Particles, charged electrodynamic properties

The electric and magnetic polarization fields P(x), M(x) are invoked to describe the electrodynamic properties of charged particles they enter the theory through a representation of the lagrangian interaction potential for a closed system of electric charges and the electromagnetic field... 

In this last section we mention a few cases, where properties other than the energy of a system are considered, which are influenced in particular by the change from the point-like nucleus case (PNC) to the finite nucleus case (FNC) for the nuclear model. Firstly, we consider the electron-nuclear contact term (Darwin term), and turn then to higher quantum electrodynamic effects. In both cases the nuclear charge density distribution p r) is involved. The next item, parity non-conservation due to neutral weak interaction between electrons and nuclei, involves the nuclear proton and neutron density distributions, i.e., the particle density ditributions n r) and n (r). Finally, higher nuclear electric multipole moments, which involve the charge density distribution p r) again, are mentioned briefly. 

Sensing techniques that are applicable to the measurement of solids concentration can be classified into four groups electrical, attenuation, resonance, and tomographic. The electrical methods utilize the dielectric and electrostatic properties of solids. Typical electrical sensors are capacitive and electrodynamic sensors the capacitive sensors measure the dielectric property of the solids, whereas the electrodynamic sensors detect the static charges that develop because of collisions between particles, impacts between particles and pipe wall, and friction between particles and gas stream. Attenuation methods are used with optical, acoustic, and radiometric sensors. Both optical and acoustic sensors are applicable to relatively low concentrations of solids. Radiometric sensors, in which y-rays or X-rays are used, are expensive and may raise safety concerns. They can, however, offer accurate and absolute measurement of particle velocity and thus can be used as calibration tools for other low-cost sensors such as the capacitive sensor. Resonance and tomographic methods, which are still in developmental stages, will be briefly introduced in Section 6.5. 

An atom, for present purposes, consists of a positively charged nucleus plus negatively charged electrons that are distributed about the nucleus in a more or less spherical cloud. Important properties of atoms as far as chemistry is concerned are largely determined by the charges and masses of these particles. One might, therefore, conclude that problems in chemistry are leaUy problans in electrostatics (or electrodynamics). While in a sense that is ttne, at the practical level it is convenient to approach the problon in a different way. 

---