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Thread: Microwave ovens cook from the inside out

  1. #1
    Member
    Registered: Mar 1999
    Location: California, USA

    Microwave ovens cook from the inside out

    Some of you are old enough to remember when microwaves was a new appliance to the general public. Back then, a really stupid explaination of how microwaves work was used by the salesmen (at places like Sears and everywhere) that I think they used as a sales pitch to allow the layman to "understand" how microwaves work. Yes, you youngins, there was actually a time when people did not have microwaves and when they were first introduced people had to be convinced to buy them.

    Anyways. This stupid explaination is alive even today. I remember finally taking physics in college and learning that microwaves do NOT "cook from the inside out". Rather, the frequency range of electromagnetic waves they emit transfer kinetic energy to the H2O molecules in the food, and this is what makes the food "heat up". Because the waves are bouncing all over the place, there will be places where the food is the first receptor of the microwaves within the box which causes hotspots (not sure if constructive nodes are a factor). At any rate, it's not about "food being heated from the inside out", unless you're talking on the cellular level (which most people aren't).

    The LIES my parents told me!

  2. #2
    Member
    Registered: Jan 2002
    Location: Sculptured highway
    I do remember that, but I have noticed over the years that the center of my frozen chicken and rice is the last thing to thaw. That kind of thing flies in the face of the whole "cook from the center" argument. I bet the tendency of things like sausages and hamsters to burst in the microwave furthered the misconception, but then lots of things will burst while being fried. I suppose a frozen dinner wouldn't burst while fried. It's container would melt releasing the steam that causes the bursting, but sausages will still burst while beinf fried.

    Then there's that whole Deer fly fever thing that actually has nothing to do with deer fly. It's caused by ticks. You don't usually notice ticks biting you, but if you were bit by a tick, you most likely got noticiably bit by a deer fly too.

  3. #3
    Member
    Registered: Jun 1999
    Location: Occupied Minerva
    Yeah, the rotational energy transitions in water are in the microwave range. I believe you're right about "hot spots" relating to nodes, as a standing wave exists in the oven cavity during operation.

  4. #4
    Member
    Registered: Apr 2003
    Location: Great White North
    I've never ever heard of this "cook from the inside out" thing of which you speak.

    The first time I asked my parents how the microwave worked I got a hardcore physics lecture. They wouldn't leave me alone until I understood.

    It was terrifying

  5. #5
    Member
    Registered: Jan 2002
    Location: Ohio
    Quote Originally Posted by kfgecko
    Anyways. This stupid explaination is alive even today. I remember finally taking physics in college and learning that microwaves do NOT "cook from the inside out".
    My various experiments on TV dinners prove you to be correct, sir.

  6. #6
    Member
    Registered: Oct 2002
    Location: Germantown, MD--USA
    Quote Originally Posted by NeoPendragon
    My various experiments on TV dinners prove you to be correct, sir.
    Ever tried to experiment with an egg--Still in the shell?

  7. #7
    Member
    Registered: Mar 1999
    Location: California, USA
    Quote Originally Posted by jbairdjr
    Ever tried to experiment with an egg--Still in the shell?
    "I'm a zit... get it?"

  8. #8
    Member
    Registered: Jan 2002
    Location: Sculptured highway
    What happens to metal like foil in the microwave? I know I've left fragments in there by accident and it'll start to throw sparks or something. Why is it this happens?





    Giuseppe Arcimboldo

  9. #9
    Quote Originally Posted by The inscrutable po
    but sausages will still burst while beinf fried.
    That's why I always pierce sausages with a fork before cooking them. (with a plate under the grill for the grease)

  10. #10
    BANNED
    Registered: Aug 2000
    Location: DU, .de
    Microwave devices that have a built-in rotating plate where you put your dish with the food on are best. Since the waves do not flood the food evenly, this guarantees that each part gets its bombardement equally.

  11. #11
    Member
    Registered: Jan 2002
    Location: Sculptured highway
    I was looking for info on foil in the microwave when I found this stuff.

    -----
    Below are examples of some people who are doing farily dangerous
    experiments.

