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Several papers in this journal have dealt with the fluorescence in orange neon plastic, olive oil, and soda. In each case, the fluorescent emission was excited by either green or violet-blue laser light. In this paper, we examine the fluorescent emission spectra of so-called neon colored papers and plastic clipboards available in department and office supply stores. We also employ violet-blue and green laser pointers as excitation sources. We conclude with a brief discussion of neon pigments in terms of the "day glow" or "daylight fluorescence" phenomenon.

Many teachers like to introduce the Bohr atom toward the end of an introductory physics course. This is an excellent idea, given the historic importance of Bohr's 1913 work, which provided the bridge from Planck's quantized interaction of matter and radiation (1900) to the full theory of quantum mechanics (1925-28). Unfortunately, the version of the Bohr atom that appears in many textbooks and is no doubt often presented to students is more wrong than right and may leave both teachers and students wondering why, more than a hundred years later, it is still being taught. This "pedagogic" version postulates that an electron in a stationary state moves in a circular orbit with an angular momentum that is an integral multiple of h/2p (L = nh/2p = nh)--h for the lowest-energy state, 2h for the next state, and so on. This picture of the hydrogen atom is wrong in two senses. First it doesn't conform to our present understanding of the hydrogen atom. This, in itself, is not a reason to scrap it, for the historical development of quantum physics is certainly of interest. But second, it doesn't conform to the essence of what Bohr actually did. That "is" a reason not to teach about circular orbits and L = nh. Much excellent scholarship has been devoted to Bohr's 1913 work. This article is not intended to extend or enrich that scholarship. Rather, I want to draw the attention of teachers of introductory physics to the high points of Bohr's classic first 1913 paper on the hydrogen atom and to clarify what in that paper is right and what is wrong (as well as what is weird). As I have pointed out in an earlier short communication, there is more right and less wrong than is widely recognized. As to what is weird, well, it is interesting.

Physics teachers are most effective when their students are active learners who think and participate in every class. This extends beyond the classroom too: ideally, students would tackle challenging questions and exercises after every class--not just before the exam or the night before the weekly homework is due. Just-in-Time-Teaching was developed to encourage this by having students submit daily homework online; their answers can be quickly graded (by hand) and then used as a springboard for class discussions that day. More recently, online homework services have become available that can automate the grading process and provide instantaneous feedback to students. Unfortunately in both of these cases, the range of possible questions is limited to what can be easily answered via computer. But while pencil and paper is still an easier medium for expressing diagrams and equations, daily collection of paper homework is cumbersome and does not allow same-day feedback. This paper describes a hybrid strategy in which students solve what may be "standard" pencil-and-paper homework problems, and then use a simple online form to self-report their degree of success.

Students can be seen throughout any campus in America carrying their cell phones, laptop computers, and iPhones. I've seen a tremendous increase in the student use of laptop computers during lectures and students often ask for electronic copies of lectures rather than printed versions. In an attempt to adapt to my students' increasingly technology-driven lifestyle, I issued a tablet computer to all of my students, and for a year all course materials were digital, with no distribution of paper.

In Benjamin Franklin's one fluid theory of electrification, ordinary unelectrified matter consisted of a matrix of matter suffused with a certain amount of "electrical fluid." Electrical effects were due to an excess or deficit of electrical fluid, hence the terms positive and negative. Before the development of a modern view of the atom, diagrams showing charged objects would simply have "+" or "-" signs to indicate the charged state. As physicists we know how to interpret these diagrams and understand what they are telling us about the underlying atomic model of charging. However, novice students may not readily make the connection between the atomic model, in which a charged solid object either gains or loses electrons but does not gain or lose positive charges. Furthermore, when isolated objects become charged, the total number of electrons must be accounted for as charge is a conserved quantity. To really understand the changes that occur in charging by contact, conduction, or induction, it is useful for students to visually represent the processes in a way that emphasizes the atomicity of the processes, including the induced polarization of objects, and the requirement that charge be conserved.

