Businesses in order to prove that the radiation-proof clothing can shield radiation, you will be taught to wrap your cell phone in radiation-proof clothing, if you can not get into a phone call, it means that it is really shielded off! "radiation".
In the buyer evaluation, everyone has proved that the experiment does work. Plus an authoritative TV program has an expert stand for a brand of anti-radiation clothing to wave the flag.
Since even the experts have said so, it is better to buy a few pieces of radiation protection clothing, which is a kind of peace of mind.
But the business experts to do radiation experiments, really no interest in it? It is really harmful to prevent radiation? After reading this article, you will be able to judge for yourself.
In the article Dark Side of Light (above), we introduced the concept of light as an electromagnetic wave, the electromagnetic spectrum, and the powerful gamma rays. Next, other types of electromagnetic waves will be introduced.
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X-rays have wavelengths between 0.001nm-10nm, and are also high-energy short-wave rays. After reaching a certain radiation dose, it may damage DNA and increase the risk of cancer.
Almost every adult has experienced an X-ray, and then gotten a picture that shows the insides of the bones so the doctor can look at the damaged area.
This convenient medical treatment would have been unimaginable more than 100 years ago. At that time, it was very difficult for doctors to know what was going on inside the body without making an incision.
For this visual benefit, it was worth the risk to understand the injury. Even if x-rays are damaging, it depends on the size of the dose of visual radiation.
Just like gamma rays, which have a higher radiant energy than x-rays, they are almost harmless to the human body in small, precisely controlled doses.
03
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Ultraviolet light is in the 10-400nm band, and its radiation can kill bacteria with rapid DNA breaks.
For girls who focus on whitening, UV can be said to be the number one enemy! But how many people can distinguish between UVA and UVB?
In summer, if you don't do a good job of sun protection, your skin will easily be red, or even sunburned and peeled. This is because the epidermis absorbs UVB in the 280-320nm band and is damaged by the light energy carried by UVB, which can cause skin cancer in severe cases.
The wavelength of 320-400 UVA, its energy is less than UVB, will not cause serious skin damage. UVA can penetrate clothing and epidermis to reach the deep dermis. Out of the protective mechanism, melanin is deposited in the epidermis, making the skin darker to increase UV resistance.
Now it's clear that UVB causes skin damage and cancer, and UVA is the culprit behind skin darkening and aging.
Some entertainment venues use black lights to add to the ambiance, which radiate UV rays that can make fluorescent substances emit dreamy colors.
But there is a price to be paid for enjoying this kind of beauty. Exposure to UV light for too long can easily lead to cataracts and skin cancer.
As long as the proper protection, ultraviolet light is still quite useful, such as pest control, anti-counterfeiting, detection, printing and a wide range of fields are inseparable from it.
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The gamma rays, x-rays, and ultraviolet rays described in the previous section are electromagnetic radiation that can directly harm the human body, or cause cancer. The types of radiation described after this section are not harmful in this way.
Cosmic rays outside the electromagnetic spectrum, such as alpha rays, beta rays, these two types of rays belong to the high-speed charged particle stream, but and γ-rays, x-rays and the same belong to the ionizing radiation, are high-frequency, short-wavelength, high-energy rays.
Among them, α-rays and β-rays can be weakened by clothing and skin blocking. α-rays have the worst penetrating ability, but the radioactive radon gas released by building materials will decay into α-particles after entering the human body along with breathing, destroying the respiratory system and causing lung cancer.
The building materials that release the most radon gas are stone coal carbonized bricks 363±15Bq/m?, phosphogypsum 131±7.2Bq/m?, and granite only 31.5Bq/m?. To avoid radon gas damage, please do not stay in a small closed room for a long time and pay attention to keep ventilation.
Gamma rays and x-rays are usually used in industry, medical treatment and other fields, and ordinary people will not be exposed to them too much. The only equipment in the home that can emit x-rays is presumably the old-fashioned tube TV.
Ultraviolet light has low energy, is non-ionizing radiation, can be absorbed by the human skin, as long as the work of sunscreen, and to avoid direct vision, usually harmless.
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Visible light is an electromagnetic wave that can be seen by the human eye, with a wavelength range of about 380-770nm or so, and the range of feelings for each person is not fixed.
If you think visible light radiation is harmless, you are totally wrong!
In the radiation emitted by the sun, visible light radiation accounts for about 45-50% of the total, and its wave peak is concentrated between 400-500nm, which is the location of blue light.
Blue light has a shorter wavelength and higher energy, which can easily cause cataracts and macular degeneration after entering the retina. Blue light will also inhibit the pineal gland secretion of melatonin, affecting sleep.
So violet light is shorter in wavelength and higher in energy than blue light, isn't it more harmful?
Yes! However, in addition to UV lamps, life rarely use violet light appliances. So on the whole, blue light is more harmful.
Like cell phones, bathtubs, TVs, fluorescent lights, LED lights, all emit a lot of blue light radiation. The amount of blue light in warm white light is much less than cold white light, so it's best to use warm lighting for eye protection, and try to adjust your cell phone screen to a warm screen as well.
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Infrared wavelength between 760nm-1mm, above absolute zero "-273.15 ℃" of the material will produce infrared, people and animals will be the same will be emitted infrared, the gun in the film of the thermal imager
Infrared technology is a powerful tool for monitoring and searching for life forms, and it is based on this principle.
Infrared radiation produces heat by accelerating motion at the atomic level. Sunlight contains infrared rays, and when exposed to sunlight for long periods of time in the summer, infrared rays can overheat the body and cause death.
