a mysterious thick white fume. Question: is this the nytrogen oxyde that the article speaks about, or was it only the plastic burning (other than the fumes, there were no obvious traces of burn on the bottle). Worrying that the fumes might be toxic, I didn't repeat the experiment.

Re:GDP thruster?

[Sunda666]

GDP thrusters are a very kewl concept, but I think they might be very poluent.

Man, that site is full of cool research, check it out, especially the lifter experiments.

Re:Big deal

[XNormal]

The flame of a match is just hot gas, not plasma. The flame's light comes from incandescent particles of carbon, not ionized atoms.

Re:Just as much fun...

[Deltan]

If the threaded metallic end is not submerged the metal will spark in the microwave and you might blow up the whole works.