Microwave Oven Diagnostics with Indian Snack Food

http://www.evilmadscientist.com/2011/microwave-oven-diagnostics-with-indian-snack-food/

by gus_massa • 11 years ago

311 67 11 years ago

joezydeco• 11 years ago

"Did you know that if you take apart microwave ovens, there is a really great ceramic magnet inside of the magnetron?"

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.

foobarian• 11 years ago

No doubt the material is toxic, but it doesn't seem breaking it would create a whole lot of dust, similar to any other ceramic. You'd have to machine or sand it.

http://en.wikipedia.org/wiki/Beryllium_oxide#Safety

AlyssaRowan• 11 years ago

Careful. ₄Be compounds are not your friend. Do not breathe or touch ANY beryllium dust - ever - at all.

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.

cellularmitosis• 11 years ago

Anytime I see someone mention hacking on magnetrons, I feel it my duty to remind us that the back of your eyeballs don't have pain receptors. If you were to power up thatagnetron outside of the microwave and point it at your face, it's possible you'd blind yourself before you even realized you were in danger.

asteli• 11 years ago

IIRC, the danger is actually to the /fronts/ of your eyeballs, the result being cataracts rather than retinal damage.

weland• 11 years ago

Just wanted to add something. Itching is the first sign. If you feel itching in your eyes, turn the damn thing off immediately. I nearly blinded myself when I was an idiot undergrad. Kids, take the idiot adult's advice and don't play with it before you understand the theory and working principles extremely well.

x0x03• 11 years ago

I read the Beryllium oxide page and found this interesting note:

   Formation of BeO from beryllium and oxygen releases the highest energy per 
   mass of reactants for any chemical reaction, close to 24 MJ/kg [1]

and this comment would be incomplete w/o sharing the findings of my wikipedia browsing which lead to making plasma in microwaves with grapes. https://www.youtube.com/watch?v=RwTjsRt0Fzo

[1] http://en.wikipedia.org/wiki/Beryllium_oxide#Safety

lfowles2• 11 years ago

All roads lead to Rome.

I assume this article was posted because it was mentioned in XKCD[0] , which also ends on the grape plasma tangent.

[0] https://what-if.xkcd.com/131/

cmurf• 11 years ago

When I was 12 I disassembled a microwave, unplugged from the wall, and got electrocuted. Not the visible kind like from static or from an outlet, but... I don't know how to describe it. Inside was a boxed case the size of a Kleenex cube, and my hand, palm side, just got sucked right on it like a magnet and bam I nearly passed out and fell off the chair. That was the end of playing with microwaves for me.

wierdaaron• 11 years ago

You can do the same with sliced cheese, I've heard.

detaro2• 11 years ago

Or chocolate bars.

BrainInAJar• 11 years ago

cheese is expensive, papadams are cheap

Luyt• 11 years ago

If you microwave slices of smoked cheese (on baking paper), they become crispy crackers (lowcarb, even).

akjetma• 11 years ago

All these microwaves just need a more complex 'plate spinner' that actually translates the rotating plate across field lines. Kind of like a spirograph... http://i1216.photobucket.com/albums/dd371/benice_chen/hypo_h...

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

SomeCallMeTim• 11 years ago

Like a slow-speed random orbit sander? :) [1] Some of the dead areas looked too big for even that to help, and it would mean the maximum plate size would be smaller. Hmm...

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.

[1] https://en.wikipedia.org/wiki/Random_orbital_sander

TheLoneWolfling• 11 years ago

Many microwaves do something similar - they have a spinning "fan" that's designed to perturb the standing wave pattern.

chris_va• 11 years ago

This is actually a fun way to measure the speed of light. You can measure the wavelength by looking at the distance between the bubbles. That plus the operating frequency of the microwave will give you the phase velocity.

sombremesa• 11 years ago

I just tried this with papad(ams) and this is what it looks like at 30 seconds: http://i.imgur.com/oclJIS9.jpg

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)

blahedo• 11 years ago

Experiment replication: one of the core requirements of scientific exploration.

Hooray science!

latcampbell• 11 years ago

I make appalams in microwave too and have the same uneven cooking problem - putting them vertically seems to help. Here is a commercial product that says so too. https://www.papadumexpress.com

anigbrowl4• 11 years ago

I got rid of mine several years ago and have never once found myself thinking 'gee, I wish I still had a microwave.' You know what takes up less space, saves money, and provides constant utility, which most American kitchens don't have? An electric kettle. The most appliance-happy country on earth (except maybe Japan) and you still boil water on the stove like it's 1815.

ebiester• 11 years ago

So, when heating up leftovers, you have to clean up an extra pot. That is what the microwave does for me. (That said, I also love my kettle.)

anigbrowl4• 11 years ago

I have a toaster oven for that, but since I cook 6 days out of the week unless I've very busy it's that big a deal. I got sick of the uneven heating and other well-known microwave problems and realized the only things I ever used it for were soup and popcorn, both of which are just as easy to do in a pot.

ianlevesque• 11 years ago

Or boil in our Keurig machines.

snarkulosity• 11 years ago

I've heard that electric kettles don't work as well in the US as in (say) England because our mains voltage is much lower -- and I guess a transformer would be too bulky.

jarvist• 11 years ago

I think this is probably true - in the UK (and EU) our kettles are 3 kW, maxing out our 230 V / 13 A plug/sockets.

