Showing papers in "American Journal of Physics in 1953"
TL;DR: In this article, a method for determining the position of an atom in a molecule from spectroscopic measurements on two isotopic species of the molecule is described, and explicit expressions are derived for linear, symmetric top, planar, and nonplanar asymmetric top molecules.
Abstract: A method is described for determining the position of an atom in a molecule from spectroscopic measurements on two isotopic species of the molecule. The method is applied to various types of molecules; explicit expressions are derived for linear, symmetric top, planar, and nonplanar asymmetric top molecules. The number of isotopic species on which measurements must be made to complete the structural determination, i.e., determine the position of every atom in the molecule, is discussed for various types of molecules. An application of the method to the determination of mass difference ratios is also considered.
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TL;DR: In this article, a brief outline of the spin-wave approximation to the near ground states of ferromagnetic and antiferromagnetism is given, and simple pictorial models of spin waves are introduced.
Abstract: A brief outline is given of the spin-wave approximation to the near ground states of ferromagnetism and antiferromagnetism. Simple pictorial models of spin waves are introduced. These models clarify the striking difference between ferromagnetic spin waves, which obey the dispersion law ω ∝ k2, and antiferromagnetic spin waves, which obey the law ω ∞ k. The proper normal modes for antiferromagnetic spin waves are presented. The nature of ferromagnetic and antiferromagnetic resonance is illuminated from a spin-wave point of view.
68 citations
TL;DR: A grate basket for hammer crushers is composed of at least two segments respectively made up of a plurality of parallel grate basket walls in the form of ring sections arranged coaxially with regard to the rotor and of grate bars extending parallel with the rotor axis while being exchangeably connected to the grate basket wall interconnected by longitudinal connecting elements as discussed by the authors.
Abstract: A grate basket for hammer crushers composed of at least two segments respectively made up of a plurality of parallel grate basket walls in the form of ring sections arranged coaxially with regard to the rotor and of grate bars extending parallel to the rotor axis while being exchangeably connected to the grate basket walls interconnected by longitudinal connecting elements. The grate basket is characterized primarily in that the grate basket walls are respectively divided into a base wall held by the longitudinal connecting elements and into a bar carrier which is adapted to receive the grate bars and which is secured against rotation in circumferential direction and against displacement in axial direction, the grate bar carrier being exchangeably connected to the inner surface of the base wall.
TL;DR: In this paper, the formation of an optical image by a lens is often treated so that the image appears as the double Fourier transform of the object, limited by the aperture of the lens and other stops.
Abstract: The formation of an optical image by a lens is often treated so that the image appears as the double Fourier transform of the object, limited by the aperture of the lens and other stops. This treatment is here presented including details that are usually omitted in articles where an application of the treatment is the primary purpose.Separate developments are presented that are most adaptable, respectively, to the configuration usually used with a microscope objective with a short object distance and a large image distance, and to the configuration normally used with a telescope objective.
TL;DR: In this paper, the familiar method of fitting a straight line to a set of experimentally observed points by use of least squares is reviewed and variations of it briefly discussed, and methods, apparently not so familiar to many physicists, for estimating the adequacy of the fit obtained, and for comparing the results of several such experiments, are explained.
Abstract: The familiar method of fitting a straight line to a set of experimentally observed points by use of least squares, is reviewed, and variations of it briefly discussed. Then methods, apparently not so familiar to many physicists, for estimating the adequacy of the fit thus obtained, and for comparing the results of several such experiments, are explained. A few of the principles of mathematical statistics underlying these methods are given in the Appendix.
TL;DR: In this paper, the interactions of π mesons with nuclei are reviewed and interpreted in terms of the Serber model of nuclear reactions at high energies, which involves introducing the concept of a mean free path for both meson scattering and absorption in nuclear matter.
