1, radio communication
Radio broadcasting and television both utilize electromagnetic waves. In radio broadcasting, one first transforms sound signals into electrical signals, and then these signals are carried by high-frequency oscillating electromagnetic waves that propagate into the surrounding space.
And in another location, people use the receiver to receive these electromagnetic waves, and then the electrical signals are reduced to sound signals, which is the general process of radio broadcasting and in television, in addition to the sound signals to be processed as in radio broadcasting, but also the light signals of the image into electrical signals;
and then the two signals will be the same together by the high-frequency oscillation of the electromagnetic wave band to the surrounding space, and television receivers to spread. The television receiver receives these electromagnetic waves and then reduces the electrical signals into sound and light signals, thus displaying the picture of the television and the sound from the speakers.
Radio broadcasting utilizes electromagnetic waves at a very high frequency and over a very wide range, while television utilizes electromagnetic waves at an even higher frequency and over a much wider range.
2, medical
"Specific electromagnetic spectrum" (TDP) is a specific electromagnetic wave generated by a specific heater to the treatment plate with a wavelength range of 2-25μm, intensity range (28-35mw/cm2) distributed within the specific electromagnetic wave;
When the human body matches the reception with the same substances contained in the body cells to produce resonance, and thus can enhance the role of microcirculation, promote metabolism, resulting in the repair of the human body lesions, so that the sick can quickly recover, non-diseased patients can improve their own resistance.
3, other
In addition, electromagnetic waves are also used in cell phone communications, satellite signals, navigation, remote control, positioning, home appliances (microwave ovens, induction cookers) infrared waves, industrial, medical equipment and other aspects.
Electromagnetic spectrum
According to the length of the wavelength, starting from the long wave, electromagnetic waves can be categorized as radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays and so on. A spectrometer used for common experiments is sufficient to analyze electromagnetic waves with wavelengths ranging from 2 nanometers to 2,500 nanometers. Using such instruments, the detailed physical properties of objects, gases or even stars can be learned.
This is an essential instrument for astrophysics. For example, because of hyperfine splitting, hydrogen atoms emit radio waves with a wavelength of 21.12 centimeters.
The human eye can observe electromagnetic waves with wavelengths between about 400 nanometers and 700 nanometers, called 'visible light'.
For each type of electrodynamic molecule, there are microwaves corresponding to certain specific frequencies, causing the electrodynamic molecules to rotate along with an oscillating electric field, a mechanism known as dielectric heating.
Because of this mechanism (not heat transfer), the electrode molecules absorb the energy of the microwaves. Microwave ovens apply this principle of operation by rotating the water molecules to heat the food more evenly and reduce the waiting time.
Refer to Baidu Encyclopedia - Electromagnetic Waves
The above references? Baidu Encyclopedia - Electromagnetic Waves