ISSN:0002-9505    

DOI:10.1119/1.1986612

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

In introducing beginners to Gauss's law, we first emphasize the separate roles played by charges within and outside a Gaussian surface. We illustrate this in detail for the specific simple example of finite and infinite line charges. Students can thereby see more tangibly how unenclosed charges affect the flux distribution and the electric field, but not the total flux magnitude, on a Gaussian surface. The exact role of symmetry in Gauss's law applications to electric-field computations is also thereby elucidated for beginners.

ISSN:0002-9505    

DOI:10.1119/1.1986613

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

The year 1971 marked the quadricentennial of Kepler's birth. Born in the medieval town of Weil der Stadt near Stuttgart, neither his parentage nor early education augured any future greatness as a natural philosopher or astronomer. Though he studied theology at the renowned University of Tuebingen, it was only after he was assigned to teach mathematics and astronomy in the remote Styrian town of Graz that he started on his way to fame as an astronomer. At first his own inclinations were more toward the classical and even mysterious ideals, but his later association with Tycho Brahe, the keen Danish astronomical observer, in Prague caused him to consider also the more mathematical-mechanical views. Though we owe to him the basic operational laws of planetary motion among many important contributions, he nevertheless mystifies us with his dream of a lunar voyage and his astrological views. In spite of the fact that his private life was racked with many personal problems and tragedies, he never lost his appreciation for the beauty and harmony of the universe.

ISSN:0002-9505    

DOI:10.1119/1.1986614

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

This paper discusses the quantization of electromagnetic fields interacting with nonrelativistic atoms and molecules in the dipole approximation. Quantizing the field variablesDandHand taking the interaction density−ε0−1P·D,we obtain a quantum theory corresponding to classical electrodynamics with no free currents and the induced dipole moments as the only sources of the radiation field. The resulting equations are found to agree with those Power and Zienau obtained from causality requirements. A comparison with the conventional approach is given.

ISSN:0002-9505    

DOI:10.1119/1.1986615

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

The dispersion force between two ideal metal plates is derived using a new method which places the emphasis totally on the sources of the electromagnetic radiation. Using this approach, the conceptual difficulty of how radiation in a perfectly reflecting cavity can ever achieve equilibrium with the surrounding medium is eliminated.

ISSN:0002-9505    

DOI:10.1119/1.1986616

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

A simple procedure for observing alpha particle tracks in cellulose nitrate is described with emphasis on qualitative understanding of the underlying principles. The technique is shown to be feasible for use in the undergraduate nuclear laboratory as well as offering a variety of possibilities for independent student investigations at very low cost. The results of a Rutherford scattering experiment are included as an example of the type of measurements for which this detector can be used.

ISSN:0002-9505    

DOI:10.1119/1.1986617

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

The Galilean invariance of nonrelativistic laws is reviewed with particular attention given to the transformation properties of field-theoretic quantities. It is then shown that Galilean-invariant nonrelativistic laws generally manifest a broader covariance, the laws retaining their form under coordinate transformations to noninertial frames which move with arbitrary accelerative translational motion (without rotation) with respect to inertial frames.

ISSN:0002-9505    

DOI:10.1119/1.1986618

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

A brief, elementary review of the basic concepts of Bayesian statistics is presented with the focus being on those aspects of the theory which are especially suitable for physics applications. Examples illustrating the usefulness of these concepts are taken from the field of nuclear physics.

ISSN:0002-9505    

DOI:10.1119/1.1986619

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

An undergraduate laboratory experiment is described which allows the student to make direct contact with his lecture course. The magnetic field of a circular loop and of a long straight wire is investigated using only a magnetic compass. As a result of this experiment the magnitude of the horizontal component of the Earth's magnetic field is determined.

ISSN:0002-9505    

DOI:10.1119/1.1986620

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

Diffraction of light by a liquid carrying a sound wave enables a direct measurement of the acoustic wavelength in the liquid, and hence the acoustic velocity, if the frequency is known. The method of Debye and Sears for such measurements and an alternative method (striation or schlieren method) based on a visual display of standing wavefronts on a screen are reviewed. Measurements carried out with a He-Ne laser indicate that both methods work on the same diffraction phenomenon. Interpretation is given to the cause of image formation in the striation method, and a formula for the intensity distribution in the striation pattern is obtained. While utilizing a minimum of equipment, both methods illustrate some salient aspects of the compressional wave as well as physical optics and provide an excellent experiment for an advanced undergraduate laboratory or a lecture demonstration at an introductory level.

ISSN:0002-9505    

DOI:10.1119/1.1986621

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP