Microwaves and the Speed of Light

Written by Science Knowledge on 9:49 PM

New physics tricks for the most underestimated of kitchen appliances

You can find a microwave oven in nearly any American kitchen— indeed, it is the one truly modern cooking tool that is commonly at hand—yet these versatile gadgets are woefully underestimated. Few see any culinary action more sophisticated than reheating leftovers or popping popcorn. That is a shame because a microwave oven, when used properly, can cook certain kinds of food perfectly, every time. You can even use it to calculate a fundamental physical constant of the universe. Try that with a gas burner.

To get the most out of your microwave, it helps to understand that it cooks with light waves, much like a grill does, except that the light waves are almost five inches (12.2 centimeters) from peak to peak—a good bit longer in wavelength than the infrared rays that coals put out. The microwaves are tuned to a frequency (2.45 gigahertz, usually) to which molecules of water and, to a lesser extent, fat resonate.

The water and oil in the exterior inch or so of food soaks up the microwave energy and turns it into heat; the surrounding air, dishes and walls of the oven do not. The rays do not penetrate far, so trying to cook a whole roast in a microwave is a recipe for disaster. But a thin fish is another story. The cooks in our research kitchen found a fantastic way to make tilapia in the microwave. Sprinkle some sliced scallions and ginger, with a
splash of rice wine, over a whole fish, cover it tightly with plastic wrap and microwave it for six minutes at a power of 600 watts. (Finish it off with a drizzle of hot peanut oil, soy sauce and sesame oil.)

The cooking at 600 W is what throws many chefs. To heat at a given wattage, check the power rating on the back of the oven (800 W is typical) and then multiply that figure by the power setting (which is given either as a percentage or in numbers from one to 10 representing 10 percent steps). A 1,000-W oven, for example, produces 600 W at a power setting of 60 percent (or “6”). To “fry” parsley brushed with oil, cook it at 600 W for about four minutes. To dry strips of marinated beef into jerky, cook at 400 W for five minutes, flipping the strips once a minute.

If you are up for slightly more math, you can perform a kitchen experiment that
Albert Einstein would have loved: prove that light really does zip along at almost 300 million meters per second. Cover a cardboard disk from a frozen pizza with slices of Velveeta and microwave it at low power until several melted spots appear. (You don’t want it rotating, so if your oven has a carousel, prop the cardboard
above it.) Measure the distance (in meters) between the centers of the spots. That distance is half the wavelength of the light, so if you double it and multiply by 2.45 billion (the frequency in cycles per second), the result is the velocity of the rays bouncing about in your oven.

Source of Information : Scientific American Magazine 

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In its broadest sense, science (from the Latin scientia, meaning "knowledge") refers to any systematic knowledge or practice. In its more usual restricted sense, science refers to a system of acquiring knowledge based on scientific method, as well as to the organized body of knowledge gained through such research.

Fields of science are commonly classified along two major lines: natural sciences, which study natural phenomena (including biological life), and social sciences, which study human behavior and societies. These groupings are empirical sciences, which means the knowledge must be based on observable phenomena and capable of being experimented for its validity by other researchers working under the same conditions.


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