电脑辐射最大在键盘谣言（Computer radiation at the keyboard The rumor）

电脑辐射最大在键盘谣言（Computer radiation at the keyboard The rumor） 电脑辐射最大在键盘谣言(Computer radiation at the keyboard The rumor) Computer radiation at the keyboard? The rumor? Some netizens wrote that the computer radiation is the biggest in the keyboard, and there are specific Numbers: 1. Keyboard 1000V/m; 2. Mouse 450V/m; Screen 218V/m; 4. Mainframe 170V/m. These Numbers are very real, and they seem real and scientific. In fact, this is just netizens' ignorance of the science. (1) make clear four units: electric field intensity, magnetic field intensity, magnetic induction intensity, and power density 1. Electric field intensity (E), whose unit is volt/meter, or "V/m", the electric field intensity is used to describe the intensity of the space electric field. 2. Magnetic field intensity (H), whose unit is ampere/meter, also known as "A/m", magnetic field intensity is used to describe the intensity of the space magnetic field. 3. Magnetic induction intensity (B), whose unit is tesla T, is a basic physical quantity, which should be specified in particular: Magnetic field intensity and magnetic induction intensity are both physical properties of magnetic fields, and the strength of magnetic field can be expressed in two ways: In the case of uniform magnetic media, the magnetic induction intensity B is used to represent the tesla T, which is a basic physical quantity when the magnetic field is included in the magnetic field. The magnetic field that is caused by the current or the motion charge alone (excluding the magnetic field generated by the magnetization of the dielectric) is represented by magnetic field intensity H, and its unit is A/m, which is an auxiliary physical quantity. Due to historical reasons, and the electric field intensity corresponding to describe the basic physical quantities of the magnetic field is known as "magnetic induction intensity" (not called magnetic field strength), and the other auxiliary materials are referred to as "magnetic field", it is really a bit inconsistent actuality, easy to confuse. But there's no way to do it, because you're going to have to use the good name first, and then the convention is done. The Internet also often USES magnetic induction intensity, or tesla (T), to illustrate the magnitude of electromagnetic radiation. 4, power density, said at a point in space on the electromagnetic wave energy, the international unit for W/m ^ 2. The concept of poynting, he thinks that the electric field in an electromagnetic field intensity and magnetic field intensity H E fork the vector obtained by the E x H, on behalf of the field can flow density, namely in unit time through the perpendicular to the direction vector of the surface of the unit of energy. The power density actually includes electric field strength and magnetic field intensity. (2) the division of electromagnetic radiation fields The electromagnetic radiation field is generally divided into the distance zone and the near area field. 1. Near field and features. The field source as the center, in a region of a wavelength range, is usually called the near area field, and the near field usually has the following characteristics: Near the field, The intensity of electric field has no definite proportional relation with the magnitude of magnetic field intensity. In general, the electric field is much stronger than the magnetic field in the field source (such as the transmitting antenna, etc.) of the voltage high current. The magnetic field is much larger than the electric field for the current large field source. The intensity of the electromagnetic field in the near field is much larger than that of the distant field. From this perspective, the focus of electromagnetic protection should be in the near field. The intensity of electromagnetic field in the near field is faster than that of distance, and the inhomogeneity in this space is larger. 2. Remote field and features At the center of a field source, the radius is a range of space beyond a wavelength, which can also be called a radiation field. The main features of the remote field are as follows: In the remote field, all electromagnetic energy is transmitted in the form of electromagnetic radiation, which is much slower than the induction field. In the field, the intensity of the electric field is related to the strength of the magnetic field: in the international system of units, E = 377H, the field of electric field and magnetic field are perpendicular to each other, and are perpendicular to the propagation direction of electromagnetic waves. The field is weak and its electromagnetic field is less intense. 3. The significance of the division between the near field and the far-field field Usually, for a fixed can produce a certain intensity of electromagnetic radiation sources, radiation area near field of electromagnetic field intensity is bigger, so we should especially pay attention to area near field electromagnetic radiation protection. The protection of the electromagnetic radiation near the field is firstly the protection of the workers and the personnel in the near area environment, and the second is the protection of various electronic and electrical equipment in the near field. The main factor that we should consider is the protection of signal. In addition, there should be a concept of the near area field, the frequency range of 3000MHz from the short wave segment 30MHz to the microwave segment that we are most frequently exposed to, the corresponding wavelength