The Electromagnetic Wave

The interaction of UV/VlS radiation with matter, i.e. atoms or molecules, takes place within their electron shell, i.e. between the atomic or molecular orbitals (AOs or MOs) by promoting one electron from its ground to an electronically excited state. By this process (i.e. energy absorption), the electron is transferred to 

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The frequency of microwave radiation lies between that of IR radiation and high frequency radio waves and the boundaries between these regions are not fixed [221]. The microwaves are generated in a transmitter (magnetron) which possesses a stalk which penetrates Uke a radio antenna into a hollow energy guide (Fig. 48). This leads the electromagnetic waves into the reaction chamber (power about... 

In a modem course, no one tries to explain the electromagnetic waves as elastic waves of some special medium in an attempt to reduce the physics of EM to an application of NM. On... 

FIGURE 1.1 Electromagnetic wave. At any time the elongations of the electric wave E(x) and of the magnetic wave H(x) into space appear perpendicnlar to each other. The fignre shows two full periods of the electromagnetic wave. 

Now we assume that the wavelength of the electromagnetic wave is much larger than the atomic dimensions. This is, of course, true for the optical range, as the shortest wavelength is around 200 nm while the atomic dimensions are of the order of 0.1 nm. In this case, the electric field does not vary within the atomic volume and so E = E (0, t) = Eo sin ojt. Therefore, we can write... 

Heat transfer does not occur until the electromagnetic waves or photons strike an object. This impact causes motion of the molecules on the surface. The heat generated is spread to the interior of the object through conduction (NFPA, 1997). 

Polar Molecule a molecule where the centers of positive and negative charge differ, creating a permanent dipole moment Polarizability ability of an electron cloud in a neutral atom to be distorted Polarized Light light in which the electromagnetic wave vibrates in only one plane Polyatomic Ion an ion consisting of more than one atom... 

Fig. 6.23. The direction of the electric-field vector of the electromagnetic wave defines the direction of polarization. In the upper diagram, the electric-field vector travels in the y-direction (y-polarized light), and in the lower diagram, in the x-direction (x-polarized light).

The interaction of a nucleus with the oscillating magnetic field B0, created by the electromagnetic wave, can be understood if it is assumed that it results from the composition of two half vectors, rotating in opposite directions in the xOy plane with identical angular velocities (Fig. 9.6). The vector rotating in the same direction as the precession is the only one that can interact with the nucleus. 

The first point to be made is that in a crystal the refractive index depends not on the direction in which the electromagnetic waves are travelling but on the direction of the electrical disturbances transverse to the line of travel—the vibration direction . We have to consider the shape of the graph connecting refractive index with vibration direction for each crystal system, and the methods available for measuring the refractive indices of crystals in different vibration directions. 

Propagation Delay of Lossless Lines. The minimum propagation delay (Tpd expressed in picoseconds per centimeter) for a unit length of lossless line is the inverse of the phase velocity (op) of the electromagnetic waves propagating through the dielectric medium surrounding the conductor line ... 

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