红外线对人体的影响（The influence of infrared rays on human body）.docVIP

红外线对人体的影响（The influence of infrared rays on human body） What is the essence of infrared rays? What are the basic characteristics of it? To get to the bottom of these problems, first of all, you have to understand what electromagnetic waves are. Common sense in physics tells us that there is an electric field around any charged object that produces an action on the other charged body. Similarly, there is a magnetic field around a magnet or other magnet that produces an action on other ferromagnetic substances. Although the two fields can not be seen or touched, it is indeed an objective substance. It can be proved by a test instrument. Physicists found that, at any point in space, when the change of electric field intensity, produce magnetic field or magnetic field intensity changes around the point; on the contrary, when the change occurs in a magnetic field, will cause the change of electric field around or electric field strength of the new. That is to say, the changing electric field and the changing magnetic field are not isolated, they are interrelated and excited each other, forming a unified electromagnetic field. The so-called electromagnetic wave, the electromagnetic field is due to vibration caused by the vibration of water molecules to say like waves, to spread out from the near to the distant space. Since it is inevitable wave, wavelength and frequency of electromagnetic wave, the former refers to the length, often with micron, mm, cm, m unit; the latter refers to the electromagnetic vibration speed, i.e. the number of vibrations per second, often in Hz (1 Hz =1 / sec), kHz, MHz for the unit. As scientists have shown, electromagnetic waves travel at the same speed as light, or 300 thousand kilometers per second. Therefore, the relation between the wavelength and the frequency can be calculated according to the formula: Wavelength = speed / frequency In a general scientific book or an electronic instrument manual, what frequency do you have to tell as lon