摘要:

A novel method has been employed at the Technion to expose senior physics students to physics teaching. Students were allowed to substitute for one three‐week laboratory experiment, an ’’experiment in teaching physics.’’ The setting for the experiment was the eigth grade class of an unsophisticated Israeli village. The experiment provided a remarkably stimulating experience for the students, the pupils, and the elementary teachers. The experience even changed the career goals of a number of the students involved.

ISSN:0002-9505    

DOI:10.1119/1.10741

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

Computer‐graded multiple‐choice problem sets provide some of the advantages of homework graded in a traditional manner. Solution sheets for each set provide a solution to each problem and hints which will help the student identify his misconceptions.

ISSN:0002-9505    

DOI:10.1119/1.10742

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

This is the concluding part of the English rendition of Einstein’s 1907 essay on relativity, of which part I appeared in the June 1977 issue of this Journal and part II in the September 1977 issue. It consists of a direct translation of the last part of the essay, part V, entitled ’’Principle of Relativity and Gravitation,’’ and of a few added footnotes.

ISSN:0002-9505    

DOI:10.1119/1.10743

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The strong principle of equivalence is usually formulated as an assertion that in a sufficiently small, freely falling laboratory the gravitational fields surrounding the laboratory cannot be detected. We show that this is false by presenting several simple examples of phenomena which may be used to detect the gravitational field through its tidal effects; we show that these effects are, in fact, local (observable in an arbitrarily small region). Alternative formulations of the strong principle are discussed and a new formulation of strong equivalence (the ’’Einstein principle’’) as an assertion about the field equations of physics, rather than an assertion about all laws or all experiments, is proposed. We also discuss the weak principle of equivalence and its two complementary aspects: the uniqueness of free fall of test particles in arbitrary gravitational fields (’’Galileo principle’’) and the uniqueness of free fall of arbitrary systems in weak gravitational fields (’’Newton principle’’).

ISSN:0002-9505    

DOI:10.1119/1.10744

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

A quantatative experiment in plasma physics requiring only a modest investment is presented. The plasma source is a seeded propane flame. The object of the experiment is to measure the characteristics of a cylindrical Langmuir probe and the ion density in the flame plasma.

ISSN:0002-9505    

DOI:10.1119/1.10745

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

This paper describes an exercise developed for a liberal arts astronomy course in which the students obtain values for the diameter of Venus by timing the intervals between contacts in a videotaped occultation of that planet by the Moon. Approximate expressions relating the planetary diameter to this time interval are obtained for occultations of a planet in the crescent or gibbous phases. We note that classroom playback of certain videotaped astronomical events demonstrates clearly their dynamic nature.

ISSN:0002-9505    

DOI:10.1119/1.10746

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

Electrostatic problems having a simple dielectric boundary are solved using the concept of polarization charge. Using elementary mathematics, it is shown that the electrostatic field due to the total polarization charge distributed on a boundary surface between two homogeneous and isotropic dielectrics, is equivalent to that due to the lumped image charge used conventionally in teaching these problems. The demonstration of the equivalence of the surface polarization charge to the image charge will help students to understand the physical base of the image charge. Two problems are treated: a plane dielectric boundary, and a dielectric sphere immersed in a uniform field.

ISSN:0002-9505    

DOI:10.1119/1.10869

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

Linear‐polar molecules in an external field contribute to two kinds of polarization effects which may be described in classical terms. First, the external field E produces a torque on each molecule which tends to align its electric dipole moment μ in the direction of the field. At high temperatures the average alignment energy is 〈μ⋅E〉=−μ2E2/3kT. Second, each molecule experiences an internal electric field due to nearby molecules which tends to align the dipole moment of a molecule along the internal field it experiences. This results in an average attractive interpair potential energy 〈U〉=−2μ4/3r6kT. A method of estimating 〈U〉 is described, which is based on the division of molecules into two classes, ’’slow’’ or ’’fast’’, according to their rotational speed. This approach can also be used to estimate 〈μ⋅E〉. Results for a three‐dimensional gas are contrasted with those for a two‐dimensional gas, and the approach to equilibrium of 〈μ⋅E〉 for a two‐dimensional gas is described in detail.

ISSN:0002-9505    

DOI:10.1119/1.10747

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

The diffraction of a plane δ‐function pulse by a black half plane is treated by Stokes’ diffraction formula. The solution is a superposition of the incident pulse terminated at the geometric shadow boundary and a separate cylindrical boundary pulse exhibiting diffusion. The boundary pulse satisfies Lamb’s theorem, and its Fourier transform yields the monochromatic boundary wave. The mathematical reason for the π/4 phase shift is seen in the Fourier transform of the pulse tail. The character of the solution is sufficient to show that the boundary pulse originates at the edge of the diffracting aperture, and to illustrate clearly the kinematical aspects of diffraction at a black screen.

ISSN:0002-9505    

DOI:10.1119/1.10748

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP

摘要:

This paper treats the scattering of wave packets in one space dimension at the mathematical level of the first‐year graduate student. The analytic properties of the general‐scattering solutions are emphasized, thereby making the analysis useful as introductory material for a more sophisticatedS‐matrix treatment. Resonant scattering, time delay, and line shape, as well as the relationship between bound and resonant states, all follow as a natural consequence of the analysis.

ISSN:0002-9505    

DOI:10.1119/1.10854

出版商:American Association of Physics Teachers    

年代:1977

数据来源: AIP