On this Dorkolopogous adventure, we will investigate the mysterious and magical
properties of the magnificent microwave oven. This famous machine has been
making delicious burritos and popcorn for over fifty years since its commercial
debut in 1947 (Did they have microwave burritos in the fifties?). Still it is
not commonly known how a microwave can cook cheesy rolled tortillas in less than a minute.
The key to the microwave oven is really the water molecule. H2O has the special feature of electric polarization, meaning one side is more
positively charged while the other is more negatively charged. Now if we put
this water molecule in an electric field, the little guy will flip so that the
poles align with the direction of the field. This is great and good, but now the little fella is just sitting there. Now, let’s reverse the direction of the electric field once more: our little water
molecule will flip again,–180 degrees–to realign with the electric field another time. Neat.
Okay, now let’s start flipping the electric field rapidly. That little molecule will start
flipping out like Gary Busey, bouncing off all the other molecules and making
things really tense and awkward for everyone, and this is how we get heat. (So the Busey metaphor doesn’t hold throughout the entire process, but it’s a good place to start). Each time that water molecule bounces off another molecule, it creates friction, and friction = heat. (If you need proof of this, just rub your hands together really hard and fast for about ten seconds.)
(See?)
This is where microwaves finally come in. They’re actually electromagnetic waves that have a wavelength of about a micrometer,
or 0.000001 meters. Electromagnetic waves contain electric fields that change
direction periodically, at a frequency of about…really fast. This causes our water molecules to do the Busey flip and bump many,
many times per second, causing lots of friction, which causes the heat and makes your cheesy burrito
all melty and good!
Extra Credit:
The skin depth of an electromagnetic wave with a wavelength of a micrometer
incident on to your food is pretty great compared with the actual size of your food, allowing water
molecules even in the middle of your burrito to feel the electromagnetic waves
instantly. Thus we don’t have to wait for the heat to start on the outside layer and slowly work its
way toward the center of the burrito as we do with a regular oven. Voilà!–a delicious, cheesy burrito in under a minute.
Now why doesn’t the microwave cook you as well as the burrito? Because the microwaves are
encased in a metal conducting box which acts as a shield for electromagnetic
waves and does not allow them to escape. If it weren’t for this metal box, we certainly would be cooked along with our food. What is
scary about this notion is that the U.S. Military is developing a weapon that
is basically a microwave gun, which wouldl eradicate the battlefield and cook
enemies just like your burrito (not that your burrito is your enemy). I don’t recall if there is a clause in the Geneva Convention about the legality of
turning a battlefield into a microwave oven.
Microwaves: cheesy burritos, shady areas of the Geneva Convention.