range from 10 meters to 0.1 meters. Measurement units used in electromagnetic radiation measurement 1, to more than 300 MHZ microwave frequencies, the average power density of mW/cm ^ 2 as the unit of measurement; 2. Less than 300MHZ frequency band, using the electric field intensity V/m and magnetic field strength A/m as the unit of measurement. In the measurement of electromagnetic environment, the measurement standard of interference field strength is in mV/m. (iv) national standards Environmental electromagnetic wave allowable radiation intensity grading standard (gb9175-88) The wavelength unit allows the field level (safety zone) level 2 (intermediate zone). Long, medium, short wave V/m < 10 < 25 Ultra short wave V/m < 5 < 12 Microwave mu W/cm2 < 10 < 40 Mixing V/m is strong on main band; If each band field is strong dispersion, according to the composite field strength weighted determination. In the analysis of electromagnetic radiation environment in general, should choose "environmental health standard" electromagnetic waves (GB9175-88), according to the main radiation source frequency, according to the reference table, find its radiation intensity threshold. The standard limit value is: in long, medium and short wave, the intensity of electric field should be less than 10V/m. In the ultrashort wave segment, the electric field intensity should be less than 5V/m; In the microwave band, the radiation power density should be less than 10 mu W/cm2. Considering the protection of workers in the electromagnetic radiation environment, we recommend that the corresponding limits of the electromagnetic radiation protection regulation (gb872-88) be adopted in the field of occupational safety and health. In this way, we can clearly see that the national standards of electromagnetic radiation are very severe. For long, medium, short-wave and ultra-short wave, even the second level of allowable field intensity is only 25V/m. Since this standard is mandatory, this means that all electronic products with radiation intensity greater than 25V/m are unqualified products and cannot be sold in the Chinese market at all. If you have unfortunately bought such products, please contact 12315. I think you will get double compensation. (5) some discussion on theory on the Internet So how do you get the data that is being passed online? This may be the result of private testing of some students who are interested in electromagnetic radiation. In some electronics stores, it is easy for college students to buy a simple scale to test electromagnetic radiation, with a small sensor in front of it. But once the meter is unable to "treat" the keyboard, mouse, monitor, and host, the results will be a far cry from the actual situation. And, in terms of electromagnetic radiation, 1000V/m is a very striking order of magnitude, how can it come from a small keyboard? Theoretically, the higher the electricity consumption, the higher the probability of electromagnetic radiation. Among the keyboard, mouse, monitor, and host four, it is obvious that the host and monitor consume more power. The size of the radiation depends on the size of the radiation source, and the most serious radiation on the computer is the CRT monitor, which is not very large. CRT display is very big, so there are high voltage coil radiation and using is close, the mouse and keyboard power is small, the inside of the electronic components is very few, so can't more than the display. And the iron sheet of the chassis itself has certain shielding radiation function. When it comes to the electromagnetic radiation of the computer, the CRT monitor is the most serious. As we all know, the CRT display is transmitted by electron beam. And foreign electronic launch itself will generate serious electromagnetic radiation, while the thick leaded glass screen can block radiation to a certain extent, but there are still many electronic through blocking layer and direct exposure to the user. According to the definition of physics, radiation from CRT monitors is mainly divided into light radiation, low-energy X-ray, radio field, electrostatic field and low-frequency electromagnetic field. Which is the most serious damage to human body health low frequency electric field, it is mainly composed of the power of the display part (ignition coil), vertical and horizontal scanning electricity places between 5 hz ~ 400 hz frequency electromagnetic field. (6) radiation value test for desktop computers, laptops and accessories (measuring magnetic induction strength) It is said to be a test of laptop radiation, desktop computer radiation, display radiation and other peripheral radiation-value measurements from BTV's "science and education watch". I hope I can provide some references for friends who want to know how much radiation the computer has. CRT monitor radiation test. The screen is glued to the 1.00 mu T, and the display is attached to the side of the display. The center of the display, 0.03 meters from the screen, and 0.55 mu T of radiation, is this CRT monitor really as big as we think? What is the safe distance? The test results showed that the radiation in front of the display decreased to 0.18 mu T when the distance was 0.2 meters, so the CRT display can be used safely as long as the distance is 0.2 meters. Does a computer CRT monitor have the same radiation as a CRT TV? After the test, the discovery was not large. Some people like to use anti-radiation screensavers, does it work? After tests showed that only 10% of the screensaver radiation was reduced, the