Basics of radiation protection lenses_ electromagnetic radiation

Basics of radiation protection lenses: electromagnetic radiation

Electromagnetic radiation has become an important source of environmental pollution, directly affecting the living environment of human beings, and the United Nations Conference on the Human Environment has listed electromagnetic radiation as one of the public hazards that must be controlled. Electromagnetic radiation exists in a wide range of fields, whether in the professional workplace or in the home environment, human beings will be exposed to different degrees of electromagnetic field irradiation. The following is an introduction to the basic knowledge of electromagnetic radiation of radiation protection lenses. Electromagnetic radiationElectromagnetic waves are a form of motion of an electromagnetic field. Electricity and magnetism are two sides of the same coin, and the fluctuating electricity will produce magnetism, and the fluctuating magnetism will produce electricity. The changing electric field and the changing magnetic field constitute an inseparable and unified field, that is, the electromagnetic field, and the propagation of the changing electromagnetic field in space forms electromagnetic waves. Electromagnetic waves are transverse waves that can be transmitted with the help of a tangible medium. When the frequency is low, it is mainly transmitted with the help of a tangible conductor, and almost all of its energy is returned to the original circuit without radiation. When the frequency of electromagnetic waves is high, it can be transmitted in the marching medium or in free space. The principle of transmission in free space is that in high-frequency electromagnetic oscillations, the magnetoelectric interchange is fast, and the energy cannot all return to the original oscillation circuit, so electrical energy and magnetic energy propagate energy to space in the form of electromagnetic waves with the periodic change of electric field and magnetic field, which is a kind of radiation. The magnetic field, the electric field, and the direction of travel of an electromagnetic wave are perpendicular to each other. The amplitude varies periodically along the perpendicular direction of propagation, its intensity is inversely proportional to the square of the distance, its energy power is proportional to the square of the amplitude, and its velocity is equal to the speed of light c (3 x 108111/s per second). Refraction, reflection, diffraction, scattering, and absorption occur when passing through different media. The longer the wavelength, the less attenuation, and the longer the wavelength, the easier it is for electromagnetic waves to continue to propagate around obstacles. The electromagnetic waves produced by the interaction of electric and magnetic fields are electromagnetic radiation. Electromagnetic radiation is a special form of matter that cannot be seen or touched. The earth itself is a large magnetic field, and the thermal radiation and lightning on its surface can produce electromagnetic radiation, and the sun and other planets also continuously produce electromagnetic radiation from outer space. The natural magnetic fields, sunlight, and household appliances that surround us all emit radiation of varying intensity. The energy derived from electromagnetic radiation depends on the frequency, the higher the frequency, the greater the energy. X-rays and gamma rays, which are extremely frequent, produce large amounts of energy and are capable of destroying molecules that synthesize human tissues. In fact, the energy of X-rays and gamma rays can ionize atoms and molecules, so they are classified as "ionizing" radiation. The electromagnetic energy produced by X-rays and gamma rays is different from the electromagnetic energy produced by radiofrequency emitting devices. The electromagnetic energy of RF devices is classified as "non-ionizing" radiation because it is at the lower end of the spectrum and cannot break the chemical bonds that hold the molecules together. These two types of radiation have a wide range of applications in medicine, but excessive exposure can be harmful to health. The electromagnetic spectrum includes a wide range of electromagnetic radiation, from very low frequency electromagnetic radiation of a few hertz to very high frequency electromagnetic radiation of several hundred million hertz. In between, there are radio waves, microwaves, infrared, visible light, and ultraviolet light, among others. According to the type of radiation, it can be divided into ionizing radiation, non-ionizing radiation with thermal effect, and non-ionizing radiation with ineffective effect. The frequency range of electromagnetic waves is from the ultra-long wave of 3 kHz~30 kHz to the wavelength of 300 GHz~3 Thz. Band Name Frequency Band Range (Including Upper Limit but Not Lower Limit) Band Name Wavelength Range (Including Upper Limit but Not Lower Limit) Very Low Frequency (VLF) 3 kHz ~ 30 KHz (KHz) Very Long Wave 100 km~l0 km Low Frequency (LF) 30 kHz ~ 300 KHz (KHz) Long Wave 10 km~l km Medium Frequency (MF) 300 kHz~3 000 kHz (KHz) Medium Wave 1000 m~l00 m High Frequency (HF) 3 MHz~30 MHz (MHz) Short Wave 100 m~l0 m VHF(VHF) 30 MHz~300 MHz meter wave 10 m~l m UHF 300 MHz~3 000 MHz (MHz) Decimeter wave 100 cm~l0 cm UHF (SHF) 3 GHz ~ 30 GHz Centimeter wave 10 cm~l cm Extremely high frequency (EHF) 30 GHz~300 GHz (GHz) Millimeter wave 10 mm~l mm to high frequency 300 GHz~3 000 GHz (GHz) Silk meter wave 1 mm~0.1 mm。