摘要:

An experiment has been developed that enables students to use a nearly confocal interferometer to measure and verify the predicted frequency spacing of adjacent transverse modes of the nearly confocal interferometer.

ISSN:0002-9505    

DOI:10.1119/1.16828

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

The two‐degree‐of‐freedom oscillator consisting of two masses and three springs whose masses are not negligible is studied in terms of stationary waves. The corrected eigenfrequencies are calculated. It is shown that a recently published treatment of the same problem is valid only if the masses of the springs are very much smaller than the masses of the oscillating bodies.

ISSN:0002-9505    

DOI:10.1119/1.16570

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

The use of commercially available optical design software is described as a tool to aid in learning geometrical optics. Common optical phenomena are easily modeled and displayed graphically. The interactive nature of this type of software allows the student to develop a deeper understanding of the laws of optics.

ISSN:0002-9505    

DOI:10.1119/1.16833

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

The usual textbook treatment of electromagnetic (em) wave propagation across the boundary separating two dielectrics is generalized to materials characterized by complex refractive indices. Such materials are being investigated intensively and possess interesting and potentially useful properties in the infrared (IR) and optical bands. The sum of the transmission and reflection coefficients at the boundary in these materials does not add to unity, as in the case of perfect dielectrics, and the reason for this unexpected behavior is examined. Since these materials are usually fabricated in film form, appropriate transmission and reflection coefficients of thin and thick films with arbitrary refractive indices are derived (taking account of multiple reflections) to point out the differences introduced by the complex nature of the refractive index which have not been included in previous results or which have generally not been emphasized. Results are also presented for films deposited on thick substrates of arbitrary refractive indices since this is the common mode of fabrication. Graphs are presented to illustrate the transmission behavior of a thin absorbing film with and without a substrate.

ISSN:0002-9505    

DOI:10.1119/1.16571

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

This paper examines the possibility of applying the time‐dependent perturbation theory to the systems with a time‐dependent unperturbed part. Analyses indicate that time‐dependent perturbation theory is valid even if the unperturbed HamiltonianH0depends on time, provided that the pseudostationary states ofH0are known. It is also shown that this new perturbative treatment provides a useful tool for tackling the problem of a general driven time‐dependent oscillator.

ISSN:0002-9505    

DOI:10.1119/1.16572

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

Using the Crawford technique of calculating the energy loss of gas atoms colliding with a wall, it is demonstrated that relativistic temperature measures the average value of the product of the atomic velocity with momentum, i.e., 〈vp〉 per translational degree of freedom. This confirms a passing observation made by ter Haar and Wergeland 20 years ago. The mean number of collisions needed to attain equilibrium can also be estimated theoretically.

ISSN:0002-9505    

DOI:10.1119/1.16573

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

A magnetic model for the demonstration of structural properties and the lattice dynamics of molecular crystals is presented. It is used to visualize an orientational order–disorder phase transition. The orientational order of the low‐temperature phase observed on the model is also obtained from a mean field calculation. A simple theory for harmonic excitations of the model is presented, which gives the dispersion relation for an infinite crystal. The frequencies of the observed resonances of the finite model are compared with the results of a numerical eigensystem analysis and with the dispersion relation. Within the limitations given by the construction of the model the results are in rather good agreement.

ISSN:0002-9505    

DOI:10.1119/1.16574

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

The authors have developed a new method for doing numerical quantum mechanical perturbation theory. It has the flavor of Rayleigh–Schrödinger perturbation theory (division of the Hamiltonian into an unperturbed Hamiltonian and a perturbing term, use of the basis formed by the eigenfunctions of the unperturbed Hamiltonian) while turning out to be a variational technique. Furthermore, it is easily implemented by means of the widely used ‘‘electronic scratchpad,’’ MathCAD 2.0, using an inexpensive computer. As an example of the method, the problem of a harmonic oscillator with a quartic perturbing term is examined.

ISSN:0002-9505    

DOI:10.1119/1.16575

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

Two examples are given of the use of cumulant expansions for systems of particles with hard‐core two‐body interactions. One of these, in classical statistical mechanics, is shown to lead to virial coefficients. An analogous procedure in quantum mechanics produces energy level shifts due to hard‐core interactions that are expressed in terms of thetmatrix.

ISSN:0002-9505    

DOI:10.1119/1.16576

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.16578

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP