Showing papers in "The Physics Teacher in 2015"

Comparative Cognitive Task Analyses of Experimental Science and Instructional Laboratory Courses.

Abstract: Undergraduate instructional labs in physics generate intense opinions. Their advocates are passionate as to their importance for teaching physics as an experimental activity and providing “hands-on” learning experiences, while their detractors (often but not entirely students) offer harsh criticisms that they are pointless, confusing and unsatisfying, and “cookbook.” Here, both to help understand the reason for such discrepant views and to aid in the design of instructional lab courses, I compare the mental tasks or types of thinking (“cognitive task analysis”) associated with a physicist doing tabletop experimental research with the cognitive tasks of students in an introductory physics instructional lab involving traditional verification/confirmation exercises.

Measurement of sound velocity made easy using harmonic resonant frequencies with everyday mobile technology

Abstract: Recent articles about smartphone experiments have described their applications as experimental tools in different physical contexts.1–4 They have established that smartphones facilitate experimental setups, thanks to the small size and diverse functions of mobile devices, in comparison to setups with computer-based measurements. In the experiment described in this article, the experimental setup is reduced to a minimum. The objective of the experiment is to determine the speed of sound with a high degree of accuracy using everyday tools. An article published recently proposes a time-of-flight method where sound or acoustic pulses are reflected at the ends of an open tube.5 In contrast, the following experiment idea is based on the harmonic resonant frequencies of such a tube, simultaneously triggered by a noise signal.

Stationary waves in tubes and the speed of sound

Abstract: The opportunity to plot oscillograms and frequency spectra with smartphones creates many options for experiments in acoustics, including several that have been described in this column.1–3 The activities presented in this paper are intended to complement these applications, and include an approach to determine sound velocity in air by using standard drain pipes4 and an outline of an investigation of the temperature dependency of the speed of sound.

Defining and Developing "Critical Thinking" through Devising and Testing Multiple Explanations of the Same Phenomenon.

Abstract: Most physics teachers would agree that one of the main reasons for her/his students to take physics is to learn to think critically. However, for years we have been assessing our students mostly on the knowledge of physics content (conceptually and quantitatively). Only recently have science educators started moving systematically towards achieving and assessing this critical thinking goal. In this paper we seek to show how guiding students to devise and test multiple explanations of observed phenomena can be used to improve their critical thinking.

An Arduino Investigation of the RC Circuit

Abstract: The experimental investigation of the charging or discharging of a capacitor through a resistor is of fundamental importance to the study of electricity. Students taking the Physics SAT or the AP Physics C: Electricity and Magnetism test have to prove their knowledge of time-varying behavior in RC circuits. While the classical experiment is done using a voltmeter and a stopwatch, this procedure is tedious and prone to human errors. We have developed an alternative procedure in which the voltage, the current, and the time are all measured electronically with the help of an Arduino Uno microcontroller board.

Measuring the acoustic response of Helmholtz resonators

Abstract: Many experiments have been proposed to investigate acoustic phenomena in college and early undergraduate levels, in particular the speed of sound,1–9 by means of different methods, such as time of flight, transit time, or resonance in tubes. In this paper we propose to measure the acoustic response curves of a glass beaker filled with different gases, used as an acoustic resonator. We show that these curves expose many interesting peaks and features, one of which matches the resonance peak predicted for a Helmholtz resonator fairly well, and gives a decent estimate for the speed of sound in some cases. The measures are obtained thanks to the capabilities of smartphones.

Quantitative Comparisons to Promote Inquiry in the Introductory Physics Lab

Abstract: In a recent report, the American Association of Physics Teachers has developed an updated set of recommendations for curriculum of undergraduate physics labs. This document focuses on six major themes: constructing knowledge, modeling, designing experiments, developing technical and practical laboratory skills, analyzing and visualizing data, and communicating physics. These themes all tie together as a set of practical skills in scientific measurement, analysis, and experimentation. In addition to teaching students how to use these skills, it is important for students to know when to use them so that they can use them autonomously. This requires, especially in the case of analytical skills, high levels of inquiry behaviors to reflect on data and iterate measurements, which students rarely do in lab experiments. Often, they perform lab experiments in a plug-and-chug frame, procedurally completing each activity with little to no sensemaking. An emphasis on obtaining true theoretical values or agreement on individual measurements also reinforces inauthentic behaviors such as retroactively inflating measurement uncertainties. This paper aims to offer a relatively simple pedagogical framework for engaging students authentically in experimentation and inquiry in physics labs.

