摘要:

One low- and one high-frequency sinusoidal signal are simultaneously applied to the input of an audio-amplifier. When the high-frequency component in the output is isolated and shown on an oscilloscope, it is usually seen to be modulated by the low-frequency component. This is intermodulation distortion, IMD.As the input voltage is increased, at first the IMD increases at a faster rate, then tapers off. A multiline graph, in addition to the oscilloscope picture, is needed for a reliable indication when the IMD is greater than five percent.

ISSN:0002-9505    

DOI:10.1119/1.1933677

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

The first law is stated in a new, simpler form which is qualitative, and its quantitative content is proven as a corollary. This is done for both the Poincaré and the Carathéodory methods. A statement of the second law is given. Minimum requirements for statements of the laws are discussed, and new alternative statements suggested.

ISSN:0002-9505    

DOI:10.1119/1.1933678

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

This paper attempts to trace the development of the American high-school physics laboratory from its beginnings in the early 1800's to its culminating domination of the science-teaching scene in 1910. An effort has been made to follow lines of educational and scientific thinking during the successive stages of development, so that a total picture of the cultural and social forces that shaped this form of science education emerges.

ISSN:0002-9505    

DOI:10.1119/1.1933679

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

The balance described in this paper was employed, in preliminary experiments, to determine factors governing the force between parallel electric currents. It was then employed to measure the ampere in absolute units. A current range of 4.0 to 6.0 amperes was used in the work and the results obtained as described in the paper indicate an average error of 0.3 percent.

ISSN:0002-9505    

DOI:10.1119/1.1933680

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

When the waves from a storm at sea travel outwards, the long waves arrive first at any distant fixed point and are succeeded by shorter and shorter ones. Observation of the wavelength of the arriving train as a function of time determines the distance away of the storm center. A description of the phenomenon involves an account of the progress of an arbitrary disturbance in a dispersive medium, and it is suggested that this might prove an interesting illustration for teaching purposes of the concept of group velocity.

ISSN:0002-9505    

DOI:10.1119/1.1933681

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

Differential equations involving vector fields expressed in terms of spherical polar coordinates are readily manipulated by the use of vector spherical harmonics. The explicit definitions of these functions and a sufficient set of formulas for easy calculation are given.

ISSN:0002-9505    

DOI:10.1119/1.1933682

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

The paper deals with present-day physics textbooks and the way in which they are being used. It criticizes the current practice of treating nearly all textbooks as ephemerals, and the suggestion is made that a basic general and comprehensive physics text should find a more lasting place in the education of the scientist.

ISSN:0002-9505    

DOI:10.1119/1.1933683

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

An expression is derived that gives a good representation of the volume rate of production of ion pairs in a gas before a thin plane circular uniform source of ionizing particles. The expression is valid when the radius of the source disk is restricted to be less than one-quarter of the range at maximum ionization of the particles. This is not a severe restriction for practical cases.Curves and a table of this rate are given, in which distances are in units of the radius of the source disk, and hence are of general applicability within the restriction on the source disk radius.This work has application to a number of fields, among them the study of the optical radiation from the region in front of such a source.

ISSN:0002-9505    

DOI:10.1119/1.1933684

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

摘要:

The main empirical facts about the strength of glass are reviewed, including statistical theories effects of adsorbed moisture and of acid treatments.

ISSN:0002-9505    

DOI:10.1119/1.1933685

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1933686

出版商:American Association of Physics Teachers    

年代:1954

数据来源: AIP