All objects in nature, as long as the temperature is above absolute temperature zeroelectromagnetic waveThe form ofenergyThis is called radiation.The energy emitted by objects through radiation is called radiant energy, or radiation for short.An important characteristic of radiation is that it is "equivalent".No matter the temperature of the object (gas) is high or low, it will radiate outward. Object A can radiate to object B, and at the same time, object B can radiate to Party A.This is different from conduction, which is unidirectional.
Chinese name
Electron radiation
Foreign name
electron radiation
Radiation mode
Bidirectional radiation
Principle
Occurring heat when radiant energy is absorbed by objectseffect
Common radiation sources
RF induction of radar system transmission system, etc
The heat effect occurs when the radiant energy is absorbed by the body. The temperature generated by the different radiant energy absorbed by the body is also different.Therefore, radiation is an important way to convert energy into heat.Radiation is emitted in the form of electromagnetic waves.It transmits energy in the form of waves.Both radio waves and light waves are electromagnetic waves.Their propagation speed is very fast, the propagation speed in vacuum is the same as that of light wave (3 × 10 ^ 8 m/s), and slightly slower in air.Electromagnetic wave is a composite wave composed of waves of different wavelengths.Its wavelength ranges from 10E-10 microns (1 micron 10E-4 cm) of cosmic rays to radio waves with a wavelength of several kilometers.Gamma ray, X-ray, ultraviolet ray, visible light, infrared ray, ultra short wave and long wave radio waves all belong to the scope of electromagnetic waves.What can be seen by the naked eye is a very short section of the electromagnetic wave. The part from 0.4-0.76 microns is called visible light.Visible light longitudeprismAfter light separation, it becomes a band of seven colors, namely red, orange, yellow, green, green, blue, and purple. This band is called spectrum.Among them, the wavelength of red light is the longest, the wavelength of purple light is the shortest, and the wavelengths of other colors are in between.The wavelength longer than red light (>0.76 μ m) has infrared and radio waves;The wavelength shorter than purple light (<0.4 μ m) includes ultraviolet ray, gamma ray, X-ray, etc.Although the radiation is invisible to the naked eye, it can be measured by instruments.The wavelength of solar radiation is mainly 0.15-4 μ m, and the average maximum radiation wavelength is 0.5 μ m;The radiation wavelength of the ground and atmosphere is mainly 3-120 μ m, of which the maximum radiationwavelengthThe average is 10 microns.Traditionally, the former is called shortwave radiation, and the latter is longwave radiation.Radiation is emitted in the form of electromagnetic waves.It transmits energy in the form of waves.radio wavesAnd light waves are electromagnetic waves.Their propagation speed is very fast, the propagation speed in vacuum is the same as that of light wave (3 × 1010 cm/s), and slightly slower in air.[1]
characteristic
Announce
edit
Common electromagnetic and electric field radiation sources: radar systems, television and broadcast transmission systems, radio frequency induction, medium heating equipment, radio frequency microwave medical equipment, various electrical processing equipment, communication transmission stationsSatellite EarthCommunication stations, large electric power stations, power transmission and transformation equipment, high-voltage and ultra-high voltage transmission lines, subway trains, electric trains, computers and most household electrical equipment are all sources of electromagnetic radiation that can produce various forms of electromagnetic radiation with different frequencies and intensities.
Division of radiation field: radiation field is generally divided into far field and near field.[1]
Near field and its characteristics: the area centered on the field source within a wavelength range is usually called the near field, which can be called the induction field.
