optimal shape for microwaving

[caravelair]

we've all had experiences where we microwave something, and the edges get super hot, while the middle remains cold. i was wondering what shape of food would result in the most even heating of that food. say it's rice on a plate, or something, for example - something that can take on a variety of shapes. anyways, it seems to me that a good strategy is to choose a shape where the average rice grain is closest to an edge. when i microwave things, i tend to go for a torus shape, which intuitively seems like a good choice to me. it's kinda like a long thing cylinder curved around so the ends meet.

however, i don't really know anything about the way heating is distributed by a microwave, other than that the center gets less heating than the edge. anyone know how to calculate the ideal shape, given the size limitations of a plate?

yes, i know i can just mix the food around half way through. i'm not asking for practical purposes, i've just wondered about this for a while now.

[McGargoyle]

The problem here is aborption of the microwaves. The less water molecules between the emitter and the water molecule farthest from the emitter, the better.
So the best layout would be each rice grain lying separately on a flat plate.
Have fun dispersing!

[nermal]

Here's a neat little experiment--tasty too.

Take a bunch of cheese cubes, 3/4 on a side, and with toothpicks, build a lattice cube as big as you can (you'll need a LOT of cheese cubes, mini marshmallows work too.)
Put that structure in the microwave and nuke it. If you're real anal, you can assign coordinates to each cube.

You'll notice some cubes melting, and others not. From this you can derive a real course (one course--ar ar) interference pattern for your particular microwave. Then you can play with different food shapes based on that pattern.

Bon Appetite!

Ed

[Jet Black]

Originally posted by nermal

Take a bunch of cheese cubes, 3/4 on a side, and with toothpicks, build a lattice cube as big as you can (you'll need a LOT of cheese cubes, mini marshmallows work too.)
Put that structure in the microwave and nuke it. If you're real anal, you can assign coordinates to each cube.


or take one large cube and a piece of thin wire, and slice it while holding it together. this would take less time I'd imagine.

[Occams_Razor]

Part of the problem is the way the "fan" distributes microwaves. You know that fan sound in your microwave? That's a not a fan really. What happens is that a magnetron directs its microwave output (radios waves at approximately 2,500 megahertz; 2.5 gigahertz) at something which looks somewhat like a fan shaped disco ball called a "stirrer blade." Like a disco ball disperses light in many directions, so the stirrer blade does to microwaves.

This does not work out to be an even distribution. Complicating matters are that radio waves penetrate unevenly in thick pieces of food, failing to penetrate to the middle, "hot spots" are caused by wave interference, and different foods heat at different rates depending on the amount of water, fat and sugar they contain (so, for instance, the peas in your rice may heat up faster than the rice).

So knowing this, I think we can deduce that the perfect shape is a doughnut ring of certain proportions. I'm assuming here that your microwave has a rotating plate. First food shouldn't be too thick at any one spot so that the microwaves can penetrate all the way through. So we need some type of flattened shape. Second you need to test your microwave for dispersion and hot spots. So we place a thin uniform layer of some also uniform substance across the entire bottom of the microwave, heat for a few second--long enough for the tray to make two revolutions--and see at what radius from the center the food is best heated and how wide that layer is. Now you have your probable shape: a not too thick doughnut shaped ring. Now all you need is a cuisinart and a custom made mold to the specifications you have discovered. All food should be blended to a uniform mush to equalize fats, sugars and water and then molded in a thin layer to this ideal doughnut shape for your microwave.

[caravelair]

ha ha. excellent! i knew i had something going there with a torus shape. thanks for your input folks!

[Jet Black]

I recall a range of Star Trek mugs had to be withdrawn and redesigned slightly, because they lensed microwaves and created a hotspot of superheated water. This might be an urmab myth though, sorry if it is.

[Ab_Normal]

Originally posted by nermal
Here's a neat little experiment--tasty too.

Take a bunch of cheese cubes, 3/4 on a side, and with toothpicks, build a lattice cube as big as you can (you'll need a LOT of cheese cubes, mini marshmallows work too.)
Put that structure in the microwave and nuke it. If you're real anal, you can assign coordinates to each cube.

