There is also beryllium oxide in the ceramic insulators of most magnetrons. If the insulator cracks or is broken, that dust is highly toxic if inhaled.
If you want a nice magnet, there are safer ways to get one. Leave the magnetrons alone.
If you're doing anything with it wear gloves; if you even might snap or machine it, you need to work in a fume chamber.
Formation of BeO from beryllium and oxygen releases the highest energy per
mass of reactants for any chemical reaction, close to 24 MJ/kg 
I assume this article was posted because it was mentioned in XKCD , which also ends on the grape plasma tangent.
I'm guessing 30 seconds is too much for these. (Although you can kind of see that my hotspots match #1 in the original article)
edit: nevermind, didn't realize they kept the 'plate spinners' on during the experiment. The rings in the appalam are artifacts from rotating an anti-node through the food. would have to do something different to get equal heating using ~two points vs. a line
OK, I'm going to say that the right answer is to move the microwave source linearly (or change how it's aimed? Or otherwise change its focus) at a frequency that would maximize even coverage of the heating area based on the rotation speed of the turntable.
Another (more limited) possibility is a way to mount a fixed spoon that could stir soup or other appropriate liquids while the bowl turned.
We unplugged it once to take to an ice rink and it was still hot hours later.
Also, am East Asian, can verify: it's pretty uncommon to find a household without a rice cooker, a portable butane grill, or a Zojirushi.
American plugs always seemed relatively anaemic (and scary dangerous - where are the switches? where is the Earth? though the EU are also typically unswitched), though you do get to have less bulky mobile phone chargers as a result!
well the bottom prong on a cord is the ground and anything that is not a wallwort is polarized nowadays so that the neutral and hot are always on the right wire.
by switched you mean it has a fuse in the plug? if so that's not something that america does. we have 15A circuits going to different parts of the house and if there is a possibility of water immersion there will be a GFCI circuit breaker or outlet installed to protect all downstream outlets. overall it works well enough that there aren't a massive number of deaths caused by it. usually you have do something exceptional to be electrocuted.
edit: the kettle I have is 1500 Watts and at 120 volts it's ~12A of current.
This has spread to AFCI (arc fault instead of ground fault) being put in every bedroom as a requirement as well.
If your house doesn't have GFCI and AFCI everywhere, they're required, you proobably should start retrofitting your sockets.
All of that said, you can use temporary use 1800W devices on 15A legally without tripping the breaker.
Seriously, tea, coffee (15-20 cups in a typical day, between two of us), plus cooking. It's often faster to boil water in the kettle and then pour it into a pot and switch on the gas than to boil it from cold in the pot.
One time I hit the start button and it started running based on the value of the clock (e.g. it was 4:23pm and the oven kicked on and counted down from 4 minutes and 23 seconds).
I suppose it could have been a weird coincidence, but my partner is very strict about leaving "unused time" on the microwave and obsessively hits the Clear button. Plus it seems unlikely that there would be that much unused time left (it's usually a few seconds), or that I happened to use the microwave exactly when the unused time synced up with the clock.
The same here. She gets really mad about that. I can't really blame her, since I am am just the same about a bunch of other stuff.
My microwave is my most visible clock in my apt (small sf sub). Whens its paused it doesnt show the time and just constantly blinks.
But even for heating flat items (such as Naan) I haven't noticed any uneven heating with my giant Panasonic microwave.