Lengths electromagnetic waves, which can be recorded by instruments, lie in a very wide range. All these waves have general properties: absorption, reflection, interference, diffraction, dispersion. These properties can, however, manifest themselves in different ways. The sources and receivers of waves are different.
Radio waves
ν =10 5 - 10 11 Hz, λ =10 -3 -10 3 m.
Obtained using oscillatory circuits and macroscopic vibrators. Properties. Radio waves of different frequencies and wavelengths are absorbed and reflected differently by media. Application Radio communications, television, radar. In nature, radio waves are emitted by various extraterrestrial sources (galactic nuclei, quasars).
Infrared radiation (thermal)
ν =3-10 11 - 4 . 10 14 Hz, λ =8. 10 -7 - 2. 10 -3 m.
Emitted by atoms and molecules of matter.
Infrared radiation is emitted by all bodies at any temperature.
A person emits electromagnetic waves λ≈9. 10 -6 m.
Properties
- Passes through some opaque bodies, as well as through rain, haze, and snow.
- Produces a chemical effect on photographic plates.
- When absorbed by a substance, it heats it up.
- Causes an internal photoelectric effect in germanium.
- Invisible.
Recorded by thermal, photoelectric and photographic methods.
Application. Obtain images of objects in the dark, night vision devices (night binoculars), and fog. Used in forensics, physiotherapy, and in industry for drying painted products, building walls, wood, and fruit.
The part of electromagnetic radiation perceived by the eye (from red to violet):
Properties.IN affects the eye.
(less than violet light)
Sources: gas-discharge lamps with quartz tubes (quartz lamps).
Radiated by everyone solids, for which T>1000°С, as well as luminous mercury vapor.
Properties. High chemical activity (decomposition of silver chloride, glow of zinc sulfide crystals), invisible, high penetrating ability, kills microorganisms, in small doses has a beneficial effect on the human body (tanning), but in large doses has a negative biological effect: changes in cell development and metabolism substances, effects on the eyes.
X-rays
Emitted during high acceleration of electrons, for example their deceleration in metals. Obtained using an X-ray tube: electrons in a vacuum tube (p = 10 -3 -10 -5 Pa) are accelerated by an electric field at high voltage, reaching the anode, they are sharply braked upon impact. When braking, electrons move with acceleration and emit electromagnetic waves with a short length (from 100 to 0.01 nm). Properties Interference, X-ray diffraction by crystal lattice, high penetrating power. Irradiation in large doses causes radiation sickness. Application. In medicine (diagnosis of diseases internal organs), in industry (control of internal structure various products, welds).
γ radiation
Sources: atomic nucleus(nuclear reactions). Properties. It has enormous penetrating power and has a strong biological effect. Application. In medicine, manufacturing ( γ - flaw detection). Application. In medicine, in industry.
A common property of electromagnetic waves is also that all radiation has both quantum and wave properties. Quantum and wave properties in this case do not exclude, but complement each other. Wave properties appear more clearly at low frequencies and less clearly at high frequencies. Conversely, quantum properties appear more clearly at high frequencies and less clearly at low frequencies. The shorter the wavelength, the brighter the quantum properties appear, and the longer the wavelength, the brighter the wave properties appear.
Electromagnetic waves are classified by wavelength λ or associated wave frequency f. Note also that these parameters characterize not only wave, but also quantum properties electro magnetic field. Accordingly, in the first case, the electromagnetic wave is described by the classical laws studied in this course.
Let's consider the concept of the spectrum of electromagnetic waves. Spectrum of electromagnetic waves is the frequency band of electromagnetic waves that exist in nature.
The spectrum of electromagnetic radiation in order of increasing frequency is:
Different parts of the electromagnetic spectrum differ in the way they emit and receive waves belonging to one or another part of the spectrum. For this reason, there are no sharp boundaries between different parts of the electromagnetic spectrum, but each range is determined by its own characteristics and the prevalence of its laws, determined by the relationships of linear scales.
Radio waves are studied by classical electrodynamics. Infrared light and ultraviolet radiation are studied by both classical optics and quantum physics. X-ray and gamma radiation are studied in quantum and nuclear physics.
Let's consider the spectrum of electromagnetic waves in more detail.
