Electromagnetic radiation kinds

Visible light, X rays, microwaves, radio waves, and so forth, are all different kinds of electromagnetic radiation. Collective )-, they make up the electromagnetic... 

Figure 12.11 Electromagnetic waves are characterized by a wavelength, a frequency, and an amplitude, (a) Wavelength (A) is the distance between two successive wave maxima. Amplitude is the height of the wave measured from the center. (b)-(c) What we perceive as different kinds of electromagnetic radiation are simply waves with different wavelengths and frequencies.

In a vacuum (empty space), all forms of electromagnetic radiation propagate at a velocity of 300,000 km per second, when propagating through air, water, or any kind of matter, they interact with the matter and their velocity is reduced. Differences in the manner of interaction between different forms of radiation and different types of matter generally reveal information on the nature and the constituents of matter. 

Understanding the nature of atoms and molecules begins with an understanding of light and other kinds of electromagnetic radiation that make up the electromagnetic spectrum. An... 

A further important property of synchrotron radiation concerns its polarization characteristics. The radiation is completely polarized, and the kind of polarization depends on the direction of the circulating electron beam as well as on the direction of photon emission. In order to understand these polarization properties, it is useful to recall the result for the emission of electromagnetic radiation from an electron moving with non-relativistic velocity in a circle the electric field vector follows the same shape and orientation as the projection of the electron s path onto a plane perpendicular to the observation direction. 

The term birefringence indicates an anisotropy of some kind in the real part of refractive index n exhibited by a beam of electromagnetic radiation after it traverses a medium. The best known example of birefringence, natural optical activity (NOA), was discussed in another contribution to this book by Pecul and Ruud. 

Refractive index — A fundamental physical property of materials through which light can travel. It is usually indicated by the symbol n, and it is defined as n = c/cQ, where c0 is the speed of light in vacuum and c corresponds to the speed at which the crests of electromagnetic radiation corresponding to a specific frequency propagate in a material [i,ii], A more rigorous definition for the refractive index of a dense and isotropic material composed of a unique kind of particles (atoms or... 

Electromagnetic radiation in the visible and near-ir and uv regions of the spectrum, particularly with energies between approximately 33,000 and 4,000 cm (3,000-25,000 A, 4-0.5 eV) interacts with the eleetrons in solids (or liquids and gases). These interactions give rise to the processes of absorption and reflection qualitatively observed in minerals as the properties of color and luster. The quantitative measurement of such absorption and reflection processes forms the basis of eleetronic (optieal) absorption spectroscopy. The absorption and reflection phenomena arise from electronic excitation processes involving the valence electrons, excitation processes that may be of several kinds ... 

PCS = photon correlation spectroscopy = QELS see electromagnetic radiation Pearson s rule 3.185 Peclet number 1.7.97 pendant drop see drop, pendant penetration depth (evanescent waves) [1.7.10.121 period (of a wave) 1.7.4 permeability see porous plugs perpetutd motion 1.2.8 of second kind 1.2.23... 

You come into contact with many different kinds of electromagnetic radiation in your daily life. For example, you use visible light to see the words on this page, you may cook with microwaves, and you should use sunscreen to protect your skin from the harmful effects of ultraviolet radiation. 

The present state of knowledge about invisible dark matter indicates that it represents the predominant part (about 90%) of the total mass of the universe. It includes the so-called missing mass. Dark matter is not discernible by any kind of electromagnetic radiation in the region from y rays to radiowaves, but its gravitational effects on other kinds of matter are observable. For example, the rotation of spiral galaxies such as the Milky Way can only be explained if 90% of the matter is invisible in the sense mentioned above. The question of the nature of the dark mass is still open. Various possibilities are discussed matter different from that on the earth (no protons, neutrons and electrons), remnants of the big bang, neutrinos. However, the actual mass of neutrinos is still uncertain. 

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