Section "Engineering and technology for processing hydrobionts and agricultural raw materials"

IMPACT OF ELECTROMAGNETIC MICROWAVE FIELD ON THE HUMAN BODY

Kraev A.A. (Department of Physics, MSTU)

It is almost impossible to calculate in advance the amount of radiant energy absorbed by the human body in a given section of the electromagnetic field and converted into heat. The magnitude of this energy strongly depends on the basic electrical characteristics, the position, size and structure of muscle and fat tissues and the direction of incidence of the wave, i.e., in other words, this value depends on the input resistance of this complex structure. The direction of polarization of the incident wave relative to the body axis also plays a significant role. In each individual case, an accurate examination of the existing conditions is required to establish the symptoms. The actual increase in body temperature depends on environmental parameters such as temperature and humidity, and on the body's cooling mechanism.

Irradiation in an intense microwave field of living tissues leads to changes in their properties, which are associated with the thermal consequences of radiation absorption. To study these changes, living tissues can be divided into two classes:

b) tissues that do not contain blood vessels.

By appropriately adjusting the output power of the microwave generator and the duration of irradiation, various tissues containing blood vessels can be heated to almost any temperature. The temperature of the tissue begins to rise immediately after microwave energy is supplied to it. This increase in temperature continues for 15-20 minutes and can increase the temperature of the tissue by 1-2 °C compared to the average body temperature, after which the temperature begins to fall. The temperature drop in the irradiated area occurs as a result of a sharp increase in blood flow in it, which leads to a corresponding heat removal.

The lack of blood vessels in some parts of the body makes them particularly vulnerable to ultrahigh frequency radiation. In this case, heat can only be absorbed by the surrounding vascular tissues, to which it can only flow through thermal conduction. This is particularly true for eye tissue and internal organs such as the gallbladder, bladder and gastrointestinal tract. The small number of blood vessels in these tissues complicates the process of auto-regulation of temperature. In addition, reflections from the boundary surfaces of body cavities and areas of bone marrow under certain conditions lead to the formation of standing waves. Excessive temperature increases in certain areas of standing waves can cause tissue damage. Reflections of this kind are also caused by metal objects located inside or on the surface of the body.

When these tissues are intensively irradiated with a microwave field, they overheat, leading to irreversible changes. At the same time, low-power microwave fields have a beneficial effect on the human body, which is used in medical practice.

The brain and spinal cord are sensitive to changes in pressure, and therefore the increase in temperature resulting from radiation to the head can have serious consequences. The bones of the skull cause strong reflections, making it very difficult to estimate the absorbed energy. The increase in brain temperature occurs most rapidly when the head is irradiated from above or when the chest is irradiated, since heated blood from the chest is directly sent to the brain. Irradiation of the head causes a state of drowsiness followed by a transition to an unconscious state. With prolonged irradiation, convulsions appear, which then turn into paralysis. When the head is irradiated, death inevitably occurs if the brain temperature rises by 6 °C.

The eye is one of the organs most sensitive to irradiation by microwave energy, because it has a weak thermoregulatory system and the generated heat cannot be removed quickly enough. After 10 minutes of irradiation with a power of 100 W at a frequency of 2450 MHz, the development of cataracts (clouding of the eye lens) is possible, as a result of which the lens protein coagulates and forms visible white inclusions. At this frequency, the highest temperature occurs near the back surface of the lens, which consists of a protein that is easily damaged by heat.

The male genital organs are highly sensitive to heat and are therefore particularly vulnerable to irradiation. Safe radiation density expressed as maximum level

5 mW/cm2 is significantly lower than for other radiation-sensitive organs. As a result of irradiation of the testes, temporary or permanent infertility may occur. Damage to genital tissue is especially considered, since some geneticists believe that small doses of radiation do not lead to any physiological disorders, but at the same time can cause gene mutations that remain hidden for several generations.

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Is a microwave oven dangerous to human health: truth or myth?

