In this issue: June 2021
Bet hParks, Editor
These brief summaries are designed to help readers easily see which articles will be most valuable to them. The online version contains links to the articles.
Regular readers will note the temporary increase in the length of the issue as we try to decrease the backlog of manuscripts. We think the end is in sight.
Fréedericksz transition on air
Juliette Plo, Dihya Sadi, Elio Thellier, Pawel Pieranski, Mehdi Zeghal, and Patrick Judeinstein
89(5), p. 32916 10.1119/10.0003350
An experiment is described in which the Fréedericksz transition, a phase transition involving liquid crystals, can be seen as well as heard in a classroom setting. Conceptually, the experiment uses a twisted nematic display as the capacitor in a RC oscillator circuit; changes in the oscillator frequency are induced by applied magnetic and electric fields above certain critical values and detected by a software-defined radio. Disclinations and domain walls in the liquid crystal director field are observed and discussed. The authors provide extensive supplementary materials showing how to re-create the experiment. The link above will also take the reader to the article’s video abstract.
A new look at quantal time evolution
Aparajita Bhattacharyya, Jayanta K. Bhattacharjee, and Debabrata Sinha 89(5), p. 32885
10.1119/10.0003397
The time evolution of three wave functions is evaluated using the Heisenberg approach.
Instructors of quantum mechanics will gain insight from this paper.
Algorithm to visualize a 3-D normal surface in anisotropic crystals and the polarization states of the o- and e-waves in uniaxial crystals
Luis Oscar González-Siu, Martha Rosete-Aguilar, and Neil C. Bruce 89(5), p.33011
10.1119/10.0003427
An algorithm is presented to help students and teachers visualize the propagating electromagnetic field in uniaxial and biaxial crystals. This algorithm is implemented win Mathematica and can be useful in electrodynamics and optics courses at the undergraduate and graduate level.
PLEASE CITE THIS ARTICLE AS DOI: 10.1119/10.0004797
Gravitational time dilation, free fall, and matter waves Anna P. Czarnecka and Andrzej Czarnecki
89(5), p.32735 10.1119/10.0003448
Free fall in a gravitational field is explained as the effect of refraction of the quantum mechanical wave function due to time dilation.
Interception and Rendezvous: An intuition-building approach to orbital dynamics Eric M. Edlund
89(5), p.32618 10.1119/10.0003489
The analysis of intercept and rendezvous of two spacecraft is mathematically challenging, and is typically tackled by solving multiple differential equations. In this article, the author sidesteps these complications by choosing a geometry-based approach, making the topic suitable for the junior level mechanics course. A html-javascript orbit calculator is also provided so that students (and their instructors!) can easily test their calculated solutions and strengthen physical intuition.
Why does water shoot higher if we partially block the garden hose outlet?
Mohammad-Reza Alam 89(6), p.31257 10.1119/10.0003512
The explanation is given for the phenomenon of the increase in water output speed when the outlet of a garden hose is partially blocked. The paper covers issues in fluid dynamics and dimensional analysis and is accessible to juniors, perhaps sophomores, in physics or engineering
Gravitational waves physics using Fermi coordinates: A new teaching perspective Matteo Luca Ruggiero
89(6), p.32998 10.1119/10.0003513
The study of gravitational waves has never been more topical than in the past decade, but the textbook treatment of gravitational waves remains intimidating. In this article, the physics of gravitational waves is explored through the use of an electromagnetic analogy which allows the reader more direct access to the waves' physical effects on detectors. The article is appropriate for advanced undergraduates, graduate students, and faculty who are keen to develop an intuitive sense of gravitational waves.
PLEASE CITE THIS ARTICLE AS DOI: 10.1119/10.0004797
An interactive gravitational-wave detector model for museums and fairs
S. J. Cooper, A. C. Green, H. R. Middleton, C. P. L. Berry, R. Buscicchio, E. Butler, C. J.
Collins, C. Gettings, D. Hoyland, A. W. Jones, J. H. Lindon, I. Romero-Shaw, S. P. Stevenson, E. P.