The near field usually has the following characteristics: in the near field, the electric field strength ismagnetic field intensityThe size of is not proportional.Namely: E1377H.In general, forVoltageFor field sources with high voltage and low current (such as transmitting antenna, feeder, etc.), the electric field is much stronger than the magnetic field. For field sources with low voltage and high current (such as molds of some induction heating equipment), the magnetic field is much larger than the electric field.The electric field intensity in the near field is much greater than that in the far field.From this point of view, the focus of electric field protection should be in the near field.The electric field intensity of the near field changes with the distance, which is relatively fast, and the non-uniformity in this space is large.[1]
Far field and its characteristics: the space range with the field source as the center and the radius outside of a wavelength is called far field, which can also be called radiation field.stayFar-fieldAll electric field energy basically propagates in the form of electronic wave radiation, and the attenuation of this electric field radiation intensity is much slower than that of the induction field.In the far field, the electric field strength and magnetic field strength have the following relationship. In the International System of Units, E=377H, the electric field and magnetic field are perpendicular to each other and perpendicular to each otherElectronic waveThe propagation direction of.The far field is weak, and the strength of the field wall is small.[1]
The significance of the division of near field and far field: for a fixed radiation source that can produce a certain intensity, the field wall intensity of near field radiation is large, so we should pay special attention to the protection of near field radiation.For the protection of radiation near field, the first is to protect operators and personnel in the near field environment, and the second is to protect various electronic and electrical equipment located in the near field.For the far field, because the strength of the field wall is small, the harm to people is usually small. At this time, the main factor we should consider issignalProtection of.In addition, there should be a concept of near field. For the frequency band from 30MHz in short wave band to 3000MHz in micro wave band, which we most often contact, the wavelength range is from 10m to 0.1m.[1]
Electromagnetic radiation test pen
Announce
edit
Detailed description of test pen: purpose: electromagnetic environment test:Computer RoomElectromagnetic radiation of electrical equipment such as control room, high-voltage line and transmitter tower;Computer, TV, copier, fax machine, cable, mobile phone, GSM base stationMicrowave OvenAnalysis of electromagnetic radiation of electrical equipment such as air conditioners and refrigerators.
Testing: testing the electromagnetic radiation protection function, testing the shielding function of electromagnetic protective clothing/protective materials, and testing theelectromagnetic radiationIncluding mobile phones, FM/TV/shortwave broadcasting, microwave ovens, computer wireless equipment, wireless communication, radio frequency transmitting equipment, etc;Demonstrate the relative strength and high sensitivity of various electromagnetic radiation sources.
Technical parameters: it can be used to test electric field strength, magnetic field strength, radiated power, static electricity, etc;TestedfrequencyRange: 5Hz~500Hz.[2]
Electron radiation
Electromagnetic radiation source
Announce
edit
Computer, as amodernHigh-tech products and electrical equipment, while bringing more convenience, efficiency and joy to people's lives, there are also some adverse factors harmful to human health.The hidden dangers of computers to human health mainly includecomputerElectromagnetic radiation (various electromagnetic rays and waves, etc.), sound (noise), light (ultraviolet ray, infrared ray, visible light, etc.) and other radiation "pollution" generated and emitted during work.What is the "magnetic radiation" generated by computers?When the current flows in the conductor, a magnetic field must be generated in its outer space, and the magnetic force lines with certain energy flow from one magnetic pole to the other constantly. We humans live in such a natural and artificialLarge magnetic fieldinIfmagnetic fieldIf it is too strong, it will cause "magnetic pollution" to the human body.[2]
The radiation of each component of the computer is: keyboard 1000v/m;Mouse 450v, 4n;Screen 218v, fia; host 170v, 4no.Compare the radiation amount and find that the radiation amount of the keyboard is the largest.[2]
Electromagnetic radiation verification
Announce
edit
Electron radiation
Domesticelectronic productThere are strict regulations on radiation, for example, the mandatory 3c certification is one of them, but from the actual situation, it is unrealistic to completely eliminate radiation in computer design.Therefore, as a user, we can avoid electromagnetic radiation problems by purchasing tco certified displays, selecting chassis from large brand manufacturers or using special professional anti radiation materials.althoughelectromagnetic radiationWe are always here, but as long as we have enough radiation knowledge and the correct use of computers, we do not have to panic about the electromagnetic radiation of computers.Experts have found that in fact, all daily household appliances that use electricity will produce electromagnetic radiation, which is harmful to human health. The most important thing is to see the size of the radiation energy.according toInternational Association for Radiation