Microwave ovens cook food incredibly fast, warming up even refrigerated food in minutes or less. But how does this great invention work? Read on as experts on teenkidsnews.com provide the answers.
Microwaves – A Form of Energy
Microwaves are electromagnetic waves that fly through space at the speed of light. We can’t see microwaves, but if you could, you would see the microwave cooking chamber light up with an intense glow.
Read More: Revealed: How To Calculate The Speed Of Light With Your Microwave
Microwaves which are about 12 centimeters from crest to crest are shorter than radio waves but longer than infrared radiation. At this wavelength, microwaves are readily absorbed by most foods, but the particles in a microwave, known as photons, don’t have enough energy to damage molecules and cause cancer like ultraviolet rays or X-rays.
The Microwave Oven
A component called the magnetron generates microwaves from electricity inside the microwave oven. A transformer inside the oven converts the standard household electricity from a wall socket of 120 volts to about 4,000 volts or higher. This voltage then heats a filament at the center of the magnetron, causing it to release electrons.
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These electrons rush out in straight line toward a positive terminal that surrounds the filament, but two ring magnets above and below this terminal bend the electrons back toward the filament and they fly around in a circular path.
The microwaves are then transmitted into the cooking compartment by an antenna where they are bounced around eventually penetrating the food.
The microwave door contains a metal mesh that reflects the microwaves like a mirror and keeps them from leaking out. The mesh holes are too small for microwaves to escape through but large enough that visible light can, so we can see what’s cooking inside.
Most microwaves have a glass turntable that moves the food around so that it heats evenly. If the food wasn’t being rotated, parts of your meal would get stuck in the microwave’s hot and cold spots.
How Microwaves Cook Food
When you hit the start button, it usually takes about 2 seconds to heat up a filament inside the magnetron tube. The microwaves are then blasted into the food compartment.
The commonly used frequency of microwaves, 2.45 gigahertz, is easily absorbed by water, fat, and sugar. The waves are at the right frequency to penetrate deep into food, and they deliver cooking power primarily to the food’s water content. Water-free solids barely absorb microwaves. This is the reason microwave-safe containers don’t get as hot as the food inside them.
Microwaves heat food by twisting water molecules back and forth, because water molecules are positively charged at one end and negatively charged at the other. A single water molecule looks like Mickey Mouse’s head. You can think of the negatively charged oxygen atom as Mickey’s face and the two smaller positively charged hydrogen atoms as Mickey’s ears.
The positively charged end of the water molecule tries to align itself with the microwave’s electric field while the negatively charged end points the other way. But because the field reverses 2.5 billion times a second, Mickey’s ears and face are being twisted back and forth rapidly. As the molecules twist back and forth, they rub into each other, this creates friction, which produces heat.
A microwave cooks food much faster than a conventional oven because it heats both the inside and outside of the food the same time. A conventional oven or frying pan heats the surface of the food first, and the heat gradually moves toward the center. And because the air inside the microwave oven is room temperature, foods don’t get brown or crispy as they would with other forms of cooking.
Now you know what is happening, the next time you stick a plate of food into the Microwave!
See Also: Use the Microwave Often? These 8 Items Are a Complete NO-NO
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