摘要:

The value, in absolute units, of a resistance was determined in a three-part experiment. In the first part a mica capacitor was measured in terms of resistance and the ac line frequency. In the second part an audio oscillator was calibrated in terms of the line frequency. In the third part a resonant circuit, incorporating the oscillator capacitor and a variable inductor, was tuned by varying the inductor which was then compared with a standard inductor. This gives the resistance in terms of the dimensions of the standard and ratios of resistances and frequencies.

ISSN:0002-9505    

DOI:10.1119/1.1996070

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

This report reviews procedures by which physics teachers can obtain surplus government property for use in lecture rooms and laboratories. Surplus property is a potentially valuable source of apparatus at low cost. Directors of state agencies for surplus property wish to be kept informed of the needs of physics teachers in their states. The report contains information about the procedures followed in the surplus property agencies of the United States and its territories and a typical list of surplus items of use to physics teachers.

ISSN:0002-9505    

DOI:10.1119/1.1996087

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

The practical aspects of presenting a course in physics by television are discussed.

ISSN:0002-9505    

DOI:10.1119/1.1996089

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

The task of revitalizing the laboratory of the introductory physics course becomes more imperative because of the impending growth of enrollment during the next decade. This problem can be solved by critical re-examination of existing methods of instruction, and by more concentrated attention to the training of graduate student teaching assistants.

ISSN:0002-9505    

DOI:10.1119/1.1996067

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

An interesting magneto-optical effect discovered at the close of the last century has gone unnoticed. The experimental evidence for the phenomenon is reviewed, and a qualitative explanation is presented. New experiments are required to obtain a complete understanding of the effect, and such an undertaking is strongly urged.

ISSN:0002-9505    

DOI:10.1119/1.1996068

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

Term papers on wisely chosen topics take the senior student out of the narrow textbook problem and give him an opportunity to use all his background training. Properly pursued, such assignments may stimulate and reinforce his interest in physics by demonstrating the vast extent of the unknown in physical science. Criteria for proper topics are listed and an actual assignment, “Neutrino Density in the Universe,” is discussed.

ISSN:0002-9505    

DOI:10.1119/1.1996069

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

Expressions are derived for the maximum range of a projectile in vacuum on a spherical earth in terms of the ratio of kinetic to potential energy at launch. These results are combined with those for the corresponding launch angle and presented graphically. Limiting conditions are discussed, and the effect of the earth's rotation is indicated.

ISSN:0002-9505    

DOI:10.1119/1.1996071

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

The hatchet or hacksaw blade planimeter, consists only of a sharpened pointer, a rigid arm, and a knife edge. Its theory was first given by F. W. Hill in thePhilosophical Magazinein 1894 and was later simplified by Satterly. Hill and Satterly showed that the numerical value of the area within a closed curve traversed in the proper manner by the pointer is equal to the product of the length of the planimeter arm and the net displacement suffered by the knife-edge as measured along an arc with the pointer at the center of curvature. The present paper gives a relatively simple derivation yielding essentially the same result but using an entirely different method of approach. It is also shown that the procedure for operating this planimeter can be simplified when determining areas within certain types of closed curves. The accuracy of the planimeter is discussed.

ISSN:0002-9505    

DOI:10.1119/1.1996072

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

Hamilton's principle is used as a computational device to obtain the period of a simple pendulum and a bead sliding along a parabolic wire to second-order terms in the amplitude. We assume a motion of the formθ = θ0 sinωtand ask the following question: How shall we choose the amplitudeθ0so as to make the line integral of the Lagrangian extremum for the observed periodτ = 2π/ω? In the case of planetary motion and for the simple functions selected the period is given correctly only to first-order terms in the eccentricity.

ISSN:0002-9505    

DOI:10.1119/1.1996073

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP

摘要:

The classical theory of the scattering by a conservative central force is re-examined. A variational equation and a Fourier series expansion are developed whereby approximate expressions for the trajectory can be obtained. In addition, impulse integral equations are derived from which approximate relations between energy, impact parameter, and scattering angle can be developed. These methods are applied to potentials of the formV = C/rnand the results are found to be quite superior to those from the widely used small-angle approximation.

ISSN:0002-9505    

DOI:10.1119/1.1996074

出版商:American Association of Physics Teachers    

年代:1957

数据来源: AIP