In introductory texts, some "special" rays are selected to draw the image produced by lenses and mirrors. After teaching special rays, students usually ask how to draw an arbitrary ray. One method for drawing an arbitrary ray is the "tilted principal axis." As an example, the tracing of an arbitrary ray in diverging lens is…

In 1981 I published a note on "Balancers" as part of a series of illustrations drawn from 19th-century physics texts. Some months later a wonderful present arrived from a physics teacher in Japan, showing the range of our journal. This was the Horse and Rider Balancer in Fig. 1 that was just like the woodcut in my note. The little…

The cross diagram is a way to illustrate and plan the solutions for all kinds of constant-acceleration kinematics problems--including projectile motion, multistage, and multiple-object problems. The cross diagram arranges the kinematic variables in a logical way, making the kinematic relationships between them easy to identify. Combined with a…

Possibly the greatest irony of physics education is the difficulty of demonstrating optics in a visible way. The two most common solutions to this conundrum are to either use "all-inclusive" optical apparatuses, like a large-format camera, or to rely on classic ray-tracing diagrams. While the former looks elegant while demonstrating the…

In one of the Faraday's experiments an electric current is induced in a conducting loop when a magnet in front of it moves towards or away from the loop. While the direction of circulation of the electric current in the loop has only two options, it depends on three experimental conditions that generate eight cases. Even though the Faraday law or…

The aim of this study is to illustrate how to enrich resource rooms with specialized instructional materials for the concepts of "transparent," "semi-transparent," and "non-transparent." Given the special situations of students with learning disabilities, the specialized instructional materials use their own avatars…

This paper shares a hands-on activity that introduces Feynman diagrams and the accompanying idea of using pictorial representations to describe the behavior of subatomic particles--specifically, for electrons and photons--in place of mathematical expressions. Built collaboratively by scientists and artists, it exemplifies a triumph of lateral…

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.…

The laser pointer has been widely used to demonstrate some simple optics phenomena, like reflection, refraction, total reflection, and diffraction. However, the rays of laser light cannot be seen in the air because the scattered light is too weak. Many physics teachers use milk or smoke to visualize rays of laser light in physics labs, but it is…

To a student in introductory physics, using vectors is at best an exercise in bookkeeping. A two-dimensional kinematics problem effectively doubles the number of equations that a student must know, and invites the student to memorize factoids: "The horizontal motion is constant," "Gravity is only in the y-direction," etc. Force…

X-rays are such an important and familiar part of the electromagnetic spectrum, but is there a way to safely bring x-rays into your lecture? The demo team at the University of California at Berkeley seems to have managed this. They have an x-ray safe box that they use to produce a live x-ray image on a fluorescent screen. In this article, we…

Young students show great interest in solar energy and a genuine curiosity towards the operating mechanisms of a solar cell. This study reports on a methodology that reveals an effective approach in explaining the operation of solar cells to young students with very limited knowledge in solid-state physics. The methodology can be presented in the…

Despite the fact that the free-body diagram is the most common method of representing forces in physics education, alternative means have been proposed over the years. Here we present a summary of the proposals found in the literature on physics education. We aim to discuss the pros and cons of these proposals, examine their degree of iconicity,…

A large compendium of works on bias in education and textbooks, including in science, was published in the 2012 book "The New Politics of the Textbook." Of particular interest is a chapter by Ceglie and Olivares in which they discuss and tabulate gender and race in images for two high school biology textbooks. They found a lack of…

Collisions are real-world situations from everyday life (such as car crashes, playing billiards, etc.) that can be described and understood by the principle of conservation of momentum. One might expect that learning from simple collisions might help students understand more complicated physical phenomena. However, from our teaching experiences we…