When microwave ovens first appeared, they were jokingly called a bachelor's appliance. If you follow this statement, then it is true for the first generation of kitchen appliances. However, nowadays, microwave ovens are equipped with a number of functions and unique features that deserve respect. It is very easy to control the device using a processor that works in accordance with the set parameters. That is why it is important to familiarize yourself with all the nuances of this technique in order to make sure what effect it has on the human body.

Physical performance characteristics

Over the past few years, you can see a boom in microwave ovens. The harm of a microwave oven is not a myth, but a strict reality, which has been proven by doctors and scientists. This opinion is supported by materials whose scientific evidence confirms the negative impact of microwaves on the human body. Many years of scientific research into radiation from microwave ovens have established the level of harmful effects on human health.

Therefore, it is important to adhere to the rules of technical security means or TSO. Protective measures will help reduce the power of the pathogenic influence of microwave radiation. If you do not have the opportunity to provide optimal protection when using a microwave to prepare food, you are guaranteed harmful effects on the body. It is very important to know the basics of TSO and apply them when working in a microwave oven.

If we recall the basic physics course in the school curriculum, we can establish that the heating effect is possible due to the operation of microwave radiation on food. Whether you can eat such food or not is a rather difficult question. The only thing that can be said is that such food is of no benefit to the human body. For example, if you cook baked apples in a microwave oven, they will not bring any benefit. Baked apples are exposed to electromagnetic radiation, which operates in a certain microwave range.

The radiation source of microwave ovens is a magnetron.

The microwave radiation frequency can be considered to be in the range of 2450 GHz. The electrical component of such radiation is the effect on the dipole molecule of substances. As for a dipole, it is a kind of molecule that has opposite charges at different ends. The electromagnetic field is capable of rotating this dipole one hundred and eighty degrees in one second at least 5.9 billion times. This speed is not a myth, so it causes friction of molecules, as well as subsequent heating.

Microwave radiation can penetrate to a depth of less than three centimeters; subsequent heating occurs through heat transfer from the outer layer to the inner one. The brightest dipole is considered to be a water molecule, so food that contains liquid heats up much faster. A vegetable oil molecule is not a dipole, so they should not be heated in a microwave oven.

The wavelength of microwave radiation is about twelve centimeters. Such waves are located between infrared and radio waves, so they have similar functions and properties.

Microwave danger

The human body is capable of being exposed to a wide variety of radiation, so a microwave oven is no exception. You can argue for a long time about whether such food is beneficial or not. Despite the enormous popularity of this kitchen appliance, harm from a microwave oven is not a fiction or a myth, so you should listen to the advice on TSO, and, if possible, refuse to work with this stove. During use, you need to monitor the status of the indicator.

If you do not have the opportunity to protect your body from harmful energy, you can use high-quality protection, the basics of TSO, to protect your own health.

First, you need to find out the risk that microwave oven radiation may pose. Many nutritionists, doctors and physicists are engaged in restless debate regarding food prepared in this way. Ordinary baked apples will not bring any benefit, since they are exposed to harmful microwave energy.

That is why every person should become familiar with the possible negative health effects. The greatest harm to health from microwaves comes in the form of electromagnetic radiation that comes from the oven when it is running.

For the human body, a negative side effect can be deformation, as well as restructuring and destruction of molecules, and the formation of radiological compounds. In simple words, there is irreparable damage to the health and general condition of the human body, since non-existent compounds are formed that are affected by ultrahigh frequencies. In addition, you can observe the process of ionization of water, which transforms its structure.

According to some studies, such water is very harmful to the human body and all living things, as it becomes dead. For example, when watering a living plant with such water, it will simply die within a week!

This is why all products (even baked apples) that are heat-treated in the microwave become dead. According to this information, we can summarize briefly that food from the microwave has an adverse effect on the health and condition of the human body.

However, there is no precise evidence that can confirm this hypothesis. According to physicists, the wavelength is very short, so it cannot cause ionization, but only heating. If the door opens and the protection does not work, which turns off the magnetron, then the human body experiences the impact of the generator, which guarantees harm to health, as well as burns to internal organs, since the tissue is destroyed and experiences serious stress.

