The working principle of microwave
Magnetron microwave energy into the microwave energy , when the magnetron frequency to 2450MHZ emit microwave energy when the microwave oven cavity water molecules to 2.45 billion thousand times per second change in the oscillation frequency of operation, frequency electromagnetic fields is the core component of the magnetron . Molecules in the food to vibrate in high frequency magnetic field , the molecules collide with each other , the friction to generate heat , resulting in the food is heated. This principle is the use of microwave heating for cooking food . Microwave is an electromagnetic wave , this wave energy is not only larger than the usual radio waves , such invisible microwaves can penetrate the food up to 5cm in depth , and to the water molecules in the food also will exercise , strenuous the campaign generated a lot of heat, so food "cook " ripe . This is the principle of microwave heating .
And this microwave is also very " personality" , microwave is reflected on a hit metal , a metal or a conductive there is no way to absorb it ; microwaves can pass through glass, ceramics , plastics and other insulating materials , but does not consume energy ; which contain liquid food , not through the microwave only , but its energy is absorbed , there is the cooking hob with ordinary food , heat is always outside gradually into the food from the food inside . The microwave cooking , the heat is directly deep within the food , the cooking speed is faster than the other stove 4 to 10 times , more than 80% thermal efficiency .
Note : Microwave cooking only , not roasted . Not to mention the duck , that is, baked sweet potato , baked bread too. Bread is heated up , the skin is also soft, and often did not scorched skin , steamed core first burned.
Why ? Because we learned thermal , thermal transfer , there are three ways : conduction , convection and radiation. Boil water is by heat conduction and convection . Steamed buns are heat conduction and convection . Cooking is mainly thermal conductivity , thermal radiation is baked bread . Thermal radiation spread mainly by infrared radiation . We feel that sun tan in the sun skin pain, think grilled panic that the sun infrared radiation. Characterized by the heat radiation without any equivalents of the media and directly transmitted , in addition to the outside to the inside . Baked sweet potato , the outside of the first heat , inside the post heating ; scorched skin , inside also roasted .
Clearly not the case in the microwave , the microwave does not produce heat, the heat transfer does not occur , no infrared . A high frequency it is by electromagnetic waves, which is a microwave energy transfer medium. Microwave Wavelength 1 mm to 1 meter ( frequency of 300 MHz to 300 GHz) . A microwave oven is actually generating microwave oscillator , which generates the microwave wavelength 122 mm , frequency of 2450 MHz.
Microwave oscillator in the microwave oven , and the water molecules contained in food and its oscillation with the same frequency . Causing friction between molecules and molecules . Friction can heat . The higher the oscillation frequency , the greater the amplitude , the more intense friction between the molecules , the more heat generated by it . Obviously, this way of heating the baking effects of different methods of infrared radiation , which can make the inner and outer surface of the food while heating , this heating method is very efficient , cooked rice box , just a few minutes , however , you absolutely can not get " outside and tender inside " effect.
To bake bread, kebabs, baked sweet potato , only with electric oven . Some students may have noticed , microwave not only did not " outside and tender inside ," but sometimes a " focus outside and tender inside ." Heating the bread a little longer time , the core of bread will harden zoom. Why is this ? Primarily because the microwave magnetron microwave issued not evenly distributed in the microwave , but " Focus" in the furnace at a position , that is, where the microwave intensity is the other parts of the times.
This enclave located at about the center of the upper few centimeters turntable , mushroom- shaped position. If you put a big bread heated in here , you will find that surface not hot bread , bread hearts has boiled away , forming a mushroom-shaped in heart . In order to avoid uneven heating of food , microwave features a turntable, boot time , it automatically keeps spinning , the food is evenly heated .
Microwave food container used is very picky . Generally a ceramic or a special plastic. Rather than using metal or enamel . This is because the microwave hit metal products will occur "short" and reflection . If the food heated in the metal container filled even burn an hour , the temperature of food in the container is not increased, because immediately after the microwave encounters the metal container is totally reflected back , the food can not be heat source . More dangerous things yet to come , because the high-frequency microwave all reflect back on the formation of the electronic technology of the " high-frequency short ", which will lead to emission of microwave tube anode produces heat, redness and burn damage .
Some people say that the microwave will hurt the human body , then the use of microwaves in any danger ? It should be said , the microwave is certainly harmful to humans , the key is that people designing micro- oven , taking into account this point , to prevent the microwave line dew , so that microwave oven is very safe, its metal shell and the windows can be blocked microwave , and when the furnace door is not strict , the microwave will immediately stop working , so the microwave is very safe .
Microwaves generated by the microwave power is larger , generally from 600 watts to 2,000 watts, food molecules in high-frequency microwave vibrations per second 2,450,000,000 times. Therefore, the food is heated in a very short period of time on the familiar , microwave itself is not one of the furnace or air, the heating process , but directly to the electromagnetic energy can be converted into the food , and thus high efficiency , energy loss is small .

 

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