As intriguing optical phenomena that occur in nature, mirages are widely known and often mentioned in physics classes when introducing the basics of optics. In the atmosphere, a mirage occurs under the condition of vertical variations in air density, which are usually caused by a temperature gradient. The light rays are continuously refracted and…

Experimental results are presented concerning a bead sliding on a rotating, horizontal rod. If the rod rotates at constant angular velocity then the sliding speed in the radial direction increases exponentially with time, provided that the rotation speed is sufficient to overcome friction. Otherwise the bead rotates in a circular path of constant…

An electric motor converts electrical energy into mechanical work and an electric generator converts mechanical work into electrical energy. The symmetry between the motor and generator naturally leads to questions about creating a perpetual motion machine. The allure of this question has inspired textbook problems, physics education articles, and…

The theory of the Big Bang is accepted nearly universally among the scientific community. However, there is a small cadre of individuals who dispute this consensus and they point to a handful of datums that don't fit into the picture. One such datum is the existence of a star with an age reported to be older than the cosmos itself. This star is…

Issues associated with nature of science (NOS) have long been recognized as an essential component of scientific literacy. While consensus exists regarding the importance of an explicit reflective approach, precisely how to teach NOS remains elusive. The present study explores one particularly promising approach, namely the use of historical…

Under most conditions, a liquid mixture does not have long-range structural order and may be considered to be a homogeneous collection of molecules in random motion. However, if a single-phase critical mixture of a partially miscible liquid--liquid system is subjected to a small temperature jump into the two-phase region, then structural coherence…

Water electrolysis is used to teach important and fundamental concepts in chemistry. In practical water electrolysis experiments, it is difficult to achieve the ideal 2:1 ratio of hydrogen to oxygen. This work demonstrates an experimental setup comprising multiple water electrolysis cells connected in series to simultaneously visualize the effects…

As simple and ubiquitous redox-active organic molecules, quinones participate in diverse electron transfer processes in chemistry and biological systems for energy transformation and signal transduction. We introduce here a practical exercise to study the redox potentials of benzoquinone and its two derivatives by combining the electrochemistry…

About 30 years ago I taught a series of summer enrichment programs for high school physics teachers, using funding from the Howard Hughes Medical Institutes. I deliberately chose teachers from smaller cities and towns who were unlikely to have contact with other physics teachers. One of my more interesting teachers came from a rural area in a far…

This paper starts with an introduction to the concept of momentum current. It is followed by a discussion of its strength and density with the aid of several analogies made between momentum current and electric current. Based on the novel concepts of thermal charge and its quantity (entropy), the analogies are extended to entropy current. The…

A complex terminology developed around the evolutionary concept of adaptation. One definition of adaptation is synonymous with adaptive evolution and denotes a process of population change driven by natural selection resulting in individuals better able to survive and reproduce in a particular environment (compared to the population before the…

Graphic novels are everywhere! The popularity of graphic novels is not surprising. They are colorful and engaging, marrying text to images, with diverse characters doing everything from struggling with their tennis game to solving engineering problems to battling villains from the Multiverse. Graphic novels promote both language and scientific…

Chladni patterns are one of the most fascinating physics demonstrations. They can be produced very easily using commercially available apparatus based on metallic plates attached to a mechanical driver, similar to a loudspeaker without the membrane, and a signal generator. The figures are observed using sand sprinkled on the surface of the plate.…

Already when they enter primary school, children have rich everyday experience with factors influencing the rate of liquids' evaporation. Tea spilled into a large puddle on the table evaporates more rapidly than the same amount remaining in the cup, laundry hanging on a clothesline dries faster on a hot and windy day in comparison with a cold and…

The conventional approach to teaching blackbody radiation in introductory modern physics courses relies on an oversimplified explanation of Wien's displacement law, which does not uphold students' conceptual understanding of Planck's law and can lead to well-known misconceptions. Thus, there is a need to clarify the pedagogical role of this…