Components

How microwave works. The device and principle of operation of the microwave oven

Over the past decades, the technique of quickly heating food has quickly appeared in the arsenal of kitchen equipment of every family. It is also popular in offices and work cabins.

Marketers of microwave oven manufacturers are interested in mass sales of their products. They distribute advertisements among the population showing the advantages of their equipment over similar equipment operating on other principles. At the same time, the dangerous factors of microwaves are skillfully obscured by streamlined phrases or simply hushed up.

Let's try to impartially understand this confusing issue in order to draw useful conclusions for ourselves and safely, competently use our own technique.

What are the dangers of a microwave?

Its design is like a fabulous genie hidden in a bottle - a body from which dangerous energy can fly out in the event of an accidental breakdown or due to illiterate operation or repair.

According to the degree of impact on the human body, 3 different factors can be distinguished:

exposure to microwave (microwave) radiation;
availability of high-voltage electrical voltage two to four kilovolts required for the flow direct current inside the magnetron;
connecting a microwave to a 220 volt household home network.

Let's consider them in more detail.

high frequency radiation

It provides direct heating of food in a closed space of the body. The frequency of 2.45 GHz causes water molecules in food to resonate, which raises their temperature.

Where does the h / h radiation come from

The source of microwave microwave waves is a special device - a magnetron, which has:

a cathode with a filament that provides a flow of electrons due to thermionic emission. The filament is heated by applying a voltage of 3 volts;
copper anode with cooling plates and internal resonators;
permanent magnets that create a deviating magnetic field;
microwave radiation antenna.

A simplified diagram of a microwave magnetron can be represented electronic lamp, in the body of which electrons fly out of the cathode towards the anode, but fall into the cavities of the resonators that form high-frequency waves directed to the antenna.

This issue is explained in more detail by the owner of the video Sergey Bulavinov “How the magnetron works”.

How does the RF radiation scheme work?

The longer electromagnetic waves act on food, the more it heats up. At the same time, it is important to understand that during operation, the microwave rays of the magnetron affect only certain areas, creating separate hot spots.

To smooth out this drawback, a turntable is used in the microwave, constantly rotated by an electric motor. As a result, the food moves relative to the rays and warms up more evenly.

Radiation does not penetrate inside metals, but is reflected from their surface. It is a well-known fact that initially microwave devices were used only for military purposes in radars. Electromagnetic waves of this range propagate far in space, making it possible to track even high-speed low-flying aircraft.

At the same time, they are able to affect the components of electronic equipment, disrupt the operation of mobile phones, computers, televisions and any complex equipment encountered on their way.

If you place metal dishes or even a saucer with a beautiful golden rim inside the working chamber of the microwave oven, then all the energy of the magnetron will be concentrated on this metal surface, quickly heat it up, forming arc discharges and destroy the stove. Restoring her performance is unlikely to succeed.

This is explained by the fact that the operation of the microwave chamber occurs in the circuit of the resonant mode of the microwave path, which maximizes the power of heating food. He demands obligatory presence an internal source of energy absorption, without which self-destruction occurs. The manufacturer warns about this in his instructions.

The danger of microwave exposure to the human body

A large dose of radiation, even with a short exposure, can create irreversible processes. It brings small volumes of water to a boil very quickly. Among the sad facts of statistics, there are cases when people lost their sight when rays hit the eyeball directly due to the fact that the liquid inside it almost instantly warmed up to a boiling point.
Imperceptible at first irradiation of other parts of the human body also adversely affects health, causing dangerous damage to organs. The cumulative effect of the rays does not appear immediately, but over time, when genomes, leukemia or cancer of the skin areas are formed.
People who use pacemakers while sitting near a microwave are at an increased risk.

An interesting fact is that in different countries the limits of the permissible influence of microwave rays on a person are not interpreted unambiguously. By American standards, the norm is accepted when the flux density is created electromagnetic radiation 1 W*s/m sq. A person already feels such energy with his organs and must immediately leave the danger zone, because plasmolysis of cells quickly sets in. According to the standards of the USSR, this indicator has been reduced by a million times - to 1 μW * s / sq.m.

How is protection against RF radiation made?

The design of any microwave oven model consists of a housing, inside of which equipment is hidden from access by strangers, and controls are installed on the front panel.

Rectangular metal box on the front side is equipped with an opening door with transparent glass and mesh screen. It is suspended on two locks and fixed in the body with special latches with mustache limiters.

This is a mandatory part of the electromechanical interlock system that ensures the safety of the microwave oven.

The latches tightly press the closed door to the body, enter the slotted windows, equipped with special limit micro switches with changeover contacts. Their state corresponds to one of the positions: the space of the working cooking chamber is closed or open. The switching order of the contacts is set according to time.

Due to this design, during the operation of the magnetron, the internal volume of the case is created according to the Faraday cage principle, which excludes the exit of electromagnetic microwave radiation (SHF) from the case into the room with people and equipment.

