Reciprocity relationship, radiation

Reciprocity relationship, radiation 448 Rectangular duct 87 Redman, J. 550, 566 Reduced coordinates 35... 

Since the product of v and X is a constant, they have a reciprocal relationship— radiation with a high frequency has a short wavelength, and vice versa ... 

For a given geometry, view factors are related to each other, one example being the reciprocity relationship given in equation 9.126. Another important relationship is the summation rule which may be applied to the surfaces of a complete enclosure. In this case, all the radiation leaving one surface, say i, must arrive at all other surfaces in the enclosure so that, for n surfaces ... 

To get the frequency v in centimeters-, the nonstandard notation favored by spectioscopists, one divides the frequency in hertz by the speed of light in a vacuum, c = 2.998 x lO " cm s-, to obtain a reciprocal wavelength, in this case, 4120 cm-. This relationship arises because the speed of any running wave is its frequency times its wavelength, c = vX in the case of electromagnetic radiation. The Raman spectral line for the fundamental vibration of H2 is 4162 cm-. .., not a bad comparison for a simple model. 

As the relationship between and z is a reciprocal one, we can see that short wavelength radiation corresponds to high energy and long wavelengths correspond to low energy. 

Wavenumber ( ) is another way to describe the frequency of electromagnetic radiation, and the one most often used in infrared spectroscopy. It is the number of waves in one centimeter, so it has units of reciprocal centimeters (cm ). Scientists use wavenumbers in preference to wavelengths because, unlike wavelengths, wavenumbers are directly proportional to energy. The relationship between wavenumber (in cm ) and wavelength (in m) is given by the equation... 

The wavelike character of radiation can be described by its wavelength. A by the wavenumber v, which represents the number of waves per unit of distance (the reciprocal of the wavelength) by the speed at which the wave front advances, the velocity, V and by the number of waves passing a given point in unit time, the frequency, v. The relationship among these properties is given by... 

There exists an important relationship between the position of an atom or molecule in the lattice and the intensity of the diffracted X-radiation, and to incorporate the both in one diagram the concept of weighted reciprocal lattice is introduced here and its applications in structure analysis are discussed in appropriate chapter later. 

FIGURE 4. Relationship of the reciprocal of the weight-average molecular weight (lIMw) to the dose of 313-nm radiation after DNA damage by 10 krad of Co y-rays and repair in BrdUrd. 

Electromagnetic radiation can be characterized by its wavelength A, its frequency v, or its wave number v. In the IR region the unit used for wavelength is the micrometer (/xm). The frequency unit is cycles per second or hertz (Hz). The wave number unit is cycles per centimeter or reciprocal centimeters (cm ). The wave number (cm ) is the number of waves in a continuous wave sequence 1 cm long. The relationship between the units is given in Eq. (1) ... 

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