How Do Microwaves Work

how do microwaves work

A microwave oven, better known as a microwave oven, is a useful kitchen appliance that greatly simplifies everyday life. Having it in your arsenal, you will not have to mess around in the kitchen for a long time, heating food. This household electrical appliance’s task is to cook or quickly heat cooked food, defrost food quickly. Compared to a classic oven, for example, the microwave does not heat food from the surface but throughout the entire volume. In this article, we will give a complete guide about how do microwaves work.

Microwaves,  penetrating deeply into almost any food, significantly reduce the heating time. The article will discuss the operation principle and the device of this technique, which is indispensable in the kitchen.

How the microwave works

Most food products contain the following substances: salts, fats, sugar, water. For microwaves to “work,” that is, the food must contain dipole molecules to heat food. On the one hand, they have a positive electrical charge on the other, negative. These molecules are enough in food – these are fats and sugar, but the main dipole is a water molecule. Vegetables, meat, fruits, and fish contain many dipole molecules, the number of which reaches millions.

In the presence of an electromagnetic field, they begin to “line up”: “plus” is directed in one direction, “minus” in the other. When the field reverses polarity, the molecules “unfold” 180 degrees. Microwaves in microwave ovens have a frequency of 2450 MHz. 1 hertz = 1 oscillation per second. A megahertz is a million oscillations. Polarity changes twice in one wave period. When food is exposed to microwave radiation, the molecules begin to rotate more often, literally rubbing against each other. At the same time, heat is released, which serves as a heating source for the products.

But, the heat “goes” further – the physics of heat conduction turns on. Hence, the advice follows: if you need to heat a large piece of meat, it is better to set the microwave to medium power. So it will warm up better, although it will take more time. The heat from the outer layers will begin to penetrate inward. The situation is similar to soups: it is better to periodically remove them from the oven and stir them, helping the heat to breakthrough. The currently produced oven models may have a “Double radiation” function.

Microwave oven circuit

A good example is the Samsung RE290D microwave oven. A schematic diagram will help you understand how ovens from any manufacturer work. They can differ only in specific modifications.

On the left side, you can see that the grounding pin of the plug is connected to the case, and that is connected from the midpoint of the capacitor decoupling of the filter that reduces high-frequency interference. In the area of ​​the power input, there is a fuse of the fuse type – FU1. To check its condition, they use electrical methods – they ring the circuit with a multimeter operating in ohmmeter mode.

For the magnetron, the radiation source, to start “working,” the door health contacts open, and all the others close. If you turn them off, anyway, then the supply voltage is removed from the high-voltage transformer. The circuit contains thermal fuses-sensors (2 pcs.), Which, depending on the temperature of the magnetron housing and the working chamber, open and close. The first has periodic work. It protects the magnetron from overheating. The safety relay contact provides the connection of the timer and cooling fan motors. If the “Monitor Fuse” fuse blows, the relay coil will fail. The power selection switch is located on the timer. He, following the algorithms, removes the voltage from the magnetron circuit.

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Its task is to limit the impulse caused by the capacitor (it can receive a charge before it turns on). This ensures that the microwave starts up smoothly. The power circuit of this Samsung oven is simple for those who understand. The main difference in microwave ovens is electronic components, with different designs and functionality.

How Do Microwaves Work: Microwave device

There are several mandatory parts inside the microwave, so it won’t be superfluous to know their role. The internal structure has the following design: a metal chamber in which food is heated and a door that prevents radiation from escaping outside. For food to be warmed up more evenly for this, a rotating table is provided in the chamber, powered by a motor-reducer (motor). But there are other crucial details. If you want to know about how do microwaves work, you must read this article.

Control block

The control panel is:

  • mechanical;
  • electronic.

The control unit maintains the set power and turns off the device after a set time. Inside the electronic unit is a microcomputer with rich potential. Therefore, in the course of the manufacture of furnaces, it finds other uses. For example, they build in a clock or fragments of melodies that signal the end of work.

The simplest is a rotary knob, one of which is a timer. There is also a hybrid system – with buttons. It is more functional in comparison with the “mechanics.” An increasingly common control unit in the form of a touch panel. In principle, it is similar to mechanical buttons, only more reliable. Advanced circuits support “programming” – adjustable power and time of radiation output.

Microwave radiation generating unit

This is the “heart” of the microwave oven. The element looks like a vacuum tube that could be found in old CRT TVs.

The generation unit includes not a single microwave source. They are located behind a mica plate, which “hides” behind the sidewall.

Primary and secondary protection systems

Control sensors ensure that key electronic and hardware parts are working properly and not in emergency mode. Their function is to ensure a trouble-free operation of the microwave oven and prevent dangerous failures.

