Electromagnetic wave characteristics

In this work, a microwave interferometric method and apparatus for vibration measurements is described. The principle of operation is based on measurement of the phase of reflected electromagnetic wave changing due to vibration. The most important features of the method are as follows simultaneous measurement of tlie magnitude and frequency of the rotating object high measurement accuracy weak influence of the roll diameter, shape and distance to the object under test. Besides, tlie reflecting surface can be either metallic or non-metallic. Some technical characteristics are given. 

The electric field associated with this electromagnetic wave has two notable characteristics which distinguish it from the incident beam and make it useful... 

One branch of chemistry where the use of quantum mechanics is an absolute necessity is molecular spectroscopy. The topic is interaction between electromagnetic waves and molecular matter. The major assumption is that nuclear and electronic motion can effectively be separated according to the Born-Oppenheimer approximation, to be studied in more detail later on. The type of interaction depends on the wavelength, or frequency of the radiation which is commonly used to identify characteristic regions in the total spectrum, ranging from radio waves to 7-rays. 

A significant change in the theoretical treatment of atomic structure occurred in 1924 when Louis de Broglie proposed that an electron and other atomic particles simultaneously possess both wave and particle characteristics and that an atomic particle, such as an electron, has a wavelength X = h/p = h/mv. Shortly thereafter, C.J, Davisson and L.H. Germer showed experimentally the validity of this postulate. Dc Broglie s assumption that wave characteristics are inherent in every atomic particle was quickly followed by the development of quantum mechanics, in its most simple form, quantum mechanics introduces the physical laws associated with the wave properties of electromagnetic radiation into the physical description of a system of atomic particles. By means of quantum mechanics a much more satisfactory explanation of atomic structure can be developed. 

There are numerous properties of materials which can be used as measures of composition, e.g. preferential adsorption of components (as in chromatography), absorption of electromagnetic waves (infra-red, ultra-violet, etc.), refractive index, pH, density, etc. In many cases, however, the property will not give a unique result if there are more than two components, e.g. there may be a number of different compositions of a particular ternary liquid mixture which will have the same refractive index or will exhibit the same infra-red radiation absorption characteristics. Other difficulties can make a particular physical property unsuitable as a measure of composition for a particular system, e.g. the dielectric constant cannot be used if water is present as the dielectric constant of water is very much greater than that of most other liquids. Instruments containing optical systems (e.g. refractometers) and/or electromechanical feedback systems (e.g. some infra-red analysers) can be sensitive to mechanical vibration. In cases where it is not practicable to measure composition directly, then indirect or inferential means of obtaining a measurement which itself is a function of composition may be employed (e.g. the use of boiling temperature in a distillation column as a measure of the liquid composition—see Section 7.3.1). 

At high frequencies the electromagnetic wavelength inevitably becomes comparable with sample dimensions, and lumped-circuit methods must be abandoned in favour of distributed-circuit methods in which the sample becomes the medium for propagation of electromagnetic waves. Relative permittivity and loss must then be obtained from the observed wavelength and attenuation characteristics. 

In general, lanthanide atoms or ions with an unfilled 4f shell have about 30 000 visible spectral lines. Transition metals with an unfilled 5d shell have about 7000 visible spectral lines. Main group elements with an unfilled p shell only have about 1000 visible spectral lines. Lanthanide elements, therefore, have more electronic energy levels and spectral lines than the more common elements. They can absorb electromagnetic waves from the ultraviolet to the infrared and emit their characteristic spectra. 

X-ray diffraction is one of the most widely used dry powder probing methods. The energies of the employed electromagnetic waves are several thousand electron volts. In most cases the x-ray source is the characteristic Ka radiation that... 

Because electromagnetic waves possess many of the characteristics of light, particu larly as their frequencies approach that of li t, the D6 ppler principle is applied now to electromagnetic radiations in connection with radio and radar equipment for determining velocity and distance of moving targets such as guided missiles or planes... 

List the characteristic properties of all waves. At what speed do electromagnetic waves travel in a vacuum ... 

Complete the concept map using the following terms speed, c = v, electromagnetic waves, wavelength, characteristic properties, frequency, c, and hertz. 

In classical terms, radiation is represented by an electromagnetic wave. The polarization of plane-wave radiation is defined by the way the oscillating electric field evolves in space, in a plane perpendicular to the direction of propagation. The most general polarization state is called elliptical polarization [23], but for luminescence applications the subset of linear polarization states usually suffices. In these cases the electric field vector oscillates along a well defined direction in a plane perpendicular to the direction of propagation. This direction is the polarization direction, and radiation with this characteristic is said to be linearly polarized. 

---