摘要:

A common example from intermediate‐level electromagnetic theory, the calculation of the force acting on a dielectric slab partially inserted into a parallel‐plate capacitor, is examined in detail. The physical origin of the force, ignored in most textbooks, is shown to be due to the fringe field. The standard textbook calculation, in which the fringe field is explicitly ignored, is examined. An analysis which includes the presence of the fringe field indicates that the standard result is valid, but under conditions other than those generally presented.

ISSN:0002-9505    

DOI:10.1119/1.13861

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

An experiment for undergraduate optics laboratories is described based on the interaction of light with opaque particles of 10 to 100 μm size. The experiment demonstrates the phenomena of diffraction and interference in low‐angle Fraunhofer patterns and shows how several structural parameters of microparticles can be determined from such patterns.

ISSN:0002-9505    

DOI:10.1119/1.13862

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

In an effort to clarify the role of surface charges on the conductors of elementary electric circuits and the electric fields in the space around them, we present a quantitative analysis of (two‐dimensional) circular current loops. It is also noted that, in general, lines of Poynting flux lie in the equipotential surfaces of quasistatic systems.

ISSN:0002-9505    

DOI:10.1119/1.13611

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

A body of uniform rest mass may be rotated and its energy in the rotational state clearly exceeds its energy in its rest state. The relativistic classical analysis of the ratio of these energies is carried out for spheres, cylinders, and their shells as a function of one rotational parameter. Given the initial body’s geometry, and the relevant choice for the internal ‘‘holding field,’’ the ratio of the equatorial speed to the light speed is used to characterize the relativistic to nonrelativistic moment of inertia ratio as well as the energy ratio.

ISSN:0002-9505    

DOI:10.1119/1.13612

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

The interaction of black holes of very low mass with matter is better described by methods borrowed from cosmic‐ray physics than conventional astrophysics. We discuss their ionization tracks and range in terms which emphasize both the similarities and the differences between the electrostatic and gravitational interactions.

ISSN:0002-9505    

DOI:10.1119/1.13613

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

The basic theory of a receiving antenna is presented in sufficient detail to permit the calculation of the voltage across the load of an optimally designed TV antenna circuit. The rms load voltage is given byVL=λH(30RrD)1/2, where λ is the wavelength of the incident radiation,His the rms value of the magnetic field intensity,Rris the radiation resistance of the antenna, andDis the directive gain. The result obtained from this formula for a typical monopole TV antenna is compared with that obtained from a simple, intuitive approximation. The reasons for the difference in the results are discussed.

ISSN:0002-9505    

DOI:10.1119/1.13614

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

A simple relation between the energyEand the adiabatic invariantJis derived for Hamiltonian systems with a potentialV=axkby making use of the virial theorem. By further developing a first‐order perturbation technique one arrives at a modified expression for the energy in terms ofJforV=axk+bxl. The results obtained are valid in classical mechanics, as well as in the semiclassical domain of quantum mechanics.

ISSN:0002-9505    

DOI:10.1119/1.13615

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

This paper describes a simple solid‐state physics experiment which allows the determination of the pyroelectric coefficient and spontaneous polarization of a sample from measurements of the pyroelectric charge and pyroelectric current.

ISSN:0002-9505    

DOI:10.1119/1.13616

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

A computerized angular position transducer has been developed for introductory laboratory use. The transducer employs a three‐phase synchro controller for precisely determining angular position. The computer supplies a precise three‐phase signal and also provides processing capability. Data are collected at the three‐phase frequency at high resolution. The device appears to be a very useful transducer for physics laboratory experiments involving rotational or vibrational motion.

ISSN:0002-9505    

DOI:10.1119/1.13617

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP

摘要:

A solar radiometer of novel design was used to measure the horizontal global solar irradiance. The instrument employs the principle of spectral selectivity of surfaces and gives directly an absolute determination of the solar irradiance. Construction is simple and the device is suitable for use in colleges.

ISSN:0002-9505    

DOI:10.1119/1.13618

出版商:American Association of Physics Teachers    

年代:1984

数据来源: AIP