The mode of operation of a microwave with an open door is to use it as a radar that irradiates a certain sector of space. Interlocking with micro switches prevents its creation.

If the operation of the locking devices is disrupted or the door hangers are unbalanced, then the microwave radiation of the microwave oven will penetrate through the gaps formed into the kitchen, creating a dangerous background.

How to check the door

Method number 1

There is a method available to each user. A strip 5–7 cm wide is cut off from a sheet of writing paper with a density of 90 ÷ 110. With the door open, it is alternately laid in different places:

above, below the loops and between them;
around the latches in the same way.

When the door is closed, a strip of paper should be held. If it is removed, then the hinge bolts inside the mounting holes need to be adjusted.

Method number 2

Ordinary mobile phone is placed in the working chamber and the door is closed.

Attention!
Don't turn on the microwave!

The mobile phone periodically sends signals to the nearest receiving station for exchange official information with it at a frequency of 0.9÷1.9 GHz.

If the shielding is good, then it will disrupt the operation of this connection.

You can check this with a simple phone call.

The result will be one of the results:

the phone is silent, and the station reports that the subscriber was not detected with proper microwave protection;
creating a connection - if broken.

It is worth noting that both methods allow you to identify obvious defects. More accurate methods are based on measurements with special devices, which are not in the arsenal of the home master.

But there can be several channels for the passage of microwave radiation through the case, in addition to a loosely closed door. It “siphons” well through the smallest slots of the waveguide, penetrating through any conductors of electric current protruding outwards.

The magnetron antenna radiates microwave oscillations into the waveguide, which transmits them through the window into the working chamber to the products.

If there are design defects that were not detected during production or allowed during operation, then part of the high-frequency radiation will leave the housing with all the ensuing consequences.

This is a pretty good reason not to be closer than two meters from it when the microwave is working. It is especially relevant for young children, whose body is still developing.

It is impossible to find and eliminate the cause of microwave radiation at home without special equipment and training, and it is quite likely to worsen it with self-repair.

high voltage

To provide the magnetron with power, a transformer operates, which creates 2 kilovolts at the output. They come through a high-voltage capacitor, which accumulates a charge and a diode, which cuts off half of the harmonic, to the electrodes.

All these elements of the circuit are very dangerous, they can cause serious electrical injury if mishandled.

Disconnecting the power from the mains does not guarantee the absence of high-voltage voltage on the equipment. The capacitor stores it for a long time.

If you decide to disassemble the factory design, then at least follow the recommendations below.

The sequence of preparatory operations

Access to high voltage equipment is carried out in the following order:

the microwave oven is disconnected from the mains by pulling out the plug from the power outlet;
the time of 20 minutes is recorded, which is necessary for the discharge of the capacitance of high-voltage capacitors by standard resistors;
after the end of the exposure, the ground wire is disconnected (often they are not used at all);
wait 1 hour for the end of the discharge process.

When all four points are sequentially completed, you can remove the casing and look for a malfunction. Checking the absence of dangerous potentials will be useful. And it is generally unacceptable to apply voltage to the circuit for trial inclusions or checks.

Remember not only the danger of high voltage, but also microwave radiation from the magnetron, which is extremely dangerous without shielding with a protective housing.

Household voltage 220 volts

The microwave oven is made for safe work in a three-wire network made according to the TN-S grounding scheme. To connect it, you need to use everything.

In the power circuit of a microwave oven, a radio interference reduction filter is often used to smooth out possible voltage ripples issued to the network. For his effective work apartments must also be taken into account. Otherwise, a dangerous potential of about 110 volts may form on the microwave housing.

This means that the minimum discomfort from the passage of an electric current through your body has already been prepared, and more sad incidents are not excluded.

Electrical diagram of a microwave oven

Let's look at it with an example Samsung models RE2900. It allows you to understand the principle of operation, which is used in all models of any manufacturer and is distinguished by various specific modifications.

Explanatory notes are already made in the diagram in red.

Immediately on the left side, it can be seen that the grounding contact of the electrical plug is connected to the housing, which has a connection from the midpoint of the capacitor decoupling of the RF noise reduction filter.

A fuse FU1 is located at the power input of the circuit. Its condition needs to be checked. electrical methods- a multimeter switched to ohmmeter mode.

The second available fuse, which can blow, protects the microwave from being used in emergency mode when the door microswitches are out of sequence.

In order for the magnetron circuit to start producing microwave radiation, it is necessary to open the health contact of the door microswitches and close all the others. Turning off any leads to the removal of the supply voltage from the high-voltage transformer.

The circuit includes two thermal fuses-sensors that open their position depending on the temperature of the monitored objects:

housing of the magnetron on which it is installed;
working chamber.

The first of them works periodically, protecting the magnetron from overheating, and the second - when the ventilation holes are clogged or the fan malfunctions. This is manifested by the premature shutdown of the microwave until the time set by the programmer.

The electric motors of the timer and the cooling fan are connected by a safety relay contact, the winding of which is disabled by blowing the Monitor fuse fuse.

