Radio waves are much bigger, but they also have "personality". As soon as the microwave touches the metal, it will be reflected, and the metal can't absorb it or conduct it at all.
It; Microwave can pass through insulating materials such as glass, ceramics and plastics, but it will not consume energy. For food containing water, microwave not only
It cannot penetrate, but its energy will be absorbed. Microwave ovens are made by using these characteristics of microwaves. Stainless steel for microwave oven shell
As well as other metal materials, can prevent microwaves from escaping from the furnace, and does not affect people's health. Food containers are made of insulating materials.
Material. The heart of microwave oven is magnetron. This electron tube is called magnetron, which is a microwave generator and can generate vibration frequency every second.
Microwave at a rate of 2.45 billion times. This invisible microwave can penetrate the food to a depth of 5 cm and make the water molecules in the food follow.
Exercise, strenuous exercise produces a lot of heat energy, so the food is cooked. This is the principle of microwave heating. Use an ordinary stove.
When cooking food, heat always gradually enters the food from the outside. When cooking in a microwave oven, heat goes directly into food.
Internal, so the cooking speed is 4 to 10 times faster than other stoves, and the thermal efficiency is as high as 80%. At present, other stoves have no thermal efficiency.
By contrast. Because of the short cooking time, microwave oven can keep the vitamins and natural flavor of food well. For example, using the
Cooking green peas in a microwave oven can almost keep vitamin C from losing at all. In addition, microwave can also be used for disinfection and sterilization.
1. Why can microwave ovens heat food?
Let's talk about water first Water molecules consist of one oxygen atom and two hydrogen atoms. Oxygen atoms are very attractive to electrons, so water
Electrons in the molecule are concentrated at the end of oxygen atoms, and there are fewer corresponding hydrogen atoms. Generally speaking, water molecules have one end.
At the other end are positive and negative charges. Chemically, such molecules are called "polar molecules".
In normal water, water molecules are arranged in disorder, with positive and negative charges in any direction. When water is in an electric field
Wait, the positively charged end will turn to the negative pole of the electric field, and the negatively charged end will turn to the positive pole of the electric field-the so-called "opposites attract, like attracts".
Sex is mutually exclusive. "
If it is an electrostatic field, the water molecules will line up and be quiet. If the electric field keeps rotating, then water molecules will
Turn around and try to be consistent with the electric field. If the electric field rotates fast, then the water molecules also rotate fast-similarly.
Friction generates heat and the water temperature rises.
Electromagnetic waves are equivalent to such a rotating electric field. Electromagnetic waves used in microwave ovens rotate more than 2 billion times per second, and water molecules
If you follow this speed, you will naturally "get hot all over" and the temperature will rise sharply in a short time. Once the microwave stops, rotate.
When the electric field disappears, the water molecules will be quiet and their world will be clean again. In this process, water molecules themselves will not
Will not be changed by microwaves.
Microwave can not only heat water, but also other polar molecules. Usually food contains water and other polar molecules, so in micro
It can be heated quickly under the action of waves. Non-polar molecules such as air and some containers will not be heated. We usually
After the food is heated, it feels that the container is also hot, and it is often "burned" by high-temperature food.
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Second, does microwave heating cause cancer?
Because microwave is a kind of radiation, many people naturally think it will cause cancer. Microwave is an electromagnetic wave, similar to radio and telegraph.
The radio waves, infrared rays and visible light used are essentially the same thing. The only difference between them is the frequency. Microwave frequency
The speed is higher than that of radio waves and lower than that of infrared rays and visible light. Neither radio waves nor visible light can cause cancer, so it is not difficult to understand that the frequency is between the two.
Microwave does not cause cancer. In fact, the "radiation" mentioned here only refers to the energy that can emit microwaves, similar to X-rays and radiation.
Radioisotopes produce different kinds of radiation. Although X-ray is also an electromagnetic wave, its frequency is much higher than that of microwave, so energy
It is also very high. Radioisotopes release particles during decay, so they can make organisms cancerous.