To protect yourself, protection must be at the highest level, so it is important to adhere to the TCO base. Do not forget that there are absorbing objects for these waves, and the human body is no exception.

Effect on the human body

According to studies of microwave rays, the moment they hit a surface, the tissue of the human body absorbs energy, which causes heating. As a result of thermoregulation, blood circulation increases. If the irradiation was general, then there is no possibility of instant heat removal.

Blood circulation has a cooling effect, so those tissues and organs that are depleted of blood vessels suffer the most. Basically, clouding occurs, as well as destruction of the lens of the eye. Such changes are irreversible.

The tissue that contains a large amount of liquid has the greatest absorption capacity:

• blood;
• intestines;
• gastric mucosa;
• lens of the eye;
• lymph.

As a result, the following happens:

• the efficiency of the exchange and adaptation process decreases;
• the thyroid gland and blood are transformed;
• the mental sphere changes. Over the years, there have been cases where the use of microwaves causes depression and suicidal tendencies.

How long does it take for the first symptoms of a negative impact to appear? There is a version according to which all the signs accumulate for quite a long time.

They may not appear for many years. Then a critical moment comes when the general status indicator loses ground and the following appear:

• headache;
• nausea;
• weakness and fatigue;
• dizziness;
• apathy, stress;
• heart pain;
• hypertension;
• insomnia;
• fatigue and much more.

So, if you do not follow all the rules of the TCO database, the consequences can be extremely sad and irreversible. It is difficult to answer the question of how long or years it takes for the first symptoms to appear, since it all depends on the microwave model, manufacturer, and the person’s condition.

Protection measures

According to TCO, the impact of a microwave depends on many nuances, most often these are:

• wavelength;
• duration of exposure;
• use of specific protection;
• types of rays;
• intensity and distance from the source;
• external and internal factors.

In accordance with TSO, you can defend yourself using several methods, namely individual and general. TCO measures:

• change the direction of the rays;
• reduce the duration of exposure;
• remote control;
• indicator status;
• Protective shielding has been used for several years.

If it is not possible to follow TSO, you can guarantee that the condition will worsen in the future. TCO options are based on the functions of the furnace - reflection, as well as absorption capabilities. If there are no protective measures, it is necessary to use special materials that can repel the adverse effect. Such materials include:

• multilayer bags;
• shungite;
• metallized mesh;
• workwear made of metallized fabric - an apron and potholder, a cape equipped with glasses and a hood.

If you use this method, then there is no reason to worry for many years.

Apples in the microwave

Everyone knows that baked fruits and vegetables are very nutritious and healthy, baked apples are no exception. Baked apples are the most popular and delicious dessert, which is prepared not only in the oven, but also in the microwave. However, few people think that fruits baked in the microwave can be harmful.

Baked apples contain many vitamins and nutrients, giving them a more tender and juicy texture. Baked fruits are not harmful, so it is important to choose the cooking method. As it became known, baked apples in the microwave do not cause harm, since they do not ionize.

In simple words, baked apples are a very tasty, valuable food that can be cooked in a microwave oven without harm to health. If you do not follow the operating rules and neglect the indicator, you can harm your condition. Baked apples are very easy to prepare because the microwave reduces the cooking time. The indicator on the display is responsible for all other functions, so it is important to keep an eye on it.

It is important! If the indicator malfunctions, it cannot be repaired. The indicator is a special LED light bulb. That is why, thanks to the indicator, you can find out about the health of the device.

Answering the question whether microwave ovens are harmful - myth or reality, we can say for sure that this is not a myth. By following the suggested recommendations and operating rules, you will protect yourself from negative influences.

The development of microwave technology in the last two decades has contributed to its introduction into physiotherapy practice. Microwaves have a number of physical properties that can be used to treat certain diseases (e.g. psoriasis , rheumatism and other autoimmune diseases). The properties of these waves are the following: a) their energy can be concentrated on individual parts of the body; b) they are reflected from dense surfaces; c) their frequency is close to the frequency of relaxation vibrations of water; d) they are more thermogenic than ultrashort waves.