screensaver did not appear to be significant. LCD liquid crystal display radiation test. The display screen is 0.11 mu T at 0.12 mu T, and 0.11mu T is switched on and 0.11mu T is turned off, and the display side of the display is 0.05m 0.12mu T. It seems that the LCD is quite reassuring. Desktop computer host radiation test. The first 0.17 mu T, but the main operating panel of the host operation is slightly stronger, the distance is 0.03 meters, 0.26 mu T; The main engine side is 0.29 mu T, the left side of the chassis is in the center, and the distance is 0.03 meters, 0.23 mu T. It's 0.46 mu T, but we usually have some distance from behind the host, so it doesn't matter much. And the boot moment, standby state is 0.17 mu T. The other thing to say is the desktop computer power connection if the radiation in the connection state is 0.47 mu T, so it should be kept at a distance when using the desktop computer. The sound box radiation test. Operation panel center, distance 0.03 meters, 0.63 mu T; The center of the right side of the speaker box is 0.03 meters, 5.68 mu T; Radiation is not small, so what is its safe distance? After careful testing, when the distance was 0.4 meters, Its radiation is reduced to 0.17 mu T. Therefore, the low-pitched sound box is severely radioactive, and should be kept at least half a meter. Normal mouse radiation: 0.1 mu T. Normal keyboard radiation: 0.11mu T. Wireless mouse radiation: 0.53 mu T over the mouse. Wireless keyboard radiation: 0.96 mu T above the keyboard. Wireless router radiation: 0.15 mu T above the router. Printer radiation: 0.11 mu T. Digital camera power adapter radiation: 0.11mu T MP4 power adapter radiation: 0.16 mu T Laptop radiation test. The display front is 0.1m 0.13mu T, 0.10mu T in front of the display, 0.13m 0.13mu T on the side of the display, 0.19mu T above the keyboard, and 0.22mu T of the power adapter. The test results show that the laptop has a slightly higher radiation and the largest power adapter. Computer radiation test results: LCD screens have small radiation and a slightly larger CRT display, but all are safe; The rear side of the host, the side radiation is bigger, the strong suggestion do not want to heat the convenience, open the case to use; The low-pitched sound box radiation is serious, at least half meter distance is used; Laptop radiation is concentrated on the top of the keyboard and should be kept at a distance from the power adapter when using the laptop. The normal keyboard, mouse, and wireless gateway, printer, digital camera and MP4 power source are not much radiation, but can be used safely. But wireless keyboard, wireless mouse radiation is bigger. (7) an article on the Internet that has a computer screen that has an electric field strength and magnetic field intensity If a substation is built around the neighborhood, will it have an impact on life? The question has also been a concern for shen mengpei, a representative of the state council and the municipal legislature. "I was trained in science, and it was only with objective and real data that I could stand the test." Shen, who served as a researcher at the China seismological bureau analysis and forecasting center, asked experts to test the electromagnetic environment in our lives. At 4 p.m., the most mundane household appliances in Mr. Shen's home became the "target" of yuan's capture. He put the test distance limit for these appliances near 10 centimeters or so, whenever tester is close to the target, the numerical are a bit surprised how much a: energy-saving lamp tube of the electric field intensity of 230 v/m, computer screen of the electric field intensity and magnetic field intensity, respectively is 15 v/m and 0.88 tesla, no boot refrigerators electric field intensity of 39 v/m, magnetic field intensity is 0.2 tesla, and the intensity of microwave electric field intensity and magnetic field respectively 4 v/m and 17.5 tesla. It is clear that many of the values measured in household appliances are higher than the so-called "electromagnetic radiation" of the substation. Cactus anti-radiation, rumor! Scientific experiments show that cactus is placed near a computer to prevent or absorb radiation. Cactus just absorbs ultraviolet radiation from the sun and the computer emits electromagnetic radiation. The spread of cactus to prevent the absorption of computer radiation is just a business copy. Celestial being itself, radiation protection, put it on the computer, it can absorb radiation, but the radiation from the radiation source is ray to direct out around him, according to this one had to hide at the back of the celestial being to avoid radiation. (radiation, which is a straight line, does not move towards it because of an object, but unless it is a black hole) there is no scientific basis for the cactus radiation. Cellphone radiation can be boiled eggs? ! Rumors! Some netizens did the experiment as follows: Internet phone microwave radiation can boil eggs, according to the method of online, I also prepared two mobile phones, plus the FM radio as a way to simulate the call hr30min tested a total of 2. After hand over eggs no fever and no abnormal reaction, reoccupy two instrument + antenna, two mobile phones were sent to the two instruments, and the phone power transferred to the largest, eggs are added to the mobile phone, and he made more than two hours. Until the phone was out of power, the eggs were not cooked, and there was no heat, and there was no online phenomenon of boiling eggs. But believe this egg no one dare to eat ~