What exactly happens in a microwave during heating, and how the food in the microwave oven is heated, is unclear to many. Therefore, the numerous rumors about the danger of "irradiated food" come. How a microwave actually works exactly, read in this post.
Many people think of the word "radiation" in Chernobyl and radioactive contamination. That's nonsense, of course. The food is not "irradiated" in the microwave but only excited by electromagnetic field energy.
This field energy is an electromagnetic field in waveform. Electromagnetic waves are, for example, also:
- radio waves
- heat radiation
- light and
The impact on substances, living tissue and food, however, always depends on the wavelength and frequency of the radiation used. For example, visible light is in a different frequency and wavelength range than, for example, the heat radiation of a tiled stove, which only an infrared camera can visualize. Microwaves usually use decimetre beams.
Apart from a few deviations, wavelengths of 12 cm (hence "decimeter waves", approx. Wavelength around 10 cm = 1 dm) are used today for microwaves. The frequency is usually 2.455 GHz.
Effect of Decimeter Waves
Waves of this wavelength and frequency stimulate molecules to move. In particular, water molecules are set in strong motion by these waves. The movement of the water contained at the molecular level results in frictional heat in the food, which causes it to heat up.
This principle also explains why non-aqueous foods or substances in the microwave can not be heated. Molecules other than water are only very slightly moved by the decimeter jets and thus generate no friction.
Components near the microwave oven
The core of every microwave oven and the most important component for the entire functioning is the so-called microwave generator, formerly known as a magnetron. This component generates the electromagnetic field energy and directs the resulting waves in the cooking chamber of the microwave. For the conduction of the waves, a so-called waveguide is used.
Powering the microwave generator
For a microwave generator to work, it requires a high anode voltage, usually at least 5 kV. This high voltage is generated by a high-voltage transformer built into the device and some special circuits.
Only 65% of the absorbed energy is converted into microwave radiation, 35% is lost as heat. A microwave oven thus basically has only a very low electrical efficiency. To dissipate the heat in order, a fan cools the microwave generator continuously.
The heat is dissipated through vents, which can be located at different points of the device. These slots must not be blocked, otherwise heat accumulation and fire danger can threaten.Tips & TricksThe waste heat from the microwave generator is also blown through the oven to keep it dry. Steam inside the cooking chamber is thus automatically "dried up".