ProtectionandInternational Labour OrganizationAccording to the regulations of, the safety strength of electromagnetic field is 0.2-0.4 micro tera (this is the safety limit of electromagnetic field when contacting computer for 24 hours), and there is no harm to human body below this strength.Some specialized research institutions have tested the electromagnetic field strength of computers and found thatFluorescent screenThe intensity of electromagnetic field is 0.9, but it is less than 0.1 when it is about 5cm away from the screen, and then it is 30cm away (this is the habit between the computer operator's body and the screendistance）Its strength is almost impossible to measure.In addition, electromagnetic waves in space are indeed ubiquitous, but in general, the intensity of such electromagnetic radiation is very small and will not cause harm to human health.The Regulations on Electromagnetic Radiation Protection promulgated by China stipulates thatElectromagnetic radiation pollutionEquipment and personnelinfluenceOnly when the electromagnetic wave reaches a certain strength can it be protected[3]。
Thermal effect: more than 70% of the human body is water. Water molecules rub against each other after being radiated by electronic waves, causing the body to heat up, thus affecting the normal work of internal organs.[3]
Non thermal effect: there are weak electromagnetic fields in human organs and tissues, which are stable and orderly. Once disturbed by external electric field, the weak electric field in equilibrium will be destroyed, and the human body will also be damaged.[3]
Cumulative effect: after the thermal effect and non thermal effect act on the human body, before the damage to the human body can be self repaired (usually referred to as human endurance - internal resistance), it will be affected againElectron wave radiationIf so, the degree of injury will accumulate, and over time it will become a permanent pathological condition, endangering life.
For long-term exposureElectron wave radiationEven if the power is very small and the frequency is very low, it can also induce unexpected pathological changes in the body, so we should be alert.Electronic waves of various frequencies, especially high-frequency waves and strong electric fields, have a direct impact on the human body, which leads to unconsciously decreased energy and physical strength, and is prone to cataractleukemia、brain tumor，cardiovascularDiseases, brain dysfunction, women's miscarriage and infertility, etc., even lead to low human immune function, resulting in cancer and other diseases.Statistics show that the incidence of the above diseases is significantly higher among people who often work in front of monitors than among the general population.Electric field radiationIs one of the main reasons.[3]
There was a literature report: 1998world health organizationList five major effects of electromagnetic radiation on human body:
3、 Electromagnetic radiation is the inducing factor of abortion, infertility, malformation and other diseases of pregnant women;
4、 Electromagnetic radiation directly affects children's development and bone development, resulting in decreased visionRetinal detachmentHepatic hematopoietic function decreased;
5、 Although electromagnetic radiation can cause physiological function decline, female endocrine disorder and menstrual disorder, many media confuse "magnetic pollution" with "magnetic effect" of normal survival. What should be distinguished is:harmThe problem of human body comes from the "pollution" of excessive electromagnetic, which will not occur in products with appropriate application of electromagnetic shielding materials.From the data provided by many environmental protection materials, it can be seen that when the computer is running, the electromagnetic waves emitted by the chassis body and the display will cause damage to the surrounding environmentcontaminatedIs not conducive to health.[3]
prevention
Announce
edit
With the rapid development of science and technologydevelopmentAll kinds of scientific and technological products and household appliances have come into people's lives, which has greatly improved people's working efficiency and life. However, with the high voltage electricity and transmitting towers around the city getting higher and higher, there are more and more electrical equipment in the home. People feel convenient, but they are also hurt.Electromagnetic radiation pollutionIt has become the fourth largest environmental pollution after water, air and noise.From a professional point of view, electromagnetic radiation is the phenomenon that energy spreads through space in the form of electromagnetic waves.Almost any electrical appliance in our home will produce electromagnetic radiation.For example, microwave ovens, televisions, computers, mobile phones, etc.Protective clothing: including coats, vests, aprons, maternity clothes, etc., made of special fibers, with good electromagnetic radiation protectionAntistaticeffect.Especially families with microwave ovens should be equipped with protective aprons to effectively prevent electromagnetic radiation.Radiation shield: It has many functions such as anti radiation, anti-static, anti glare, etc. It also has a certain effect on protecting eyesight.Another way is to pay attention to time and distance.hurtThe degree is proportional to the time, that is to say, the longer you are exposed to electromagnetic radiation, the greater the damage you will suffer.It is inversely proportional to the distance. When the distance is ten times larger, the radiation received is one percent of the original, and when the distance is one hundred times larger, the radiation received is one thousandth.[3]