The power control microswitch is located on the timer and removes voltage from the magnetron power circuit according to its algorithm.

Resistor R1 reduces the inrush current of the transformer by a few milliseconds due to the operation of the relay contact inrush relay. It limits the impulse caused by the discharge of the high-voltage capacitor when turned on until it acquires a charge. Due to this, the furnace smoothly enters the operating mode without pulse switching.

Such a power circuit of electrical connections, as you can see, is quite simple and reliable in operation. But the electronic components used by various manufacturers are distinguished by the variety of their designs and functionality. But, this is a topic for a completely different article.

We hope that we helped you understand how safe your microwave circuit works, and how to use it in the future - decide on your own, taking into account the information received.

A microwave oven is one of the indispensable appliances in the kitchen, without which it is difficult for housewives today. Everyone knows perfectly well how to use it: put the dish, press 1-2 buttons and wait 2-3 minutes, after which it remains to get the already heated food. However, few people understand the principle of operation of a microwave oven, that is, how its main elements work. Let's try to understand this issue.

The principle of operation of the microwave

All microwave ovens work on the same principle, and the main element is the magnetron - a special device capable of emitting short waves and a frequency of 2450 MHz. In modern devices, its power is 700-1000 watts. Note that during operation it gets very hot, so a fan is installed near it, which performs several functions at once: first of all, it removes heat from the magnetron, and secondly, it provides air circulation in the microwave oven chamber. In turn, this ensures uniform heating of the products.

Actually, the whole principle of the microwave oven is based on this: the magnetron delivers short waves with a high frequency, which affect the food and heat it up. Of course, such an explanation is primitive, but it also makes it possible to understand the essence of the process.

More detailed explanation

Microwaves emitted by the magnetron pass into the furnace chamber through a special waveguide - a channel with metal walls that reflect magnetic radiation. After these waves enter the chamber, they affect food, or rather, water molecules that are contained in any food product. As a result, dipoles (molecules) under the action of microwaves begin to move quickly, rub against each other, which contributes to the release of thermal energy. This is how food is heated.

The peculiarity of microwaves is that they can penetrate up to 3 centimeters deep. The rest of the product is heated from the top layer. This principle of operation of a magnetron in a microwave oven explains why, after heating, food can be hot on top and cold inside at the same time. Deep heat penetrates due to natural thermal conductivity.

If you have used a similar device before, you could not help but notice that it rotates during the heating process. This is necessary so that the microwaves reach all areas of the heated products.

Microwave protection

Considering the principle of operation of a microwave oven, it is logical to think about the dangers to human health. Of course, the microwaves emitted by the magnetron are harmful to humans. However, after opening the door, the magnetron stops its work, so a person cannot physically feel their influence. And so that they do not go beyond the chamber for heating, special protection is provided. All its walls are made of metal, which reflects waves, and they cannot leave the device. As for the glass door (it simply has to be so that the user can see the heating or cooking process), it is covered with a special grid that reflects microwaves. If this grid is removed, then the waves can leave the space of the camera, and this can really harm a person. It is unacceptable to use the microwave oven if there is damage, for example, to the door seal or its mesh.

By the way, given the fact that metal reflects microwaves, it is unacceptable to use metal utensils.

Device design

All microwave ovens work in the same way, hence they have the same parts composition. In particular, the following structural elements can be distinguished:

Magnetron - the main unit, which is the source of microwaves.
A chamber with a rotating podium and metal walls that reflect radio waves.
Transformer to increase voltage.
door with protective mesh and transparent glass.
Communications and control scheme.
Waveguide.
Fan for cooling the magnetron.

All these elements take part in the operation of the furnace.

Magnetron operation

As already mentioned, the magnetron is the heart of the microwave oven. It is an electrovacuum diode made of a large cylindrical anode. The anode itself is copper, it combines 10 sectors of the copper wall.

In the center of the device there is a rod cathode, inside the channel of which there is a filament. It is designed to emit electrons. In order for the device to generate microwaves, a magnetic field must be created in the cavity. Ring magnets are used for this. high power- they are located at the ends of the part. And to create emission, a voltage equal to four thousand volts is applied to the anode. To achieve this voltage, a microwave transformer comes into play. The principle of operation of any model implies its presence.

Also inside the device there are wire loops that are connected to the cathode, and that to the radiative antenna. It is from this element that microwaves enter directly into the waveguide itself, from where they exit and enter the chamber with food.

Power control

If less power is needed to cook food, then the magnetron can cycle on or off. In science, this technology is called pulse-width modulation.

In order for a device with a power of 400 W to give out half of it within 20 seconds, it is activated for 10 seconds, after which the power is turned off for the same 10 seconds. Of course, all this happens on full automation.

Magnetron cooling

Note that during operation, the device generates a large amount of heat, therefore, it needs to be cooled. To do this, the device itself is installed in a plate radiator, and a cooler is placed nearby. It blows over the radiator and removes heat from the magnetron. If the fan does not work, then the device may simply overheat during operation and simply fail. But to prevent this from happening, it is additionally equipped with a special thermal fuse - a protective device.