Using Research-Based Interactive Video Vignettes to Enhance Out-of-Class Learning in Introductory Physics

Abstract: Ever since the first generalized computer-assisted instruction system (PLATO1) was introduced over 50 years ago, educators have been adding computer-based materials to their classes. Today many textbooks have complete online versions that include video lectures and other supplements. In the past 25 years the web has fueled an explosion of online homework and course management systems, both as blended learning and online courses. Meanwhile, introductory physics instructors have been implementing new approaches to teaching based on the outcomes of Physics Education Research (PER). A common theme of PER-based instruction has been the use of active-learning strategies designed to help students overcome alternative conceptions that they often bring to the study of physics.2 Unfortunately, while classrooms have become more active, online learning typically relies on passive lecture videos or Kahn-style3 tablet drawings. To bring active learning online, the LivePhoto Physics Group has been developing Interactive...

The Atwood machine revisited using smartphones

Abstract: The Atwood machine is a simple device used for centuries to demonstrate Newton's second law. It consists of two supports containing different masses joined by a string. Here we propose an experiment in which a smartphone is fixed to one support. With the aid of the built-in accelerometer of the smartphone, the vertical acceleration is registered. By redistributing the masses of the supports, a linear relationship between the mass difference and the vertical acceleration is obtained. In this experiment, the use of a smartphone contributes to enhance a classical demonstration.

Angular velocity direct measurement and moment of inertia calculation of a rigid body using a smartphone

Abstract: In this paper, we focus on smartphones as experimental tools; specifically we use the gyroscopesensor of a smartphone to study the turning motion of a rigid body. Taking into consideration recent work concerning that topic, we try to use the gyroscopesensor in studying the complex motion of a rolling cylinder on a slope.

Light-Emitting Diodes: Learning New Physics.

Abstract: This is the third paper in our Light-Emitting Diodes series. The series aims to create a systematic library of LED-based materials and to provide the readers with the description of experiments and pedagogical treatment that would help their students construct, test, and apply physics concepts and mathematical relations. The first paper, published in the February 2014 issue of TPT,1 provided an overview of possible uses of LEDs in a physics course. The second paper2 discussed how one could help students learn the foundational aspects of LED physics through a scaffolded inquiry approach, specifically the ISLE cycle. The goals of this paper are to show how the activities described in our second paper help to deepen student understanding of physics and to broaden student knowledge by exploring new phenomena such as fluorescence. Activities described in this paper are suitable for advanced high school courses, introductory courses for physics and engineering majors, courses for prospective physics teachers, and professional development programs.

The Physlet Approach to Simulation Design.

Abstract: Over the past two years, the AAPT/ComPADRE staff and the Open Source Physics group have published the second edition of Physlet Physics and Physlet Quantum Physics , delivered as interactive web pages on AAPT/ComPADRE and as free eBooks available through iTunes and Google Play. These two websites, and their associated books, add over 1000 interactive exercises for the teaching of introductory physics, introductory and intermediate modern physics, and quantum mechanics to AAPT/ComPADRE.

Analyzing Oscillations of a Rolling Cart Using Smartphones and Tablets

Abstract: It is well known that “interactive engagement” helps students to understand basic concepts in physics. 1 Performing experiments and analyzing measured data are effective ways to realize interactive engagement, in our view. Some experiments need special equipment, measuring instruments, or laboratories, but in this activity we advocate student use of mobile phones or tablets to take experimental data. Applying their own devices and measuring simple phenomena from everyday life can improve student interest, while still allowing precise analysis of data, which can give deeper insight into scientific thinking and provide a good opportunity for inquiry-based learning.2

Workshop Physics and Related Curricula: A 25-Year History of Collaborative Learning Enhanced by Computer Tools for Observation and Analysis

Abstract: This article describes the 25-year history of development of the activity-based Workshop Physics (WP) at Dickinson College, its adaptation for use at Gettysburg Area High School, and its synergistic influence on curricular materials developed at the University of Oregon and Tufts University and vice versa. WP and these related curricula: 1) are based on Physics Education Research (PER) findings and are PER-validated; 2) feature active, collaborative learning; and 3) use computer-based tools that enable students to learn by making predictions and then collecting, displaying, and analyzing data from their experiments.

