摘要:

Several studies and researches carried out in connection with the manufacture of harmonicas are briefly reviewed. A stroboscopic device used in tuning the harmonica reeds and a constant pressure device for sounding them during test are described. The manufacture of the reeds is discussed in some detail. It is pointed out that the primary problem in the manufacture of harmonicas is to produce them at a cost which will meet European competition. It is concluded that harmonica manufacture presents interesting problems for the physicist, engineer, and metallurgist.

ISSN:0002-9505    

DOI:10.1119/1.1933229

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

Rumford developed his concept of heat by analogy with the acoustic waves emitted by a bell. He felt that temperature was a measure of the frequency of vibration of the emitting source; the higher the temperature, the higher the frequency. This led him also to the belief in the existence of frigorific rays as separate entities from calorific rays.

ISSN:0002-9505    

DOI:10.1119/1.3416888

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

The equations of motion of the Foucault pendulum are set up in polar coordinates. The oscillation is shown to be simple harmonic for a particular angular velocity,−Ω sinφ, whereΩis the angular velocity of rotation of the earth andφis the latitude. In general, the motion involves a constant areal velocitycand a nonlinear oscillation given byr̈+ω2r−c2/r3 = 0. This equation is integrated through the energy equation and shown to give the same precession as in the harmonic case.

ISSN:0002-9505    

DOI:10.1119/1.1933230

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1933231

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

This note points out that excellent reproductions in color of Netscher's fine portrait of Christiaan Huygens may be purchased at small cost from the Municipal Museum, the Hague.

ISSN:0002-9505    

DOI:10.1119/1.1933232

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

In continuance of earlier work (references below) the rocking of bodies of other shapes resting on different supports has been studied. The examples afford a useful study of the dynamical equations appropriate to such vibrations and provide simple and inexpensive experiments for students in the laboratory. Rocking bodies are often observed in every day occurrence, and interest in such motion is well worth development.

ISSN:0002-9505    

DOI:10.1119/1.1933233

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1933234

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

The basic concepts and rules of quantum mechanics are shown to be immediate consequences, on the basis of simple reasoning, of a postulate of continuity in the domain of macroscopic thermodynamics. The continuity principle leads first to the concept of a fractional likeness between two states in general, as opposed to the classical alternative of either like or unlike. Then all possible states of a system can be arranged in sets of mutually unlike or “orthogonal” states, with membersAandBof different sets interconnected by fractional likeness factorsq(A,B) between zero and unity. These factorsqare identical with the relative intensities in a splitting effect of a state into components, ruled by probability relations and by the basic principle of quantum statistics of not counting permutations of individual particles. The problem of relation between the various fractional likenesses, or probabilities of transition under analysis, is a purely mathematical problem and is solved by the introduction of probability amplitudes necessarily subject to a matrix law of multiplication, i.e., to the principle of superposition. Thus, starting from the continuity postulate of thermodynamics, quantum theory in its general outline is obtained by simple reasoning. All further details, such as the duality of waves and particles, the uncertainty relation, and the mechanics of special systems, need only one more bit of empirical information, namely, the symmetric and periodic form of the amplitude ψ of fractional likeness between a state of given coordinate and a state of given momentum.

ISSN:0002-9505    

DOI:10.1119/1.1933235

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

The ampere current balance herein described has been in use for four years as a regular experiment of a sophomore physics course. It has the following merits: (1) It is simple to construct; (2) it is absolute in that the current may be calculated from the dimensions and balancing weight only; (3) it is subject to a high degree of accuracy, especially for the larger currents; (4) it may be used for alternating as well as direct currents; (5) when current is passed through the movable conductor only, the balance may be used to measure the horizontal component of the earth's magnetic field.

ISSN:0002-9505    

DOI:10.1119/1.1933236

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP

摘要:

It is pointed out that the classical analog to a wave function is not a single orbit but a set of paths as defined by the solution of the Hamilton-Jacobi equation. A review is given of Hamilton-Jacobi theory in language appropriate to these path concepts. It is shown that there is a classical analog to a wave packet. Quantum-mechanically, constants of motion are not arbitrary but must be characteristic values of commuting operators. It is shown by examples that the possible classical states are similarly restricted. The conditions are discussed under which a classical set of paths is derivable from the solution of a Hamilton-Jacobi equation.

ISSN:0002-9505    

DOI:10.1119/1.1933237

出版商:American Association of Physics Teachers    

年代:1952

数据来源: AIP