June 2023 issue American Journal of PhysicsJune 2023 Issue,

Volume 91, No. 6


Sarah Frances Whiting, pioneer of laboratory instruction in astronomy

Sarah Frances Whiting developed innovative and influential laboratory work in her introductory astronomy classes at Wellesley College in the late 1800s and early 1900s. Whiting was strongly influenced by Edward Pickering and the early physics laboratory education at the Massachusetts Institute of Technology. This article explores the early development of laboratory work in astronomy education at Wellesley and Whiting's underlying philosophy of education. By laboratory work, Whiting meant day-time work, including work with astronomical photographs and spectroscopy. Her pedagogy was encapsulated in her phrase “to sharpen the pencil sharpens the mind,” which referenced the importance of a student's familiarity with tools as well as the role of drawing in astronomical work. Whiting further modeled her instruction after the work being conducted at the Harvard College Observatory in order to prepare her students for potential future employment as astronomers.



In this issue: June 2023 by Joseph C. Amato; John Essick; Harvey Gould; Claire A. Marrache-Kikuchi; Raina Olsen; Beth Parks; Donald Salisbury; Jan Tobochnik. DOI: 10.1119/5.0155778.


The computer revolution in physics education? It's here! by Edward F. Redish. DOI: 10.1119/5.0155772
Please enjoy this letter and consider writing one yourself. I'd love to hear from you.


Sarah Frances Whiting, pioneer of laboratory instruction in astronomy by Joanna Behrman. DOI: 10.1119/5.0131617
It is hard to imagine teaching physics or astronomy without a laboratory component, but that was the common state of affairs in the late 19th century in the United States.  Sarah Frances Whiting was among the first educators to make lab work central to the teaching of astronomy.  This article discusses the influences on her work, the challenges she faced, and the “hands-on” teaching philosophy she adopted as she launched laboratory instruction at Wellesley College.

Optimal trajectories for symmetric turns by Stephen Kaczkowski. DOI: 10.1119/5.0114235
Say that you're traveling along a wide, straight road and suddenly realize that you want to be going the other direction. What's the fastest way to turn around, if you're constrained by the maximum acceleration due to friction with the road? This sort of constrained motion problem has a long history in physics. The solution, which shows the importance of choosing the right variables, could make a good starting point for student projects in mechanics.

Investigating the magnetic field outside small accelerator magnet analogs via experiment, simulation, and theory by Kelley D. Sullivan; Antara Sen; M. C. Sullivan. DOI: 10.1119/5.0068701
In upper-level electromagnetism, multipole expansions are one of the standard tools used to solve Laplace's equation. However, it's hard to gain a physical intuition for the higher order multipoles. This paper shows how students can gain understanding of multipole fields, while also gaining skills in numerical computation, simulation, data collection, and analysis, by measuring and modeling the magnetic fields of configurations of commercially available magnets. The measurements can be made using a smartphone sensor, and the open-source Python library Magpylib can be used to simulate the fields. The modular organization allows instructors to pick and choose among multiple activities according to the ability and interest of their students.

A magnet falling inside a conducting pipe: Dependence of the drag force on the magnet orientation by Chang Hyeon Lee; Byung-Yoon Park. DOI: 10.1119/5.0062860
Dropping a magnet in a conducting pipe to visualize the eddy current-induced braking is a classic classroom demonstration of induction. Usually, the magnet is dropped in such a way that its magnetic moment is vertical. Here, the authors explore what happens if the magnetic moment is horizontal. Then, the eddy currents are not of cylindrical symmetry, so that things get more complicated. Rather than solving Maxwell's equations numerically, the authors show that the problem is equivalent to having the magnet fall in a quadrupolar magnetic field. They can then derive the expression of the drag force for various magnetic moment orientations. The model is validated through experiment. All or part of this combination of classical electromagnetism, modeling and experiment could be used as an undergraduate exercise, a student project, or a numerical physics problem.

Beyond the ABCDs: A better matrix method for geometric optics by using homogeneous coordinates by Theodore A. Corcovilos. DOI: 10.1119/5.0083069
This article presents a mathematical technique that can alter the direction of the optical axis for compound optical systems while still retaining the small angle approximation. The use of the homogeneous coordinates furthermore delivers a simplified procedure for computing image points for these compound arrangements. This can be of use both in undergraduate instruction and in the laboratory.

Endless fun in high dimensions—A quantum card game Lea Kopf; Markus Hiekkamäki; Shashi Prabhakar; Robert Fickler. DOI: 10.1119/5.0062128
by It's notoriously difficult to develop intuition for quantum mechanical systems, but the need to train students to contribute to quantum technologies inspires us to try new approaches. This paper presents a card game that can be used to learn about basic quantum mechanical concepts such as randomness, superposition, interference, and entanglement while manipulating the quantum state of a virtual quantum computer. The game can be played by students at a wide range of levels and even by the general public.

Free expansion of a Gaussian wavepacket using operator manipulations by Alessandro M. Orjuela; J. K. Freericks. DOI: 10.1119/5.0083964
The spreading of a free Gaussian wavepacket as it evolves in time is a familiar problem to quantum mechanics instructors. But as is frequently the case, revisiting this problem with a different approach can yield significant new insights. This paper shows how the problem can be solved by mapping it onto the application of a squeezing operator on a simple-harmonic-oscillator ground state, providing students with a solution that uses very little calculus while also emphasizing the use of operators. This approach will be particularly useful in courses that emphasize quantum information.


Cost-effective measurement of magnetostriction in nanoscale thin films through an optical cantilever displacement method by David L. Tran; Paymon Shirazi; Mohanchandra K. Panduranga; Gregory P. Carman. DOI: 10.1119/5.0134187
This article presents the design of a cost-effective apparatus for magnetostrictive measurements on nanoscale thin-film samples. Magnetostriction is a property of magnetic materials that causes them to expand or contract during the process of magnetization. The measurement capability of the apparatus is investigated via the measurements on an amorphous 200-nm-thick Terfenol-D sample, where magnetostriction values up to approximately 100 parts per million are obtained. In addition, it is demonstrated that the acquired magnetostriction data can be used to produce a plot of the sample's normalized magnetization as a function of applied magnetic field. The article will be of especial interest to those teaching a magnetic materials and devices course.


Simulating gravitational motion, gas dynamics, and structure in the cosmos by J. W. Powell; L. Caudill; O. Young. DOI: 10.1119/5.0144906
Just as many experimentalists use sophisticated hardware to aid their research, computational physicists use efficient and complex software that has been developed by many people. However, it is important to have some insight into how the algorithms underlying the software work. This paper provides important insights into the nature of ChaNGa, which can be used to simulate the motion of gravitationally interacting sources and gas dynamics in cosmology.


Snow Crystals: A Case Study in Spontaneous Structure Formation by Kenneth Libbrecht Erik S. Thomson, Reviewer. DOI: 10.1119/5.0149392.


Erratum: “A compact disc under skimming light rays” [Am. J. Phys. 86(3), 169 (2018)] by R. De Luca; M. Di Mauro; O. Fiore; A. Naddeo. DOI: 10.1119/5.0146809

Additional Resources