Low frequency waves
Low frequency waves are electromagnetic waves whose oscillation frequency does not exceed 100 kHz). It is this frequency range that is traditionally used in electrical engineering. In industrial power generation, a frequency of 50 Hz is used, at which transmission occurs electrical energy along lines and voltage conversion by transformer devices. In aviation and ground transport Frequency 400 Hz is often used, which offers weight advantages electric machines and transformers 8 times compared to the frequency of 50 Hz. IN pulsed sources nutrition last generations transformation frequencies are used alternating current units and tens of kHz, which makes them compact and energy-rich.
The fundamental difference between the low-frequency range and higher frequencies is the drop in the speed of electromagnetic waves in proportion to the square root of their frequency from 300 thousand km/s at 100 kHz to approximately 7 thousand km/s at 50 Hz.
Radio waves
Radio waves are electromagnetic waves whose wavelengths are greater than 1 mm (frequency less than 3 10 11 Hz = 300 GHz) and less than 3 km (above 100 kHz).
Radio waves are divided into:
1. Long waves in the length range from 3 km to 300 m (frequency in the range 10 5 Hz - 10 6 Hz = 1 MHz);
2. Medium waves in the length range from 300 m to 100 m (frequency in the range 10 6 Hz -3*10 6 Hz = 3 MHz);
3. Short waves in the wavelength range from 100m to 10m (frequency in the range 310 6 Hz-310 7 Hz=30 MHz);
4. Ultrashort waves with a wavelength less than 10m (frequency greater than 310 7 Hz = 30 MHz).
Ultrashort waves, in turn, are divided into:
A) meter waves;
B) centimeter waves;
B) millimeter waves;
Waves with a wavelength of less than 1 m (frequency less than 300 MHz) are called microwaves or ultra-high frequency waves (microwave waves).
Due to the large wavelengths of the radio range compared to the size of atoms, the propagation of radio waves can be considered without taking into account the atomic structure of the medium, i.e. phenomenologically, as is customary when constructing Maxwell's theory. The quantum properties of radio waves appear only for the shortest waves adjacent to the infrared part of the spectrum and during the propagation of the so-called. ultrashort pulses with a duration of the order of 10 -12 sec - 10 -15 sec, comparable to the time of electron oscillations inside atoms and molecules.
The fundamental difference between radio waves and higher frequencies is a different thermodynamic relationship between the wavelength of the wave carrier (ether), equal to 1 mm (2.7°K), and the electromagnetic wave propagating in this medium.
Biological effects of radio wave radiation
The terrible sacrificial experience of using powerful radio wave radiation in radar technology showed the specific effect of radio waves depending on the wavelength (frequency).
The destructive effect on the human body is not so much the average as the peak radiation power, at which irreversible phenomena occur in protein structures. For example, the power of continuous radiation from the magnetron of a microwave oven (microwave), amounting to 1 kW, affects only food in a small closed (shielded) volume of the oven, and is almost safe for a person nearby. The power of a radar station (radar) of 1 kW of average power emitted by short pulses with a duty cycle of 1000:1 (the ratio of the repetition period to the pulse duration) and, accordingly, a pulse power of 1 MW, is very dangerous for human health and life at a distance of up to hundreds meters from the emitter. In the latter, of course, the direction of the radar radiation also plays a role, which emphasizes the destructive effect of pulsed rather than average power.
Exposure to meter waves
High-intensity meter waves emitted by pulse generators of meter radar stations (radars) with a pulse power of more than a megawatt (such as the P-16 early warning station) and commensurate with the length of the spinal cord of humans and animals, as well as the length of axons, disrupt conductivity these structures, causing diencephalic syndrome (HF disease). The latter leads to the rapid development (over a period of several months to several years) of complete or partial (depending on the received pulse dose of radiation) irreversible paralysis of a person’s limbs, as well as disruption of the innervation of the intestines and other internal organs.
Impact of decimeter waves
Decimeter waves are comparable in wavelength to blood vessels, covering such human and animal organs as the lungs, liver and kidneys. This is one of the reasons why they cause the development of “benign” tumors (cysts) in these organs. Developing on the surface of blood vessels, these tumors lead to the cessation of normal blood circulation and disruption of organ function. If such tumors are not surgically removed in time, the death of the body occurs. Decimeter waves of dangerous intensity levels are emitted by the magnetrons of such radars as the P-15 mobile air defense radar, as well as the radar of some aircraft.