Described is a simple circuit with which students can observe the effect of common dielectric materials in a capacitor and measure the dielectric constant of a piece of paper. Discussed are the theory, apparatus construction, and experimental procedures for this activity. (CW)

Graphite, an allotrope of carbon, is also a moderately good conductor of electricity. The shading pencil lead consists of graphite mixed with clay and, therefore, can conduct electricity, allowing one to construct and demonstrate different properties and the underlying concepts of circuit elements. The grade displayed on the pencil relates to the graphite-to-clay ratio, with higher B grades indicating a higher graphite-to-clay ratio. In this paper, the main objective is to show the dependence of resistance and capacitors on different physical parameters and to calculate the value of π electrically. The materials used in this activity are readily available, affordable, and suitable for demonstration purposes. The materials used to perform these activities are shading pencils of different grades, A-4 size papers, crocodile clips, and an LCR meter. [ABSTRACT FROM AUTHOR]

( I Thanks to Trevor Lipscombe at Catholic University of America and Carl Mungan at the U.S. Naval Academy for the question. i ) Question 2: Toilet paper How much toilet paper does the U.S. use in a year? For more Fermi questions and answers, see I Guesstimation 2.0: Solving Today's Problems on the Back of a Napkin i , by Lawrence Weinstein (Princeton University Press, 2012). [Extracted from the article]

The article describes an experiment involving a solid ball resting in a smooth sheet of paper. Topics discussed include the behavior of the ball being independent on the acceleration of the paper as well several different paper removal speeds being investigated experimentally. Also mentioned are calculations involving ball rolling without slipping and ball rolling with slipping.

The article contains experiment to demonstrate fluorescent emission spectra of neon colored papers and plastic clipboards. The findings indicate that the shorter wavelength light is utilized by the “Daylight" pigment contained in these neon papers to enhance the reflected light in the longer wavelength regions thus making them appear brighter.

This article discusses the challenges students face in understanding the concept of angular momentum and presents a 3D-printed launcher that can be used to perform experiments related to angular momentum conservation. The launcher is designed to be attached to a rotating platform and can be used to launch a ball. The article provides detailed instructions on how to assemble and use the launcher, as well as how to calculate the moment of inertia and angular momentum of the system. The authors report that the experiment has been successfully performed in a physics laboratory and provides students with valuable experience in understanding angular momentum. [Extracted from the article]

Science presented as magic is one way to engender surprise and curiosity in students, and perhaps interest and motivation for further inquiry.

The article discusses findings of a study that analyzes paper-clip top and also presents procedure for making a paper-clip top. Topics discussed include ways to balance stable top from a single paper, role of gravity in achieving stable rotation of a paper clip bent, and measurement of total mass of two Sakai spinners. Also mentioned are studies on the subject such "Topics on tops which enable anyone to enjoy himself" by Takao Sakai and "Hands-on physics with paper clips" by Christian Ucke. INSET: How to make your paper-clip top.

When doing optics experiments, a method of securely holding optical elements is necessary. In school laboratories, optics experiments can be conducted using an optical breadboard or an optical bench. Alternative low-cost experimental kits have been proposed for optics experiments. For instance, the optical bench can be made from a plastic surface cable raceway (a cable conduit), and paper clips can be used to hold paper screens. [ABSTRACT FROM AUTHOR]

Fluid Dynamics and Paper Airplane Design "Aerodynamics Explained by a World Record Paper Airplane Designer" with an Introduction to the Coanda Effect His 17-minute WIRED video "Aerodynamics Explained by a World Record Paper Airplane Designer" demonstrates building and flying five different plane designs and analyzes each. An appealing physics of fluids introductory conceptual/vocabulary tutorial illustrated with paper airplanes. [Extracted from the article]

A wonderful illustration of the impact of using a ratio of 2 scaling in SI formatted paper on graphic design (the European answer to U.S. letter size paper is A4). Tinyurl.com/WS-metricpaper My newest favorite video on scaling since "Powers of Ten.". [Extracted from the article]

YouTube videos by Cambridge mathematician Tadashi Tokieda: "Math Encounters - Toy Models: Extracting Mathematical Surprises from Everyday Life", "Mathematics with Paper Clips, Ribbon, Rubber Bands (Math-Byte)" and "Toy Models" Since then, several folks have directed me to a number of videos by Tokieda analyzing other interesting "simple" phenomena, including his "Toy Models" talk. A nice hands-on activity with a paper strip, paper clips, and rubber bands ends the Princeton video, and is then explored at greater length in the second I Mathbytes i video. [Extracted from the article]

Discusses why light is able to pass through a thick piece of glass but not through a thin piece of paper. (JN)