Takeva, S. Vinciguerra, A. Vecchio, C. M. Mow-Lowry, A. Freise 89(6), p.32392
10.1119/10.0003534
Details are given of the construction of a gravitational-wave model for both permanent (exhibits) and portable (demonstrations) use. Materials and instructions are given for construction of the device, along with many practical tips on the use of the device and set up exhibits and
demonstrations. The article is meant very specifically for those who might want such outreach materials.
The true story of Newtonian gravity Eugene Hecht
89(6), p.32967 10.1119/10.0003535
Under pressure of time we often teach the law of universal gravitation F = GmM/r2 as if it emerged fully formed out of the mind of Isaac Newton, perhaps with brief nods to the contributions of Kepler, Huygens, and Halley. But physically-motivated theories of mass and force go back to at least the thirteenth century and involve many players, both pre- and post-Newton. This paper, which is accessible to readers at all levels, traces the development of this famous expression.
Hysteresis in a simple V-shaped spring-mass system Christopher Ong
89(6), p.33133 10.1119/10.0003536
Students are often introduced to hysteric behavior by studying ferromagnetism or non-linear elastic materials. But hysteresis can also occur in exceedingly simple systems, such as the mass- spring system analyzed by the author. The simplicity of the analysis may allow instructors to introduce this important topic in introductory mechanics courses, and a physical model of the system could be used as a demonstration or laboratory apparatus. The link above will also take the reader to the article’s video abstract.
Rubidium isotope shift measurement using noisy lasers
Theodore J. Bucci, Jonathan Feigert, Michael Crescimanno, Brandon Chamberlain, and Alex Giovannone
89(6), p. 32146
PLEASE CITE THIS ARTICLE AS DOI: 10.1119/10.0004797
10.1119/10.0003540
An inexpensive laser diode can be used to study hyperfine splitting in rubidium using saturated absorption spectroscopy, without the need for an external cavity diode laser, allowing students to directly see the effect of the nucleus through both motional and nuclear-size effects.
Soil analysis using a 2NaI gamma detector
Rebekah Aguilar, Patrick Powers, Nina Abramzon, and P. B. Siegel 89(6), p.32460
10.1119/10.0003490
This paper shows how students can use a 2-inch NaI detector to measure the main sources ofterrestrial gamma radiation in their environment, i.e., 40K, the 238U and the 232Th decay series, and learn how to calibrate the detector for efficiency and sample self-absorption. This apparatus allows the experiments to be performed over two three-hour laboratory sessions so that even students in lower-level courses can learn about natural radiation in the environment.
Scattering problems via real-time wave packet scattering M. Staelens and F. Marsiglio
89(6), p. 33040 10.1119/10.0003689
In a lattice tight-binding model, wave packets with certain average momenta don't spread.
The authors harness this behavior to develop intuition about 1d scattering processes -- everything that happens to the wave packet is caused by scattering off of lattice impurities. Several types of impurities are considered, and the wave packet dynamics are solved for with a straightforward numerical diagonalization.
Oscillation of a balanced hollow cylinder on an inclined plane R. De Luca
89(6), p. 32856 10.1119/10.0003797
The author studies the behavior of a thin-walled cylinder lying on its side atop an inclined plane. The cylinder is balanced against rolling by a mass attached to its inner rim. The system’s stable and unstable equilibria are found using geometry and trigonometry, while oscillations about equilibrium are examined using a Lagrangian approach. The former presents a challenging exercise for introductory physics students, while the latter is suitable for an upper level mechanics class. The system is simple and inexpensive to construct, making it ideal for experimental verification of the author's results.
Haidinger–Michelson rings in white light
PLEASE CITE THIS ARTICLE AS DOI: 10.1119/10.0004797
Youssef El Azhari and Saïd Tagmouti 89(6), p. 32584
10.1119/10.0003798
The bulls-eye pattern typically seen at the output of a Michelson interferometer cannot be observed when the input is white light. However, inserting a glass slide into one of the arms not only allows Haidinger-Michelson rings to be observed, but also enables the measurement of the index of refraction of the glass.
