Keywords:
Electromagnetic spectrum
Visible spectrum
Ultraviolet
Abstract Electromagnetic radiation is emitted from sources in space and from anthropogenic sources on earth. It travels at a constant speed, i.e., the speed of light. The overall electromagnetic spectrum is illustrated in Figure 10–1. Energy is transmitted as a sinusoidal wave form, by time varying electric and magnetic fields. The transmission velocity, c, is described by the formula: The health effects of exposures to the various components of the electromagnetic spectrum vary greatly with frequency, and the discussion that follows outlines the sources, as well as the nature and extent of the effects that they produce. There are separate discussions on component bands within the overall spectrum, i.e., ionizing radiation, UV, visible, IR, and radio frequency (RF). The electric and magnetic fields induced by these radiations can also produce biological responses, and these responses will also be reviewed.
Electromagnetic spectrum
Non-ionizing radiation
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‘Electromagnetic waves’ considers the history of the scientific investigation into the electromagnetic spectrum, including Einstein’s insight into the quantized nature of electromagnetic radiation. It explains that the only difference between light, radio waves, and all the other forms of electromagnetic radiation is the length of the fictitious-but-convenient waves or, equivalently, the energy of the photons involved. These different energies lead to different mechanisms for the formation and absorption of the different kinds of radiation, and it is this which gives rise to their different behaviours. Radio waves, microwaves, infrared radiation, light, ultraviolet light, X-rays, and gamma rays are all discussed.
Electromagnetic spectrum
Metamaterial cloaking
Radiation properties
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Electromagnetic spectrum
Visible spectrum
Ultraviolet
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Electromagnetic fields and waves exist everywhere in nature in various forms. The planet
produces its own electromagnetic field, depending on its diameter, circumference and its speed of rotation. Electromagnetic radiation of various characteristics exists within the limits of the atmosphere, created by cosmic radiation, the sun, and radioactive materials. Within the ionosphere, the usage of many forms of electromagnetic energy is high, from satellite transmissions and communications, to wi-fi signal and radio waves.
In a sense, one could say that the greater spectrum of today’s technological progress is based upon the usage of the properties of electromagnetism. Τhe transmission of electrical energy throughout the world, includes the study of both electric and magnetic fields, conductance effects, proximity and skin effect, and Corona discharges. The following paper will study these effects on transmission lines.
When an electromagnetic wave travels through a solid medium, its wavelength is slightly
reduced. Also, an electromagnetic wave penetrates through a medium with almost no losses, when its wavelength is smaller than the length of the molecular structure of the medium. Conclusively, the smaller the wavelength, the higher the penetration. The electromagnetic spectrum of which man is familiar with, lies between 500kHz (AM radio signal) and wavelength from 100-600m, up to 300GHz and wavelength 1mm, used in telemetry and communications. Electromagnetic waves are produced and interfere in transmission and distribution lines, as an outcome of Faraday’s, Ampere’s and Maxwell’s laws. In this paper an approach is made to understand how these fields are produced and affect the conductors and matter in general.
Electromagnetic spectrum
Electromagnetism
Faraday cage
Terahertz gap
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Electromagnetic spectrum
Optical radiation
Radiation properties
Transition radiation
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The origin of radiation is almost as old as the history of the creation of matter. The term “radiating energy” is used to refer to energy conveyed by electromagnetic waves. This chapter uses the terms “exchange” or “transfer by radiation” to refer to all of the energy transfers occurring at a distance, between bodies, by electromagnetic waves. It presents the electromagnetic wave spectrum with the wavelengths and corresponding frequencies. This spectrum covers all of the radiations encountered in nature, including cosmic radiations, X-rays, microwaves, telephone waves and radio waves. The range of wavelengths between 0.1 µm and 100 µm admits specific characteristics: when electromagnetic radiation belonging to this range reaches a given surface, it produces excitation of the matter, which is reflected by an increase in the temperature: this is thermal radiation. The chapter also summarizes the characteristics of the different regions of the electromagnetic spectrum.
Electromagnetic spectrum
Radio spectrum
Radiation properties
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In Chapter 3, we saw that the human eye is sensitive to that part of the electromagnetic spectrum known as the visible range. We also saw that the energy transmitted by electromagnetic radiation can be related to its wavelength through a simple equation (Eq. 3.1) involving the Planck constant and the speed of light. The speed of light – 186000 miles per second – is perhaps one of the most familiar physical constants. This is actually the velocity of any electromagnetic radiation in a complete vacuum, and its precise value, in SI units, is 2.9979 × 108 m/s, or ~300000 km/s. When light travels through material, it is slowed down, which results in the path of the light bending or refracting. This has two very important consequences:
Electromagnetic spectrum
Optical radiation
Visible spectrum
Radiant energy
Constant (computer programming)
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Electromagnetic spectrum
Radiation oncology
Non-ionizing radiation
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Electromagnetic spectrum
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