The paper "Leaving the "One True Path": Teaching Physics Without Single Correct Answers" by Mylène DiPenta[1] raises important issues related to the problems that students solve learning physics. 53, 210-216 (April2015).10.1119/1.4914558 6 Gorazd Planinsic and Eugenia Etkina, "The mysteries of conductive thread: Physics and engineering combined", Phys. 52, 212-218 (April2014).10.1119/1.4868933 5 Gorazd Planinsic and Eugenia Etkina, "Light-emitting diodes: Learning new physics", Phys. [Extracted from the article]

If the heat capacities of people and air are the same, then a 1 °F human temperature change will cause a 10 SP -7 sp °F atmospheric temperature change (due to the mass ratio). Water has a very high heat capacity, so we can estimate that air has a heat capacity that is 10 times smaller. In that case the atmospheric temperature change would be 10 times larger or 10 SP -6 sp °F. We can also use some simple thermodynamics (only a physicist would ever write the phrase "simple thermodynamics") to estimate the heat capacity of air. [Extracted from the article]

Demonstrates the third law of using magnets by mathematician Isaac Newton through combined kinesthetic experience with quantitative experiments. Procedure of a kinesthetic demonstration that allows the students to feel the interaction forces between a magnet and a piece of iron; Guide for determining Newton's third law in repulsion through the combination of kinesthetic experience with quantitative experiments.

The article discusses several ways on how to make capacitors from common materials. The materials used include a roll of aluminum foil, sheets of paper, and a book. The types of capacitors that were created and discussed include parallel plate capacitor, radial electrolytic capacitor, and two-plate book capacitor.

The article discusses about science being presented as magic to develop the interest of students. Topics include improving the scientific interest in students through the practical application of science, inquiry-based instruction and demonstrate examples that show the use of static frictional force.

Fluorescence spectra excited by laser pointers have been the subject of several papers in TPT. These papers all describe a fluorescence phenomenon in which the reflected laser light undergoes a change in color: this color change results from the combination of some partially reflected laser light and additional colors generated by fluorescent emission. Here we examine the fluorescence spectra of highlighter inks using green and violet laser pointers. We use an RSpec Explorer spectrometer to obtain spectra and compare the emission spectra of blue, green, yellow, orange, pink, and purple highlighters. The website Compound Interest details the chemical composition of highlighter inks; in addition, the site discusses how some base dye colors can be combined to produce the variety commercially available colors. Spectra obtained in this study were qualitatively consistent with the Compound Interest site. We discuss similarities and differences between various highlighter colors and conclude with the relevance of such studies to physics students. [ABSTRACT FROM AUTHOR]

The article presents questions and answers on topics including air pressure, crest and trough of an ocean wave, and weight of printed documents.

The article discusses two 19th-century methods to capture magnetic field images including blue magnetic field and iron gall printing. Topics discussed include analysis of how the blue magnetic field imaging process differs from the plotting compass method, discovery of blue magnetic field imaging method in 1842 by mathematician Sir John Herschel, and iron filings allowing more direct engagement with field geometry.

Presents a parabolic reflector construction through a paper-folding exercise. Description of a parabola; Role of the directrix in a parabola; Definition of an ellipse and a hyperbola.

In this paper we describe a simple alternative to the telephone book friction experiment, a classic demonstration where a small force (generated for example by the bending of the outer pages) is amplified by the large number of surfaces in contact, resulting in a huge maximum static friction force that has to be counterbalanced in order to separate the books. The aim of our experiment is to illustrate the friction force in a dramatic way and to simplify the tedious job of interleaving a large number of book pages, by using the minimum number of sheets necessary to sustain the weight of a person using the normal force produced by their fingers. [ABSTRACT FROM AUTHOR]

This paper proposes a simple method to design experiments for drawing the light paths at a lens to find its effective focal length and principal planes. In the designed experiments, long-exposure photography was used to record the light scattered using a moving sheet of paper, thus revealing the light path. According to the proposed experimental method, (1) the effective focal length of a lens and (2) the principal planes of a lens can be measured. Moreover, the system is easy to build, inexpensive, and can promote students' understanding of geometric optics by providing an intuitive physical phenomenon. The work is also of pedagogic interest as it reveals a new simple experimental method to find the principal planes of a thick lens and its effective focal length. [ABSTRACT FROM AUTHOR]