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!

illicium• 11 years ago

They still work much better than a stovetop kettle or heating water in the microwave

gambiting• 11 years ago

It has absolutely nothing to do with use of transformers. Sockets in US and in UK are fused at approximately 13Amps for safety reasons. And 110V at 13amps is 1430W, while 230V at 13 amps is 2990W. You can make a kettle which uses only 1430W of power, but it would take much longer to boil water than a 3kW kettle would. You could raise the voltage to any number you like,but if the socket is fused at 13A you are not going to draw any more power out.

DiabloD32• 11 years ago

They make 1800W kettles in the US. My 1500W kettle boils 8 cups of fridge-cold water in about 4 minutes.

tarminian• 11 years ago

I've got an electric kettle (glass) that will boil 1.7L in about 4 minutes. It even shuts off it self off when the water boils. Works very well, not bulky at all. It is this one: http://www.amazon.com/Hamilton-Beach-40865-Electric-1-7-Lite...

stbtrax• 11 years ago

What are you doing with all this boiled water?

x0x03• 11 years ago

tea and/or coffee

anigbrowl4• 11 years ago

Letting it cool down so I can have the thrill of boiling it again.

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.

x0x03• 11 years ago

A kettle plus a toaster oven strictly dominates microwaves and toasters, particularly for things like reheating pizza or cooking chicken breasts. Toaster ovens also get hot much quicker than an oven, making them far more convenient to use.

lfowles2• 11 years ago

Recently moved into a house without a microwave, but we do have a toaster oven, so it evens out. I often wish I had a teeny tiny microwave to melt a stick of butter quickly though.

jedberg2• 11 years ago

Electric kettle? Having an Asian wife, I have learned there is an even better choice, a countertop hot water boiler. It boils the water and then keeps it hot in a super insulated container so the energy use is really low and you always have hot water ready for tea, so you don't have to wait!

We unplugged it once to take to an ice rink and it was still hot hours later.

anigbrowl4• 11 years ago

Funny, my wife's Asian too and I know the exact thing you mean. We like being able to tote the kettle around rather than having the bring the container to it, though. I agree it's more energy efficient.

washadjeffmad• 11 years ago

Since realizing most people only have coffee makers and microwaves and are missing out on tools to simplify making great tea, I've made it a habit of giving out airports (dewar flask pump liquid dispensers) as gifts to everyone I know along with some tea-making utilities, like the IngenuiTEA. Water stays piping hot all day, no power needed beyond the initial boil.

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.

troels• 11 years ago

Really? Is that true?

wyc2• 11 years ago

Receipt paper could serve the same heat-sensitive purpose and might be easier to find.

officialjunk2• 11 years ago

dry heat-sensitive paper won't work; microwaves work by resonating with water molecules to vibrate them and cause them to heat up.

lvs• 11 years ago

Uhh... you think water is the only molecule with a dipole moment?

aioprisan• 11 years ago

Can't you just coat them lightly with oil? That ensures that they get heated up more evenly.

lake99• 11 years ago

True, and fried appalams are tastier anyway.

anonetal• 11 years ago

xkcd had a nice what-if on this recently (http://what-if.xkcd.com/131/). He points to the way ice and water react to microwave radiation as one of the main culprits for uneven heating (of frozen stuff).

dbbolton• 11 years ago

My microwave has a feature that when you press the "Start" button without entering a time, it just runs for 30 seconds on high.

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.

mortenlarsen• 11 years ago

but my partner is very strict about leaving "unused time" on the microwave and obsessively hits the Clear button.

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.

w-ll• 11 years ago

I'm the one that hates it.

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.

danellis• 11 years ago

Cooking them in a pan of hot oil is so much more satisfying anyway. They double in size in about a second.

geon• 11 years ago

And taste much better.

sjtrny• 11 years ago

Most things your microwave aren't so flat though. Usually they have a bit of height which reduces the uneven heating somewhat.

But even for heating flat items (such as Naan) I haven't noticed any uneven heating with my giant Panasonic microwave.

minthd• 11 years ago

That seems like a useful thing for a small crowdsourcing site to. It's useful information to know before buying a microwave.

jpalomaki• 11 years ago

Previously I've seen similar tests done with oatmeal and sugar. Put oatmeal on plate and then sprinkle sugar on top. The purpose of the oatmeal is to insulate. The sugar should get brown on those places where the microwaves hit.

castratikron• 11 years ago

What would happen if they raised the plate a few inches from the bottom? With this experiment they're only looking at a cross-section of the wave.

Microwave Oven Diagnostics with Indian Snack Food

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