To protect a person from exposure to microwaves, microwave ovens have a locking mechanism consisting of several switches:

  • Primary Switch;
  • Secondary Switch;
  • Door Switch;
  • Monitor Switch.

The task of the door switch is to block the operation of the power control relay.

How do microwaves work resonance: Microwave functions

Most people use a microwave oven to heat food. But this technique can do more. You can even use it for cooking barbecue, grilled chicken, baked potatoes, and so on. The only thing is that the “grill” mode requires a 1500 W power, which means there will be a lot of light to “pull” the oven. And the magnetron, a unit that generates radiation, is not eternal. Therefore, the less often you use the oven, the longer it will last. Nowadays, few people completely abandon traditional stoves in favor of how do microwaves work. List of functions available in microwave ovens and their purpose:

  • movable grill. It allows you to change the angle of inclination. Those who prefer grilled chicken choose ovens with this feature;
  • Hot air blowing of food. As stated by the manufacturers, this feature is for baking purposes. True, models of stoves with it are expensive, heavy, and bulky. It is not surprising, since a rather large fan is placed behind the equipment, forcing air;
  • bio-coating. Otherwise – a ceramic coating, although manufacturers call them differently. Its advantages: resistance, strength, biological inertness (microbes will not multiply inside the oven, even if it is not washed for a long time). The more expensive the microwave oven model is, the more sophisticated the coating is;
  • auto cooking.  With this mode, it remains only to select the weight of the product, and the power and time will be set automatically;
  • It’s simple – the oven operates at the minimum power required to defrost food; Intellowave. A system that allows you to heat food evenly, such as a large piece of meat. Built-in sensors “observe” individual areas.
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What is a magnetron

A microwave magnetron is an element that generates high-frequency radiation in a working chamber. The emitted electromagnetic waves affect the molecules in the food, causing it to heat up. It is for this reason that the temperature in microwave ovens does not exceed +100 degrees Celsius. The magnetron is the main part that sometimes fails. But for this, full compatibility in terms of power, frequency, and location of terminals is considered.

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How the magnetron works

A microwave oven works like this: It converts electricity into high-frequency electromagnetic radiation. As a result, the water molecules in the food begin to “move,” which leads to warming up.

Which operates due to the phenomenon of thermionic emission. The high temperature “forces” active electrons to leave the surface.  The generated electric field sets the electrodes in motion.  An electron trapped in a magnetic field changes its trajectory.

Their trajectory is broken, and they begin to rotate around the cathode. Electrons passing near the resonators give them part of their own energy (interchangeability). As a result, a powerful microwave field is formed in the cavity. The magnetron “starts up” when a high voltage of 3000 – 4000 V is applied to the anode. For this reason, in household power grids, the magnetron must be connected through a high-voltage transformer.

How do microwaves work: Magnetron device

A magnetron is an element responsible for generating high-frequency oscillations. There are devices with a similar operation principle – klystrons and platinum-trans, but they have not received the proper distribution.

  • The magnetron was first used in a microwave oven in 1960.  Its components and their descriptions: anode. Copper cylinder with multiple sectors. It has resonator cavities that create an annular oscillation system;
  • The filament cylinder is located in the center of the magnetron. So, this part is responsible for the emission of electrons;
  • ring magnets. Located at the ends of the furnace. They create a magnetic field parallel to the magnetron. Electrons move in the same direction;
  • wire loop. It is located in the resonator. Connected to the cathode and output to the radiating antenna. The purpose of the loop is to output high-frequency radiation into the waveguide. From there, it enters the microwave working chamber.

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How do microwaves work chemistry: Magnetron connection

Switching circuit – half-wave rectification of high voltage. The transformer output operates in the short-circuit mode of the output winding (no longer than 5 minutes).

It makes no sense to carry a damaged magnetron to repair – even well-equipped workshops do not do this. Therefore, they acquire a new part. Removing it from the microwave, mark the connector pins so as not to confuse them when reinstalling.  The magnetron will not work.

But a similar part will do.  Regardless of the manufacturer, magnetrons have a single device. Only the design differs. Therefore, when replacing a part.

Thanks to the serial production of microwave units, the microwave becomes a simple but useful kitchen technique, which greatly facilitates the procedure for cooking or heating food. It is easy to service, and the design does not imply irreplaceable parts, which increases reliability. There is an opinion that radiation from microwaves is harmful, but this is nothing more than a myth. Facebook Twitter contact with Google+

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Microwave principle

The principle of operation of a microwave is fundamentally different from conventional ovens. Products penetrated by ultra-high-frequency waves are heated throughout the entire volume, and not over the surface, as with heat. This is why the heating / defrosting process is so short. Microwave action can raise the temperature of an object to the value required by the user in minutes. Their frequency is 2450 MHz.

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