Microwave will not cause cancer to people, nor will it cause cancer to food. Even, it helps to avoid carcinogens. For fish,
For meat and other foods, traditional heating methods, especially barbecue and frying, can easily lead to meat zooming, thus producing some carcinogens. Published in 2004
In this paper, the generation and carcinogenicity of this kind of carcinogen are introduced scientifically, and finally it is pointed out that microwave heating can effectively reduce this kind of carcinogen.
The production of carcinogens.
Third, microwave oven, is it safe?
Sunlight is an electromagnetic wave with higher energy than microwave. Sunshine, is it safe?
Microwave is as safe as sunlight-whether it hurts people depends on the strength of energy. Warm sunshine makes people comfortable, and hot sunshine exposes them to the sun.
It can cause serious skin burns. So is microwave-since it can heat food, it can naturally heat human body. crux of the matter
The key is: how much energy is left in the microwave that reaches the human body?
Scientists have done a lot of research for us and found the minimum microwave power that can harm human body. An intact microwave oven and drain pipe.
The leaked microwave power is far from reaching the intensity that harms the human body-the regulation in the United States is that at a distance of about 5 cm from the microwave oven, every
The power per square centimeter does not exceed 5 milliwatts; China's standard is stricter, which is 1 MW. In addition, the energy of microwave is proportional to the distance.
A reduced square. That is to say, if it is 1 milliwatt at 5 cm, it will be reduced to 1 milliwatt at 50 cm, which is even more "neither human nor animal".
Harm. "
Therefore, for microwave ovens, as long as they are qualified products and are not damaged in use, they will not leak microwaves that are harmful to human body.
Let's go
Another safety problem when using microwave ovens is the harmful substances released by plastic containers. In fact, some plastics can be heated.
Release some harmful ingredients. The FDA has identified the hazards that various plastic containers may be released into food when heated in ordinary microwave ovens.
The amount of substances required to be less than 1% or even 1% of the harmful dose determined by animal experiments can be marked as "OK".
Microwave heating ". So it is quite safe for those qualified plastic containers that can be heated by microwave. Of course, if it is still
If you don't trust, or don't believe that the label of the manufacturer is worthy of the name, you can trust with a ceramic or glass container.
4. Where did the microwave oven safety accident come from?
Are these traditional heating methods safe? At least because of cooking, someone got burned and there was a fire.
The US Food and Drug Administration (FDA) said that it has received many reports of "injuries" caused by the use of microwave ovens. However, this
These "accidents" have nothing to do with the microwave oven itself, but are caused by improper use Not as long as you know and avoid using the microwave oven incorrectly.
There was an accident. The following are the two most common types of accidents:
1, liquid overheating. Traditionally, water will flow when it is boiled, and it will "open" when it reaches the boiling point. However, microwave heating water does not flow, only the temperature.
If it goes up, it may not be above the boiling point. But the water temperature at this time is already very high, as long as there is a little disturbance, it will
It will boil violently. If this disturbance is caused when you go to fetch water, it will be more scalding than boiling water. The cleaner the capacity.
The cleaner the water, the more likely it is to happen. Therefore, for the sake of safety, it is best not to "try the law" to experience it.
The hot water is overheated. Other liquids, such as milk and soup, are not easy to overheat because of other ingredients, but they are added for a long time.
Heat can easily "boil" and rush out of the container. Not to say that you can't heat these things in the microwave oven, but to calculate the heating time.
2. The egg exploded. It is probably common sense that the microwave oven can't heat eggs. The reason for the explosion of eggs is somewhat similar to the "violence" of water.
Boil. "The inside of the egg is overheated and under great pressure. When it was disturbed by the outside world, the pressure was released and the egg exploded. If an explosion happens,
When an egg enters your mouth, it is probably equivalent to setting off firecrackers in your mouth.
Conclusion: The rumor is shattered. Generally speaking, it is a rumor that microwave ovens "cause cancer" and "produce harmful substances". Although the microwave oven
It is difficult to help us cook delicious food, but convenience and quickness are one of its great advantages. For the elderly and children
Generally speaking, it is much safer to heat dishes and rice in a microwave oven than to use an electric stove or gas.
Author: cloud unintentional
Link: /article/96408/
Source: Shell
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