Physics students encountering electric circuits for the first time often ask why adding more resistors to a circuit sometimes increases and sometimes decreases the resulting total resistance. It appears that these students have an inadequate understanding of current flow and resistance. Students who do not adopt a model of current, voltage, and…

Since 1987, the Statistical Research Center at the American Institute of Physics has regularly conducted a nationwide survey of high school physics teachers to take a closer look at physics in U.S. high schools. We contact all of the teachers who teach at least one physics course at a nationally representative sample of all U.S. high schools-both…

The traditional lab report is known to create several pedagogical shortcomings in the introductory physics course, particularly with regard to promoting student engagement and encouraging quality writing. This paper discusses the use of a "letter home" written to a non-physicist as an alternative to lab reports that creates a more…

Glow sticks are a popular Halloween staple familiar to most of our students. The production of light via a chemical reaction is called "chemiluminescence," and glow sticks are often used as demonstrations and experiments in the chemistry classroom to study reaction rates as a function of temperature. A black light can be used to…

The drop towers of yesteryear were used to make lead shot for muskets, as described in "The Physics Teacher" in April 2012. However, modern drop towers are essentially elevators designed so that the cable can "break" on demand, creating an environment with microgravity for a short period of time, currently up to nine seconds at…

In this paper, I describe a lay course in special relativity (SR) given at the Osher Lifelong Learning Institutes (OLLI's) at Florida International University and the University of Miami. Courses are also offered in general relativity quantum theory cosmology the nature of time, and the fine-tuned universe. Each course is presented in six…

Undergraduate physics majors typically begin their study of modern physics with special relativity. It is here that physics students first encounter the counterintuitive concepts of time dilation and length contraction. Unfortunately, the derivations of these results are often cloaked in several layers of analysis that render them rather…

Questions often arise as to how a device attached to a transformer can draw power from the electrical power grid since it seems that the primary and secondary are not connected to one another. However, a closer look at how the primary and secondary are linked together magnetically and a consideration of the role of Lenz's law in this linkage…

Introductory physics textbooks consider interference to be a process of redistribution of energy from the wave sources in the surrounding space resulting in constructive and destructive interferences. As one can expect, the total energy flux is conserved. However, one case of apparent non-conservation energy attracts great attention. Imagine that…

With a new data-acquisition system developed by PASCO scientific, an experiment on telemetry with an optical fiber can be made easier and more accurate. For this aim, an alternative strategy of the remote temperature measurements is proposed: the frequency of light pulses transmitted via the light guide numerically equals the temperature using…

The ability of our society to make informed energy-usage decisions in the future depends partly on current science and engineering students retaining a deep understanding of the thermodynamics of heat engines. Teacher imaginations and equipment budgets can both be taxed in the effort to engage students in hands-on heat engine activities. The…

A Genecon is an inexpensive hand-cranked dc electric generator. You can use it to charge a one-farad supercapacitor. If you stop cranking the handle, the capacitor will discharge, sending a current into the Genecon and thereby causing the handle to start turning as an electric motor. How does the current direction compare before and after you stop…

A vehicle starts from rest at constant acceleration, then cruises at constant speed for a time. Next, it decelerates at a constant rate.… This and similar statements are common in elementary physics courses. Students are asked to graph the motion of the vehicle or find the velocity, acceleration, and distance traveled by the vehicle from a given…

In undergraduate E&M courses the magnetic field due to a finite length, current-carrying wire can be calculated using the Biot-Savart law. However, to the author's knowledge, no textbook presents the calculation of this field using the Ampere-Maxwell law: ?B [multiplied by] dl = µ[subscript 0] (I + e[subscript 0] dF/dt) [multiplied by] 1

2014 marks the 100th anniversary of the birth of Martin Gardner, a man whose writings helped inspire generations of young students to pursue a career in physics and mathematics. From his first to his last, and many in between, Gardner's publications often combined magic and science. A recurring theme was the clever use of physical principles…