Exposure to centimeter waves
Powerful centimeter waves cause diseases such as leukemia - “white blood”, as well as other forms of malignant tumors in humans and animals. Waves of intensity sufficient for the occurrence of these diseases are generated by the centimeter range radars P-35, P-37 and almost all aircraft radars.
Infrared, light and ultraviolet radiation
Infrared, light, ultraviolet radiation amounts to optical region of the spectrum of electromagnetic waves in the broad sense of the word. This spectrum occupies the range of electromagnetic wavelengths in the range from 2·10 -6 m = 2 μm to 10 -8 m = 10 nm (frequency from 1.5·10 14 Hz to 3·10 16 Hz). The upper limit of the optical range is determined by the long-wave limit of the infrared range, and the lower limit by the short-wave limit of the ultraviolet (Fig. 2.14).
The proximity of the spectral regions of the listed waves determined the similarity of the methods and instruments used to study them and practical application. Historically, lenses, diffraction gratings, prisms, diaphragms, and optically active substances included in various optical devices (interferometers, polarizers, modulators, etc.) were used for these purposes.
On the other hand, radiation from the optical region of the spectrum has general patterns of transmission of various media, which can be obtained using geometric optics, widely used for calculations and construction of both optical devices and optical signal propagation channels. Infrared radiation is visible to many arthropods (insects, spiders, etc.) and reptiles (snakes, lizards, etc.) , accessible to semiconductor sensors (infrared photoarrays), but it is not transmitted by the thickness of the Earth’s atmosphere, which doesn't allow observe from the surface of the Earth infrared stars - “brown dwarfs”, which make up more than 90% of all stars in the Galaxy.
The frequency width of the optical range is approximately 18 octaves, of which the optical range accounts for approximately one octave (); for ultraviolet - 5 octaves ( 
), infrared radiation - 11 octaves (
In the optical part of the spectrum, phenomena caused by the atomic structure of matter become significant. For this reason, along with the wave properties of optical radiation, quantum properties appear.
Light
|
Light, light, visible radiation - the part of the optical spectrum of electromagnetic radiation visible to the eyes of humans and primates, occupies the range of electromagnetic wavelengths in the range from 400 nanometers to 780 nanometers, that is, less than one octave - a twofold change in frequency.
Rice. 1.14. Electromagnetic wave scale Verbal memory meme of the order of colors in the light spectrum: |
X-ray and gamma radiation
In the field of X-ray and gamma radiation, the quantum properties of radiation come to the fore.
X-ray radiation occurs when fast charged particles (electrons, protons, etc.) are decelerated, as well as as a result of processes occurring inside the electronic shells of atoms.
Gamma radiation is a consequence of phenomena occurring inside atomic nuclei, as well as as a result of nuclear reactions. The boundary between X-ray and gamma radiation is determined conventionally by the value of the energy quantum corresponding to a given frequency of radiation.
X-ray radiation consists of electromagnetic waves with a length from 50 nm to 10 -3 nm, which corresponds to a quantum energy from 20 eV to 1 MeV.
Gamma radiation consists of electromagnetic waves with a wavelength less than 10 -2 nm, which corresponds to a quantum energy greater than 0.1 MeV.
Electromagnetic nature of light
Light is the visible part of the spectrum of electromagnetic waves, the wavelengths of which occupy the range from 0.4 µm to 0.76 µm. Each spectral component of optical radiation can be assigned a specific color. The color of the spectral components of optical radiation is determined by their wavelength. The color of the radiation changes as its wavelength decreases as follows: red, orange, yellow, green, cyan, indigo, violet.
Red light corresponding longest length waves, determines the red boundary of the spectrum. Violet light - corresponds to the violet border.
Natural (daylight, sunlight) light is not colored and represents a superposition of electromagnetic waves from everything visible to humans spectrum Natural light occurs as a result of the emission of electromagnetic waves by excited atoms. The nature of excitation can be different: thermal, chemical, electromagnetic, etc. As a result of excitation, atoms randomly emit electromagnetic waves for approximately 10 -8 seconds. Since the energy spectrum of excitation of atoms is quite wide, electromagnetic waves are emitted from the entire visible spectrum, the initial phase, direction and polarization of which are random. For this reason, natural light is not polarized. This means that the "density" of the spectral components of electromagnetic waves of natural light having mutually perpendicular polarizations is the same.
