Experiments involving RC circuits are an integral part of introductory physics courses. Previous articles using RC circuits describe determining the charge on a Van de Graaff generator, measuring currents and voltages in a charging RC circuit using a multimeter or an Arduino, measuring the decay constants of complex RC circuits, and using the…

Electricity has shaped modern civilization in a way few other discoveries have. Nonetheless, few students successfully develop a basic understanding of voltage, current, and resistance or their mutual relationship in simple DC circuits. Despite teachers' best efforts in the classroom, so-called "alternative conceptions" often prevail…

In this study, we propose a novel and direct method of determining the focal length of a converging or diverging lens using a smartphone. The standard optical sensor used in modern smartphone cameras is an active-pixel sensor called the complementary metal-oxide-semiconductor (CMOS). The CMOS is covered by an assembly of five to seven camera…

In introductory electric circuits in middle school, students often carry strongly held alternative conceptions. Common to many of these is an idea of electric current as some kind of substance that originates from the battery and moves toward electronic components. Learners often argue that current influences those one by one as they are…

In this article, we present an intriguing experimental exercise that does not fall foul of improper use of instrumentation. The activity is designed as an electronics exercise where the role of the instruments in the measurement of the RC time constant is considered. Essentially, we study the accuracy and precision of a measurement of the RC time…

Our first experience of dimension typically comes in the intuitive Euclidean sense: a line is one dimensional, a plane is two dimensional, and a volume is three dimensional. However, following the work of Mandelbrot, systems with a fractional dimension, "fractals," now play an important role in science. The novelty of encountering…

This work provides a missing manual needed to understand permanent magnets (also known as "hard" magnets), the only source of "magnetic induction field B" (units of teslas), often called the magnetic field, that students are familiar with when they confront magnetic force acting on moving charges. Students see this magnetic…

Students experience current electricity every day in our wired world, yet the circuit problems that students work through in physics class can seem far removed from the common experience of switching on a light bulb. However, current electricity provides many opportunities to engage students in hands-on learning. Through circuit construction,…

Resistor--capacitor (RC) circuit labs help students, but most courses don't include them because of complications and cost. This work presents an easy and inexpensive Arduino-based lab on the charge and energy transfer between two capacitors with different values of the initial electric charge when they are connected through a resistor. Capacitors…

The Arduino microcontroller is finding its way into labs throughout undergraduate physics curricula, from introductory courses to a variety of beyond-the-first-year laboratory classes. At Davidson College, they use Arduinos in a gateway STEM course for students who are interested in energy and the environment. This article describes how students…

Recently, small computer fans have been demonstrated to be an effective method for teaching simple resistive circuits both qualitatively and quantitatively. The current through the fans is related to the rotational speed of the fans and allows multiple senses to be engaged (touch, sight, and hearing). Methods for learning simple circuits in an…

A simple experiment is described to verify the current dependence of Ampère's law for a long straight current-carrying conductor. A narrow and long rectangular multi-loop design is used to increase the strength of the magnetic field in between the long sides. As expected, the magnetic field is found to be linearly proportional to the electric…

Transistors are semiconductor devices that form the basis of today's electronic technology. Following the first step of developing a point-contact transistor developed by Walter Brattain and John Bardeen in 1947, the development of the junction transistor by William Shockley in early 1948 opened the way for rapid progress in electronic technology.…

A new device for teaching the physics of sound, specifically demonstrating the wavelengths of standing sound waves, is here described. I define a "Lincoln's Tube" as any hollow tube that uses lights (LEDs typically) to demonstrate the presence of sound standing waves. The name is chosen intentionally to recall a Ruben's Tube or a Kundt's…

This note is about 1000 words in length. We have been taught that this much information is contained in a single picture. But, Fig. 1 is so rich that four separate ideas can be obtained from it! The figure appears in "The Boy's Playbook of Science" by John Henry Pepper. Pepper tells us that this shows an "assistant standing on the…