Under the influence of microwaves, vibrations of ions and the dipole water molecules they contain occur in the tissues of a living organism.. Absorption of wave energy in tissues due to vibrations of ions is practically independent of frequency, while absorption due to vibrations of dipole water molecules increases with increasing frequency. However, this increase occurs up to a frequency specific for each body of molecules (the so-called relaxation frequency). At higher frequencies, due to inertia, the molecules no longer have time to react to too frequent changes in the wave fields, and therefore the absorption of wave energy decreases sharply. For water molecules, this limiting relaxation frequency is about 2-10 Hz (wavelength about 1.5 cm). Due to these features, as the wavelength shortens, the role of molecules in the overall absorption of wave energy in tissues increases. In the 10-centimeter wave range, approximately half of the total energy is absorbed due to vibrations of water molecules, and in the 3-centimeter wavelength - already 98%. Since the body consists of more than half water, the significance of this fact for the action of microwaves is clear, especially for tissue with a high water content (blood, lymph, muscles, nervous system).

Microwaves have both thermal and extrathermal effects. For the first time, their extrathermal effect on humans was established by S. Ya. Turlygin, who observed the appearance of drowsiness after exposure to centimeter waves of very low intensity. This was later confirmed by numerous observations. When a person is systematically exposed to high-power microwaves on the face, clouding of the lens, functional changes in the nervous system, dysfunction of the visual and olfactory analyzers, etc. are observed, which has led to the need to establish in industry maximum permissible doses of exposure to humans during working hours - not more than 0.01 mW/cm2.

The general effect on animals of an intense microwave field at a PFM (power flux density) of 0.2-0.3 W/cm21 causes changes in respiration, heart rate and blood pressure, while local effects under the same conditions are accompanied by rapidly passing changes in hemodynamics and respiration, obviously of reflex origin. The regulatory significance of the nervous system when exposed to a microwave field appears when the vagus nerves are transected in animals; at the same time, a smaller increase in breathing is noted, but a more severe hemodynamic disturbance as a result of turning off the regulatory influence of the vagus nerve.

In a frog, a microwave field at 0.3 W/cm2 causes changes in cardiac activity similar to the biphasic effect of a UHF electric field. In the first phase, sometimes short-term, there is an increase in heart rate and intensification, followed by a slowdown and cessation of cardiac activity in diastole. After the cessation of exposure, contractions are restored; Arrhythmias are sometimes observed. These effects are considered thermal due to the high PMT of the microwave field used in the experiments.

Of great physiological importance is the use of a low intensity microwave field (PPM 0.05 W/cm2, duration 30 minutes), when dogs usually experience a slight increase in heart rate and the disappearance of respiratory arrhythmia; in some animals, a slowdown in the rhythm appears. According to electrocardiography, with prolonged repeated exposure to a microwave field, one can judge the activation of compensatory mechanisms and the development of adaptation, which can be disrupted in dogs by stronger exposures. The established changes indicate the development of temporary dystrophic processes in the myocardium and are considered as reflex; within the first hour after exposure, these changes disappear. In dogs with artificially induced myocardial infarction, the use of a microwave field causes an increase in heart rate, a decrease in all electrocardiogram waves in each lead, and the S-T interval rises even more above the isoelectric line. The microwave field worsens the functions of a diseased heart.

When normalizing heart function indicators after an experimental myocardial infarction, the use of a low-intensity microwave field causes phase changes in cardiac activity in animals, which can be considered dystrophic. These changes are observed both with general impact and with local impact on the head area. Muscle load in combination with a weak microwave field leads to more lasting changes.

Based on electrocardiographic data, we can conclude that under the influence of the microwave field, biochemical processes in the tissues of the heart change, the severity of which depends on the intensity of exposure to microwaves.

Determination of the electrolytic composition of the peripheral blood of animals by electrophoresis after exposure to an intense microwave field (PPM 0.1-0.2 W/cm2) indicates phase changes in the content of potassium and sodium. Initially, the K/Na ratio in plasma increases and then decreases. When compared with electrocardiographic data, it is clear that after exposure to a high potassium content in the blood, pointed high T waves appear in all leads, and with a low content of potassium, low, flattened ones appear. Based on the change in the ratio of potassium and sodium in the blood, it can be assumed that under the influence of microwaves there is a change in the permeability of cell membranes to intra- and extracellular cations.

