We introduce a natural way of visualizing the entropy production in heat transfer processes between a system and a thermal reservoir. This representation highlights the asymmetric character of the ..read more

Dark matter remains one of the most significant scientific mysteries of our time. This Resource Letter provides an overview of the astrophysical evidence for dark matter and describes the broad set ..read more

We describe the physics of the “Windkessel effect” and its role in smoothing the output of water produced by piston-driven pumps found in early fire engines and modern residential well houses. We ..read more

The interference of single photons going through a double slit is a compelling demonstration of the wave and particle nature of light in the same experiment. Single photons produced by spontaneous ..read more

American Journal of Physics, Volume 91, Issue 4, Page 328-328, April 2023 ..read more

American Journal of Physics, Volume 91, Issue 4, Page 316-323, April 2023. 10.1119/5.0122766.1A smoke chamber and light-sheet video microscope setup is relatively easy to construct and provides opportunities for undergraduates to participate in a variety of advanced experiments, including the demonstration of Brownian motion and the interaction of induced electrostatic dipoles in aerosol particle agglomeration. We present results of these experiments along with information to allow replication of the setup in undergraduate physics laboratories. A theoretical model of the rate of aerosol agglom ..read more

American Journal of Physics, Volume 91, Issue 4, Page 253-254, April 2023 ..read more

American Journal of Physics, Volume 91, Issue 4, Page 278-287, April 2023. As documented by textbooks, the teaching of electromagnetic induction in university and high school courses is primarily based on what Feynman labeled as the “flux rule,” downgrading it from the status of physical law. However, Maxwell derived a “general law of electromagnetic induction” in which the vector potential plays a fundamental role. A modern reformulation of Maxwell's law can be easily obtained by defining the induced electromotive force as [math], where [math] is the velocity of the positive charges which, by ..read more

American Journal of Physics, Volume 91, Issue 4, Page 256-257, April 2023 ..read more

American Journal of Physics, Volume 91, Issue 4, Page 324-326, April 2023. A straightforward method of determining the eccentricity of Earth's orbit and the position of aphelion and perihelion relative to the vernal equinox from solstice and equinox times is described. The only assumption made is that the orbital eccentricity is small. Using dates for these phenomena adopted from a desk calendar gives the eccentricity to an accuracy of about 10 ..read more