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Fun
with James Onde
For all who don't know: James Onde is the name of my microwave oven. Since I always made experiments with other persons microwaves, one day they had the nice idea to donate a new one to me. It is a 800W model (Moulinex), which seems to be enough power for most funny applications. My microwave laboratory is also equipped with a multispectral radiation recording unit (optical range) for documentation purposes. In this sense I found the grill function of the oven quite practical, as it allows the correct focussing of the recording unit before the actual experiment starts.
The following experiments are divided into two categories: basic and advanced. Basic means that they are only fun, with no big risk for the oven and/or its environment. Nevertheless, extensive cleaning operations might be necessary afterwards. On the other hand, the results of experiments marked "advanced" are uncertain. Anything can happen, your oven might blow up, you might get heavily injured by radiation and you might even produce a black hole which swallow up your whole quarter. You have been warned (btw: most of the funny experiments are advanced).
Featured experiments (more coming soon):
Description: Microwave experiment for beginners and other mudlarks. Nice to shock your mother, astonish some friends and to find an occupation for the afternoon (cleaning up the mess).
Setup: Just place a raw egg somewhere in your microwave oven, and switch it on with full power. Wait up to two minutes until you hear an explosion and see all the mess.
Results
& discussion: The egg
explodes after a while. The microwaves heat up the egg more and more
and a establish a high pressure inside, causing finally the
explosion. Even if the egg gets cracked during the process usually it
works. Just wait. Hint: I preferred a protection in form of a
reversed glass tea pot, but it only worked partly well (see Fig. 1).
Fig.
1: Egg roasted in the microwave (click
to enlarge).
Description: The energy distribution in a microwave oven is usually not homogenous and your food heats up very much at some points and stays nearly cold at others. There are some professional models which include some additional technique to avoid this effect. But usually it is simply solved by a turning plate, which assures that each part of the food gets warm. I always asked myself how to image these standing waves in the oven. This is just a first approach using several layers of liquid protein.
Setup: First you need a big packet of raw eggs. Pitch two of them and mix the liquid content until it reaches an uniform color. Distribute the protein mix on a plate, for example the turning plate of the oven itself. Remove the turning mechanism and place your microwave detector plate in the oven. Run the microwave until you see some spots of solid egg protein appearing on the plate. Repeat the prior steps, but place the detector in different heights, for example by putting some solid objects under the plate.
Results
& discussion:
The results can be described best with images, shown in Fig. 2. The
distribution of the hot spots is astonishingly not as regular as it
can be expected. For the ground level, only two big spots on the left
side can be observed. This is the opposite side of the microwave
emitter inside the oven placed top right. With increasing height, the
hot spots wander first more to the middle, and the concentrate more
towards the front window. In all heights, a great amount of small hot
spots can be observed.
Concluding it has to be mentioned, that
this experiment might not be well suited for analyzing the energy
distribution in the oven. It is not clear how far the egg layer
itself influences the distribution. This will be addressed in further
experiments.
Fig. 2: Mapped energy nodes at heights of 0cm, 5cm, 8cm, 10cm and 13cm (from left to right) above the ground level of the microwave oven. Total height of the cooking chamber is 18cm.
Burning CD's (basic / advanced)
Description: This is the classical microwave experiment and only here for the sake of completeness. If you dont own a CD writer, burning CDs in the microwave is a very nice and cheap possibility to put content on your CDs. The resulting CDs are always good for birthday presents and similar purposes. Also good to get rid of all these free AOL CDs.
Setup: Place the CD horizontally on something like a cup in the middle of the oven, at best with the unprinted side up. Alternatively you can also remove the turning plate and attach the CD vertically. Switch on the microwave for a few seconds until you see something going on on the surface of the CD. Switch off immediatly after that!
Results
& discussion: On the CD
something like a miniature thunderstorm goes on for a short moment
(shown in Fig. 3). After cooling down, the CD surface shows kinds of
fractal structures, as well as sometimes funny color changes. The
strength of the effect varies strongly with the particular CD. I
usually get best results with mostly unprinted CDs. Green CDWs are
also very nice because of an interesting change to orange color
afterwards. Nevertheless, the best of all I ever had was a Windows
2000 installation CD!
The microwaves seem to induce strong
currents in the thin metallic layer of the CD, causing it to melt
down and to produce these nice little thunderstorms. Very quickly
this stops, and only some small spots seem to absorb all the energy.
As they heat up quickly, the plastic of the CD melts and the whole
thing starts to smoke and smell heavily.
Because of this experiment is partly advanced: Stop the microwave
when it start to smoke, or you wont want to prepare food in it
again.
Fig.
3: Miniature thunderstorm on a CDW surface (click to enlarge).