Harmonic electromagnetic waves in the light range are called monochromatic. For a monochromatic light wave, one of the main characteristics is intensity. Light wave intensity represents the average value of the energy flux density (1.25) transferred by the wave:
Where is the Poynting vector.
Calculation of the intensity of a light, plane, monochromatic wave with amplitude electric field in a homogeneous medium with dielectric and magnetic permeability according to formula (1.35) taking into account (1.30) and (1.32) gives:
Traditionally, optical phenomena are considered using rays. The description of optical phenomena using rays is called geometric-optical. The rules for finding ray trajectories, developed in geometric optics, are widely used in practice for the analysis of optical phenomena and in the construction of various optical instruments.
Let us define a ray based on the electromagnetic representation of light waves. First of all, rays are lines along which electromagnetic waves propagate. For this reason, a ray is a line, at each point of which the averaged Poynting vector of an electromagnetic wave is directed tangentially to this line.
In homogeneous isotropic media, the direction of the average Poynting vector coincides with the normal to the wave surface (equiphase surface), i.e. along the wave vector.
Thus, in homogeneous isotropic media, the rays are perpendicular to the corresponding wavefront of the electromagnetic wave.
For example, consider the rays emitted by a point monochromatic light source. From the point of view of geometric optics, many rays emanate from the source point in the radial direction. From the position of the electromagnetic essence of light, a spherical electromagnetic wave propagates from the source point. On enough long distance from the source, the curvature of the wave front can be neglected, considering the locally spherical wave to be plane. By breaking the surface of the wave front into a large number of locally flat areas, it is possible to draw a normal through the center of each section along which a plane wave propagates, i.e. in geometric-optical interpretation ray. Thus, both approaches give the same description of the considered example.
The main task of geometric optics is to find the direction of the beam (trajectory). The trajectory equation is found after solving the variational problem of finding the minimum of the so-called. actions on the desired trajectories. Without going into details of the strict formulation and solution of this problem, we can assume that the rays are trajectories with the shortest total optical length. This statement is a consequence of Fermat's principle.
The variational approach to determining the ray trajectory can also be applied to inhomogeneous media, i.e. such media in which the refractive index is a function of the coordinates of the points of the medium. If we describe the shape of the surface of a wave front in an inhomogeneous medium with a function, then it can be found based on the solution of the partial differential equation, known as the eikonal equation, and in analytical mechanics as the Hamilton-Jacobi equation:
Thus, the mathematical basis of the geometric-optical approximation of electromagnetic theory consists of various methods for determining the fields of electromagnetic waves on rays, based on the eikonal equation or in some other way. Geometric-optical approximation is widely used in practice in radio electronics to calculate the so-called. quasi-optical systems.
In conclusion, we note that the ability to describe light simultaneously both from wave positions by solving Maxwell’s equations and using rays, the direction of which is determined from the Hamilton-Jacobi equations describing the movement of particles, is one of the manifestations of the apparent dualism of light, which, as is known, led to the formulation logically contradictory principles of quantum mechanics.
In fact, there is no dualism in the nature of electromagnetic waves. As Max Planck showed in 1900 in his classic work "On the Normal Spectrum of Radiation", electromagnetic waves are individual quantized oscillations with a frequency v and energy E=hv, Where h =const, on air. The latter is a superfluid medium that has a stable property of discontinuity in measure h- Planck's constant. When the ether is exposed to energy exceeding hv During radiation, a quantized “vortex” is formed. Exactly the same phenomenon is observed in all superfluid media and the formation of phonons in them - quanta of sound radiation.
For the “copy-and-paste” combination of Max Planck’s discovery in 1900 with the photoelectric effect discovered in 1887 by Heinrich Hertz, in 1921 the Nobel Committee awarded the prize to Albert Einstein
1) An octave, by definition, is the frequency range between an arbitrary frequency w and its second harmonic, equal to 2w.
Many people already know that the length of electromagnetic waves can be completely different. Wavelengths can range from 103 meters (for radio waves) to ten centimeters in the case of x-rays.
Light waves are a very small part of the broadest spectrum electromagnetic radiation(waves).
It was while studying this phenomenon that discoveries were made that opened the eyes of scientists to other types of radiation that have rather unusual and previously unknown properties to science.