Light-Emitting Diodes: Solving Complex Problems

Abstract: This is the fourth paper in our Light-Emitting Diodes series. The series aims to create a systematic library of LED-based materials and to provide readers with the description of experiments and the pedagogical treatment that would help their students construct, test, and apply physics concepts and mathematical relations. The first paper1 provided an overview of possible uses of LEDs in physics courses. The second paper2 discussed how one could help students learn the foundational aspects of LED physics through a scaf-folded inquiry approach, specifically the ISLE cycle. The third paper3 showed how the physics inherent in the functioning of LEDs could help students deepen their understanding of sources of electric power and the temperature dependence of resistivity, and explore the phenomenon of fluorescence also using the ISLE cycle.4 The goal of this fourth paper is to use LEDs as black boxes that allow students to study certain properties of a system of interest, specifically mechanical, electric, electromagnetic, and light properties. The term “black box” means that we use a device without knowing the mechanism behind its operation.

Analyzing planetary transits with a smartphone

Abstract: Today's smartphones are getting more sensors than ever as factory-installed accessories. The time when a luxury mobile phone had only vertical and GPS sensors is gone. New smartphones come equipped with multiple sensors for many physical parameters. Smartphones are becoming portable physics laboratory data loggers for a variety of measurements in mechanics, thermodynamics, electromagnetism, and optics. All sorts of possibilities are now open, provided their sensors are calibrated. Many examples using the sensors available in smartphones have been presented, mostly in this column and a few other publications, such as acceleration sensors, 1–3 microphones, 4,5 camera,6–8 and light sensors. 9,10

The sound of church bells: Tracking down the secret of a traditional arts and crafts trade

Abstract: The sound of church bells is part of most people's everyday life and can easily be examined with smartphones. Similar to other experiments of this column, we use a suitable iOS app. The underlying physical theory of church bells proves to be difficult. A reliable prediction of their natural frequencies based on their exact dimensions is only possible using the finite element method. If you ask bell founders how they calculate the rib of a bell (half longitudinal section of a bell, which completely determines the acoustic properties, Fig. 1) in order to get a church bell with the desired frequency spectrum, you will certainly not get an answer: the art of bell casting is based on centuries of experience and knowledge of the rib structure is only shared with direct descendants. We want to have a closer look at these well-guarded secrets, knowing full well that we cannot fully unravel them. This article presents simple mathematical models and a comparison with a data set of almost 700 bells.

On Atwood's Machine with a Nonzero Mass String

Abstract: Let us consider a classical high school exercise concerning two weights on a pulley and a string, illustrated in Fig. 1(a). A system like this is called an Atwood's machine and was invented by George Atwood in 1784 as a laboratory experiment to verify the mechanical laws of motion with constant acceleration. Nowadays, Atwood's machine is used for didactic purposes to demonstrate uniformly accelerated motion with acceleration arbitrarily smaller than the gravitational acceleration g. The simplest case is with a massless and frictionless pulley and a massless string. With little effort one can include the mass of the pulley in calculations. The mass of a string has been incorporated previously in some considerations and experiments. These include treatments focusing on friction, justifying the assumption of a massless string, incorporating variations in Earth's gravitational field, comparing the calculated value of g based on a simple experiment, taking the mass of the string into account in such a way that the resulting acceleration is constant, or in one exception solely focusing on a heavy string, but with a slightly different approach. Here we wish to provide i) a derivation of the acceleration and position dependence on the weights' masses based purely on basic dynamical reasoning similar to the conventional version of the exercise, and ii) focus on the influence of the string's linear density, or equivalently its mass, on the outcome compared to a massless string case.

Modern Gravitational Lens Cosmology for Introductory Physics and Astronomy Students

Abstract: Recent and exciting discoveries in astronomy and cosmology have inspired many high school students to learn about these fields. A particularly fascinating consequence of general relativity at the forefront of modern cosmology research is gravitational lensing, the bending of light rays that pass near massive objects. Gravitational lensing enables high-precision mapping of dark matter distributions in galaxies and galaxy clusters, provides insight into large-scale cosmic structure of the universe, aids in the search for exo-planets, and may offer valuable insight toward understanding the evolution of dark energy. In this article we describe a gravitational lensing lab and associated lecture/discussion material that was highly successful, according to student feedback. The gravitational lens unit was developed as part of a two-week summer enrichment class for junior and senior high school students. With minor modifications, this lab can be used within a traditional classroom looking to incorporate topics of modern physics (such as in a unit on optics).

Cracking knuckles ¿ A smartphone inquiry on bioacoustics

Abstract: Cracking (or popping) knuckles (or joints) is an (bio-) acoustic phenomenon of which most of you are aware (with dislike, in some cases), and some of you may have wondered where it comes from. We will first give a short explanation, followed by a smartphone experiment validating a central phenomenon of the sound generation mechanism.

