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…

There are hundreds of satellites in orbit around Earth. Readily available data about them can be a treasure trove for investigations by students at all levels. Orbital parameters and energy changes can be explored. Many of these satellites transmit signals that can be detected by an inexpensive radio receiver--a scanner--designed to receive FM…

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…

The electric field inside a uniformly charged long cylindrical shell is a standard example discussed in introductory university physics. The field is zero inside the cylinder; outside of the cylinder, the field behaves like a long wire at the center carrying the same amount of charge per unit length, analogous to that of a uniformly charged…

A Finderscope is a low-power telescope with a relatively large field of view. It has the same line of sight as the main telescope, helping the main telescope easily find the target. One of the differences between a telescope and a finder is that the finder has crosshairs to aid in accurately pointing at a target. You can see the crosshairs and the…

Problems involving chains, cables, or ropes that are dropped, folded, or pass around pulleys attract ongoing interest, in part because they can become variable-mass situations if the chain is partitioned into sections for analysis. Less attention has been paid to trying to intentionally project the end of a string as far as possible. Here we…

In this paper, an experimental setup composed of a color-mixing device, power supply, and spectrometer is developed. This setup is available for students to do hands-on color mixing with red, green, and blue light in undergraduate labs. LED volt-ampere and spectrum characteristics are investigated. The apparatus was used to perform additive color…

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…

Quantum computers are at the forefront of computing; however, few people understand how they work and their capabilities. We present two versions of an interactive activity designed for high school students (ages 13 to 18) that introduce a core quantum concept--"entanglement." The first version illustrates a simple connection between two…

Most physics courses begin with one-dimensional kinematics, which is usually restricted to the case of constant acceleration. Here we report a unique exercise for an introductory algebra-based physics course involving the running and non-constant acceleration of the theropod dinosaur "Dilophosaurus wetherilli" and the world-famous…

Here is presented an interesting problem that can be used to introduce students to a variety of physics topics including non-inertial frames and frictional forces, rotational dynamics, and damped oscillations; the normal force also appears, but not in its usual guises. The problem is a generalized version of problem 3.34 presented in the…

The stately fall of magnets through conducting pipes is a favorite classroom and laboratory activity used in teaching electromagnetic induction, Lenz's law, eddy currents, electromagnetic braking, and even Newton's third law. When a neodymium magnet is used, the terminal velocity is reached in just a few milliseconds as the induced eddy currents…

Before students learn Kirchhoff's rules, they are typically taught how to solve "combined series-parallel" circuits. The method presented in many textbooks begins by drawing a series of simplified circuits, replacing series and/or parallel elements with their equivalent resistances, eventually reducing the circuit to a voltage source and…

The standing vertical jump (SVJ) is a classical topic in Newtonian mechanics (Fig. 1). Although the topic has also been treated by others (other terms used are "standing high jump" or "squat jump"), the present paper shows how a smartphone can be used to capture video of a jump and determine the jump height. A crucial…

Active learning techniques are generally considered to be any classroom activities in which students become an active participant in learning, instead of a passive listener to a lecture. Service learning activities are generally experiential (real life) and reflective problem-based learning activities in which students enrolled in an academic…