Electromagnetic radiation
The cardinal difference between various types There are no electromagnetic radiations. All of them represent electromagnetic waves, which are formed due to charged particles, the speed of which is greater than that of particles in a normal state.
Electromagnetic waves can be detected by monitoring their effect on other charged particles. In an absolute vacuum (an environment with a complete absence of oxygen), the speed of movement of electromagnetic waves is equal to the speed of light - 300,000 kilometers per second.
The boundaries established on the measurement scale of electromagnetic waves are rather unstable, or rather conditional.
Electromagnetic radiation scale
Electromagnetic radiations, which have a wide variety of lengths, are distinguished from each other by the method in which they are obtained (thermal radiation, antenna radiation, as well as radiation obtained as a result of slowing down the speed of rotation of the so-called “fast” electrons).
Also, electromagnetic waves – radiations – differ in the methods of their registration, one of which is the electromagnetic radiation scale.
Objects and processes existing in space, such as stars, black holes resulting from the explosion of stars, also generate listed species electromagnetic radiation. The study of these phenomena is carried out with the help of artificially created satellites, rockets launched by scientists and spaceships.
In most cases, research papers aimed at studying gamma and x-ray radiation. The study of this type of radiation is almost impossible to fully study on the surface of the earth, since most of the radiation that the sun emits is retained by the atmosphere of our planet.
A decrease in the length of electromagnetic waves inevitably leads to quite significant qualitative differences. Electromagnetic radiation, which has different lengths, differs greatly from each other in the ability of substances to absorb such radiation.
Radiations with low wavelengths (gamma rays and X-rays) are poorly absorbed by substances. For gamma and x-rays, substances that are opaque to radiation in the optical range become transparent.
The electromagnetic radiation scale conventionally includes seven ranges:
1. Low frequency vibrations
2. Radio waves
3. Infrared radiation
4. Visible radiation
5. Ultraviolet radiation
6. X-rays
7. Gamma radiation
There is no fundamental difference between individual radiations. All of them are electromagnetic waves generated by charged particles. Electromagnetic waves are ultimately detected by their effect on charged particles. In a vacuum, radiation of any wavelength travels at a speed of 300,000 km/s. The boundaries between individual regions of the radiation scale are very arbitrary.
Radiations of different wavelengths differ from each other in the method of their production (antenna radiation, thermal radiation, radiation during deceleration of fast electrons, etc.) and registration methods.
All of the listed types of electromagnetic radiation are also generated by space objects and are successfully studied using rockets, artificial satellites Earth and spaceships. This primarily applies to X-rays and gamma radiation, which are strongly absorbed by the atmosphere.
As the wavelength decreases, quantitative differences in wavelengths lead to significant qualitative differences.
Radiations of different wavelengths differ greatly from each other in their absorption by matter. Short-wave radiation (X-rays and especially g-rays) are weakly absorbed. Substances that are opaque to optical waves are transparent to these radiations. The reflection coefficient of electromagnetic waves also depends on the wavelength. But the main difference between long-wave and short-wave radiation is that short-wave radiation exhibits particle properties.
Infrared radiation
Infrared radiation is electromagnetic radiation that occupies the spectral region between the red end of visible light (with wavelength λ = 0.74 μm) and microwave radiation (λ ~ 1-2 mm). This is invisible radiation with a pronounced thermal effect.
Infrared radiation was discovered in 1800 by the English scientist W. Herschel.
Now the entire range of infrared radiation is divided into three components:
short-wave region: λ = 0.74-2.5 µm;
mid-wave region: λ = 2.5-50 µm;
long-wave region: λ = 50-2000 µm;
Application
IR (infrared) diodes and photodiodes are widely used in remote controls remote control, automation systems, security systems etc. They do not distract a person’s attention due to their invisibility. Infrared emitters used in industry for drying paint surfaces.
Positive side effect so is sterilization food products, increasing the corrosion resistance of painted surfaces. The disadvantage is the significantly greater unevenness of heating, which in some cases technological processes completely unacceptable.
An electromagnetic wave of a certain frequency range has not only a thermal, but also a biological effect on the product and helps accelerate biochemical transformations in biological polymers.
In addition, infrared radiation is widely used to heat indoor and outdoor spaces.
In night vision devices: binoculars, glasses, sights for small arms, night photo and video cameras. Here, an infrared image of an object invisible to the eye is converted into a visible one.
