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What is Electromagnetic Wave?

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Nowadays, we come in contact with daily waves such as telephone waves, radio waves, radio waves …. Each type of wave will have different characteristics. All of these types of waves are also collectively referred to as electromagnetic waves. There are many technologies that use electromagnetic waves to connect and transmit data. These applications appear daily and attached to our lives. In this article I will introduce you to the basics of electromagnetic waves.

1. What is Electromagnetic Wave?

Electromagnetic waves, or electromagnetic radiation, are a combination of vibrating electric and magnetic fields perpendicular to each other. They will propagate through space as a kind of wave, and because they are waves they will have a particle property often called a “photon”. During the propagation of electromagnetic waves, they will carry information, energy and momentum. The wavelengths of electromagnetic waves will fall between 400nm and 700nm and they can be observed with the naked eye through the light they emit.

Characteristics of electromagnetic waves

Typically, electromagnetic waves will have similar characteristics and, in particular, they will have the following characteristics:

  • They can be spread in solid, liquid, gas and vacuum environments and they are the only type of wave that can be spread in a vacuum.
  • They also have properties of mechanical waves such as reflection, refraction, interference, etc.
  • Electromagnetic waves with wavelengths from several meters to several kilometers used in communication are called radio waves
  • The electromagnetic wave is of the horizontal wave type, which means that it is the propagation of vibrations related to the directional property (namely the electric and magnetic field strength) of the elements whose direction is perpendicular. with the direction of wave propagation.
  • The speed of propagation of electromagnetic waves in a vacuum is greatest and is equal to c = 3,108 m/s.
  • Oscillation of electric and magnetic fields at a point is always in phase with each other.

2. Classification of electromagnetic waves

Electromagnetic waves will have the same nature, but the factors used to classify their radiation will be their wavelength, associated energy level, and frequency of transmission. For each specific wavelength, frequency and energy level we will have a different type of wave. And so the application of that kind of wave in reality is completely different. Specifically we have 7 types as follows:

  • Radio waves: has a wavelength of 1mm ~ 100000km, frequency of 300 MHz ~ 3 Hz, energy carrying is 12.4 feV ~ 1.24 meV.
  • Microwaves: wavelength is 1 mm ~ 1 m, frequency is 300 GHz ~ 300 MHz, energy carrying is 1.7 eV ~ 1.24 meV.
  • Infrared: with wavelength of 700 nm ~ 1 mm, frequency of 430 THz ~ 300 GHz, energy carrying is 1.24 meV ~ 1.7 eV.
  • Visible light: is the type of light visible to the naked eye, they have a wavelength of 380 nm ~ 700 nm, frequency is 790 THz ~ 430 THz, energy is 1.7 eV ~ 3.3 eV.
  • Ultraviolet rays: wavelength is 10 nm ~ 380 nm, frequency is 30 PHz ~ 790 THz, energy is 3.3 eV ~ 124 eV.
  • X-rays: has wavelength of 0.01 nm ~ 10 nm, frequency is 30 EHz ~ 30 PHz, energy carrying is 124 eV ~ 124 keV.
  • Gamma waves: wavelength is <= 0.01 nm, frequency is >= 30 EHz, energy is 124 keV – 300+ GeV.

3. Features of each wave type

In the process of interaction between molecules, atoms or elementary particles. The properties of electromagnetic waves will depend more or less depending on the wavelength of each type. And here are some specific evidence:

3.1 Radio Waves

Radio waves usually have little interaction with matter because the energy of the photons is very small. Therefore, they can travel over long distances without losing energy for interaction, thus being used to transmit information from a distance, such as in radio and broadcasting techniques.
When we acquire radio by antenna, we take advantage of the interaction between the electric field of the wave and the conducting material. Electric currents will oscillate back and forth in the conductor under the influence of electrical vibrations in radio waves.

3.2 Microwaves

The most common type of this wave is in the microwave application. The oscillation frequency of the microwave will coincide with the resonant frequency of many organic molecules and in foods. The waves in microwaves are therefore strongly absorbed by the organic molecules and heat them up, when the wave energy is converted to the thermal energy of the molecules. The degree of influence of microwaves in microwaves is as follows:

  • Mild level: the wave will denature some of the protein molecules in the cell, that is, cause a slight distortion of the molecular structure, it will not die and still be involved in living activities of the cell. If this discrepancy occurs in the DNA molecule, then if the lymphatic system is not strong enough to eliminate these defective cells then they develop into cancer.
  • Heavy level: will be strongly modified, the molecule can no longer participate in living activities. If the number of molecules is greatly modified, the cell dies.

>>> Because of the nature of this type of microwave wave we have mentioned above, we should be careful in using devices or microwaves. Since the waveguides cannot block the entire emitted wave, it is necessary to keep the distance from the microwave at least 1m.

3.3 Infrared

Infrared rays are also electromagnetic radiation and have longer wavelengths than light waves, shorter than microwaves. The phrase “Infrared” means the wavelength will be below the wavelength of red light.
In medicine and treatment, infrared rays are often used to treat diseases. Helps destroy damaged or damaged cells. In addition, it can be used to diagnose diseases.

3.4 Visible Light

For this part, needless to say you can feel it for yourself. Light waves help us recognize colors in space. sunlight through the prism or through the steam curtain after rain will also create a light rainbow of 7 colors.

3.5 Ultraviolet-rays

Ultraviolet rays are radiation with wavelengths of 10-8m to 10-7m and frequencies from 3000THz to 3.1016Hz. They are emitted from sources with temperatures above 300 ?C, in sunlight or in electrical arc and mercury lamp applications.

3.6 X-rays

X-rays are also a type of electromagnetic wave commonly used in medicine. Especially the applications for the treatment of shallow cancers. Destroying excess cells such as keloid scars. In addition, they are also used in radiological fields, in orthopedic injuries.

3.7 Gamma Waves

Gamma rays have a wavelength range of 10-14m to 10-10m. The difference between gamma and X-ray radiation is at the origin: gamma radiation is emitted from the atomic nucleus, while X-rays are generated outside the nucleus.

Above is the information and knowledge related to electromagnetic waves. Hope to be helpful for you in the learning process. Because it is the knowledge gathered from websites, it will inevitably make mistakes, and look forward to your contributions through the comment below.

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