Biochemical studies are of great interest for the mechanism of action of the microwave field on the body. The study of redox processes in tissues (liver, kidneys, heart muscle) by determining the activity of enzymes in them (cytochrome oxidase, dehydrase and adenosine triphosphatase) reveals the effect of the microwave field on the body. The use of an intense microwave field (PPM 0.1-0.3 W/cm2) leads to a sharp decrease in redox processes in rabbit tissues; in this case, the thermal effect of the microwave field is manifested. A weak microwave field (PPM 0.005-0.01 W/cm2) causes a noticeable increase in redox processes in tissues. Repeated exposure of rabbits to a microwave field leads to smaller shifts in redox processes compared to a single exposure. This can be explained by the fact that repeated exposure stimulates compensatory and adaptive mechanisms and causes smaller shifts in redox processes in animal tissues. The influence of compensatory mechanisms was more pronounced in the central nervous system than in the heart.

The study of protein metabolism in animals both under local and general exposure to microwave fields revealed some features. Exposure to the heart area daily for 10 days (PPM 0.02 W/cm2 with an emitter area of ​​10 cm2) did not cause any significant changes in the protein metabolism of the heart muscle, but with more intense exposure (PPM 0.1 W/cm2) an increase in the content of proteins with phosphorylase activity while a simultaneous decrease in the myogen fraction.

In the heart muscle of animals, significant changes in the content of individual protein fractions were noted, which depended on the intensity of exposure.

The precipitation reaction in Uchterlon agar was used to study the antigenic composition of the blood serum of animals exposed to general exposure to microwaves in the form of a course of 20 procedures for 10 minutes daily (PPM 0.006 and 0.04 W/cm2). Blood serum was examined on the 24-25th day after the last exposure. The precipitation reaction in agar showed that the general effect of microwaves (PPM 0.006 W/cm2) does not lead to a change in the antigenic composition of animal blood serum. Antiserum to the serum of experimental animals reacted equally with the serum of both experimental and healthy animals.

In immunological studies of the blood serum of animals exposed to general exposure to microwaves with a PPM of 0.04 W/cm2, a smaller number of precipitation lines were found in the precipitation reaction in agar, which indicated a simplification of the antigenic composition of the blood serum and strengthening immunity. Sera versus serum from healthy animals reacted differently with serum from healthy and experimental animals; at the same time, the sera against the experimental serum reacted with the serum of healthy and experimental animals in the same way. The findings appear to indicate that the serum of healthy animals contains antigens that are not present in the serum of microwave-exposed animals.

Simplification of the antigenic composition of blood serum when exposed to thermal doses of microwaves indicates a profound shift in the body's metabolism. No such phenomenon was observed under the influence of non-thermal doses of microwaves.

A study of the higher nervous activity of dogs using the method of conditioned reflexes shows that exposure to a microwave field causes significant changes that depend on the power flux density, duration of exposure and typological characteristics of the animal. Changes in the functional state of the cerebral cortex in dogs were observed even after a single exposure to a weak microwave field (PPM 0.005-0.01 W/cm2). Since this field power did not cause an increase in body temperature, the observed effect was not associated with overheating. A weak microwave field enhanced the process of excitation, and a strong one, in which shortness of breath and overheating were observed, led to the development of inhibition in the central nervous system.

Strengthening both conditioned and unconditioned reflexes indicates that the microwave field acts on both the cerebral cortex and subcortical formations. With prolonged exposure to a weak microwave field, phase changes in higher nervous activity are observed: first, an increase in the excitation process, and then a weakening of it to the initial level with increased inhibition.

The study of electroencephalographic parameters in animals under general exposure revealed a relationship between the nature of the bioelectrical activity of the brain and the intensity of exposure to the microwave field. Intense and prolonged exposure caused changes in the basic rhythms of electrical activity, as well as amplitude. When exposed to the animal's head, these changes appeared under weak influences of the microwave field.