Thermal imagers are used in construction when assessing thermal insulation properties designs. With their help, you can determine the areas of greatest heat loss in a house under construction and draw a conclusion about the quality of the materials used. building materials and insulation.
Strong infrared radiation in hot areas may cause eye hazard. It is most dangerous when the radiation is not accompanied by visible light. In such places it is necessary to wear special eye protection.
Ultraviolet radiation
Ultraviolet radiation (ultraviolet, UV, UV) is electromagnetic radiation occupying the range between the violet end of visible radiation and x-rays (380 - 10 nm, 7.9 × 1014 - 3 × 1016 Hz). The range is conventionally divided into near (380-200 nm) and far, or vacuum (200-10 nm) ultraviolet, the latter so named because it is intensively absorbed by the atmosphere and is studied only by vacuum devices. This is invisible radiation with high biological and chemical activity.
The concept of ultraviolet rays was first encountered by a 13th century Indian philosopher. The atmosphere of the area he described contained violet rays that cannot be seen with the ordinary eye.
In 1801, physicist Johann Wilhelm Ritter discovered that silver chloride, which decomposes when exposed to light, decomposes more quickly when exposed to invisible radiation outside the violet region of the spectrum.
Ultraviolet sources
Natural springs
The main source of ultraviolet radiation on Earth is the Sun.
Artificial sources
UV OUs of the “Artificial Solarium” type, which use UV LLs that cause fairly rapid tan formation.
Ultraviolet lamps are used for sterilization (disinfection) of water, air and various surfaces in all spheres of human life.
Germicidal UV radiation at these wavelengths causes dimerization of thymine in DNA molecules. The accumulation of such changes in the DNA of microorganisms leads to a slowdown in the rate of their reproduction and extinction.
Ultraviolet treatment of water, air and surfaces does not have a prolonged effect.
Biological effects
Destroys the retina of the eye, causes skin burns and skin cancer.
Beneficial features UV radiation
Contact with the skin causes the formation of a protective pigment - tanning.
Promotes the formation of vitamins D
Causes the death of pathogenic bacteria
Application of UV radiation
Using invisible UV inks to protect bank cards and banknotes from counterfeiting. Images and design elements invisible in normal light are applied to the card, or the entire card is made to glow in UV rays.
Technological progress has reverse side. The global use of various electrically powered equipment has caused pollution, which is given the name electromagnetic noise. In this article we will look at the nature of this phenomenon, the degree of its impact on the human body and protective measures.
What is it and sources of radiation
Electromagnetic radiation is electromagnetic waves that arise when a magnetic or electric field is disturbed. Modern physics interprets this process within the framework of the theory of wave-particle duality. That is, the minimum portion of electromagnetic radiation is a quantum, but at the same time it has frequency-wave properties that determine its main characteristics.
The spectrum of frequencies of electromagnetic field radiation allows us to classify it into the following types:
- radio frequency (these include radio waves);
- thermal (infrared);
- optical (that is, visible to the eye);
- radiation in the ultraviolet spectrum and hard (ionized).
A detailed illustration of the spectral range (electromagnetic radiation scale) can be seen in the figure below.
Nature of radiation sources
Depending on their origin, sources of radiation of electromagnetic waves in world practice are usually classified into two types, namely:
- disturbances of the electromagnetic field of artificial origin;
- radiation coming from natural sources.
Radiations emanating from the magnetic field around the Earth, electrical processes in the atmosphere of our planet, nuclear fusion in the depths of the sun - they are all of natural origin.
As for artificial sources, they are a side effect caused by the operation of various electrical mechanisms and devices.
The radiation emanating from them can be low-level and high-level. The degree of intensity of the electromagnetic field radiation completely depends on the power levels of the sources.
Examples of sources with high levels of EMR include:
- Power lines are usually high-voltage;
- all types of electric transport, as well as the accompanying infrastructure;
- television and radio towers, as well as mobile and mobile communication stations;
- installations for converting the voltage of the electrical network (in particular, waves emanating from a transformer or distribution substation);
- elevators and other types of lifting equipment that use an electromechanical power plant.
Typical sources emitting low-level radiation include the following electrical equipment:
- almost all devices with a CRT display (for example: payment terminal or computer);
- Various types household appliances, starting from irons and ending with climate systems;
- engineering systems that provide electricity supply to various objects (this includes not only power cables, but related equipment, such as sockets and electricity meters).