    You can produce a ball of lightning or plasma in your microwave oven using a
    flame or a sharp metal edge as a strarting poing. DO NOT TRY SUCH THINGS -
    IT IS TOO DANGEROUS - THIS IS JUST FOR INFORMATION.

    I would not advise anyone to try out such things. These devices can kill or
    burn you to ashes.
    --------

    Ball Lightning
    in microwave ovens

    Dangerous
    ----------------------------------------------------------------------------
    ----

    Ever since the invention of the microwave oven in the 1950's,
    humans have had a fascination with "nuking stuff ". As a
    result, we now know of all kinds of interesting effects that can be brought
    about by placing non-food items such as CDs, burning toothpicks,
    metal items, lightbulbs, etc. in our microwave. Sometimes,
    bizarre things happen and a flaming ball forms in the oven,
    surviving several seconds and rising to the top of the oven where
    it then dissipates. Folks have found their own means of trying to
    reproduce the "ball lightning"- and now I share my own ideas with you!



    ----------------------------------------------------------------------------
    ----


    This is the "ball lightning" effect in the 700-watt oven in my dorm,
    captured
    via a video camera. The ball is on the order of an inch in diameter and
    glows a fiery orange / violet color. It survived about four seconds, and
    was
    produced via Procedure 1 below...


    Dangerous

    ----------------------------------------------------------------------------
    ----

    First a bit of theory...a microwave oven is a conducting cavity that
    confines the 2.54 GHz energy produced
    by the oven's magnetron. The magnetron is a really clever type of vacuum
    tube that converts DC into
    microwaves with over 70% efficiency. It usually resides in the right-hand
    side of your oven , coupled to
    a short length of waveguide that leads to the oven cavity. A typical oven
    magnetron develops 700 watts of power.
    The waveguide that leads from the "maggie" to the oven can only propagate a
    single mode of oscillations- the
    simplest transverse electric mode. But the oven itself is much larger than
    the dimensions of the wavelength of
    the microwaves, and many field configurations are possible. The energy is
    distributed among these modes.
    The fields in a microwave oven are quite high- voltage gradients of 500 V /
    cm exist in an average oven,
    according to a book on microwave heating technology (sorry- I forgot the
    name!) So this makes it possible
    to generate arcs and discharges with the RF power in the oven.
    The reason the "ball lightning" is formed is that hot ionized gas in flames
    and arcs is a pretty good conductor,
    and like a moist hunk of meatloaf, will absorb microwave power and resistive
    heating will result. Being hot and
    lighter than surrounding gas, the arc or flame will rise and can detatch
    from its source. The resulting ball is
    kept hot by continuing to absorb microwaves. When the ball reaches the
    metal walls of the oven cavity, its heat
    is absorbed and it loses its ability to conduct. Hence the discharge is
    terminated.

    People can do two things to initiate the ball: they can provide a flame to
    absorb microwaves, or they can provide an electric arc. The flame itself is
    a little difficult, since it needs to be put in the right place in the
    oven's fields to absorb sufficient power. So usually the toothpick,
    matchhead, flaming bread, candle, etc. approach will take some playing
    around before you can get a ball on a regular basis. But my devices are
    designed to put the high fields right where the flame is. They are
    quarter-wave resonators that develop a voltage antinode at the free end. My
    first design generates an arc from this point, which then develops into a
    ball. My second design uses a flame at the end of a quarter-wave element.
    Note that, as I said earlier, the wavelength in the oven is different from
    that in free space, and so my dimensions may be off. But the devices work
    well...

    This is Design 1. Cut a disk "B" of aluminum or copper, 2.4 inches in
    diameter. Solder or tape a 1.5-inch long piece of metal sheet "A" to its
    midpoint, cut a sharp point at the free end, and bend it within a few
    centimeters of the disk edge as shown. Aluminum foil works, but it's not
    durable, as you can easily observe after firing the toy. If you value the
    nice paint job in your oven cavity, don't set the toy directly on the bottom
    of the oven, but rather on a glass or other standoff so it can't spark
    through your paint and blacken it. The toy works best if it's not rotated
    (disable your oven turntable) and if your oven doesn't have a "mode stirrer"
    fan. If it does, you can disable that also with a rubber band (find out how
    yourself.) This device wants a powerful oven, 700 watts or more.