Currently, scientists are trying to treat malignant tumors with microwave waves, which may finally make it possible to create a unique treatment breast cancer. However, everything is still in the stage of animal experiments.

Androsova Ekaterina

I. Microwave radiation (a little theory).

II. Impact on humans.

III. Practical application of microwave radiation. Microwave ovens.

1. What is a microwave oven?

2. History of creation.

3. Device.

4. The operating principle of a microwave oven.

5. Main characteristics:

a. Power;

b. Internal coating;

c. Grill (its varieties);

d. Convection;

IV. Research part of the project.

1. Comparative analysis.

2. Social poll.

V. Conclusions.

Download:

Preview:

Project work

in physics

on the topic of:

“Microwave radiation.
Its use in microwave ovens.
Comparative analysis of furnaces from different manufacturers"

11th grade students

GOU secondary school "Losiny Ostrov" No. 368

Androsova Ekaterina

Teacher – project leader:

Zhitomirskaya Zinaida Borisovna

February 2010

Microwave radiation.

Infrared radiation- electromagnetic radiation occupying the spectral region between the red end of visible light (with a wavelengthλ = 0.74 µm) and microwave radiation (λ ~ 1-2 mm).

Microwave radiation, Ultrahigh frequency radiation(microwave radiation) - electromagnetic radiation including the centimeter and millimeter range of radio waves (from 30 cm - frequency 1 GHz to 1 mm - 300 GHz). High-intensity microwave radiation is used for non-contact heating of bodies, for example, in everyday life and for heat treatment of metals in microwave ovens, as well as for radar. Low-intensity microwave radiation is used in communications, mainly portable (walkie-talkies, latest generation cell phones, WiFi devices).

Infrared radiation is also called “thermal” radiation, since all bodies, solid and liquid, heated to a certain temperature, emit energy in the infrared spectrum. In this case, the wavelengths emitted by the body depend on the heating temperature: the higher the temperature, the shorter the wavelength and the higher the radiation intensity. The radiation spectrum of an absolutely black body at relatively low (up to several thousand Kelvin) temperatures lies mainly in this range.

IR (infrared) diodes and photodiodes are widely used in remote controls, automation systems, security systems, etc. Infrared emitters are used in industry for drying paint surfaces. The infrared drying method has significant advantages over the traditional convection method. First of all, this is, of course, an economic effect. The speed and energy consumed during infrared drying is less than the same indicators with traditional methods. A positive side effect is also the sterilization of food products, increasing the corrosion resistance of painted surfaces. The disadvantage is the significantly greater unevenness of heating, which is completely unacceptable in a number of technological processes. A special feature of the use of IR radiation in the food industry is the possibility of penetration of an electromagnetic wave into capillary-porous products such as grain, cereals, flour, etc. to a depth of up to 7 mm. This value depends on the nature of the surface, structure, material properties and frequency characteristics of the radiation. An electromagnetic wave of a certain frequency range has not only a thermal, but also a biological effect on the product, helping to accelerate biochemical transformations in biological polymers (starch, protein, lipids).

Impact of microwave radiation on humans

The accumulated experimental material allows us to divide all the effects of microwave radiation on living beings into 2 large classes: thermal and non-thermal. The thermal effect in a biological object is observed when it is irradiated with a field with a power flux density of more than 10 mW/cm2, and tissue heating exceeds 0.1 C, otherwise a non-thermal effect is observed. If the processes occurring under the influence of powerful electromagnetic fields of microwaves have received a theoretical description that is in good agreement with experimental data, then the processes occurring under the influence of low-intensity radiation have been poorly studied theoretically. There are not even hypotheses about the physical mechanisms of the impact of low-intensity electromagnetic studies on biological objects of different levels of development, from a single-celled organism to humans, although individual approaches to solving this problem are being considered

Microwave radiation can affect human behavior, feelings, and thoughts;
Affects biocurrents with a frequency from 1 to 35 Hz. As a result, disturbances in the perception of reality, increased and decreased tone, fatigue, nausea and headache occur; Complete sterilization of the instinctive sphere is possible, as well as damage to the heart, brain and central nervous system.