Abstract: The interactions of π mesons with nuclei are reviewed and interpreted in terms of the Serber model of nuclear reactions at high energies. This involves introducing the concept of a mean free path for both meson scattering and absorption in nuclear matter. These quantities are discussed in relation to the relevant experimental data. A discussion of the “optical model” of nuclear scattering is also included.
TL;DR: In this paper, the authors present a formal solution for the integrated equation of motion X = X(T) in the general case by determining X and T parametrically as functions of the proper time s of the rocket.
Abstract: In the relativistic theory of one-dimensional rocket motion in empty space, Ackeret has found the differential equation of motion and the mass-ratio formula. One can obtain a formal solution for the integrated equation of motion X = X(T) in the general case by determining X and T parametrically as functions of the proper time s of the rocket.
TL;DR: In this paper, two modern statistical tests for possible rejection of outlying observations are presented, which apply in a majority of the actually occurring situations and because they are so easy to use.
Abstract: This paper makes available to the physicist two of the modern statistical tests for possible rejection of outlying observations. These two methods have been selected because they apply in a majority of the actually occurring situations and because they are so easy to use.
TL;DR: In this article, two general physics laboratory groups were compared in achievement with a group enrolled in the same course without laboratory, measured by two pencil-paper examinations and two laboratory performance tests.
Abstract: Two general physics laboratory groups were compared in achievement with a group enrolled in the same course without laboratory. The achievement was measured by two pencil-paper examinations and two laboratory performance tests. The analysis of variance and covariance method was used to hold constant three measures of initial differences among students. There were no statistically significant differences between the means of the groups on the mechanics theory test. The laboratory groups were significantly better than the no-laboratory group on all tests dealing with laboratory work.
TL;DR: In this article, the Eckart conditions for a polyatomic molecule are discussed, which are introduced to insure the smallness of the interaction between vibration and rotation and define a system of coordinates in which the vibration of the atoms around their equilibrium positions is described.
Abstract: The Eckart conditions for a polyatomic molecule are discussed. They are introduced to insure the smallness of the interaction between vibration and rotation and define a system of coordinates in which the vibration of the atoms around their equilibrium positions is described.
TL;DR: Some concepts and ideas of contemporary physics are surveyed in this article in order to find a pattern of scientific thought broader and more meaningful than that permitted by strictly technical approach may be achieved.
Abstract: Some concepts and ideas of contemporary physics are surveyed in order that a pattern of scientific thought broader and more meaningful than that permitted by strictly technical approach may be achieved.
TL;DR: In this article, the role of the group velocity was discussed in a way similar to that given in Tamm's 1939 paper on the theory of the Cerenkov radiation in a dispersive medium.
Abstract: Attention is called to the disagreement between a recent statement of Sommerfeld that the direction of propagation of Cerenkov radiation in a dispersive medium is determined by the group velocity, and the generally accepted result that the phase velocity must be used. The latter is shown to be correct, and the role of the group velocity is discussed in a way similar to that given in Tamm's 1939 paper on the theory of the Cerenkov radiation.
TL;DR: The history of electricity was at first the history of the "amber effect" as discussed by the authors, that is, of the attraction for light objects displayed by rubbed amber, and the earliest explanations of these phenomena were anthropomorphic, being followed, in classical antiquity, by teleological organismic explanations and also materialistic mechanistic explanations.
Abstract: The history of electricity was at first the history of the “amber effect,” that is, of the “attraction” for light objects displayed by rubbed amber. This effect was well known in antiquity and was coupled and confused with the attraction for iron by the loadstone. The earliest explanations of these phenomena were anthropomorphic, being followed, in classical antiquity, by teleological organismic explanations and also materialistic mechanistic explanations. In the 15th century the lack of a directive (north-south) property in amber was noticed. By the 16th century several substances exhibiting the amber effect were known. From this time onward, attempts were made to provide a theory for the amber effect independently of magnetic phenomena. Effluvium theories, so important in the later history of electricity, first began to develop in the 16th century. The present paper covers the period up to the work of Gilbert in 1600.