Purpose of the fuse

In order for the grill and magnetron not to overheat, in some models special thermal fuses (thermal switches) are installed. They may be different. In particular, the main difference lies in the amount of heat they are able to withstand.

This device is quite simple in terms of its work. It is made of aluminum alloy, fastened with a flange connection that provides reliable contact with the area where the temperature is measured. A bimetallic plate is installed inside the case, which can resist a certain temperature. And if the temperature value goes beyond a certain limit, then the plate contracts and activates the pusher, and it opens the circuit of the contact group. After that, the supply of electricity to the unit stops, the magnetron turns off and gradually cools down, the plate returns to its original position as the magnetron cools down. Through certain time contacts close again.

Here is such a simple principle of operation of the microwave, in particular the overheating fuse. Note that in cheap models this element may be absent, since it is completely unnecessary for normal functioning devices. This is only a protection element that increases the reliability and service life of the furnace, nothing more.

The role of the cooler

Speaking about how a microwave oven works, the principle of operation must be explained taking into account all the structural elements that can be used in it. Cooler is one of them. Certainly this important component system, without which the device and operation of the microwave will not be complete.

His tasks:

Magnetron cooling. This is the most important task, without which the magnetron would burn out on the very first day of using the furnace.
Cooling other components that generate heat during operation. In particular, we are talking about microcircuits.
In models where there is a grill, the cooler cools the thermostat.
Creating excess pressure in the chamber where the food is located. Because of this, vapors and air are expelled through the ventilation ducts.

Most often, only one fan is enough to perform all these functions. Due to the presence of air holes in the chamber, the air itself is distributed evenly.

Camera device

In principle, the physics of a microwave oven is not complicated, because it has been known since school that strong electromagnetic radiation is dangerous for humans. It is it that comes from the magnetron and enters the chamber with food, so this device requires a strong multi-level protection system.

The entire working chamber is covered with enamel inside, which blocks electromagnetic radiation. On top is a metal casing that prevents the penetration of waves into the room. And to protect the glass door, a steel mesh with small cells is provided - it blocks radiation with a frequency of up to 2450 Hz and a wavelength of up to 12 cm.

Note that the door is the weakest point through which microwaves can leak, so it must fit as tightly as possible to the body and have no gaps. If there is a gap, then the operation of the device is prohibited. In this case, it is necessary to correct the hinges of the door and return it to its original position.

In addition, the microwave oven operation algorithm provides for the use of a special protective device from turning on with the door open. Similar system can be implemented in different ways, most often microswitches are used to control the position of the door. These switches can turn off the magnetron, transmit information about the position of the door to the control unit.

Control Panel

It is available on every model. In older devices, the control panel is presented in the form of only two (or even one) mechanical switches. One sets the operating mode (heating, defrosting, etc.), the other time. The scheme is primitive, but working and simple.

However, modern models are equipped with a large touch panel. Such control panels provide the user with great functionality and even the ability to program the mode. For example, you can set a specific start time for heating food, the duration of the process, you can even specify the food or dishes that will be heated. And although it seems that such devices are more advanced, technically there are few differences. The electronic control panel does not change how the microwave oven works.

Control block

There is a command device in every device (not only in microwave ovens), where at a certain moment this or that action must be performed. It provides various functions. In particular, the device with its help can maintain a given temperature, turn on or turn off the furnace after a given operation.

In older microwave ovens, this device is presented in the form of two electromechanical switches - they are responsible for the functions described above and play an important role in the overall microwave device. Of course, over time, electronics have evolved, and as a result, fully electronic control units have appeared. Now in microwave ovens (and not only in them) microprocessors and special programs, according to which the device can perform a particular function:

Built-in clock.
Defrosting food.
Innings sound signal the completion of the defrosting, cooking or reheating process.

Conclusion

Now you more accurately understand how a microwave oven works. The principle of operation of this device is relatively simple. It is based on the elementary laws of physics.

Let's consolidate the learned: the magnetron (the main element of the microwave oven) emits very short radio waves with a high frequency. They act on water molecules, because of which they begin to actively move. This process is accompanied by the release of heat. Given the fact that the waves penetrate shallowly into the food, only the surface of the food is heated, and then, due to natural thermal conductivity, the heat goes deeper.

This is the basic principle of the microwave oven. We also reviewed the device and the main elements in this article. All of them are classic and are used in absolutely all models from any manufacturer. On the this moment described above working scheme is the only one though different manufacturers may use modules that differ in some way. For example, in one model, a more powerful magnetron can be used, which can heat up food much faster. In other compact models, this element may have a low power, which allows you to create a device of small size. There are hundreds of similar differences, but the principle of operation from this does not change at all. Of course, a stronger magnetron determines how long the microwave oven works in time to heat food of the same volume. Therefore, if you do not like to wait, then it is better to choose a more powerful model.

