摘要:

If all magnetic quantities are defined via fields, with no use of poles and with magnetic moment defined as the volume integral of magnetization, energy considerations yield the torque on a magnet immersed in a permeable fluid in an external field. Although the torque on a disk magnet is proportional to B, the torque on a needle magnet is proportional to μ0H, as reported experimentally by Whitworth and Stopes‐Roe. The experiment does not prove either A. E. Kennelly [J. Eng. Educ. 27, 290 (1935)] or Sommerfeld to be right or wrong, but demonstrates that magnetic theory based onpolescannot be applied tomagnets, and thereby strengthens the philosophy that electromagnetic theory should be based on fields.

ISSN:0002-9505    

DOI:10.1119/1.10570

出版商:American Association of Physics Teachers    

年代:1976

数据来源: AIP

摘要:

We calculate the rangeRof a rotating water sprinkler as a function of the angles ϑ,φ specifying the orientation of the nozzles, the mass rate of water ejection, and the area of the orifice of the nozzles. In order to compare the two approaches, we solve the problem completely in both a laboratory and a rotating frame of reference. We discuss advantages and disadvantages presented by each reference frame in solving the problem. We displayR(ϑ,φ) in three‐dimensional plots, treating water ejection rate and nozzle orifice area as fixed parameters.

ISSN:0002-9505    

DOI:10.1119/1.10571

出版商:American Association of Physics Teachers    

年代:1976

数据来源: AIP

摘要:

A useful expression for the tidal gravitational field due to a radiating source is found. In electromagnetic theory the electric field E in the radiation zone is determined by two time derivatives of the component of the dipole moment which lies in the plane perpendicular to the line of sight. This result generalizes in a natural fashion for the tidal gravitational field E. The gravitational field in the radiation zone for several physical systems of interest is determined. A critical discussion of the applicability of the linear theory of gravitation and of the long‐wavelength or quadrupole approximation is given.

ISSN:0002-9505    

DOI:10.1119/1.10572

出版商:American Association of Physics Teachers    

年代:1976

数据来源: AIP

摘要:

The principle of maximum entropy and the principle of minimum energy lead to inequalities which are useful in testing the validity of fundamental equations. It can be seen that these principles are actually conditions on the curvature of functions containing the variablesS,U,V, andn. Several theorems illustrating the nature of these functions are proved by simple methods. The condition for the equivalence of the two principles is shown.

ISSN:0002-9505    

DOI:10.1119/1.10573

出版商:American Association of Physics Teachers    

年代:1976

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.10575

出版商:American Association of Physics Teachers    

年代:1976

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.10576

出版商:American Association of Physics Teachers    

年代:1976

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.10202

出版商:American Association of Physics Teachers    

年代:1976

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.10203

出版商:American Association of Physics Teachers    

年代:1976

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.10204

出版商:American Association of Physics Teachers    

年代:1976

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.10205

出版商:American Association of Physics Teachers    

年代:1976

数据来源: AIP