ELECTROMAGNETIC RADIATIONS IN THE RADIO FREQUENCY RANGE (RF EMR).

SanPiN 2.2.4/2.1.8.055-96 Maximum permissible levels of energy flux density in the frequency range 300 MHz - 300 GHz depending on the duration of exposure When exposed to radiation for 8 hours or more, MPL - 0.025 mW per square centimeter, when exposed to 2 hours, MPL - 0.1 mW per square centimeter, and for exposure of 10 minutes or less, MPL - 1 mW per square centimeter.

Practical application of microwave radiation. Microwave ovens

A microwave oven is a household electrical appliance designed for quickly cooking or quickly heating food, as well as for defrosting food, using radio waves.

History of creation

American engineer Percy Spencer noticed the ability of microwave radiation to heat food when he worked at the Raytheon company. Raytheon ), which manufactures equipment for radars. According to legend, when he was conducting experiments with another magnetron, Spencer noticed that a piece of chocolate in his pocket had melted. According to another version, he noticed that a sandwich placed on the switched-on magnetron became hot.

The patent for the microwave oven was issued in 1946. The first microwave oven was built by Raytheon and was designed for rapid industrial cooking. Its height was approximately equal to human height, weight - 340 kg, power - 3 kW, which is approximately twice the power of a modern household microwave oven. This stove cost about $3,000. It was used mainly in soldiers' canteens and canteens of military hospitals.

The first mass-produced household microwave oven was produced by the Japanese company Sharp in 1962. Initially, demand for the new product was low.

In the USSR, microwave ovens were produced by the ZIL plant.

Microwave oven device.

Main components:

1. microwave source;
2. magnetron;
3. magnetron high-voltage power supply;
4. control circuit;
5. a waveguide for transmitting microwaves from the magnetron to the chamber;
6. a metal chamber in which microwave radiation is concentrated and where food is placed, with a metallized door;
7. auxiliary elements;
8. rotating table in the chamber;
9. circuits that provide security (“blocking”);
10. a fan that cools the magnetron and ventilates the chamber to remove gases generated during cooking.

Principle of operation

Magnetrons convert electrical energy into a high-frequency electric field, which causes water molecules to move, which leads to heating of the product. The magnetron, creating an electric field, directs it along a waveguide into the working chamber in which the product containing water is placed (water is a dipole, since the water molecule consists of positive and negative charges). The effect of an external electric field on the product leads to the fact that the dipoles begin to polarize, i.e. The dipoles begin to rotate. When the dipoles rotate, frictional forces arise, which turn into heat. Since polarization of dipoles occurs throughout the entire volume of the product, which causes its heating, this type of heating is also called volumetric heating. Microwave heating is also called microwave heating, meaning the short length of electromagnetic waves.

Characteristics of microwave ovens

Power.

1. The useful or effective power of a microwave oven, which is important for heating, cooking and defrosting, ismicrowave power and grill power. As a rule, the microwave power is proportional to the volume of the chamber: this microwave and grill power should be sufficient for the amount of food that can be placed in a given microwave oven in the appropriate modes. Conventionally, we can assume that the higher the microwave power, the faster heating and cooking occurs.
2. Maximum power consumption- electrical power, which should also be taken into account, since electricity consumption can be quite high (especially in large microwave ovens with grill and convection). Knowing the maximum power consumption is necessary not only to estimate the amount of electricity consumed, but also to check the possibility of connecting to existing outlets (for some microwave ovens, the maximum power consumption reaches 3100 W).

Internal coatings

The walls of the microwave oven's working chamber have a special coating. There are currently three main options: enamel coating, specialty coatings and stainless steel coating.