Of course, intellectually healthy people will hide in the shade when they feel hot, and won't die directly from the sun.
Infrared radiation is widely used in medical, night vision, thermal imaging, and other fields, such as light wave ovens in recent years, is the quartz tube in the oven, replaced by halogen tubes emitting infrared radiation, low-cost and high-efficiency.
In addition, infrared light has a see-through function, such as the ancient artifact Sony F717, with infrared night vision lenses, after adding filters, you can see through the clothes and directly shoot the body of MM.
Finally, it is worth mentioning that 5000-14000nm band infrared, absorbed by the human body, can activate the cells, enhance immunity and slow down the aging process, so it is also known as the life of the light wave.
This is due to the infrared emitted by the human body, the peak is about 9500nm, and the far infrared of the life light band overlap, can form **** vibration. So sunbathing around 8 o'clock will be good for your health.
Let's brainstorm a bit: qigong meditation, is it through bioelectricity, stimulated by this band of infrared **** vibration, and then strengthen the body?
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▌ Microwave
Microwave wavelengths between 1nm-1m, is the highest frequency band in radio waves. When it comes to microwaves, we should be most familiar with microwave ovens.
Microwaves in nature are very decentralized and do not produce heat. Microwave ovens through the magnetron and waveguide, will be converted into electrical energy rotating speed of 2.45 billion times / second microwave, only to do rapid heating of food.
Microwave ovens utilize the 3 characteristics of microwave reflection, penetration and absorption:
1. Reflection
Microwave will be reflected by the metal, so the microwave oven cavity using a non-magnetic metal plate, so that the microwave in the inside of the back and forth reflection of the heating food. You can't heat metal, precisely because metal can reflect interference and damage equipment such as waveguides.
Although the microwave oven door looks transparent, there is actually a layer of metal mesh, as long as the diameter of the mesh is less than 3mm, you can shield the microwave leakage "household microwave wavelengths for the decimeter.
2. Penetration
For plastics, bamboo, wood, glass and ceramics, microwaves can pass right through. This is the reason why these 3 types of tableware are used when heating. But be careful, always use microwave-specific tableware.
3. Absorption
Microwave wavelengths are longer and lower in energy than infrared, and infrared can vibrate at the atomic level, while microwaves can only accelerate the movement of the molecular level.
The absorption of microwaves in water is very strong, and food with high water content heats up faster. If you add a little water to the bottom of the bowl when you heat it, the food will heat up quickly and evenly.
▌ Short wave + medium wave + long wave
Radio waves can be transmitted through three ways:
1. Sky wave, relying on the reflection of the ionosphere in the atmosphere to propagate, the transmission distance is extremely long, subject to the influence of the climate, the signal is not stable enough.
Electromagnetic waves with a wavelength greater than 1m can be reflected by the ionosphere, and short waves are less absorbed by the ionosphere, which is suitable for sky wave propagation, and the reflection can jump 4000 kilometers once.
The ionosphere in the daytime density, conductivity, can absorb the radiation energy of the medium wave, the night ionospheric density decline, the same medium wave can also be transmitted over long distances.
2. Ground waves, which travel along the surface of the Earth, are transmitted over shorter distances, but the signal is stable.
Since the ground is also a conductor, the higher the frequency of the wave, the greater the absorption, so long waves are more suitable for ground propagation.
3. Straight wave, the Earth's surface is curved, the attenuation is very fast microwave short wave, in the visual range to establish a relay station, you can ensure its signal strength.
In terms of application, microwaves and ultra-short waves are commonly used in radio and radar technology, short-wave medium waves are used in mobile communications, broadcasting, and long-wave is mainly used in navigation and ocean communications.
Having said that, what exactly are radio waves indoors?
Radio waves are mainly directed outdoors, but when they enter the room, they are directed around the edges of obstacles.
That's the reason there's always wifi from other homes - they sneak in through window cracks.
Bypassed waves make up the vast majority of indoor radio waves, which evenly distributes the signal in the room. There are also a small number of high-frequency waves that are in a penetrating state, and the thicker the barrier they penetrate, the more they attenuate.
How scary is the radiation from a wall-penetrable wireless router?
The 2.4GHz transmitter power of a legitimate wireless router is limited to 100mW, which is the maximum power of the through-the-wall mode, and routers exceeding this power are banned from selling.
However, to be on the safe side, it's usually best not to increase the transmit power to 100mW, and never to buy an overclocked wireless card that claims to have a super strong signal.
Router radiation will be reduced with the distance, even if you open the through-the-wall mode, pull 1 meter distance, the radiation will be reduced several times, if the wall, the radiation is negligible.
So, just don't hold the router in your arms all day.
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Any electromagnetic radiation, can not be separated from the 3 major principles of radiation protection: distance, duration, shielding. The farther the distance, the greater the attenuation of electromagnetic waves; the shorter the time to be radiated, the more adequate shielding measures, the less harm.
The fear of the unknown is the root cause of the demonization of radiation!
Like the radiation suit mentioned earlier, the shielding is only part of the radio waves, according to the characteristics of the radio wave reflection, want to completely shield it, unless staying in the Faraday cage.
Other anti-radiation products, such as titanium rings and green plants, are used to deceive fools. Instead of worrying about the radiation of household appliances all day long, you should do the following:
1. Do a good job of protecting yourself from the sun, and get some sunshine in the morning.
2. Maintain indoor ventilation, do not stay in the closed room, decorate with good materials.
3. Use warm lighting, cell phone to adjust to the micro-warm screen.
4. Put the wireless router far away from the bed position, do not use the super standard rubbing card.
5. Don't take x-rays more than 2 times in a year.