That's all. We completely disassembled the device of this piece of household appliances and answered most of the questions related to it.

The working principle of a microwave oven: 6 main elements

Thanks to the microwave oven, you can easily and quickly heat up any dish. Microwave oven (MW) is currently very popular, it is the most popular kitchen appliance. With the help of a microwave oven, you can not only heat or cook food, but also defrost food and even disinfect some kitchen utensils that do not contain metal. This device has become quite commonplace today.

Microwave device: basic structural elements

The microwave oven is a household electrical appliance, which is intended mainly for cooking or heating food in fast mode. Microwaves are also used in some industries where you need to heat the necessary materials.

The microwave oven, despite its small size, consists of many parts.

Unlike conventional ovens, heating different foods in this device happens quite quickly, since radio waves are able to penetrate deep into the products. This drastically reduces the heating of any product and helps to preserve all the useful substances in it.

The device of all microwave ovens consists, as a rule, of the same components. The design of microwave ovens has basic and auxiliary elements. Appearance these devices can be very diverse. Sizes, colors and functions may vary, for each individual oven, they may be different.

The structure of the microwave oven:

Camera equipped with a rotating podium;
Magnetron, is the main element - a microwave emitter;
Transformer;
Metal case with a door that is blocked when the device is in operation;
Scheme of management and communications;
Waveguide.

Also inside the microwave oven must be equipped with a fan. Its purpose is very large, since without it the device itself will not work. Such a device ensures excellent operation of the magnetron and cools the electronic circuits.

How a microwave oven works: its varieties

The operation of a microwave oven is very simple, it is based on microwave radiation. The heart of every microwave oven is an element such as a magnetron. He is the source of radiation. The frequency of microwaves is approximately 2450 MHz, and the power of modern microwaves can be 700 - 1000 watts. This oven is powered by electricity.

The microwave oven heats the dish evenly from all sides

In order for the magnetron to work well and not overheat, a fan is installed next to it. It also circulates air inside the oven itself and contributes to uniform heating of food or products.

Microwaves enter the oven through a waveguide, and then the walls, which are made of metal, reflect the magnetic radiation itself. Radiation, penetrating deep into the products, makes their molecules move very quickly. These actions contribute to friction, as a result of which heat is released (there is physics). This is warm and will reheat food.

Types of electrical appliances:

With grill;
Convection oven;
Inverter controlled device;
An appliance with microwaves that are distributed evenly;
Mini microwave.

The main advantage of all microwaves is the design. The market provides a huge selection of devices, you can choose both a stylish and ergonomic model. The description of these models will allow you to choose the model you like, which will become not just a decoration of the kitchen, but also its highlight. An example would be a Samsung microwave oven.

Control unit: the principle of operation of the microwave

Each microwave oven has such an important element as a control unit. It, in turn, performs two main functions: it maintains the set power and turns off the device when set time expired. To date, technology has developed a new type of this element - electronic.

Today, the electronic unit can support not only its basic functions, but also some additional ones. Some of them are necessary, while others are not needed at all. Many modern models there is a grill, it is also controlled by the control unit.

Among the advantages of a microwave oven, it is worth noting the low price and long service life.

Today, the command block is equipped with different microprocessors, which, in turn, support the functionality of other programs. Therefore, the power supply may be responsible for the operation of additional functions.

Additional service functions:

Built-in clock;
Power indicator;
Automatic defrosting;
A sound signal that indicates the completed operation.

The electronic unit is closely connected with the display panel and keyboard. The most important part of such a block is the relay block. He is responsible for the operation of the fan, convector, built-in lamp and even the magnetron.

Microwave frequency: magnetron and its components

The principle of operation of the microwave oven is that the magnetron, when the microwave oven is turned on, begins to release energy, and then it is converted into heat. This heat is used to heat food. Magnetron is translated as an electrovacuum diode, which consists of a copper anode. This is the most expensive part of the furnace.

The heating of food that is inside the microwave occurs under the influence of electromagnetic radiation, that is, microwave radio waves. Due to the fact that radio waves penetrate deep into the heated product, it is heated very quickly and efficiently.

If the magnetron breaks down, then without the appropriate experience it is quite difficult to fix it yourself

Decoding a magnetron is a device that produces a huge amount of heat, due to the frequency of radiation. The radiation frequency is 2.4 GHz. The coefficient of efficiency (COP) of the magnetron is 80%, and the power consumption of this type of furnace during radiation can be 1100 W.

The magnetron device consists of the following parts:

The cylindrical anode is its base, consisting of 10 sectors, each of them is made of copper;
In the center is a cathode with a filament;
The end parts are occupied by magnets, they create the magnetic field necessary for radiation;
Leaded to the antenna, which radiates energy, a wire loop.

With the help of the antenna-emitter, the energy first enters the waveguide, and then into the furnace chamber. The voltage supplied to the anode is 4 thousand watts, the filament is 3 thousand watts. The magnetron housing is located in a plastic radiator, where a built-in fan blows air over it, and a special fuse is responsible for overheating it.