Not the garden hose instability: Wavelength selection in a buckling garden hose Tianyi Guo, Xiaoyu Zheng, and Peter Palffy-Muhoray
89(6), p. 32902 10.1119/10.0003819
Imagine this. On a nice summer day, you have just watered your plants with a garden hose.
You close the water inlet valve, before releasing the water pressure by opening the outlet valve. As a consequence, the hose elongates, and assumes a sinusoidal shape. This paper shows how this will happen if your garden hose is lined with a helical reinforcing mesh. The elongation or contraction of the tube upon pressure release actually depends on the helix angle of the mesh. The hose will then spontaneously exhibit a buckling instability, which is responsible for its undulating shape. This effect has interesting consequences for the rigidity of hydroskeletons – fluid-filled tubes reinforced by helical filaments – in nature. This article provides a nice application of Euler’s self-buckling instability for undergraduate mechanics lectures or labs.
Integrating numerical modeling into an introductory physics laboratory
Diana Sachmpazidi, Manuel Bautista, ZbigniewChajecki, Claudio Mendoza, and Charles Henderson
89(6), p. 32765 10.1119/10.0003899
This paper shows how computational physics can be introduced into an introductory laboratory using Excel and documents student and instructor reactions to the new curriculum.
The floating point: Tales of the unexpected The floating point: Rounding error in timing devices David A. Faux and Janet Godolphin
89(6), p. 32497
10.1119/10.0003915, 10.1119/10.0003919
PLEASE CITE THIS ARTICLE AS DOI: 10.1119/10.0004797
Floating point errors can pop up in interesting and unexpected places in computational physics, as demonstrated in this article.
Accompaniment to longer article. Shows a very interesting case of how floating point errors can affect timing devices in ways that have measurable impacts.
On viewing the Himalayas from the plains Vijay A. Singh and Arnav Singh
89(6), p. 32915 10.1119/10.0003920
Clearer skies due to the pandemic-induced lock-down inspired a fresh look at reported sightings of Himalayan peaks in the historical record. This pedagogical article can inspire problems for undergraduate students.
Classical behavior of a quantum particle in a refringent medium V. E. Kuzmichev and V. V. Kuzmichev
89(6), p. 32887 10.1119/10.0003966
Quantum particles are known to recover a classical behavior in the ℏ →0 limit. However, there is another road to classicality: one can engineer the potential field in such a way that a quantum particle of mass and energy evolving in this medium has a classical momentum = √2 . Schrödinger’s equation then amounts to a wave-optics equation within a medium of effective index of refraction , and quantum effects no longer govern the particle’s motion. The position and energy dependences of are here derived in the 1D and 3D cases. This paper is appropriate for advanced undergraduate quantum mechanics, where the relationship between the quantum and the classical worlds is explored.
On the consistency of the Lagrange multiplier method in classical mechanics Nivaldo A. Lemosa and Marco Moriconi
89(6), p. 33039 10.1119/10.0004135
This work explores the relationship between the mathematical method of Lagrange multipliers and the physical forces which can be determined through its use. In this article, readers interested in classical mechanics will find conditions under which the technique of Lagrange multipliers is physically consistent.
The force required to operate the plunger on a French press
PLEASE CITE THIS ARTICLE AS DOI: 10.1119/10.0004797
Fabian B. Wadsworth, Caron E. J. Vossen, Michael J. Heap, Alexandra Kushnir, Jamie I.
Farquharson, Diana Schmid, Donald B. Dingwell, Lukas Belohlavek, Mila Huebsch, Lucille Carbillet, and Jackie E. Kendrick
89(6), p. 33114 10.1119/10.0004224
What can a cup of coffee teach you about fluid mechanics? This article helps answer this question by examining the force F one has to exert on a French press plunger to make the water flow through the coffee grounds. Analyzing the laminar flow of water through this permeable medium, the authors relate F to the initial mass of coffee, its density, the average grain size, and to the velocity of the plunger the operator imposes during brewing. They propose a simple model that can be used to illustrate undergraduate fluid mechanics lectures, but also simple at-home experiments, and more in- depth characterization in the lab, suitable for a student project.
