What is electromagnetic radiation?

 Electromagnetic radiation is a type of energy that surrounds us from everywhere, and takes many forms, such as: radio waves, (microwaves), X-rays, and gamma rays, and sunlight is also a form of electromagnetic energy, while visible light is considered A small fraction of the electromagnetic spectrum, and it has a wide range of electromagnetic wavelengths.

Electromagnetic theory.

It was previously believed that electrical and magnetic waves are separate forces, however, in 1873 AD, the Scottish physicist (James Clark Maxwell) developed a unified theory of electromagnetism, as it is concerned with the study of electromagnetism, how electrically charged particles interact with each other, and with magnetic fields, and there 4 main types of electromagnetic reactions are:

 Magnetic poles are in the form of pairs that attract and repel each other, much the same as electrical charges do.

 An electric current through a wire creates a magnetic field whose direction depends on the direction of the current.

Maxwell also developed a set of laws; To explain these phenomena, they are called: (Maxwell's equations).

Waves and fields.

Electromagnetic radiation arises when an atomic particle, such as an electron, is accelerated by an electric field, moving it, and that motion produces electric and oscillating magnetic fields that travel in directions perpendicular to each other, in the form of a beam of light energy, called a photon, that these photons travel In the form of homogeneous waves at the fastest possible speed in the universe: 186,282 miles per second, (299,792,458 meters per second) in a vacuum, this speed is also known as the speed of light, and the waves have certain characteristics represented in frequency, wavelength or energy.

(Electromagnetic waves arise when an electric field (red arrow) combines with a magnetic field (blue arrow), and the magnetic field and electric field of an electromagnetic wave are in a position perpendicular to each other and with the direction of the wave).

The wavelength is the distance between two successive peaks of the wave, and that distance is measured in units of a meter, or fractions of it, and the frequency is the number of waves formed in a particular time, and it is usually measured by the number of revolutions per second, or Hz, and the small wavelength means that the frequency will be higher. Because one cycle will complete in less time, and likewise, longer wavelength has lower frequency; Because the cycle will take longer to complete.

The electromagnetic spectrum.

Electromagnetic radiation exhibits a huge range of wavelengths and frequencies, and this range is known as the electromagnetic spectrum, and the magnetic spectrum is generally divided into 7 regions, in the order of decreasing wavelength, increasing energy and frequency, and the common names are: radio waves, microwaves, and infrared rays Red, visible light, ultraviolet rays, X-rays, and gamma rays, and usually, the lower energy radiation, such as: radio waves, is referred to by frequency, and referred to as microwave, infrared, visible light, and ultraviolet rays. , In wavelength, and the higher energy radiation, such as: X-rays and gamma rays, are referred to as the energy per photon.

Radio waves.

Radio waves are found in the lower range of the electromagnetic spectrum, with frequencies up to about 30 billion Hz, or 30 gigahertz (GHz), and wavelengths longer than about 10 millimeters (0.4 inches). Radio (radio) is used mainly in the field of communications that include Voice, data and entertainment.

Microwaves.

Microwaves fall in the electromagnetic spectrum between radio waves and infrared rays, and have frequencies between 3 GHz, 30 trillion Hz, or 30 terhz (THz), and wavelengths between 10 millimeters (0.4 inches) and 100 micrometers ( 0.004 in.), Microwave is used in high-bandwidth communications, radar, and as a heat source in microwave ovens, and industrial applications.

Infrared.

Infrared rays are located in the electromagnetic spectrum between microwave and visible light, and they have frequencies between 30 terHz and about 400 terHz, and wavelengths between 100 micrometers (0.004 inches) to 740 nanometers (0.00003 inches), Infrared rays are invisible to the human eye, but we can feel them as heat, if the intensity is sufficient.

Visible light.

Visible light lies in the middle of the electromagnetic spectrum, between infrared and ultraviolet, and has frequencies between 400 terhz and 800 terhz, and wavelengths between 740 nm (0.00003 inch) to 380 nm (0.000015 inch) In general, visible light is known as the visible wavelengths of most human eyes.

UV rays.

UV rays fall in the electromagnetic spectrum between visible light and x-rays, and have frequencies between 8 * 1014Hz to 3 * 1016Hz, and wavelengths between 380 nanometers (0.000015 inches) to 10 nanometers (0.0000004 inches). ), And ultraviolet light is made of sunlight, however, it is not visible to the human eye, and despite the presence of many medical and synthetic applications for it, it can destroy living tissues.

X ray.

X-rays are classified into two types: light X-rays and sharp X-rays, light X-rays occupy the electromagnetic spectrum between ultraviolet rays and gamma rays, and have frequencies between 3 * 1016 Hz and 1018 Hz, and wavelengths between 10 Nanometers (0.0000004 inch), to 100 pm (4 * 10-9 inches), while sharp X-rays occupy the same space of the electromagnetic spectrum as gamma rays, and the only difference between them is the source of both: X-rays are generated by accelerating electrons, while they are generated Gamma rays in the atomic nucleus.

 

Gamma rays.

Gamma rays fall in the electromagnetic spectrum above the light X-rays, and have frequencies higher than 1018 Hz, and wavelengths less than 100 pm (4 * 10-9 inches), and these rays destroy living tissues, making them useful for eliminating cancer cells when used in doses Carefully calculated over small areas; Therefore, exposure to it in an uncontrolled way makes it extremely dangerous for humans.