Light has a fascinating property: it always travels the path that takes the least time between any two points. This is the motivating property behind optical phenomena such as reflection and refraction. The unreasonable economic efficiency of light is captured by a single proposition: the principle of least action (PLA) in optics. Unlike reflection and refraction, which emerge from optimizing a one-dimensional function, the PLA emerges from optimizing an infinite-dimensional functional. The PLA can be difficult for students to comprehend, as the formulation of the Lagrangian is often left unexplained. To this end, this paper presents various simulations to demonstrate the action principle, including a numerical solution to a generalization of the brachistochrone problem to an arbitrary refractive profile. The interactive simulations discussed in the paper are available at Ref. 1. [ABSTRACT FROM AUTHOR]

Refrigerator magnets belong to a group of simple devices that we use all the time but rarely question how they work. While refrigerator magnets have received considerable attention in physics education literature, the focus of these papers was mainly on the explanations of their structure or demonstrations of the structure of the magnetic layer. The goal of the present paper is to describe a set of activities that can be performed with general physics students to help them understand how refrigerator magnets are constructed and to simultaneously engage them in such science practices as creating and evaluating models, developing predictions based on hypotheses, performing experiments to evaluate the proposed hypothesis, and switching between different representations. This sequence of activities follows the logical progression of the Investigative Science Learning Environment (ISLE) approach. We piloted all materials with high school physics students, undergraduate physics majors, and graduate level physics education students, and revised based on student feedback. All courses where we implemented the activities were ISLE-based courses; therefore, the students were accustomed to working in groups devising explanations, devising experiments to test them, and sharing their ideas with the rest of the class. All activities that we propose require only the equipment that students commonly have at home (the most sophisticated is a smartphone with a magnetic field sensor). Therefore, the activities can also be used while teaching online. These activities took between 45 and 90 min for the students to complete. The students found them valuable and interesting. [ABSTRACT FROM AUTHOR]

A quiz on the miles of spaghetti and the amount of wrapping paper respectively consumed and used by Americans yearly, is presented.

Describes a physics experiment describing the oscillation of a paper-clip chain. Materials; Procedure; Mathematical formula.

Generally, the goal of a student activity involving analysis of video data is to obtain the ( I x i , I y i ) position of a particular object in as many frames of the video as possible. Recent years have seen an explosion of interest in analyzing the motion of objects in video data as a way for students to connect the concepts of physics to something tangible like a video recording of an experiment.[[1]] Inexpensive devices can now record videos at 120 or 240 frames/s, and, among instructors, there is an appetite for substantially rethinking the objectives of introductory labs (e.g., Refs. In this paper, we both include some general advice to help object-tracking algorithms locate an object and provide our own algorithms that are simpler and potentially more effective than the sophisticated image-processing algorithms that are currently being used. [Extracted from the article]

Shine a laser into a pan of shallow water, but on the bottom of the pan place a piece of paper. The result will be an interesting perfect circle of light (Fig. 1). This is caused by internal reflection of the diffusely reflected light. The diameter of the circle depends on both the depth of the water and the index of refraction of the liquid. In this article, I investigate this very simple activity and show examples of how students and teachers can use this phenomenon as a laboratory or demonstration to investigate concepts of the critical angle and total internal reflection. [ABSTRACT FROM AUTHOR]

The article offers ideas on creating capacitors by drawing graphite lines on paper or plastic. Graphite lines can function as resistors for resistivity experiments. They can be used to analyze the dependence of capacitance on plate area and separation. Using a pencil with very soft lead is recommended in constructing graphite lines. When using plastic, surfaces should be slightly roughened to that graphite can attach to it.

The article demonstrates how to use paper waves to demonstrate's Young's double-slit experiment. The three-dimensional model described will assist students in visualizing the phenomena which would be difficult to achieve if only static text diagrams are used. Instructions to make the paper waves and to illustrate the double slit experiment are presented.

Alpha-particle sources are widely used in industrial and medical applications. Such applications include smoke detectors, static charge eliminators, and radiation therapy. This paper is concerned with the detection of alpha particles. A number of techniques are known for the detection of alpha particles. Those techniques include the Geiger–Müller tube, the ZnS scintillator, the air-filled ionization chamber, and the spark chamber. All the techniques that are currently known are based on the interaction of the ionizing radiation with matter. Charged particles, such as alpha particles, upon entering a medium (such as air), encounter many collisions with bound electrons and lose kinetic energy in the process. The atoms of the medium also become ionized, and a large number of free electrons are released inside the medium. The theory describing the interaction of ionizing radiation with matter is well known and includes formulas such as the Bethe-Bloch formula for the stopping power of matter and formulas for calculating the range of the ionizing radiation in matter. Essentially, all the known techniques for the detection of alpha particles are based on detecting the presence of free electrons inside the medium. This paper presents a new technique for the detection of alpha particles that does not depend on the theory of the interaction of alpha particles with matter. Instead, the technique is based on the direct detection of the positive charge that is carried by the alpha particles. Furthermore, it is the objective of this paper to demonstrate that the direct detection of the charge carried by alpha particles can be done with a tiny and inexpensive component: a metal–oxide–semiconductor field-effect transistor (MOSFET). [ABSTRACT FROM AUTHOR]

