摘要:

A teaching device is described which can be used in lectures on the interference of white light. The wave forms of four selected components of white light, in the violet, green, yellow, and red regions, are shown one above the other on a cardboard chart, inked in their respective colors. A sheet of clear plastic with an identical set of waves drawn on it is placed over the chart so that the two sets are in register. The combination represents a beam of white light as it arrives at the retina. A retardation of part of the beam is illustrated by displacing the plastic sheet laterally. Since the sine waves differ among themselves in wavelength, the various phase changes which result among the four components are shown quite clearly.The principle has been embodied in slide rule form with the wave trains appearing at a large plastic window. Five smaller windows indicate, respectively, path difference in millimicrons, dominant wavelength and purity of the resulting light when C.I.E. IlluminantCis used, and relative energies and resultant hue for the four components shown.

ISSN:0002-9505    

DOI:10.1119/1.1933360

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

Two ballistics problems that may arise in future transportation have been formulated and solved in detail. The first problem is that of a vehicle moving along a great circle of the earth; the second problem is that of a rocket moving radially away from the earth. In both cases the magnitude of the resultant acceleration applied to the body has been set equal to a constant. The value of this acceleration will be determined ultimately by the maximum acceleration that human beings or material objects can withstand.

ISSN:0002-9505    

DOI:10.1119/1.1933361

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

The present theory of magnetism, in which it is treated as a phenomenon of current electricity, suffers from objections which are pointed out. The meanings ofBandHon an atomic scale are considered, and a method of picturingBandH, inside a ferromagnetic body, without mentioning magnetic poles or dipoles, is developed. It is shown that this method satisfactorily accounts for the demagnetizing field in certain simple cases and that it also makes clear whyHoccurs in the circuital theorem whileBis used in Laplace's equation. Rigorous definitions ofBandHat any point in a magnetic medium are then developed. In the concluding section the advantages of the suggested method are summarized.

ISSN:0002-9505    

DOI:10.1119/1.1933362

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

This article describes equipment for studying antenna patterns without the use of cumbersome outdoor apparatus. Patterns for numerous arrays, in good agreement with theory, are readily obtained. Construction of arrays observed by students is encouraged.

ISSN:0002-9505    

DOI:10.1119/1.1933363

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

The Dirac δ-function is used in solving the problem of bending of a beam and also some problems of vibration. It is seen that fairly general results can be obtained without complicated calculations.

ISSN:0002-9505    

DOI:10.1119/1.1933364

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

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.

ISSN:0002-9505    

DOI:10.1119/1.1933365

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

An excellent caricature of Sir John Leslie, Professor of Natural Philosophy in the University of Edinburgh and inventor of the differential thermometer, was made by John Kay shortly before his death. It is here reproduced together with some amusing biographical notes.

ISSN:0002-9505    

DOI:10.1119/1.1933366

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

Two panel boards were devised for use in obtaining data for student computations in electricity, the first for study of Ohm's law and Kirchhoff 's laws applied to networks, and the second for study of line loss in power transmission. The boards are effective teaching aids because of their good visibility and the ease with which circuits can be altered. The data are sufficiently precise to provide for results in agreement with physical laws.

ISSN:0002-9505    

DOI:10.1119/1.1933367

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

A mechanical system of special design, primarily for instructional purposes, is proposed, mathematically analyzed, and tested experimentally. It may be regarded as a hybrid form between the compound wheel-and-axle and the differential pulley or chain hoist. Although the design is simple, the analysis is not too obvious at the start, and is somewhat complicated, exhibiting coordinated angular and linear motions with constant accelerations due entirely to the weight of the movable pulley. While the analysis assumes no friction, the actual heat loss can be readily calculated from time and displacement measurements and the equivalent friction force determined. Numerous equations and numerical data are included. The system offers various challenges to student interest in classical mechanics, both on the lower-division and advanced levels. Particular experimental work is suggested and analytical exercises given for use by teachers.

ISSN:0002-9505    

DOI:10.1119/1.1933368

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

The uniform model of the nucleus, proposed by Wigner in 1937, assumes that the motion of the nucleons within the nucleus are so complicated, and the interactions between them are so strong, that the details of the motion are of no great importance. This model, therefore, differs diametrically from the shell model of the nucleus, in which each nucleon is assumed to move independently of all others to a first approximation, the various nucleons filling up a regular sequence of possible orbits (shells). In this paper we re-examine the evidence for the uniform model to see whether, in the light of data accumulated since the time the model was proposed, the agreement between the predictions of the uniform model and experimental binding energies is sufficiently good to serve as an argument against the shell model. This is found not to be the case. The uniform model gives qualitative agreement with experiment, but the detailed quantitative agreement is only moderately good. This rather indifferent record must be compared with the excellent evidence for nuclear shell structure in the same region of mass numbers. Nevertheless, we feel that the uniform model should not be abandoned altogether, but rather should be reinterpreted to apply to the “characteristic state” postulated by Hurwitz and Bethe, rather than to the ground state. No test of this hypothesis is possible until more is known experimentally about the level spectra of nuclei. In this connection a modified semiempirical form is suggested for the density of nuclear levels as a function of excitation energy.

ISSN:0002-9505    

DOI:10.1119/1.1933369

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP