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The wave of the microwave

The home microwave device we know was invented by accident, thanks to chocolate that warmed up in the pocket of an American engineer who was working on a radar device. How does microwave radiation work? And is she dangerous?

Microwaves are electromagnetic waves used for communication, for locating objects such as airplanes, for astronomy and physics research, and of course for rapid heating of food. Photo: alexunderwood910.
Microwaves are electromagnetic waves used for communication, for locating objects such as airplanes, for research in astronomy and physics, and of course for rapid heating of food. Photo: alexunderwood910.

Written by: Zvi Atzmon, Young Galileo

Microwaves are electromagnetic waves used for communication, for locating objects such as airplanes, for research in astronomy and physics, and of course for rapid heating of food.

Electromagnetic waves are periodic changes that propagate in space from the source of the wave (for example, from a lamp or from the antenna of a radio transmitter). The spreading change is a change in the strength of the electric field and the strength of the magnetic field of space.

The space can be the empty space, such as electromagnetic waves that reach the earth from the sun through the empty space, or a space in which there is a substance that transmits the waves. In empty space all types of electromagnetic radiation progress at the same speed - the speed of light. Therefore in empty space the different types of electromagnetic radiation differ not in their speed but in their wavelength.

The range of microwaves (microwaves) is roughly between a wavelength of one millimeter and one meter. In electromagnetic radiation, the longer the wave, the lower the frequency. The microwave range extends from 300 MHz to 300 GHz.

Diagram of the electromagnetic spectrum. The range of microwaves (microwaves) is roughly between a wavelength of one millimeter and one meter. Source: United States Dept. of Labor - OSHA - Safety and Health Topics.
Diagram of the electromagnetic spectrum. The range of microwaves (microwaves) is roughly between a wavelength of one millimeter and one meter. Source: United States Dept. of Labor - OSHA - Safety and Health Topics.

Waves longer than one meter are radio waves, and waves shorter than one millimeter are infrared waves. Waves shorter than infrared waves are electromagnetic waves that our eyes are sensitive to - these are the waves of visible light.

We cannot see the microwaves - they are much longer than those that our eyes are sensitive to. For different needs, the limits of microwaves are defined a little differently, but in any case, the microwave domain is located between the infrared domain and the radio wave domain.

Communication and radar

Radar (abbreviations: finder of direction and distance; in English - radar) is a device that transmits electromagnetic waves that strike objects (planes, missiles, spaceships, ships, cars, clouds, flocks of birds in flight). Few of the waves hitting the bone are returned to the device and are used to identify the bone's location, speed and size. Radar installations operate in the field of radio waves and also in the field of microwaves.

Radar. Source: Wikimedia.
radar. source: Wikimedia.

Microwaves are widely used in the field of communication. For example, in wireless phones - communication between the base of the phone and the handset; in some of the cell phone networks; in Wi-Fi networks in the fields of television and the Internet; in communication with spaceships and communication satellites. Some of the global navigation networks (such as GPS) also use microwaves.

Microwaves are important in astronomical research and the development of instruments in physics.

All thanks to the chocolate

Visible light is created by "light sources" such as lamps and lanterns. The microwaves are created by completely different devices, such as a magnetron that works in microwave ovens. The magnetron converts electrical energy into microwave energy. The magnetron is based on electrons that are accelerated by means of electric voltage in a device in which there is a vacuum, and during their movement a magnetic field is applied to them. This results in the emission of electromagnetic waves in the microwave field.

Radar installations were of enormous military importance in World War II, and during this period they were rapidly developed. Percy Spencer was an American engineer and inventor at that time, and he excelled in the development of magnetrons for radar installations used by the American forces. It is said that one day, while working on a magnetron for a radar device, he had a chocolate bar in his pocket, and it melted - thus the idea of ​​the microwave oven was born in his head.

Microwave magnetron. Source: HCRS Home Labor Page.
Microwave magnetron. source: HCRS Home Labor Page.

It's getting warmer, it's getting warmer - but how?

How is food heated in a microwave oven? The water molecules in the food, as well as other molecules that make up the food, such as fats, have one electrically positive part and another electrically negative part.

Such molecules follow the electric field of the microwaves, which changes with the high frequency of the waves. During the tracking, the molecules move in rotational movements - increased movement of molecules means the temperature of the material increases. The range of frequencies in home microwave ovens is very narrow, so as not to harm communication based on microwaves in other frequencies.

Safety:

In electrically conductive bodies, and especially in metals, electric currents are created when they are exposed to microwaves, and sparks may be created, especially when it comes to metal objects with sharp edges, such as forks. Therefore, before turning on the microwave oven, it is important to make sure that there are no such metal utensils in it!

Some warn that exposure to microwave radiation is dangerous. Is it true? Microwave radiation is non-ionizing radiation, meaning that microwaves do not have enough energy to displace electrons from atoms and turn them into ions. Therefore, microwaves cannot cause chemical changes in materials, especially not in our genetic material - DNA. Hence they cannot cause direct hereditary damage or directly cause cancer. We note that since microwave radiation is electromagnetic radiation, no radiation remains in the food after it is removed from the device.

However, direct exposure to strong micro radiation (this should not occur during normal use of the device) may heat the body tissues, and in severe cases cause burns.

The article was published in Young Galileo - the monthly for curious children. For a gift digital sheet Click

4 תגובות

  1. Effects of microwave radiation

    "The conducted investigations indicate high biological activity and unfavorable influence of millimeter radiowaves on the organism"

    Affected:
    Liver, spleen, kidneys, lungs and heart, lymph, thymus, DNA, RNA,
    - amino acids decreased by 22%,
    -substantial change in the protein metabolism which occurs under the influence of (millimeter radiowaves)
    - caused a suppression of all functions of the organism

    STUDY:
    https://www.cia.gov/library/readingroom/docs/CIA-RDP88B01125R000300120005-6.pdf

  2. There is a problem that the public does not understand the difference between ionizing radiation and non-ionizing radiation and that is why there is a primal fear of radio and microwave radiation or electrical cables or cell phones and their antennas.
    Environmental testing institutes walk around with radiation detectors that are actually magnetic field meters and not Geiger counters, scaring the public from the radiation.
    There is a standard of the Ministry of Environmental Protection that is based on European standards.
    The problem started in the 80s-90s with international standards of the WHO, etc., which arose more from ignorance and lack of information and primal fear than from facts. - They are all based on a position paper from 1998 which reviews all the knowledge that existed at the time, raises all kinds of concerns about indirect damages only, but does not have any clear conclusions about damages to health.
    In my opinion, today after each of us walks around for hours and hours with smartphone devices that radiate directly to the head much more radiation than is allowed in the standard.
    Therefore, there should already be more knowledge than in 1998, perhaps we should re-examine all these standards of electromagnetic radiation at a frequency lower than visible light. (and I think you can quietly cancel them)

    http://www.nzdl.org/gsdlmod?e=d-00000-00—off-0cdl–00-0—-0-10-0—0—0direct-10—4——-0-1l–11-en-50—20-about—00-0-1-00-0–4—-0-0-11-10-0utfZz-8-10&a=d&c=cdl&cl=CL2.25.11&d=HASH018d1f318bd898f7adc5d6fe.2

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