Teaching Physics with Music

Abstract: The uniting of two seemingly disparate subjects in the classroom provides an interesting motivation for learning. Students are interested in how these subjects can possibly be integrated into related ideas. Such is the mixture of physics and music. Both are based upon mathematics, which becomes the interlocking theme. The connecting physical properties of sound and music are waves and harmonics. The introduction of instruments, including the voice, to the musical discussion allows the introduction of more advanced physical concepts such as energy, force, pressure, fluid dynamics, and properties of materials. Suggestions on how to teach physics concepts in the context of music at many levels are presented in this paper.

Discovery of Hubble's Law as a Series of Type III Errors

Abstract: Recently much attention has been paid to the history of the discovery of Hubble's law—the linear relation between the rate of recession of the remote galaxies and distance to them from Earth. Though historians of cosmology now mention several names associated with this law instead of just one, the motivation of each actor of that remarkable story still remains somewhat obscure and is addressed here.

Photogate Timing with a Smartphone

Abstract: In a previous article we demonstrated that a simple, passive external circuit incorporating a thermistor, connected to a mobile device through the headset jack, can be used to collect temperature data.1 The basic approach is to output a sine wave signal to the headset port, through the circuit, and input the resulting signal from the headset microphone. By replacing the thermistor with other variable resistors, the circuit can perform other data measurements. A photoresistor in the circuit will change the amplitude of the returning signal by varying the resistance, depending upon the intensity of light reaching it. The circuit used is shown in Fig. 1 (a discussion of alternative circuits is given in Ref. 2). Two or more photoresistors can be placed in series to form multiple photogates, as shown in Fig. 2. The photoresistors used here have a resistance of about 120 kΩ in the dark and 5 kΩ under lamp light. Ordinary household lamps were used as light sources.

Origins of Newton's First Law

Abstract: Anyone who has taught introductory physics should know that roughly a third of the students initially believe that any object at rest will remain at rest, whereas any moving body not propelled by applied forces will promptly come to rest. Likewise, about half of those uninitiated students believe that any object moving at a constant speed must be continually pushed if it is to maintain its motion. 1 That's essentially Aristotle's law of motion and it is so “obviously” borne out by experience that it was accepted by scholars for 2000 years, right through the Copernican Revolution. But, of course, it's fundamentally wrong. This paper tells the story of how the correct understanding, the law of inertia, evolved and how Newton came to make it his first law.

Making the Most of Your First Day of Class.

Abstract: Instructors of physics courses face the demanding challenge of creating a safe, nurturing community in their classroom while maintaining sufficient rigor. First-day activities are especially important, because they need to both motivate their students and prepare them for the course. Experienced instructors happily share their successful first-day activities,1,2 but what works for one instructor or class might not be as successful for another. We postulate that to be successful, an activity will set expectations, attend to the face needs of the students, and build the instructor's credibility. By modeling the course activities and fostering a supportive learning community, well-suited activities can both orient and motivate students.

Teaching astronomy with case studies

Abstract: Breaking the students into small, collaborative learning groups to solve a meaningful task together is one of the most successful and fully evaluated teaching techniques implemented over the last century. Although there are many ways to accomplish small group learning, a long-standing and consistently successful collaborative class activity is to use the case study teaching strategy. The use of case studies is common in medical schools and law schools, but not so common in the teaching of astronomy. Case studies create meaningful conversations among students and with the professor by focusing on life-like dilemmas to be solved. Case study tasks ask audience members to synthesize several ideas or evaluate scenarios that have not been explicitly presented to them in the lecture or in available readings.

Measuring Musical Consonance and Dissonance

Abstract: Most combinations of musical tones are perceived as either consonant, “pleasing” to the human ear, or dissonant, which is “not pleasing” Despite being largely subjective in nature, sensations of consonance and dissonance can be quantified and then compared to the judgments of human subjects The following is a description of several simple studies that can be carried out in the classroom of a physics of music or science of sound course

Teaching Critical Thinking: Sense-Making, Explanations, Language, and Habits

Abstract: The conjunction of three events has encouraged me to devote significant time to thinking about the pedagogical framework in my introductory courses. The three events were: doing a workshop addressing the Advanced Placement restructuring of the Physics B course with a stronger focus on critical thinking, finding out that TPT was planning an issue about the “science and art” of teaching, and dealing with a course that I haven't taught in about a decade, where the students behaved very differently from students in the same course in the past.