First, electromagnetic interference is everywhere
1. A star-studded planet
The most harmful to humans by electromagnetic interference is actually the earth we live in. Thunder and lightning interference is the most harmful to human life. Lightning not only poses a great threat to human survival, but also causes great damage and damage to trees, forests, houses, buildings, and electrical equipment.
According to statistics, the Earth has more than 100 lightnings per second. The energy generated by each lightning can be lit up by a 100-watt bulb for three months. In the rainy season, one person is hit by lightning every six minutes. Thousands of people were killed by lightning strikes, and large forests were hit by fire and lightning. The lightning also often caused high-voltage power grids and communication failures, disrupting urban power supply and communications, causing urban traffic. There was chaos out of control; even the Buckingham Palace in the UK was severely damaged by lightning. In the 1950s, Buckingham Palace was hit by a piece of curtain cloth that was hit by lightning; Shanghai TV station suffered an average of 33 large lightning strikes per year. Lightning strikes will cause electronic equipment to suffer varying degrees of damage; on June 22, 1992, multiple computer interfaces of the Beijing National Meteorological Center were destroyed by inductive lightning strikes, losing more than 20,000 yuan; on August 23, 1992, 60% of Chenzhou City Cable TV and 50% of CCTV have been struck by lightning, 91 of which were destroyed by lightning strikes; on June 9, 2006, a large passenger plane in South Korea was caught in the air. Suddenly, the head disintegrated and fell off. Fortunately, there were no casualties.
Many people are not clear, the earth is also a charged body. According to experimental tests, there is a vertical downward stable electric field on the surface of the earth. The electric field strength E is about 100 volts/meter, and the magnitude of the field strength decreases with increasing height. In addition, according to experimental tests, the conductivity σ0 of the atmosphere near the ground is about 3 & TImes; 10-14 Simon / meter, and increases with height. It can be seen that the direction of the current density j of the earth's surface points to the center of the earth, and the size is:
The charging mentioned here is strictly speaking the potential difference of the charged body with respect to infinity, or the potential neutrality of the object. When people conduct theoretical analysis, they define the infinity as zero potential, but in practical applications, people have become accustomed to treating the earth as zero potential, which will not have a big impact on general practical applications. But this assumption sometimes hinders our horizons.
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