In this article we describe how the classic pinhole camera demonstration can be adapted for use with digital cameras. Students can easily explore the effects of the size of the pinhole and its distance from the sensor on exposure time, magnification, and image quality. Instructions for constructing a digital pinhole camera and our method for…

Educators have found that kinesthetic involvement in an experiment or demonstration can engage students in a powerful way. With that as our goal, we developed three activities that allow students to connect with and quantitatively explore key physics principles from mechanics with three fun physical challenges. By presenting these activities as…

The study of the ideal solenoid is a common topic among introductory-based physics textbooks and a typical current arrangement in laboratory hands-on experiences where the magnetic field inside a solenoid is determined at different currents and at different distances from its center using a magnetic probe. It additionally provides a very simple…

In this work, an educational experience is described in which a microwave communication link is used to make students aware that all electromagnetic waves have the same physical nature and properties. Experimental demonstrations are linked to theoretical concepts to increase comprehension of the physical principles underlying electromagnetic…

Newton's second law is one of the cornerstones of the introductory physics curriculum, but it can still trouble a large number of students well after its introduction, hobbling their ability to apply the concept to problem solving and to related concepts, such as momentum, circular motion, and orbits. While there are several possibilities for…

In this note we synthesize and extend expressions for the magnetic field at the center of very short and very long current-carrying coils. Elementary physics textbooks present the following equation for the magnetic field inside a very long current-carrying coil (solenoid): B[subscript sol] = µ[subscript 0] (N/L) I, (1) where I is the current, N…

Al Bartlett's video "Arithmetic, Population, and Energy" spells out many of the complex issues related to energy use in our society. Bartlett makes the point that basic arithmetic is the fundamental obstacle preventing us from being able to grasp the relationships between energy consumption, population, and lifestyles. In an earlier…

The bicycle generator is often mentioned as an example of a method to produce electric energy. It is cheap and easily accessible, so it is a natural example to use in teaching. There are different types, but I prefer the old side-wall dynamo. The most common explanation of its working principle seems to be something like the illustration in Fig.…

The traditional introductory-level meterstick-balancing lab assumes that students already know what torque is and that they readily identify it as a physical quantity of interest. We propose a modified version of this activity in which students qualitatively and quantitatively measure the amount of force required to keep the meterstick level. The…

While observing the bounce heights of various kinds of sports balls dropped from different heights onto a variety of surfaces, we thought of the following question: Could measurements of drop and bounce heights of balls of different diameters, but of the same material, falling from different heights, but on the same surface, be expressed by a…

The standard method to create dramatic color images in astrophotography is to record multiple black and white images, each with a different color filter in the optical path, and then tint each frame with a color appropriate to the corresponding filter. When combined, the resulting image conveys information about the sources of emission in the…

In this paper, we examine a first-year torque and angular acceleration problem to address a possible use of the forelimbs of "Tyrannosaurus rex." A 1/40th-scale model (see Fig. 1) is brought to the classroom to introduce the students to the quandary: given that the forelimbs of "T. rex" were too short to reach its mouth, what…

Physics Education Research (PER) focuses on understanding how students learn physics at all levels and developing strategies to help students with diverse prior preparations learn physics more effectively. New physics instructors are encouraged to visit http://PhysPort.org, a website devoted to helping instructors find effective teaching resources…

In the class of 2013, a record number of students earned bachelor's degrees in physics: 7,363. This is more than double the number of students doing so only 14 years earlier. Over the same time period, the total number of bachelor's degrees awarded in all disciplines was up also, but only by about 40%. The graph shows the number of…

In this time of concern over climate change due to the atmospheric greenhouse effect, teachers often choose to extend relevant classroom work by the use of physical models to test statements. Here we describe an activity in which inexpensive backyard models made from cardboard boxes covered with various household transparent materials allow…