ISSN:0002-9505    

DOI:10.1119/1.14962

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

The familiar problem of two separated, noninteracting spin‐ 1/2 particles in a state of zero total spin is analyzed using the consistent history interpretation of quantum mechanics and shown to behave in many respects like a classical system of two noninteracting objects whose individual properties are unknown but strongly correlated with each other. There is no action at a distance between the particles and a measurement on one has no effect whatsoever on the other. However, the result of a measurement of a spin component of one of the particles can be used to infer (correctly) its value prior to the measurement, and also the corresponding spin component of the other particle at all times prior to when that particle interacts with something else. In these respects the quantum system behaves like its classical counterpart. On the other hand, the paradoxical (nonclassical) aspects of the quantum situation seem to be precisely those already present in the quantum theory of a single particle.

ISSN:0002-9505    

DOI:10.1119/1.14965

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

A common undergraduate experiment to measure thee/mratio uses a magnetic field produced by Helmholtz coils to deflect an electron beam. It is usually assumed that the beam is in the symmetrical plane of the coils and that it is in a uniform field identical to the field at the center of the coils. The magnetic induction field at the central position can be calculated from the geometry of the coils. In this paper the magnetic field in the region of the electron beam is calculated and compared to the field at the center of the coils. The height of the beam increases as it traverses the semicircular path and this increase is calculated.

ISSN:0002-9505    

DOI:10.1119/1.14966

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

Moving a Hall specimen perpendicular to the magnetic field and in the opposite direction to the drift motion of carriers with exactly the drift velocity results in a compensation of the Hall voltage. Thus a drift velocity of, e.g., 0.6 mm s−1in Cu can be directly observed.

ISSN:0002-9505    

DOI:10.1119/1.15307

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

We review the prehistory and early history of cosmic ray studies, concentrating on the period 1900–1927. Following the discoveries of the electron and radioactivity just before the turn of the century, the old problem of leakage of charge from a conductor in air was investigated in terms of the new concept of ionization and ionizing radiation, part of which was found to be highly penetrating and to be of extraterrestrial origin. At first supposed to consist only of ultrahigh energy gamma rays, the cosmic ray primaries are now known to be mainly charged particles. The modern period of cosmic ray research began in 1927, when individual particles were studied by cloud‐chamber and coincidence counting techniques.

ISSN:0002-9505    

DOI:10.1119/1.14967

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

In the mid‐1700s a debate raged between Jean d’Alembert, Leonhard Euler, and Daniel Bernoulli concerning the proper solution to the classical wave equation. This controversy was partially solved by Lagrange and, more conclusively, by Fourier (50 years later) and it provides an interesting case study for the role of mathematics in the modeling of physical phenomena. Of particular note in this debate, was the meaning of boundary conditions. The controversy is summarized from the point of view of this mathematical physics perspective.

ISSN:0002-9505    

DOI:10.1119/1.15311

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

An older approach to the problem of projectile motion with quadratic drag force is presented with the fly ball as an example. In this approach, analytical solutions for the velocity, curvature, and arc length are obtained as functions of the slope angle. It is shown that the velocity and curvature do not have their extrema at the top of the trajectory but during the early phase of descent. The entire problem is reduced to simple integrations over the slope angle.

ISSN:0002-9505    

DOI:10.1119/1.14968

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

The lateral force on a spinning baseball in a wind tunnel has been measured. The magnitude of the force is nearly independent of the orientation of the seams of the ball. The drag coefficient appears to be at most weakly dependent on Reynolds number and to be principally a function of the ratio of the rotational speed of the equator of the ball to the wind tunnel speed. This is to be compared to the work of Briggs, which implies a strong effect of Reynolds number on the drag coefficient.

ISSN:0002-9505    

DOI:10.1119/1.14969

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

A torsional pendulum consisting of an 8‐mil boron–tungsten fiber and inertial member is described. The torsional oscillations are excited electrostatically and detected by a frequency modulation technique. Both the dynamic shear modulus and the internal friction can be measured. In addition, this system exhibits the resonance behavior characteristic of a highQoscillator.

ISSN:0002-9505    

DOI:10.1119/1.14957

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP

摘要:

Seventeen one‐semester undergraduate laboratory courses are managed by a microcomputer system at Concordia University. Students may perform experiments at any time during operating hours. The computer administers pre‐ and post‐tests. Considerable savings in manpower costs is achieved. The system also provides many pedagogical advantages.

ISSN:0002-9505    

DOI:10.1119/1.14958

出版商:American Association of Physics Teachers    

年代:1987

数据来源: AIP