December 2019 Issue,
Volume 87, No. 12
When dipping toast into a cup of tea leads to a scientific investigation
This article recounts a scientific investigation that started from the observation of an ordinary everyday phenomenon. In a cup of tea, dipping buttered toast produces on the surface of the tea beautifully evolving lenses, which are pierced repeatedly by moving holes. To unravel this dynamic observation, we show here how we simplified the system into its basic ingredients, and how we excluded several hypotheses such as thermal convection. We reproduce the phenomenon with an inverse emulsion of surfactant-laden water droplets. Depending on the spreading of the lens, we also observe and explain the formation of an oil lacework and “swimming” lenses.
GUEST EDITORIAL
Family or faculty? by Richelle Teeling-Smith. DOI: 10.1119/10.0000187
PAPERS
When dipping toast into a cup of tea leads to a scientific investigation by Philippe Marmottant, Florian Orthion and Salima Rafaï. DOI: 10.1119/10.0000025
A sundial with hour lines portraying the Earth by Joachim Heierli. DOI: 10.1119/10.0000033
Equilibrium and stability of thin spherical shells in Newtonian and relativistic gravity by Philip LeMaitre and Eric Poisson. DOI: 10.1119/10.0000026
An alternative formulation of the magnetostatic boundary value problem by L. Nasser and Z. Chacko. DOI: 10.1119/10.0000004
Low-cost Fourier ghost imaging using a light-dependent resistor by Ritz Ann Aguilar, Nathaniel Hermosa and Maricor N. Soriano. DOI: 10.1119/10.0000163
Particle sliding down an arbitrary concave curve in the Lagrangian formalism by Leonardo Balart and Sebastián Belmar-Herrera. DOI: 10.1119/10.0000037
A simple mechanical apparatus for measuring the surface tension of soap bubbles by Martin Specht, Tom Frömbgen, Hannah Wessely and Moritz Sokolowski. DOI: 10.1119/10.0000003
BACK OF THE ENVELOPE
Scaling exponents by Sanjoy Mahajan. DOI: 10.1119/10.0000188
COMPUTATIONAL PHYSICS
Molecular dynamics simulation of a two-dimensional dusty plasma by István Donkó, Peter Hartmann and Zoltán Donkó. DOI: 10.1119/10.0000045
NOTES AND DISCUSSIONS
Estimating the size of Earth's umbral shadow using sky brightness light curves during a lunar eclipse by Jennifer J. Birriel and J. Kevin Adkins. DOI: 10.1119/10.0000134
APPARATUS AND DEMONSTRATION NOTES/
Energy-resolved coincidence counting using an FPGA for nuclear lifetime experiments by Mario Vretenar, Nataša Erceg and Marin Karuza. DOI: 10.1119/1.5122744
Audio encryption through synchronization of chaotic oscillator circuits: Teaching non-linear dynamics through simple electrical circuits by Keyur Mistry, Sudeshna Dash and Siddharth Tallur. DOI: 10.1119/10.0000024
BOOKS RECEIVED
American Journal of Physics 87, 1020 (2019); https://doi.org/10.1119/10.0000174
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