The device and principle of operation of the microwave oven (video)

With in English such a statement Microwave oven, can be deciphered as a microwave oven. This design is a household appliance that runs on electricity and is distinguished by the fact that it defrosts or heats food very quickly. This happens due to microwave radiation.

How exactly does a microwave oven work? What causes food, water and other substances to heat up, while air or glass in a microwave oven almost does not heat up? How to properly handle the microwave so as not to spoil it and the dish being prepared? You will find the answers to these questions in our article!

The principle of operation of the microwave

The correct full name of the microwave oven is an oven with microwave currents. inside it (for dashboard) there is a special device for emitting radio waves - a magnetron, which can be seen from the diagram:

When the magnetron is operating, the electromagnetic oscillations of a certain frequency emitted by it cause the dipole molecules inside the furnace to oscillate at the same frequency. The most common dipole molecule in nature is the water molecule (in foods there are also fats and sugars). At the molecular level high frequency fluctuations translates into a rise in temperature, so any food with a high water content quickly heats up. If there are very few or no water molecules inside the products (or materials), heating almost does not occur.

The depth of penetration of microwaves is small - 2-3 centimeters, however, the surface of the prepared dish is easily pierced by microwaves, and in depth they meet the resistance of water molecules, so the product actually warms up from the inside.

Any conductive materials inside the microwave will get hot. Different ability to conduct current in our case means a different heating rate.

In order for the heating of products to occur evenly, several approaches are used:

Heat-resistant glass disc at the bottom of the microwave oven. It rotates together with the dish, exposing all its sides to the radiation of the magnetron.
Microwave. They are fed through a special waveguide (wide tube) from the magnetron to a rotating reflector, usually located in the upper part of the microwave oven. In such microwave ovens, it is possible to heat motionless dishes of large size and weight.

There are also so-called inverter microwave ovens. They differ from conventional models in that the magnetron operates continuously, but with reduced power consumption. This is achieved by using a so-called inverter (DC-to-AC converter) in the furnace instead of a traditional transformer.

Vitamins are better preserved in inverter ovens, and the surface structure of the dish is less destroyed, but there is no fundamental difference.

In many models of microwave ovens, the magnetron is covered with a special translucent plate. It is transparent to microwave rays, but does not allow steam, splashes of grease and other foreign matter to enter the microwave oven through a hole in the shielding. Do not remove this plate, and if it is required for cleaning from fat, then after complete drying, be sure to return it to its place.

Look for everything about cleaning the microwave oven in this article:.

Despite popular belief, microwave radiation does not kill germs. At least not scientifically proven. On the other hand, the complex effect of high temperature and microwaves on water molecules inside bacteria and viruses within a few minutes reduces their number many times over, and your immune system copes with those that remain.

Microwave operating frequency

Most magnetrons emit waves at a frequency of 2450 MHz (megahertz, or millions of oscillations per second). These are waves of decimeter length (12.25 cm long). Some industrial installations, for example in the USA, operate at 915 MHz. Forced vibrations of water molecules are not resonant vibrations, since for them resonant frequency an order of magnitude higher - 22.24 GHz (gigahertz, or billions of oscillations per second).

There is no need to be afraid of harmful radiation from the microwave. The first mass production of microwaves was made in Japan by Sharp in 1962. Many years have passed since then, tens of millions of Japanese have been heating food in microwave ovens for decades, and the average life expectancy of the Japanese is the envy of the whole world.

At a distance of half a meter from the microwave oven, the effect of microwaves weakens 100 times, so if you are afraid of getting radiation, it is enough to stay away from the microwave at arm's length.

You can find more information about the effect of a microwave oven on a person. Only scientific facts!

How does a microwave grill work?

The grill allows you to grill food in the microwave using regular heat instead of microwaves. It is she who makes an appetizing crust on dishes, which does not appear during conventional microwave processing.

The grill spiral is located at the top of the oven and there are two types:

heating elements(thermal electric heaters). A heating element is a metal tube, inside of which there is a thin spiral made of an alloy of nickel and chromium. A current passes through the coil, and it heats up.
Quartz. A quartz grill is also a heating element, only instead of a metal tube there is a glass shell, between the spiral and the tube there is insulating quartz sand.

Ordinary metal heating elements can often be adjusted - moved to the back wall or lowered, but the glass surface of a quartz grill is easier to clean (grease and carbon deposits do not eat into glass like they do into metal).

There are designs of microwave ovens with grill and convection. Convection is simply blowing hot air around your food while cooking. For such blowing, a fan is installed in the microwave, blowing heated air from the grill spiral towards the dish.

Most models of microwaves allow you to use both the heating element and the microwave at the same time. However, keep in mind that this combination can get the outlet and wires in your room very hot.

Read the following article about the principles of choosing a microwave oven for your needs:.

Microwave Instructions

To properly handle your microwave, you need to carefully approach all points - from the choice of dishes to the correct shutdown after use.

What utensils to use?