This paper addresses a popular topic in science teaching and competitions for primary and secondary school students. Experiments with colliding coins are relatively easy to perform and therefore popular in science lessons. We used the idea in the science competition we organized for pupils aged 6 to 13 years. The science competition is based on a few experiments that the participants have to carry out before the competition. Some years ago, 10- and 11-year-old pupils had to experiment with coins. These were 1-, 10-, 20- and 50-euro cent coins (see Fig. 1), but the experiments can also be carried out with quarters and dimes. The experiments were simple elastic collisions with some obvious but also some profound outcomes, which will be described below. Even if the bodies are moving fast and the collision itself is an instantaneous event, it is possible to reconstruct the trajectories from known initial and final positions of the coins. At the end of this paper, we will present the set of problems that were given in the competition. [ABSTRACT FROM AUTHOR]

The key difference between math as math and math in science is that in science we blend our physical knowledge with our knowledge of math. This blending changes the way we put meaning to math and even the way we interpret mathematical equations. Learning to think about physics with math instead of just calculating involves a number of general scientific thinking skills that are often taken for granted (and rarely taught) in physics classes. In this paper, I give an overview of my analysis of these additional skills. I propose specific tools for helping students develop these skills in subsequent papers. [ABSTRACT FROM AUTHOR]

Historically, classical thermodynamics was developed during attempts to improve the efficiency of steam engines. Those investigations led to the well-known zeroth, first, and second laws of thermodynamics. Although these laws are presented independently, linkages between the zeroth and second laws have been pointed out in the physics teaching literature. In our 2020 paper, "What if Energy Flowed from Cold to Hot? Counterfactual Thought Experiments," we imagined a universe in which energy spontaneously flowed from colder to hotter objects. That paper inspired us to explore the connections between the first law and the Clausius statement of the second law in the present paper. [ABSTRACT FROM AUTHOR]

Loudspeakers are devices that create sound, controlling the interaction between a permanent magnet and an electromagnet induced by a varying electric current in a coil. The physics behind loudspeakers makes them popular educational resources to discuss the principles of electromagnetism and the generation of sound waves. This same idea also applies to electric motors and generators. In this work, we combine electric motors and loudspeakers to build a set of headphones, which are presented to preservice primary school teachers as a "mind control helmet," to demonstrate the basic ideas of electromagnetism and sound physics, but also the nature of science. [ABSTRACT FROM AUTHOR]

In the companion paper, "Aerodynamic Lift, Part 1: The Science," I described the key features of lifting flows. The objective of the present paper is to explain those features and the cause-and-effect relationships between them in a manner consistent with the laws of physics. [ABSTRACT FROM AUTHOR]

The blue color of the sky is due to scattering of sunlight by molecules of air. The process is called Rayleigh scattering in honor of Lord Rayleigh, the physicist who first explained it. Blue light is scattered much more efficiently than light with longer wavelengths, so blue is perceived as the sky's dominant color. [ABSTRACT FROM AUTHOR]

Transfer of structural math knowledge to physics is difficult for students. While research suggests various improvement techniques, enhancing parallelism of algebraic structures used in physics to those studied in mathematics courses seems underrepresented. This paper proposes an alternative way of introducing wave functions as a set of parametric equations. Research shows that the mathematical underpinnings of the mechanical wave function are problematic for students. As seen from the math perspective, there can be several drawbacks that likely impede scientific analysis and interpretation of the wave function: y (x , t) = A cos ( 2 π λ x − 2 π T t). [ABSTRACT FROM AUTHOR]

The article discusses how infrared (IR) imaging can be used to teach mechanisms of heat transfer in the classroom. It argues that an IR image provides various information about an experiment that can be rapidly recognized by the human brain. It mentions that IR visualization may help uncover the heat flow. It suggests that the universality of heat lends itself to the versatility of IR imaging