Theoretical Physics: Second Edition (Dover Books on Physics)
Language: English
Pages: 592
ISBN: 0486609723
Format: PDF / Kindle (mobi) / ePub
Chiefly devoted to mechanics, electrodynamics, quantum mechanics, and statistical mechanics, this book stresses atomic, nuclear, and microscopic matters. Subjects include the quantum theories of radiation, dispersal, and scattering and the application of statistical mechanics to electromagnetic fields and crystalline bodies. Particularly strong in its coverage of statistical physics, the text examines Boltzmann statistics, Bose and Fermi distributions, Gibbs statistics, thermodynamic quantities, thermodynamic properties of ideal gases in Boltzmann statistics, fluctuations, phase equilibrium, weak solutions, chemical equilibria, and surface phenomena. Many of the 137 exercises feature complete solutions. Translated by George Yankovsky under the author's supervision.
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an electron always has projections ±h/2 and no others. Therefore, spin is a purely quantum property of the electron; in the limiting transition to classical mechanics it becomes zero. We must not take the word “spin” too literally, for the electron actually does not resemble a rigid body like a top or a spindle. Spin degree of freedom. The analogy between an electron and a top consists in the fact that their motion is not described by their position in space alone, but possesses an internal
eigenfunctions and eigenvalues of the operator (0) are determined from the equation Allowing for perturbation, the wave function satisfies the equation Considering that (1) is a small perturbation, we represent the wave function in the form the ‘product“ (1) ψ(1) will be neglected as being of the second order. Then, for ψ(1) we obtain the nonhomogeneous equation We shall look for ψ(1) in the form of an eigenfunction expansion of the operator ψ(0): each of the functions satisfying
determines the perihelion for the approaching particles. However, if U (r) tends to infinity more rapidly than then, as r → 0, there will be no point at which U M (r) becomes zero. In place of a hyperbolic orbit, as in the case of Newtonian attraction, a spiral curve leading to one particle falling on the other results. The turns of the spiral diminish, but the speed of rotation increases so that the angular momentum is conserved, as it should be in any central field. But the “centrifugal”
external parameters λ are constant, the quantity of heat being equal to the change in energy of the body: If the pressure does not change (an isobaric process), d A = — p d V = = — d (p V). Then The quantity like energy, is a unique function of the state of the body. It is called the heat function, or the enthalpy, of a body and is denoted by the letter I. Thus, the quantity of heat in an isobaric process is equal to the change of enthalpy of the body Reversible processes. A definite
whose radius is less than then this drop evaporates once again, and further condensation on it is highly improbable, since it is a fluctuation phenomenon. Only if inequality (52.12) is reversed can the drop begin to grow. But the spontaneous formation of a large drop, like any large fluctuation, is highly improbable. Therefore, condensation usually begins on small nuclei that are already in the vapour, for example, ions. In exactly the same way we can explain why a highly purified superheated