The best material for heating in the microwave is heat-resistant glassware. Porcelain and other ceramic products, paper (cardboard) are also well suited. Microwaves pass through them very easily and almost do not heat them. But dishes from the following materials must be discarded:

Plastic. It transmits microwave radiation well, but due to toxic components during manufacture (for example, polystyrene foam), it can be hazardous to your health.
Metal. They spend electricity without skipping microwaves. So cooking or simply reheating a dish in an aluminum pan or cast iron pot will not work. The metal simply will not let electromagnetic waves through to the products, and they will remain cold. In this case, the metal itself, of course, heats up, and products can also heat up from its heat. But this can lead to a breakdown of the microwave oven, and it will take a long time to cook the dish. Read the microwave oven repair manual.

Some materials may contain metals, and this can be difficult to guess in advance. For example, it is crystal. So you should carefully read on the label what materials were used in the production of a particular dish.

Melamine. This is a light and beautiful material for dishes, similar to porcelain, but it cannot be placed in a microwave oven. The fact is that when heated, it releases toxins that are dangerous to your health.

As for the shape of the dish, it can be any, but not with a narrow neck, since when used for heating in the microwave, it can be dangerous. The fact is that some liquids are heated to the boiling point, but there is no vigorous mixing inside the volume. But when you take out such a jug or flask from a microwave oven, the liquid will instantly boil, boiling foam will pour out of the container, and you can get burned. For example, distilled water and some refined vegetable oils behave in this way under certain conditions.

Proper handling of products

Initially, it is worth determining exactly what cannot be defrosted in the microwave:

Butter. If you put it in the microwave and leave it for a long time, it will not only melt, but also boil, staining the entire oven from the inside. This happens because inside the oil there is not only oil itself, but also water. It boils at 100 degrees, and oil at about 120. So water can turn into steam before the oil melts, and the water vapor will spread the oil all over the stove.

Approximately the same thing can happen with other products that sometimes need to be melted, for example, with chocolate, so it is better to do this not in the microwave, but in a couple.

Hard shell products. For example, these are eggs, tomatoes, whole bird liver. When heated, some of the water does not just gradually heat up, but immediately turns into steam. If you heat food for a long time, then even more steam is formed from direct heating. This steam has nowhere to go, so the pressure inside the container increases and leads to an explosion.
Hermetically sealed container. For example, canned food and bottles. The reason is the same as in the previous paragraphs - the probability of an explosion is high.

Sausages tightly packed in a casing must be pierced with a fork before microwave heating to create holes for steam to escape, otherwise it will turn the sausages from the inside.
In eggs and other products, you need to destroy all the outer and inner shells, for example, make an omelet or cut the liver.
For cooking eggs and other products in the microwave, special saucepans with shielding are used. Water is poured into it, it is it that is heated by microwave waves, and electromagnetic radiation does not reach the eggs - they are covered by a screen.
If a small dish is placed in the microwave, you should add a regular glass of water to it. So you will avoid overheating of the magnetron.
It is better to salt any liquid dishes in the microwave in advance, and not after cooking. This way you save time and energy. The fact is that distilled (unsalted) water in the microwave heats up and boils, but longer than ordinary water.
A very heavily frozen product (meat, for example) will be defrosted in the microwave for quite a long time, and you need to turn on the microwave oven at the minimum power. The reason is that ice molecules are not water molecules, microwaves do not shake them as intensely. In addition, ice molecules form a fairly rigid structure and are not as easy to "rock" as water molecules.

Dry bread is often recommended to be "tenderized" in the microwave, but may ignite with prolonged exposure and maximum microwave power. The same can happen even with microwave-safe popcorn. Therefore, when such foods are placed in the microwave oven, one must be vigilant.

On/off rules

You can not turn on an empty microwave, especially at full power:

Inside the oven, all walls (and even the door) are a special metallized screen that reflects microwaves back into the microwave. The only place where there is no screen is the hole for the exit of electromagnetic waves from the magnetron.
When food is on the tray, the microwaves use their energy to heat the food. If there is nothing to absorb the energy, microwave radiation is reflected from the walls of the shielding surfaces, while the wave density increases more and more.
Microwave radiation gets back into the magnetron, and if it consists of metal, it will simply overheat and may fail.

It is believed that after heating a dish in a microwave oven, it is better to let it stand for 3-5 minutes. Then the so-called “free radicals”, that is, parts of molecules that have broken apart under the influence of microwaves, have time to neutralize.

Video: How does a microwave work?

All of the above about the principle of operation of the device is well illustrated in the following video:

After reading our article, you have become much better at understanding the principle of operation of a microwave oven. Now you know what it can do better than a conventional oven and electric stove, and what it can’t, and what actions are generally unacceptable when working with a microwave.

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14 011

In order to understand whether a microwave oven is harmful, you need to have an idea what microwaves are. To do this, we turn not to rumors, but to the scientific data of physics, which explains the nature and properties of all physical phenomena.