Description: This is a visually very impressing experiment, although I suspect that it might be quite bad for the microwave oven. I has two benefits: A very nice buzzing noise produced by the oven, combined with flickering colors of different kind. Perfect for rave parties when combined with a cool bass beat. Also good in the case of emergency that you run out of a proper socket for your light bulb and still want to have some light. Disadvantages: Light bulb might burst, spreading small sharp-edged particles of glass all over the oven.
Setup:
Very simple. Attach a light
bulb of choice to some kind of mounting device (I used a cup), and
place the whole thing on the turning plate. Switch on the oven. For
making photos, it is better to remove the turning plate and to put
everything on a fixed place for better focussing. As the enery
distribution inside a microwave oven is not homogenous, this might
need some adjustment before finding a good position.
Fig.
4: Orignal experimental setup. When the turning table is not uses, it
is necessary to find a good position for maximum performance.
Results
& discussion: For a short moment, all the metallic parts
inside the bulb glow up brightly, before they burn through and melt
mostly (Fig. 5). After a few moments, instead the whole inside of the
bulb starts to glow in changing colors from violet to orange while
the oven starts to buzz loudly (Fig. 6) This goes on for a while,
until usually the bulb burst, stopping the effect. With small French
bulbs I observed a different effect. They seem to be stable enough
not to burst, instead the glass melts at one point, and the glowing
gas shoots out with a kind of darting flame (Fig. 7). Don't touch the
bulb after stopping the experiment, it is extremely hot. Wait for
some minutes to analyse the interesting structures on the
bulb.
Obviously, the energy pumped into the bulb in the bulb is
large enough to ionize the inert gas contained in it, maybe initiated
by the glowing metal. Once some gas is ionized, energy is absorbed
directly in the gas, keeping the effect running. In the meantime, the
bulbs heats up more and more, especially at its lower end where the
metallic socket is placed, causing the final burst or meltdown.
Fig.
5: Shortly after starting the microwave, all metallic parts start to
glow before they melt and the glowing is limited to the lower end of
the bulb.
Fig.
6: Then the gas inside the bulb starts to glow. The glowing zone is
pulsating, getting bigger and smaller while changing again and again
the color.
Fig.
7: If the bulb does not burst, after a while the glas melts at one
point, and the glowing gas shoots out suddenly.
Description: This is also a visually quite impressive experiment. It does not only produce funny light effects, but also smoke, bad smell, as well as big dancing flames inside the microwave. The original setup can be quite small, therefore this experiment is perfectly suited for annoying people you don't like by leaving a small piece of plasma foil somewhere in there microwave. Disadvantages are the same as the advantages: Smoke and bad smell in the microwave. But lot of people seem like barbecue taste in their food....
Setup: You need a kind of metalised plastic or paper foil. These foils are sometimes used for chips bags, or to close new glasses of instant coffee or nougat creme (under the cap). Take care that really metal is used and not only a cheap look-alike. In the described experiment I used one of a Nescafe instant coffee, seems to be a quite good choice. Place the foil on something robust in the microwave, and start the oven. Additionally you might want to place a kind of security above the setup in order to limit the extension of the emerging flames. I used a tea pot out of glass, which was placed reversed above the coffee cup holding the foil. If the tea pot has some metallic part (common), remove them before!
Results
& discussion: Quickly the foil starts to burn, at the
beginning only on one small spot. The emerging flames are very big,
and seem to get amplified by the microwaves (Fig. 8). But rapidly
this region extends, and the flames eat up the whole foil, leaving
only some carbonized rests. Additionally, from time to time, glowing
balls pop out of the foil and rise up to the ceiling (Fig. 9). They
have a color between blue and violet (at least for Nescafe foils),
and survive alone up to 5-10sec, while making a buzzing sound. During
this time the flames on the foil seem to be of normal size. When the
foil has disappeared, the reaction stops of course.
A repeated
experiment with a plastic instead of a glass protector didn't deliver
many new results. The flames seem to be quite hot, as the plastic
melted down quickly, producing a really bad smelling smoke not only
in the oven, but all over the lab (Fig. 10 & 11).
An
explanation for the observed effects is not easy. The metal on the
foil heats up quickly, setting the plastic/paper underneath to fire.
Any fire in microwaves ovens with carbon involved is really fun, and
so it is here (see other experiments). I don't know how these "plasma
balls" are forming, but I suspect that they consist mainly of
ionized carbon. They seem to survive because they absorb most of the
oven's energy (flame on foil gets normal), but it is not clear how
they manage to keep together. I heard that lot of people believe that
this effect has something to do with the mysterious ball lightning.
Fig.
8: Amplified flames shoot out of the foil shortly after switching on
the microwave oven, quickly eating up all the foil.
Fig.
9: Glowing balls pop out the the burning foil and resist up to 10sec
on the ceiling. The have a blue color and buzz loudly.
Fig.
10: Same experiment, but with plastic protector (mineral water
bottle). Finally not a good idea....
Fig.
11: Since then, we have a new mascot in the microwave lab. Isn't it
cute?