摘要:

The pressure exerted by an ideal gas on the face of a moving piston is calculated for constant piston speeds that are small compared to the average speed of the gas molecules, and is found to be proportional to the expression,1 − (8/π)α + (8/π)α2, whereαis the ratio of piston speed to the average molecular speed, or, better, is the ratio of the piston speed, corrected for the motion of the gas in the direction of piston motion, to the average molecular speed. The drift speed of the gas is investigated and found to be proportional to the displacement of the piston and the difference between piston speed and molecular speed. Work done in isothermal and adiabatic processes is calculated. Possible experimental verification is considered.

ISSN:0002-9505    

DOI:10.1119/1.1975769

出版商:American Association of Physics Teachers    

年代:1969

数据来源: AIP

摘要:

A review is given of three methods of defining heat, viz., the definition using the first law of thermodynamics, the definition through heat capacities, and the definition using the ice-calorimeter. It is shown that the concept of heat and a measure for the heat absorbed by a body can be defined in all its generality only through the use of the first law.

ISSN:0002-9505    

DOI:10.1119/1.1975771

出版商:American Association of Physics Teachers    

年代:1969

数据来源: AIP

摘要:

A general method is shown for embedding Riemannian spaces in Euclidean or Minkowskian spaces. This method differs from those of others in that emphasis is placed on the pedagogical value of regarding Minkowskian spaces as Euclidean. The technique is applied to two-dimensional Riemannian surfaces. When the metric of the Riemannian surface depends on only one of the coordinates, the intrinsic geometry of the surface is the same as that of a surface of revolution curved in a Euclidean or Minkowskian three-space. The Schwarzschild radius-time plane and the radius-azimuth plane are given as illustrations of the technique.

ISSN:0002-9505    

DOI:10.1119/1.1975773

出版商:American Association of Physics Teachers    

年代:1969

数据来源: AIP

摘要:

The quantum-mechanical problem of a particle under the simultaneous influence of a linear potential and one-dimensional infinite square-well is considered. A graphical technique is described whereby approximate solutions are obtained for the general case, and some analytical methods are discussed by which exact solutions may be obtained for various special cases. The results should provide insight into a problem of current theoretical and experimental interest: the behavior of electrons in solids under the influence of an applied electric field.

ISSN:0002-9505    

DOI:10.1119/1.1975775

出版商:American Association of Physics Teachers    

年代:1969

数据来源: AIP

摘要:

The first part of this article is a discussion of some ambiguities and sources of confusion in the presentation of electromagnetic induction in introductory texts. Particular attention is paid to the use of special relativity theory in these presentations. The second part of the paper discusses various examples of electromagnetic induction that have acquired reputations as “exceptions to the flux rule”. The origin of these exceptions is traced to an inappropriate choice of contour or its motions. We explicitly show that in these examples no exceptions occur, and give a general prescription for evaluating induced emf's.

ISSN:0002-9505    

DOI:10.1119/1.1975777

出版商:American Association of Physics Teachers    

年代:1969

数据来源: AIP

摘要:

The temperature distribution found in standing waves in air in a Kundt tube is investigated by making use of the change in resistance of a thermistor moved the length of the tube. Two procedures are used. In one, values of thermistor currents are read along the tube and plotted against distances. In the other, actual thermistor resistances are measured and similarly plotted. Periodic variation of both current and resistance is evident. Using data obtained from the resistance variation curves, the actual temperature excursion is estimated. From the locations of the nodes and antinodes on current-distance graphs, the velocity of sound is calculated.

ISSN:0002-9505    

DOI:10.1119/1.1975779

出版商:American Association of Physics Teachers    

年代:1969

数据来源: AIP

摘要:

This demonstration-experiment was developed as part of a one-semester course for upperclass nonscience students. Materials are offered which allow student data taking and analysis of radar moon echoes.

ISSN:0002-9505    

DOI:10.1119/1.1975781

出版商:American Association of Physics Teachers    

年代:1969

数据来源: AIP

摘要:

A brief survey is given of four new approaches to the teaching of special relativity, namely the so-calledkcalculus, methods based on the invariance of the space-time interval, the dynamical approach, and the introduction by means of thought experiments. Each approach has been illustrated with a few examples.

ISSN:0002-9505    

DOI:10.1119/1.1975783

出版商:American Association of Physics Teachers    

年代:1969

数据来源: AIP

摘要:

The diffraction problem for the Fresnel half-period zone plate is solved. The zone plate behaves as a lens with marked chromatism which can be taken advantage of for use in a spectrometer. The multiplicity of foci associated with the zone plate are examined in detail, and it is shown that the spectral range that can be focused without overlap is3λmin≥λmax. The wavelength resolution isλ/Δλ ≈ (m+1)/0.445, wheremis the number of transparent half-period zones. Form = 300, this corresponds to a34-wave number resolution at 20 microns. The intensity at the focus is given approximately by4I (m+1)2, whereIis the intensity at the zone plate. The transmitted power that falls within the airy disk is proportional to the area of the zone plate.

ISSN:0002-9505    

DOI:10.1119/1.1975785

出版商:American Association of Physics Teachers    

年代:1969

数据来源: AIP

摘要:

The dispersion equation for a plane wave propagating in an arbitrary direction with respect to the external magnetic field in an unbounded ferrite medium is recast as a quartic equation in the square of the wave number for the case in which neither the effective exchange magnetic field nor the electric field is neglected. This quartic equation is solved by a perturbation procedure to obtain, in particular, an expression for the wave number in the very close neighborhood of the ferromagnetic resonance frequency, where there is a rapid variation in the dispersion.

ISSN:0002-9505    

DOI:10.1119/1.1975787

出版商:American Association of Physics Teachers    

年代:1969

数据来源: AIP