摘要:

The construction and operation of a simple Wadsworth-mounted 21-ft 10-in. diffraction grating spectrograph is described. The instrument covers the range from 9000A to 1800A in the first order with a linear dispersion of 5A/mm.

ISSN:0002-9505    

DOI:10.1119/1.1933413

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

A routine analytic method for the solution of problems in statics is given. The method requires no geometry other than that required for the identification of the coordinates of certain cardinal points involved in the problem. The method is illustrated by the detailed solution of an actual case.

ISSN:0002-9505    

DOI:10.1119/1.1933414

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

The article discusses the sensitivity of a constant battery Wheatstone bridge and shows that under certain conditions the bridge sensitivity will be independent of the magnitude of the resistance to be measured. A chart is given, which indicates for a given resistance the bridge ratio which provides the highest sensitivity.The bridge is insensitive for measuring resistances which are large in comparison with the resistance of the ratio arms.

ISSN:0002-9505    

DOI:10.1119/1.1933415

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

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 lawω ∝ k2, and antiferromagnetic spin waves, which obey the lawω ∞ 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.

ISSN:0002-9505    

DOI:10.1119/1.1933416

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

Attention is called to the disagreement between a recent statement of Sommerfeld that the direction of propagation of Čerenkov radiation in a dispersive medium is determined by thegroup 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 tothat given in Tamm's 1939 paper on the theory of the Čerenkov radiation.

ISSN:0002-9505    

DOI:10.1119/1.1933417

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

This is a review of recent work in which the atomic theory of ferromagnetism and the domain theory of magnetization are applied to new materials.

ISSN:0002-9505    

DOI:10.1119/1.1933418

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1933419

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

A ring stands, with axis horizontal, on a horizontal table and a cylinder is placed, also with axis horizontal, resting within it. If motion in thesamehorizontal direction be given to both, they both roll and the motion is of no particular interest. If, however, motion inoppositedirections be given to the ring and the cylinder “rocking” occurs. This motion is interesting because its theoretical solution involves the use of Lagrangian equations, there being two degrees of freedom. Theory and experiment are here given for rings (thin and thick, complete and semicircular) and cylinders (hollow and solid) of different sizes. Good agreement is observed.

ISSN:0002-9505    

DOI:10.1119/1.1933420

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

The general solution of the classical equation of motiondμ/dt = g(μ×H), whenHconsists of a constant field plus a perpendicular rotating component can easily be obtained after transformingthe problem to a properly chosen rotating coordinate system. The value of this method for teaching purposes is discussed.

ISSN:0002-9505    

DOI:10.1119/1.1933421

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP

摘要:

The fundamental problem of not exceeding the critical saturation of nitrogen in a diver's body requires both physics and physiology in its solution. The basic differential equations of nitrogen saturation and desaturation in a specific tissue are integrated over an idealized dive. Constants determined through physiological research can be substituted and a time-depth ascent curve for any tissue established. A stepwise method is outlined whereby critical tissues at each portion of the ascent can fix the proper ascent curve for the entire body. The advantage of pure oxygen breathing is demonstrated numerically and the failure of helium-oxygen mixtures to shorten ascents is explained by use of the derived equations.

ISSN:0002-9505    

DOI:10.1119/1.1933422

出版商:American Association of Physics Teachers    

年代:1953

数据来源: AIP