摘要:

The apparatus described is a macroscopic crystal-lattice analog which may be used for a quantitative investigation of the Bragg law of diffraction. Three-cm microwaves are used rather than expensive and dangerous x-ray equipment. The data obtainable agree with the theory to within less than 10%.

ISSN:0002-9505    

DOI:10.1119/1.1935829

出版商:American Association of Physics Teachers    

年代:1960

数据来源: AIP

摘要:

An extremely versatile mass spectrometer, suitable for an undergraduate laboratory and simple enough to be constructed by an average departmental shop, is described. The data obtained when using the potassium isotopesK41andK39indicate an instrument resolving power of 75. The auxiliary equipment required is conventional and inexpensive. The apparatus structure and construction techniques are described in detail.

ISSN:0002-9505    

DOI:10.1119/1.1935830

出版商:American Association of Physics Teachers    

年代:1960

数据来源: AIP

摘要:

A summary is given of the development of nuclear models, both for the description of structure and of scattering and reaction processes. The treatment is qualitative, and follows mainly the historical development. Models discussed are the liquid drop model, the potential well model for nuclear reaction processes, the compound nucleus model for nuclear reactions, and the shell model. Then a summary and comparison is made, followed by a brief sketch of the unified or collective model, which is a unification of the liquid drop and the shell model. Finally the nuclear optical model or complex potential well model is discussed.

ISSN:0002-9505    

DOI:10.1119/1.1935831

出版商:American Association of Physics Teachers    

年代:1960

数据来源: AIP

摘要:

The assumption is made that creative thinking, like playing tennis or bridge, is an activity rather than a phenomenon; that it can be cultivated through coaching and practice. An individual's ability at creative thought is not fixed in the same sense that the size of his feet are fixed. Therefore, the method which is often used for fostering it in the schools, namely,sorting outthe creative thinkers and giving them special opportunities, meets only a part of the problem. A discussion of the creative process is given, with examples from the writings of Poincaré and others, followed by some words of advice which can be passed on to students.Experimental science projects are discussed, with particular reference to those which are entered in science fairs. A sharp distinction is drawn between projects which are scientific investigations and those which are demonstrations. The former follows the pattern of question, hypothesis, experiment, modified hypothesis, etc. More new questions are raised than are answered, and the true flavor of research is tasted. The project which merely demonstrates a scientific process or principle may be a good teacher of facts, but it does not provide the experience of finding an answer by the scientific method. Some examples of the two types of projects are described.

ISSN:0002-9505    

DOI:10.1119/1.1935832

出版商:American Association of Physics Teachers    

年代:1960

数据来源: AIP

摘要:

The clock paradox is studied both from the point of view of special and general relativity. A solution for the case of a space ship moving in a straight line path with arbitrary acceleration is given in terms of special relativity. It is pointed out that an appeal to general relativity is not necessary as long as a single clock in the accelerator frame is considered, but that general relativistic considerations are necessary if two clocks separated by an appreciable distance are introduced into the accelerated frame. A solution for this case is given.

ISSN:0002-9505    

DOI:10.1119/1.1935833

出版商:American Association of Physics Teachers    

年代:1960

数据来源: AIP

摘要:

This paper describes a simple method of determining the thickness or the refractive index of thin films using double-slit Fraunhofer diffraction fringes. To illustrate the method, the thickness of a gray photographic film and the refractive index of a cellulose acetate film have been determined.

ISSN:0002-9505    

DOI:10.1119/1.1935834

出版商:American Association of Physics Teachers    

年代:1960

数据来源: AIP

摘要:

A method is described for making graphical comparisons of galvanometers of different resistances and periods. The effective sensitivities in a given circuit can also be easily compared.

ISSN:0002-9505    

DOI:10.1119/1.1935835

出版商:American Association of Physics Teachers    

年代:1960

数据来源: AIP

摘要:

Described here is a simple static-field mass spectrometer which has had usefulness both as an undergraduate laboratory instrument and as a piece of demonstration apparatus. The design provides for the adjustment of such parameters as magnet position, slit widths and heights, and allows the use of different types of sources and detectors. Ion currents are large enough to be easily measured or displayed on an oscilloscope.

ISSN:0002-9505    

DOI:10.1119/1.1935836

出版商:American Association of Physics Teachers    

年代:1960

数据来源: AIP

摘要:

Many of the most interesting mechanical and electrical properties of solids, especially at high temperatures or after radiation damage, depend on the presence of point defects—interstitials and vacancies—in the crystal lattice. Ionic crystals are especially suited for the study of these defects, because in them the defects are electrically charged. The ionic conductivity mechanism is reviewed, with reference to the information it yields about the properties of the defects. Recently, further information about the defects has been derived from the thermoelectric power (Seebeck effect), and these new developments are summarized.

ISSN:0002-9505    

DOI:10.1119/1.1935837

出版商:American Association of Physics Teachers    

年代:1960

数据来源: AIP

摘要:

During the year 1960 there will be major anniversaries of the birth or death of one woman and seven men who have figured importantly in the development of physics. Brief accounts of their lives and contributions are presented here.

ISSN:0002-9505    

DOI:10.1119/1.1935838

出版商:American Association of Physics Teachers    

年代:1960

数据来源: AIP