What are microwaves and their place in the spectrum of electromagnetic radiation.
Microwave It is one of the types of electromagnetic radiation. And, as you know, the electromagnetic radiation of the Sun is the main source of energy for life on Earth. It consists of visible and invisible radiation.

All the colors we see are the visible part of the radiation. Invisible is radio waves, infrared (thermal), ultraviolet, x-ray and gamma radiation. All these waves are manifestations of the same phenomenon - electromagnetic radiation, but they differ in wavelength and oscillation frequency. The longer the wavelength, the lower the frequency of their oscillations. These parameters determine the properties of a particular type of radiation.

The entire spectrum of electromagnetic waves can be sequentially arranged as the wavelength decreases (and, accordingly, the frequency of oscillations increases) in the following order:

radio waves- electromagnetic waves with a wavelength of more than 1 mm. These include: a) Long Waves - Wavelength from 10 km to 1 km (frequency 30 kHz - 300 kHz);
b) Medium waves - wavelength from 1 km to 100 m (frequency 300 kHz -3 MHz);
c) Short waves - wavelength from 100 m to 10 m (frequency 3 - 30 MHz);
d) Ultrashort waves with a wavelength less than 10 m (frequency 30 MHz - 300 GHz). Ultrashort waves, in turn, are divided into:
meter, centimeter (including microwaves), millimeter waves.
Microwave is a form of electromagnetic energy that is on the frequency scale between radio waves and infrared radiation. Therefore, they have some properties of their neighbors. Microwave or ultra-high frequency waves (SHF) are short electromagnetic radio waves with a wavelength of 1 mm - 1 m (frequency less than 300 MHz). It is called super high frequency (UHF) radiation because it has the highest frequency in the radio range. The physical nature of microwave radiation is the same as that of radio waves. They are used for telephone communication, Internet operation, television program transmission, in microwave ovens.
Infrared radiation- electromagnetic waves with a wavelength of 1 mm - 780 nm (frequency 300 GHz - 429 THz). It is also called "thermal" radiation, as it is perceived by the human skin as a feeling of warmth.
Visible radiation- electromagnetic waves with a wavelength of 780-380 nm (frequency 429 THz - 750 THz).
ultraviolet radiation e - electromagnetic waves with a wavelength of 380 - 10 nm (frequency 7.5 1014 Hz - 3 1016 Hz).
x-ray radiation- electromagnetic waves with a wavelength of 10 nm - 5 pm (frequency 3 1016 - 6 1019 Hz).
gamma rays- electromagnetic waves with a wavelength less than 5 pm (frequency more than 6 1019 Hz).

The amount of energy it carries depends on the wavelength and frequency. Waves with long wavelengths and low frequencies carry little energy. Waves with a small wavelength and high frequency - a lot. The more energy radiation has, the more destructive effect it has on a person.

According to the ability to cause such an effect as the ionization of a substance, all the above types of electromagnetic radiation are divided into 2 categories: ionizing and non-ionizing.
These 2 types of radiation differ in the amount of energy they carry.

1. ionizing radiation otherwise known as radioactive. It includes x-rays, gamma rays, and in some cases ultraviolet radiation.
ionizing radiation is characterized by high energy, capable of ionizing substances, and causes such changes in cells that disrupt the course of biological reactions in the body and pose a health hazard.
The maximum energy is inherent in gamma radiation. As a result of its impact, food becomes radioactive, and a person develops radiation sickness. That is why exposure to all ionizing radiation is very dangerous for a living organism.

2. Non-ionizing radiation - radio waves, infrared, visible radiation.
These types of radiation have insufficient energy to ionize matter, therefore they cannot change the structure of atoms and molecules. The boundary between non-ionizing and ionizing radiation is usually considered a wavelength of about 100 nanometers.
The energy of long radio waves is not enough even to heat something - they will simply pass through any food. The energy of infrared radiation (thermal) is absorbed by all objects, including food, therefore it is successfully used, for example, in toasters. Microwaves are in the middle of them and therefore also have low energy.

Microwaves used in microwave ovens.
Household microwave ovens use microwaves with a radiation frequency of 2450 MHz (2.45 GHz) and a wavelength of approximately 12 cm. These figures are significantly lower than the frequencies of X-rays and gamma rays, which cause an ionizing effect and are dangerous to humans. Microwaves are located between radio and infrared waves, i.e. they have insufficient energy to ionize atoms and molecules.
In serviceable microwave ovens, microwaves do not directly affect a person. They are absorbed by food, causing a heat-generating effect.
Microwave ovens do not create ionizing radiation and do not emit radioactive particles, therefore they do not have a radioactive effect on living organisms and food. They generate radio waves, which, according to all the laws of physics, cannot change the atomic and molecular structure of matter, they can only heat it.
So, microwaves are a kind of radio waves. Being in the frequency scale between radio waves and infrared radiation, they have properties in common with them.
However, neither the heat nor the radio waves that surround us have any effect on food, and therefore there is little reason to expect the same from microwaves.