Some of my family members shun the microwave oven, and insist that preparing food with it is tantamount to nuking ourselves, albeit gradually. But what exactly are microwaves? Why did we start using them? Are they, or are they not, dangerous? What does the scientific world think of them? What does the consumer world think of them?
Frequency is the number of complete cycles per second in alternating current direction. The standard unit of frequency is the hertz, abbreviated Hz. If a current completes one cycle per second, then the frequency is 1 Hz; 60 cycles per second (cps) equals 60 Hz.
A microwave is a magnetic field caused by an electric current (electromagnetic energy) with a frequency above 1 000 000 000 cps (or 1 000 000 000 hertz, or 1 gigahertz), corresponding to a wavelength shorter than 300 millimeters.
Okay, so a microwave is electromagnetic energy that oscillates more than 1 billion times a second, and whose waves or cycles are not longer than 3 centimetres. Think of ocean waves. They move through water and transport energy, and have cycles of 200 centimetres or more (when one wave is 200 centimetres away another one comes in). Perhaps ocean waves have a frequency of 2 hertz, depending on the calmness or anger of the ocean. When two ocean waves bash against the shore, 1 billion microwaves in the oven sear through your food.
Why did we start using microwaves to cook?
Like most things we do today, we started cooking with microwaves because it’s easier than with conventional methods, and it’s much faster, too. Progress, if you will. I think the question is equivalent to asking why we started using the gas-stove and not the wood-fire. Microwave ovens also heat or cook only the food, and nothing else, which implies that they save energy.
Cooking food with microwaves was discovered by Percy Spencer while building magnetrons for radar sets at Raytheon. He was working on an active radar set when he noticed a strange sensation, and saw that a peanut candy bar he had in his pocket started to melt. Although he was not the first to notice this phenomenon, as the holder of 120 patents, Spencer was no stranger to discovery and experiment, and realized what was happening. The radar had melted his candy bar with microwaves. The first food to be deliberately cooked with microwaves was popcorn, and the second was an egg (which exploded in the face of one of the experimenters) Wikipedia.org.
How do they cook food?
All liquids and foods are made up of molecules, as are most other things under the sun and beyond. These molecules have positive and negative particles, so they usually behave like microscopic magnets, for magnets also have polarity (a +ve side and a -ve side). Microwaves, too, have a positive and a negative half cycle. Imagine the ocean wave again, and imagine that what is above sea-level, the peak, is +ve and what is below, the trough, is -ve. When the peak (+ve) of the microwave reaches your chicken, the negative particles of the chicken molecules are attracted (opposites attract) and attempt to align themselves with this +ve field of energy. But when the microwave alternates to the trough (-ve) half cycle, the opposite occurs: the -ve chicken particles are repelled and the +ve chicken particles are attracted. This causes a back and forth motion and allows the molecules to rub against each other to cause friction, which produces heat, the heat that cooks your chicken.
In other words, the microwave energy shakes the water molecules in food hard enough to get them to brush against one another; this brushing against each other produces heat, just like rubbing palms together when we’re cold; this heat cooks the food.
This means that heat is produced inside the food, as opposed to conventional cooking where heat comes from outside and enters the food. That’s why microwaves just warm or cook the food without heating the container or the oven itself. Since the waves that hit the chicken are instantly converted to heat energy inside the chicken, there can be no question of radioactive contamination. In other words, when you switch your oven off and remove your chicken, it has absolutely no radiation on it. Bon appetit.
I will add a few more thoughts to this post, mainly, the hazards of using microwave ovens improperly, and my favourite microwave recipe. I hope my favourite food experts (from both ends of the fork!) Jeanne and Brian won’t mind my veering off tradition too much, if they do mind at all.