What is electromagnetic radiation? What is electromagnetic wave?
What is electromagnetic radiation?
An alternating electric field generates an alternating magnetic field, which in turn triggers an alternating electric field. That is to say, as long as there is an alternating electric field somewhere in space, a new alternating magnetic field will be generated around it, and this new alternating magnetic field will excite an alternating electric field in the distance. This alternating electric and magnetic field is called an electromagnetic field. This alternating electromagnetic field will propagate in space in a form similar to water waves, from near to far, which is called electromagnetic waves.
The phenomenon of electromagnetic waves being emitted into the air is called electromagnetic radiation. In the field of environmental protection, electromagnetic radiation usually refers to three physical phenomena or quantities: electric field strength, magnetic field strength, and radio interference.
What is electromagnetic wave?
There are two main sources of electromagnetic radiation (electromagnetic field):
(1) Natural phenomena such as light, lightning, and geomagnetic fields are electromagnetic phenomena in nature;
(2) Artificial (derived from electrical energy conversion) can be divided into two types: power frequency electric field, magnetic field, and radio frequency electromagnetic field.
The generation of power frequency electric and magnetic fields can be further divided into two situations:
Products such as color televisions, refrigerators, washing machines, computers, copiers, electric irons, dishwashers, electric mixers, electric ovens, hair dryers, heaters, air conditioners, stereo receivers, vacuum cleaners, electric stoves, and lights are the main sources of power frequency electromagnetic fields in homes and workplaces; High voltage transmission lines, substations and electric locomotives, light rail, maglev, etc. are the main sources of power frequency electromagnetic fields in the public environment.
A radiation source capable of generating radio frequency electromagnetic fields with a frequency greater than 100KHz. Common radiation sources include radio and television transmission towers, radars, mobile phones and base stations, satellite earth stations, microwave stations, microwave ovens, electronic anti-theft systems, etc. These are all RF electromagnetic field emission sources that can be seen everywhere in our daily environment.
Radio electromagnetic radiation can be divided into the following categories based on the working characteristics of artificial electromagnetic radiation sources in the public environment:
(1) Broadcasting and television transmission equipment?
Short wave, medium wave broadcasting, high-frequency broadcasting, television broadcasting, etc. The main departments are broadcasting and television in various regions
(2) Communication, radar, and navigation transmission equipment
Communication is the fastest developing industry in China, especially mobile communication. This category includes shortwave transmitting stations, microwave communication stations, ground satellite communication stations, mobile communication base stations, professional communication websites, paging communication base stations, various radar equipment and navigation equipment, etc.
Radar and navigation are mostly directionally and irregularly transmitted, and the transmitted signals are also radiated out through antennas.
Due to improper media promotion, in recent years, the vast majority of radio electromagnetic radiation disputes among urban and rural residents have been directed towards mobile communication base stations.
