What Is Electromagnetic Frequency?

An alternating electromagnetic field, or electromagnetic wave, that propagates in space. Its propagation speed in a vacuum is about 300,000 kilometers per second. Electromagnetic waves cover a wide range. Experiments have shown that radio waves, infrared, visible light, ultraviolet, X-rays, and gamma rays are all electromagnetic waves. The frequency of light waves is much higher than the frequency of radio waves. The wavelength of light waves is much shorter than the wavelength of radio waves. The frequencies of X-rays and gamma rays are higher and the wavelengths are shorter. In order to have a comprehensive understanding of various electromagnetic waves, people arrange these electromagnetic waves in order of their wavelength or frequency, wave number, and energy. This is the electromagnetic spectrum.

By wavelength, frequency, and

Radio wave

Wavelength from 3000 meters to 10 ^ -3 meters, general TV and radio broadcasting, mobile phones, etc.

According to the way in which various electromagnetic waves are generated, it can be divided into three components:

High frequency area (high energy radiation area)

These include x-rays, gamma rays, and cosmic rays. They are produced by bombarding certain substances with charged particles. These radiations are characterized by their high quantum energy, and when they interact with matter,

Different electromagnetic waves generate different mechanisms and methods. Radio waves can be artificially made

Electromagnetic waves are composed of photons. The electromagnetic waves emitted by stars in the deep universe contain a large number of photons. Because the photons are scattered during the transmission process, the farther they are from the star, the fewer the number of photons obtained per unit area per unit time. Of attenuation. The change in the frequency of the electromagnetic wave is small.

The electromagnetic spectrum of various types of radiation sources in nature is quite rich and wide. What is directly related to optoelectronic imaging technology is the X-ray, ultraviolet, visible light, infrared, and microwave electromagnetic spectra. Their characteristic parameters are wavelength , Frequency f and photon energy E. The relationship between the three is f = c / , E = hf = hc / and E = 1.24 / , where E and are eV (electron volt) and m, and h is the Planck constant ( 6.6260755X10 J · S); c is the speed of light, and its approximate value in vacuum is equal to

m / s, in engineering practice, according to different needs and habits, different units of spectrum parameter measurement.

For x-ray, ultraviolet, visible and infrared, m and nm are usually used to indicate the wavelength; for radio frequency spectrum, Hz or m is used to indicate its frequency and wavelength, respectively; for high-energy particle radiation, eV is often used to indicate energy.

It can be known from physics that the essence of "radiation" is the result of the energy level transition of the electrons in the atom and the exchange of energy. The low-level electrons are excited by some external energy and can transition to high energy levels. When falling into a lower energy level, energy is transmitted outward in the form of radiation. The above-mentioned E = 1.24 / is just to associate the wavelength of the radiation with its energy E. For example, when E high -E low = 1.24 eV, the wavelength of radiation = 1 m.