Antiochus, your comments are inappropriate for the General Questions forum.
Please be civil while in GQ.
-xash
General Questions Moderator
Antiochus, such fun-n-games can damage your oven in various ways, although there are ways to reduce the risk.
One way that these experiments can cause damage is fairly obvious–you have arcs and fireballs flying around in the cavity that can damage the interior coating. Once the coating is compromised, you run the risk of further arcing on the cavity walls themselves, and of corrosion that can eventually ruin the cavity. Keeping stuff away from the walls and covering the bottom of the cavity helps, but is no guarantee that you won’t cause damage.
The other potential source of damage is more subtle. The oven is designed to operate with a certain minimal amount of material in the cavity to absorb the radiation. Some of the proposed hijinks involve microwaving masses below the intended minimum. The problem is that the small objects won’t absorb enough of the energy, and while most of the unabsorbed waves will just bounce around the cavity until they get absorbed, some will bounce back up the waveguide to the magnetron. In extreme cases, this can destroy the magnetron. If you restrict your experiments to very brief periods (say, no more than 10 seconds, with a 30-second cooldown in between), this should not happen.
A couple of final warnings: Anything you burn in your oven may get into your food later, and don’t leave the oven running unattended with anything odd in it.
Thank you Balance.
FYI -
The TV show Mythbusters is going to do a segment on microwaves this friday. The previews showed them putting a ball of tin foil into the microwave. It will be interesting to see what all they put in there.
Also -
Here are some interesting things to put into a microwave (note - while a modern microwave is a lot more robust for this sort of thing, it is still very possible to damage the magnatron, so do this at your own risk):
http://www.bazilians.org/microwave.html
http://freeside.laidback.org/humour/cd.html
http://apache.airnet.com.au/~fastinfo/microwave/oven/steelwl.html
http://isaac.exploratorium.edu/~pauld/activities/sweden/microwaves.html
http://www.physics.sfsu.edu/~senglish/microwaves_are_pretty_cool.htm
http://www.geocities.com/CapeCanaveral/Campus/1245/experiments/microwave.htm
MythBusters is on the Discovery channel.
No, this is definitely an electrical phenomenon, not actual flame.
… or perhaps I should say, there’s definitely an electrical phenomenon going on, not just actual flame, so what is it about the burning bits of carbon rising from the toothpick that provides such great fuel for an electric light show?