摘要:

An analytic expression is derived for the intensity distribution in the Fresnel diffraction “image” of a transparent object with arbitrary phase shift. Comparisons are made with theCornu spiral treatment of slits and fine wires. The effects of wavelength variation and finite source width are indicated and appear in a brief mathematical appendix; methods of evaluatingFresnel integrals for plotting purposes are briefly described.

ISSN:0002-9505    

DOI:10.1119/1.1941895

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

This article draws the attention of physicists to the simple yet powerful mathematical technique of “generating functions” and illustrates the method by solving the problem: “How many ways are there of distributingmidentical marbles betweennnumbered boxes when no box may hold more thanMmarbles?” This problem, which includes both Bose-Einstein and Fermi-Dirac statistics, has been considered recently in this Journal by McLachlan and Chamberlain using geometrical analogies.

ISSN:0002-9505    

DOI:10.1119/1.1941896

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

The surface energies of several alkali halide crystals were measured by two techniques which are within the capabilities of the undergraduate physics laboratory. One method involves slow cleavage and the other involves impact cleavage under a falling weight. The experimental findings are comparable to previously published results.

ISSN:0002-9505    

DOI:10.1119/1.1941897

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

A microwave zone plate not only illustrates some of the principles of optical (visible light) zone plates but exhibits also interesting differences which are due primarily to the wide aperture which is required for a practical microwave zone plate. These properties have been studied for a zone plate which was designed with four clear zones to focus 12-cm waves from a source 125 cm away to an equally distant image point and was constructed by pasting aluminum foil zones onto a sheet of cardboard. This zone plate operates by reflection as well as by transmission. The experimental data are analyzed in terms of wide aperture theory which is developed in an appendix.

ISSN:0002-9505    

DOI:10.1119/1.1941898

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

A cylindrical cathode-coaxial anode proportional counter, designed for an undergraduate laboratory, is described. A collimated beam of α particles can be directed into the counter at any point along a narrow longitudinal window in the cathode wall and used to examine the electric field surrounding the anode structure at any point along its length. The anode wire has an enlarged section at one end and is surrounded at the other by an independently biased coaxial auxiliary electrode. The effectiveness of these two geometrical methods for controlling the production of secondary ionization can be studied, as can the effects of varying gas composition, pressure, and operating voltage. A variable output-2000-v power supply, pulse amplifying and counting equipment, a cathode ray oscilloscope, and a small mechanical vacuum pump are also needed for these experiments. Detailed information on construction of the counter and gas handling system is given.

ISSN:0002-9505    

DOI:10.1119/1.1941899

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

摘要:

An account is given of an experiment performed by final year students in a three-hour laboratory period which enables them to obtain a Kurie plot and a reasonable end point for the groundstate beta transition ofI128. Use is made of a 1-in. NaI crystal, a photomultiplier, and a single-channel analyzer.

ISSN:0002-9505    

DOI:10.1119/1.1941900

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1941901

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1941902

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1941904

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1941905

出版商:American Association of Physics Teachers    

年代:1962

数据来源: AIP