Loudness, or sound intensity level, is a human perceived or subjective measurement with units, decibels, based on the response of the human ear to different sound intensities. The response of the human ear at fixed frequency is close to being logarithmic. The experiment reported here investigates the relationship between measured sound intensity…

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…

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…

"The Physics Teacher's" "iPhysicsLabs" column has been dedicated to the implementation of smartphones in instructional physics labs as data collection devices. In order to understand any data set, however, one should first understand how it is obtained. This concern regarding the inclusion of smartphones in lab activities…

The Frahm resonance principle, in which resonating reeds indicate the frequency of mechanical or electrical oscillations, is a hardy perennial. In this note we will give some history, show some original apparatus, and show how it may be reproduced with relatively little effort.

We have just completed the data collection for our 2012-13 Nationwide Survey of High School Physics and expect to have results to report in the spring. In the interim, we will take a look at physics in two-year colleges (TYCs). In 2007, we surveyed undergraduate seniors in degree-granting physics departments, and we asked these students if they…

Two-Year Colleges, Physics Majors, and Diversity. As noted last month, we're taking a look at physics in two-year colleges (TYCs). We expect to have the first reports from our 2012-13 Nationwide Survey of High School Physics Teachers in the spring of 2014. Last month we noted that the high school physics experience of undergraduate physics…

In popular accounts of the time dilation effect in Einstein's special relativity, one often encounters the statement that moving clocks run slow. For instance, in the acclaimed PBS program "NOVA," Professor Brian Greene says, "[I]f I walk toward that guy... he'll perceive my watch ticking slower." Also in his earlier piece for The New York Times,…

It is hard to imagine teaching physics without doing experimental measurements of position as a function of time. These measurements, needed for the determination of velocity and acceleration, are most easily performed with the help of photogates. Unfortunately, commercial photogates are rather expensive. Many require the purchase of an additional…

In this paper we investigate the speed of sound in air as a function of temperature using a simple and inexpensive apparatus. For this experiment it is essential that the appropriate end corrections be taken into account. In a recent paper the end corrections for 2-in i.d. (5.04-cm) PVC pipes open at both ends were investigated. The air column…

The scientific method is arguably the most reliable way to understand the physical world, yet this aspect of science is rarely addressed in introductory science courses. Students typically learn about the theory in its final, refined form, and seldom experience the experiment-to-theory cycle that goes into producing the theory. One exception to…

The siphon is a very useful example of early technology, the operation of which has long been well understood. A recent article makes the claim that established beliefs regarding this device are incorrect and proposes a "chain model" in which intermolecular forces within the fluid play a large role while atmospheric pressure does not. We have…

The Physics First movement--teaching a true physics course to ninth-grade students--is gaining popularity in high schools. There are several different rhetorical arguments for and against this movement, and it is quite controversial in physics education. However, there is no actual evidence to assess the success, or failure, of this substantial…

The disparity in persistence between males and females studying physics has been a topic of concern to physics educators for decades. Overall, while female students perform as well as or better than male students, they continue to lag considerably in terms of persistence. The most significant drop in females studying physics occurs between high…

Most homes in developed countries have a sophisticated data acquisition board, namely the PC sound board. Designed to be able to reproduce CD-quality stereo sound, it must have a sampling rate of at least 44 kHz and have very accurate timing between the two stereo channels. With a very simple adaptation of a pair of regular PC microphones, a…