1. Durable enamel coating, smooth and easy to clean, found in many microwave ovens.
2. Special coatings, developed by microwave oven manufacturers, are advanced coatings that are even more resistant to damage and intense heat and are easier to clean than conventional enamel. Special or advanced coatings include LG's "antibacterial coating" and Samsung's "bioceramic coating".
3. Stainless steel coating- extremely resistant to high temperatures and damage, especially reliable and durable, and also looks very elegant. Stainless steel lining is typically used in grill or convection microwave ovens that have multiple high-temperature settings. As a rule, these are stoves of a high price category, with a beautiful external and internal design. However, it should be noted that keeping such a coating clean requires some effort and the use of special cleaning products.

Grill

Heating element grill. outwardly resembles a black metal tube with a heating element inside, located in the upper part of the working chamber. Many microwave ovens are equipped with a so-called “moving” heating element (TEN), which can be moved and installed vertically or inclined (at an angle), providing heating not from above, but from the side.
The movable heating element grill is especially convenient to use and provides additional opportunities for preparing dishes in grill mode (for example, in some models you can fry chicken in a vertical position). In addition, the inner chamber of a microwave oven with a movable heating element grill is easier and more convenient to clean (as is the grill itself).

Quartz Quartz grill located at the top of the microwave oven, and is a tubular quartz element behind a metal grid.

Unlike a heating element grill, a quartz grill does not take up space in the working chamber.

The power of a quartz grill is usually less than that of a grill with a heating element; microwave ovens with a quartz grill consume less electricity.

Ovens with a quartz grill roast more gently and evenly, but a grill with a heating element can provide more intense operation (more “aggressive” heating).

There is an opinion that a quartz grill is easier to keep clean (it is hidden in the upper part of the chamber behind a grill and is more difficult to get dirty). However, we note that over time, grease splatters, etc. They may still get on it, and it will no longer be possible to simply wash it, like a heating element grill. There is nothing particularly terrible about this (grease splashes and other contaminants will simply burn off the surface of the quartz grill).

Convection

Microwave ovens with convection are equipped with a ring heating element and a built-in fan (usually located on the back wall, in some cases at the top), which evenly distributes the heated air inside the chamber. Thanks to convection, food is baked and fried, and in such an oven you can bake pies, bake chicken, stew meat, etc.

Research part of the project

Comparative analysis of microwave ovens from different manufacturers
Social survey results

comparison table

A social survey was conducted among high school students.

1. Do you have a microwave oven?

2. Which company? What model?

3. What is the power? Other characteristics?

4. Do you know the safety rules when handling a microwave oven? Do you comply with them?

5. How do you use a microwave oven?

6. Your recipe.

Precautions when using a microwave oven.

1. Microwave radiation cannot penetrate metal objects, so you should not cook food in metal containers. If the metal utensils are closed, then the radiation is not absorbed at all and the oven may fail. Cooking in an open metal container is possible in principle, but its efficiency is an order of magnitude less (since radiation does not penetrate from all sides). In addition, sparks may occur near the sharp edges of metal objects.
2. It is undesirable to place dishes with a metal coating (“golden border”) in a microwave oven - a thin layer of metal has a high resistance and is highly heated by eddy currents, this can destroy the dishes in the area of ​​the metal coating. At the same time, metal objects without sharp edges, made of thick metal, are relatively safe in the microwave.
3. You cannot cook liquids in hermetically sealed containers or whole bird eggs in a microwave oven - due to the strong evaporation of the water inside them, they will explode.
4. It is dangerous to heat water in the microwave, because it is capable of overheating, that is, heating above the boiling point. A superheated liquid can then boil very sharply and at an unexpected moment. This applies not only to distilled water, but also to any water that contains few suspended particles. The smoother and more uniform the inner surface of the water container, the higher the risk. If the vessel has a narrow neck, then there is a high probability that when it starts boiling, superheated water will spill out and burn your hands.

CONCLUSIONS

Microwave ovens are widely used in everyday life, but some buyers of microwave ovens do not know the rules for handling microwave ovens. This can lead to negative consequences (high dose of radiation, fire, etc.)

Main characteristics of microwave ovens:

1. Power;
2. Availability of grill (heating element/quartz);
3. Presence of convection;
4. Internal coating.

The most popular are microwave ovens from Samsung and Panasonic with a power of 800 W, with a grill, costing about 4000-5000 rubles.