摘要:

A demonstration unit has been devised that provides Fourier series synthesis of regular waveforms by the use of mechanically geared sine/cosine potentiometers and a simple summing amplifier. Considerable flexibility in the design allows immediate demonstration of any common waveform via preprogrammed plug-in circuit cards for lecture use while an alternative operating mode incorporates a fully variable control panel for student use in the laboratory. Mounting of the mechanical gearing in a transparent frame provides immediate evidence of frequency ratios in the laboratory or in a lecture class by overhead projection.

ISSN:0002-9505    

DOI:10.1119/1.1986717

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

Both by theory and by experiment with an oscillating torsion pendulum it is shown that to determine the period of a damped simple harmonic motion accurately the measured intervals must be taken between the times that the oscillator passes through its equilibrium position or, less satisfactorily, between the times of maximum displacement.

ISSN:0002-9505    

DOI:10.1119/1.1986718

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

A simple discussion is given to derive several qualitative properties of the radiation fields of a one-dimensional current density distribution. At the end of the paper an elementary analytical method is also given.

ISSN:0002-9505    

DOI:10.1119/1.1986719

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.1986720

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

The “gravitational” trajectories in a cylindrically bound rotating fluid are shown to generate exponential surfaces. Buoyancy, with respect to the noninertial system, is examined for the case of a rigid body submerged off-axis in the spinning fluid. Some consequences of the buoyancy and rotational forces in such a system are illustrated by the results of several experimental demonstrations.

ISSN:0002-9505    

DOI:10.1119/1.1986721

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

We resolve the twin paradox by calculating the relative ages of the twins first in the frame of the stationary twin and then in the frame of the accelerating twin. If we account for the effects of acceleration by keeping track of the instantaneous Lorentz frame of the accelerating twin, both calculations agree.

ISSN:0002-9505    

DOI:10.1119/1.1986722

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

An exact, closed solution for the hydrogenic wave functions of an extended, uniformly-charged nucleus is presented.

ISSN:0002-9505    

DOI:10.1119/1.1986723

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

The momentum autocorrelation function for noninteracting particles is evaluated in one, two, and three dimensions for microcanonical and canonical ensembles. Although the one-dimensional problem has been solved previously, it is felt that the technique used here of solving the problem by a superposition of square-wave functions is useful in that it is simpler and more physical than the previous approaches.

ISSN:0002-9505    

DOI:10.1119/1.1986724

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

Under the assumption that the gravitational force is a central force and diminishes with distance, Newton's inverse square law is shown to be the only one for which all simple finite trajectories are closed orbits.

ISSN:0002-9505    

DOI:10.1119/1.1986725

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP

摘要:

The role which museums can play in science education is discussed in general and with particular reference to the Exploratorium in San Francisco. We describe how art, an atmosphere of playfulness, and exhibits about the mechanisms of human sensory perception, have figured in the development of our museum. It is suggested that some of the objectives of interdisciplinary survey science courses can best be achieved in museum like settings where students and general public alike can gain firsthand experience with the fabric of natural phenomena.

ISSN:0002-9505    

DOI:10.1119/1.1986726

出版商:American Association of Physics Teachers    

年代:1972

数据来源: AIP