|MadSci Network: Zoology|
David, You have discovered a very important reason for cleaning your microwave oven. The energy in a microwave oven generaly does not kill the insects that are attracted by the food matter left behind. Ants, roaches and other insects can tolerate cold, heat and radiation much better than life forms, such as people, dogs and mice. However, if you put an ant in a microwave oven like a kernal of popcorn, the popcorn will explode and the ant will not. The secret is in the way the energy of a microwave oven works. Microwave energy is selective. It heats those things best that have a lot of water or fat best. The microwaves in your oven are also big. They are about 2 inches long. Therefore, physics tells us that objects that are the size (about 1 inch wide) and composition (mostly water and fat) of a chicken egg heat the best in a standard microwave oven. As objects get smaller, they tend to lose heat more easily. A single kernal of popcorn is at the small end for microwave heating, but because it has a very hard outer coating and is about 10% water inside, the water will heat to very high pressure before the outside coating will break. Popcorn is then created. A normal ant weighs much less than a kernal of popcorn. Also, the ants external coat, its exoskeleton, is very porous and cannot build up pressure. Because of its size, the ant loses any heat it gains from microwave energy very easily. Remember that the air in a microwave oven does not get hot, so an ant being heated by microwave energy can lose that heat energy to the air surrounding it. Therefore, an ant might heat up to about 90 degrees Fahrenheit in a microwave oven if the air temperature is about80 degrees Fahrenheit (I have not verified this), while food is boiling or burning on a plate. Therefore, because an ant is small and the air is cool, the ant survives the energy it absorbs by getting rid of it easily. Note that the same thing will not occur in aregular heat oven. The ant is then heated by the hot air around it rather than by the energy that converts to heat inside its body. Very quickly, it will absorb the external heat and reach the oven temperature. In this case, being small and being able to absorb the heat so quickly works against it. Dr. Ed Peterson
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