Separately, it is worth highlighting special equipment used in medicine that emits hard radiation (X-ray machines, MRI, etc.).
Impact on humans
In the course of numerous studies, radiobiologists have come to a disappointing conclusion - long-term radiation of electromagnetic waves can cause an “explosion” of diseases, that is, it causes the rapid development of pathological processes in the human body. Moreover, many of them cause disturbances at the genetic level.
Video: How electromagnetic radiation affects people.
https://www.youtube.com/watch?v=FYWgXyHW93Q
This occurs due to the fact that the electromagnetic field high level biological activity, which negatively affects living organisms. The influence factor depends on the following components:
- the nature of the radiation produced;
- how long and with what intensity it continues.
The effect on human health of radiation, which is of an electromagnetic nature, directly depends on the location. It can be either local or general. In the latter case, large-scale exposure occurs, for example, radiation produced by power lines.
Accordingly, local irradiation refers to exposure to certain areas of the body. Coming from electronic watch or mobile phone electromagnetic waves, a striking example of local influence.
Separately, it is necessary to note the thermal effect of high-frequency electromagnetic radiation on living matter. The field energy is converted into thermal energy(due to the vibration of molecules), this effect is the basis for the operation of industrial microwave emitters used to heat various substances. In contrast to its benefits in production processes, thermal effects on the human body can be detrimental. From a radiobiological point of view, being near “warm” electrical equipment is not recommended.
It is necessary to take into account that in everyday life we are regularly exposed to radiation, and this happens not only at work, but also at home or when moving around the city. Over time, the biological effect accumulates and intensifies. As electromagnetic noise increases, the number of characteristic brain diseases or nervous system. Note that radiobiology is a fairly young science, so the harm caused to living organisms from electromagnetic radiation has not been thoroughly studied.
The figure shows the level of electromagnetic waves produced by conventional household appliances.
Note that the field strength level decreases significantly with distance. That is, to reduce its effect, it is enough to move away from the source at a certain distance.
The formula for calculating the norm (standardization) of electromagnetic field radiation is specified in the relevant GOSTs and SanPiNs.
Radiation protection
In production, absorbing (protective) screens are actively used as means of protecting against radiation. Unfortunately, it is not possible to protect yourself from electromagnetic field radiation using such equipment at home, since it is not designed for this.
- in order to reduce the impact of electromagnetic field radiation to almost zero, you should move away from power lines, radio and television towers at a distance of at least 25 meters (the power of the source must be taken into account);
- for CRT monitors and TVs this distance is much smaller - about 30 cm;
- Electronic watches should not be placed close to the pillow, optimal distance for them more than 5 cm;
- as for radio and cell phones, bringing them closer than 2.5 centimeters is not recommended.
Note that many people know how dangerous it is to stand next to high voltage lines power transmission, but most people do not attach importance to ordinary household electrical appliances. Although it is enough to put system unit on the floor or move it further away, and you will protect yourself and your loved ones. We advise you to do this, and then measure the background from the computer using an electromagnetic field radiation detector to clearly verify its reduction.
This advice also applies to the placement of the refrigerator; many people place it close to kitchen table, practical, but unsafe.
No table can indicate the exact safe distance from specific electrical equipment, since radiation may vary, both depending on the device model and the country of manufacture. At the moment there is no single international standard, therefore in different countries standards may differ significantly.
The radiation intensity can be accurately determined using special device– fluxmeter. According to the standards adopted in Russia, the maximum permissible dose should not exceed 0.2 µT. We recommend taking measurements in the apartment using the above-mentioned device for measuring the degree of electromagnetic field radiation.
Fluxmeter - a device for measuring the degree of radiation of an electromagnetic field Try to reduce the time you are exposed to radiation, that is, do not stay near operating electrical devices for a long time. For example, it is not at all necessary to constantly stand at the electric stove or microwave oven while cooking. Regarding electrical equipment, you can notice that warm does not always mean safe.
Always turn off electrical appliances when not in use. People often leave it turned on various devices, not taking into account that at this time electromagnetic radiation is emanating from electrical equipment. Turn off your laptop, printer or other equipment; there is no need to expose yourself to radiation again; remember your safety.