You'll notice some cubes melting, and others not. From this you can derive a real course (one course--ar ar) interference pattern for your particular microwave. Then you can play with different food shapes based on that pattern.

Bon Appetite!

Ed

I'll have to remember this one for my spawn the next time science project season comes up.

[liquid]

I have a friend who is doing a PhD on this very topic right now. Haven't asked too many questions about it though!

[HaysooChreesto!]

Just a quick derailment here: Why doesn't a microwave kill ants? Back when I was a single guy I used my microwave quite a bit but neglected to clean it on a regular basis-actually it was unclean on a regular basis.

Anyway, one morning I woke up and noticed that a colony of ants had decided to use the various splatters in my microwave as their new grocery store. I figured I'd fix that real quick and turned the thing on "High" for one minute. But it didn't affect them one bit.

Then I Windexed them, wiped them out with a paper towel, bit the bullet and cleaned the damn thing. But why weren't they cooked?

[Occams_Razor]

The reason ants survive in the microwave is because the microwaves inside the oven form standing waves. Energy is high in some areas -- ants would fry there -- and weak elsewhere. Ants seem to be able to find these low energy refuges and survive very nicely.

One thing working in the ants' favour is that they don't have much liquid in their bodies, so the microwaves - which cook meats by heating their water content - would act more slowly on ants than on people. That could buy the poor ants some time to save themselves.

Think about it this way: at a concert hall, can you hear equally well from all the seats?

Microwave ovens have "dead spots" just like concert halls, creating those annoying cold pockets in cooked foods. "The ants probably are quite uncomfortable when they are bathed in microwave radiation, so they try to get away. If they find a dead spot they feel better, so they stay there and survive."

http://www.iol.co.za/index.php?sf=29&click_id=29&art_id=iol955439829238S365&set_id=1

[nermal]

Originally posted by Occams_Razor
The reason ants survive in the microwave is because the microwaves inside the oven form standing waves. Energy is high in some areas -- ants would fry there -- and weak elsewhere. Ants seem to be able to find these low energy refuges and survive very nicely.

One thing working in the ants' favour is that they don't have much liquid in their bodies, so the microwaves - which cook meats by heating their water content - would act more slowly on ants than on people. That could buy the poor ants some time to save themselves.

Think about it this way: at a concert hall, can you hear equally well from all the seats?

Microwave ovens have "dead spots" just like concert halls, creating those annoying cold pockets in cooked foods. "The ants probably are quite uncomfortable when they are bathed in microwave radiation, so they try to get away. If they find a dead spot they feel better, so they stay there and survive."

http://www.iol.co.za/index.php?sf=29&click_id=29&art_id=iol955439829238S365&set_id=1

Wouldn't also have anything to do with the fact that an ant is so much smaller than the wavelength, would it? Just wondering.

Ed

[nermal]

Originally posted by caravelair
ha ha. excellent! i knew i had something going there with a torus shape. thanks for your input folks!

Torii is cool.:cool:

Ed

[nermal]

Originally posted by Jet Black
or take one large cube and a piece of thin wire, and slice it while holding it together. this would take less time I'd imagine.

How you gonna see what happens to the cubes in the middle, smarty pants?:) :)

Ed

[Nostalgic Pushhead]

Take a grape. Cut it in half down the middle (perpendicular to the stem hole) but leave a tiny bit of skin attatching the two ends. Set it down in the microwave with the open middle down.

It flames up, rather violently.

Anyone want to explain how that happens? I imagine its something about energy being transfered across the air between the two halves.... thats where it seemed to flame up, if I remember correctly.

Also, I think we discussed this a while ago, but I learned if you heat water up enough in the microwave, it won't boil... but if you break the surface tension, and its hot enough, it will explode. Ow.

You know what the hardest thing to microwave is? Pizza bites. I can even stir them around on the plate every minute, and I still get exploded ones and cold ones.