Whether WIFI does radiation damage to human body is an important issue for everyone. In addition, my new home WIFI is installed at the bedside... Teacher So Hei also studied this problem by the way.
According to Weixin and Weibo, five Danish female high school students conducted an experiment to cultivate some celery seeds in rooms with and without WiFi transmitters. Twelve days later, they found that the seeds in ordinary rooms grew normally, while those in rooms with WiFi did not grow and turned brown. Some have even died.
This information has aroused heated discussion on the Internet, and many people are worried that WiFi devices will affect human health. But professionals believe that the impact of magnetic fields on plants or human bodies cannot be judged by a single incident.
In our daily life, the radiation produced by the TV and radio equipment when working is about 1 microwatt per square centimeter. In such an environment, of course, we will not feel any discomfort.
The test results show that the current smartphone on the market transmits power between 1.55 and 1.07 watts, which is infinitely larger than the Wi-Fi transmitter, and we still use mobile phones every day.
It's not that wireless Wi-Fi signals have absolutely no impact on the human body. It's reasonable to minimize the potential hazards. Of course, it's for the main ones, not the ones that don't matter. If you want to do this, you have to use your mobile phone first.
People usually use mobile phones very close to the brain, but the wireless routes connected may be far away from other rooms. Experiments show that the human body absorbs more microwave radiation after a 20-minute phone call than a year's wireless routing.
The microwave radiation of 20 laptops plus two wireless routers is almost the same as that of a mobile phone.
- Focus 1-
What is the WIFI signal?
WiFi signal is an invisible electromagnetic wave, which is essentially different from sunlight and mobile phone signal. It belongs to the microwave band of electromagnetic wave.
The X-ray of the hospital has a strong penetration ability, and WiFi's electromagnetic wave is pitiful and helpless by comparison.
The higher the frequency of electromagnetic wave, the stronger the penetration force. Generally speaking, the frequency of WiFi we use is only 2.4 GHZ-5 GHZ, and the frequency of light we usually see is more than 100,000 times that of WiFi. The higher the frequency of X-rays, the more magic...
According to the frequency, we divide electromagnetic wave into radio wave, microwave, infrared ray, visible light, ultraviolet ray, X-ray, gamma ray and so on.
The frequency band of mobile phone signal is mainly radio frequency electromagnetic wave (300KHz ~ 300GHz). Bluetooth, WIFI and other wireless signals are in this frequency band, belonging to decimeter wave. Millimeter wave, centimeter wave and decimeter wave are collectively called microwave, and the microwave ovens we use in our daily life also fall within this scope.
- Focus 2-
Ionizing and non-ionizing radiation
What do we usually say about radiation? How does it affect the human body?
We usually say that there are two kinds of radiation, ionizing radiation and non-ionizing radiation.
The essence of the two kinds of radiation are electromagnetic waves. The difference lies in the different frequencies and wavelengths. To be frank, the former is harmful to the human body, while the latter is harmless to the human body except to feel heat in the daily state.
Ionizing radiation (nuclear radiation)
High frequency, short wavelength and high energy can release electrons from atoms, molecules or other bound states, which can ionize substances, thus destroying DNA, killing cells and causing damage to the body while penetrating human tissues.
Common ionizing radiation includes X-ray, beta-ray, gamma-ray and so on.
X-ray is the application of chest X-ray film and CT that we are exposed to in the course of medical treatment. It is worth noting that ultraviolet radiation can cause various diseases such as cataract, skin cancer and accelerate skin aging.
In addition, long-distance air travel and smoking can also be exposed to ionizing radiation, the former mainly from cosmic radiation, while the latter is thorium-210, radium-226 and lead-210 these radioisotopes.
Non-ionizing radiation (electromagnetic radiation)
Long wavelength, low frequency and low energy will not lead to atomic or molecular ionization of matter. Common non-ionizing radiation in life includes microwave oven, wireless WIFI, mobile phone, radar, television, computer and so on.
Non-ionizing radiation does not kill cells or destroy DNA, but produces a thermal effect, which is the same principle as heating up the body caused by sunshine. There are two main effects of non-ionizing radiation on human body, one is induced current, the other is thermal effect.
Induced current is produced by low frequency radiation such as radio wave and long wave radio. High voltage wires, broadcasting and some household appliances can also produce this radiation, but the human body can not feel the induced current below 0.7mA. Even if we stand under 500kV high voltage line, the induced current is only 0.005mA.
In fact, the only proven hazard of non-ionizing radiation to the human body is the thermal effect, which means that radiation accelerates the movement of molecules and increases the temperature. This is the use of microwave oven heating food.
Although the frequency band of mobile phone signal is similar to that of microwave oven, the radiation of mobile phone signal is much lower than that of microwave oven because of the great power difference, so the thermal effect of human body is almost neglected.
Since the energy of electromagnetic wave is proportional to its frequency, the frequency of visible light is about 200,000 times that of electromagnetic wave, that is to say, at the same intensity, it can be used.