Radiation electrical analogy

Radiation heat transfer in a hollow can be represented by electrical analogy as... 

With the evaluation of the view factor, in addition to the concepts of radiosity, solid angle, intensity, and emissive power (the last three from Chapter 8), we complete the concepts needed for enclosure radiation problems. Now we proceed to the solution methods for these problems electrical analogy and net radiation. 

We have already encountered the application of electrical analogy to conduction. Now we proceed to the use of electrical analogy for radiation. This method is based on two circuit elements. For the first element, reconsider the opaque gray surface of Fig. 9.3. The radiant heat flux from this surface is... 

Having learned the method of electrical analogy and its application to a number of examples, we proceed now to the second method, the method of net radiation, for enclosure radiation problems. 

So far we have only treated electric dipole radiation. In a more detailed treatment the radiation field can be described by electric and magnetic multipole fields" i.e. magnetic dipole radiation, electric quadrupole radiation etc. Magnetic dipole radiation is analogous to electric dipole radiation and it depends on the magnetic dipole moment of the atom... 

The Local Field B y analogy to what has been reported in Section 7.3.1.1, also in the case of quantum mechanical formulations of continuum solvation models, there is the need to consider the formal noncoincidence between the radiation electric field (static and optical ) acting on the molecule in the cavity and the corresponding Maxwell fields in the medium, E and Eo, [157-159, 161, 162, 184]. 

Figure 10.4. Electrical analogy of net heat transfer by radiation [Source Reference 8].

The handedness, or chirality, inherent in foundational electrodynamics at the U(l) level manifests itself clearly in the Beltrami form (903). The chiral nature of the field is inherent in left- and right-handed circular polarization, and the distinction between axial and polar vector is lost. This result is seen in Eq. (901), where , is a tensor form that contains axial and polar components of the potential. This is precisely analogous with the fact that the field tensor F, contains polar (electric) and axial (magnetic) components intermixed. Therefore, in propagating electromagnetic radiation, there is no distinction between polar and axial. In the received view, however, it is almost always asserted that E and A are polar vectors and that is an axial vector. 

When electromagnetic radiation falls on an atom or a molecule, the electric held of the radiation tends to disturb the charge cloud around the atom or the molecule. The situation is analogous to the case when a particle composed of positive and negative charges is brought near an electric, held. When the held is applied from the upper side (Figure 3.1),... 

Where (i, is the usual asymmetry parameter and is a function, in general, of E. An analogous expression holds in PES except that ip is then the angle between the direction of ejection and the electric vector of the incident radiation. 

Although there is a strong analogy between photons and materiaF particles such as electrons, this should not be pushed too far. The wave theory of radiation describes oscillating electric and magnetic fields that can in principle be measured directly. The wavefunction of a particle does not seem to correspond to any physical field that can be directly detected experimentally in this way. It should strictly be regarded simply as a mathematical device used for calculation. 

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