    Dangerous




    Design 2. This is made from copper pipe and sheet that is silver-soldered
    together to make a little alcohol lamp. The dimensions of the surface "B"
    are the same as the dimensions of "B" on the first device, and "A" is a
    piece of 3/8" refrigerator tubing about an inch long. A little ethanol is
    poured into the lamp through the tube, and a piece of string is inserted to
    wick up the alcohol. Light the lamp (please make sure it is not leaking any
    alcohol!!!) and place in oven. The flames grow and become balls.
    Last edited by The inscrutable po; 10th Jul 2004 at 11:56.

  12. #12
    BANNED
    Registered: Apr 2000
    Location: Clockwork Orange
    I remember a period of time where I delighted in making 'exploding tea'. Heat the water for 1:11 (depends on the particular oven, of course) take it out, and drop in a teabag. Swooooooosh! Fizzzzllle!

    The first time my friends saw that they were like WTF ( ) irl.

  13. #13
    Member
    Registered: Oct 2003
    Location: Off the TTLG bus
    Quote Originally Posted by kfgecko
    The LIES my parents told me!
    There's all kinds of other shit too, mate. Stuff like 91 octane has more power and cresode (and old car engine oil) is what makes the wood last longer. Multi-weight oil has a blend of oils in it, and you can't mix oils becase the oils will agglutinate.

    Some of it is a good explaination. I have friends, for whom medicine and engineering is completely fucking voodoo. VOO DOO. Little glasses of rum and cigars and hats to keep bats warm.

    Even convection ovens transfer heat from the point of contact, which happens to be the outside. So in this sense, the microwaves penetrate hella futher into the object, which comes close to cooking the inside at the same rate as the outside. For cavemen, who think that a woman going in to have her pacemaker calibrated is "dying", this is a resonable explaination.

  14. #14
    Member
    Registered: Sep 2002
    Location: First floor
    Quote Originally Posted by The inscrutable po
    I was looking for info on foil in the microwave when I found this stuff.
    Good thing you've included the original link where the images are


    Quote Originally Posted by The inscrutable po
    As a result, we now know of all kinds of interesting effects that can be brought about by placing non-food items such as CDs, burning toothpicks, metal items, lightbulbs, cats, etc. in our microwave.
    You know, there's science and curiosity, and there's being simply too sick to be really worthy of taking the benefit of ever having climbed from the tree and using that first stick as a tool.

  15. #15
    Member
    Registered: Jan 2002
    Location: Sculptured highway
    Oops. Slipped past me.

  16. #16
    BANNED
    Registered: Apr 2000
    Location: Bach lobster! BWV B-52S

    Quote Originally Posted by ejsmith
    and cresode (and old car engine oil) is what makes the wood last longer.
    "Creosote" is one of the nastiest petroleum products there is: think "tar pits". Hence, tarring wood keeps critters off essentially forever and it's bad to breathe like all petroleum products, even rubber bands. The stink of this wrecks the fun of walking on commercially made wooden sea structures,
    especially if you're trying to think and get away from traffic fumes.

    All naphtha-derived stuff is toxic to all life except for some bacteria and fungi that can thrive on the right types in proper conditions.



    Microwave oven experiment: put one uncooked poppadum
    ( http://bettertastingsnackfoods.co.uk/poppadums.htm) on the centre of glass carousel dry, use heat one notch below high set for three minutes,
    and WATCH CAREFULLY as ridges rise up and halt cooking as soon as some blackening starts. This should show the pattern of heating/wave spread by the magnetometer and every machine will be different.
    Cheap machines will have uneven spread focussed badly; better ones will cook more properly.
    I keep one in the kitchen as a topological map of how crummy mine is.

  17. #17
    Member
    Registered: Jan 2000
    Location: 15230 Frankfurt(Oder), Germany
    But is it good or bad for health? I just used mine after a long time of not using it to warm up.

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