Support for Java Applets, including Physlets, has been discontinued by browsers and Oracle. Thus, traditional Java-based Physlets are no longer supported on this website. Please note Open Source Physics (OSP) Java programs continue to run on computers with Java if users download the jar file.

The OSP team is busy updating and developing simulations using HTML5 + JavaScript.
These simulations run on almost all platforms including tablets and cellphones. Explore the Third Edition of Physlets Physics or search OSP for JavaScript to find these simulations.

Preface to the Second Edition

The second edition to Physlet Quantum Physics represents a major change in how the 200 Physlet-based interactive materials are delivered to teachers and students alike. Instead of accessing materials off of the CD that came with the first edition, now users simply access the Physlet Quantum Physics 2E Compadre site at This new partnership with ComPADRE also allows us to update materials and therefore provide the best materials to teachers and students. Housing the material on ComPADRE also lowers the barrier for adoption, since anyone can adopt these materials.

In addtion, Physlet Quantum Physics 2E:

Copyright and Conditions of Use

Except for the exercises placed in the public domain, Physlet® Quantum Physics 2E, i.e., the text and associated script for the Sections and Problems in Physlet® Quantum Physics 2E are copyrighted by Mario Belloni, Wolfgang Christian and Anne J. Cox for the English language and all other languages. The materials in Physlet Quantum Physics 2E are released under the Creative Commons Attribution-NonCommercial-NoDerivs License. More details can be found on the Conditions of Use page or by clicking the Creative Commons link at the bottom of each page in Physlet Quantum Physics 2E.

Instructor Resources

In addition to the interactive curricular material on this site, instructors may also wish to view the Physlet Quantum Physics Instructor's Guide by Anne J. Cox and Mario Belloni. The Physlet Quantum Physics Instructor's Guide is available upon request.


In addition to the lengthy and complete acknowledgements to the First Edition which can be found below in the Preface to the First Edition, there are several people we wish to thank for making the Second Edition possible. We thank Bruce Mason, Lyle Barbato, and Matt Riggsbee of ComPADRE for their tireless work in getting our materials into ComPADRE. We also thank Beth Cunningham, Bob Hilborn, and all of the American Association of Physics Teachers (AAPT) for their continuing support of Physlets and ComPADRE. We thank our colleagues at Davidson College and Eckerd College for their support over the years. We especially thank Davidson College Dean of Faculty Clark Ross and Dean of Faculty Wendy Raymond, and Davidson College President Carol Quillen. Without Davidson College's support of Mario Belloni's sabbatical, this project could not have happened.

Finally, and most importantly, we again express our sincerest thanks to those who have encouraged us the most: our spouses and our children:

Nancy and Emmy
Barbara, Beth, Charlie, and Rudy
Mike, Jordan, and Maggie

Preface to the First Edition

By now it is hard to imagine an instructor who has not heard the call to "teach with technology," as it has resounded through educational institutions and government agencies alike over the past several years. It is, however, easier to imagine an instructor of modern physics and quantum mechanics who has not heard of the current research into the teaching and learning by Styer [1,2], Robinett [3,4], and others [5,6,7,8,9]. Despite this work, which focuses on improving the conceptual understanding of students, the teaching of quantum mechanics has remained relatively unchanged since its inception.  Students, therefore, often see quantum physics in terms of misleading (such as the convention of drawing wave functions on potential energy diagrams) or incomplete visualizations, and as one dimensional and time independent (because of the focus on energy eigenstates in one dimension), and devoid of almost any connection with classical physics.  These depictions short change quantum physics.  Quantum physics is a far richer topic when non-trivial time evolution, multiple dimensions, classical-quantum connections, and research-based topics are discussed.

Physlet Quantum Physics 2E is an interactive text with over 200 ready-to-run interactive exercises which use over 250 carefully-designed computer simulations for the teaching of quantum physics.1  This material uses a standard easy-to-understand interface designed with a sound use of pedagogy in mind. The aim of Physlet Quantum Physics 2E is to provide a resource for the teaching of quantum physics that enhances student learning through interactive engagement and visualization. At the same time, Physlet Quantum Physics 2E is a resource flexible enough to be adapted to a variety of pedagogical strategies and local environments, covers a wide variety of topics, and is informed by current educational, experimental, and theoretical research.


Physlet Quantum Physics 2E contains a collection of exercises spanning many concepts from modern and quantum physics.  These exercises are based on computer animations generated in Java applets to show physics content.  Every chapter of Physlet Quantum Physics contains three quite different Physlet-based exercises: Illustrations, Explorations, and Problems.

Illustrations are designed to demonstrate physical concepts. Students need to interact with the Physlet, but the answers to the questions posed in the narrative are given or are easily determined from interacting with it. Many Illustrations provide examples of quantum-mechanical applications.  Other Illustrations are designed to introduce a particular concept or analytical tool.  Typical uses of Illustrations would include reading assignments prior to class and classroom demonstrations.  Illustrations are referred to in the text by their section number.  For example, Section 8.6 covers free-particle quantum-mechanical wave packets.

Explorations are tutorial in nature.  They provide some hints or suggest problem-solving strategies to students in working problems or understanding concepts.  Some narratives ask students to make a prediction and then check their predictions, explaining any differences between predictions and observations.  Other Explorations ask students to change parameters and observe the effect, asking students to develop, for themselves, certain physics relationships (equations).  Explorations appear in between the Illustrations in the text, making them an ideal test of knowledge gained from an Illustration or as a bridge exercise between two related concepts. Explorations can be used in group problem solving and homework or pre-laboratory assignments and are often useful as Just-in-Time Teaching exercises. Explorations are referred to in the text by their section number and their title begins with "Exploring." For example, Section 8.7 allows students to "explore" Fourier transforms by matching.

Problems are interactive versions of the kind of exercises typically assigned for homework. They require the students to demonstrate their understanding without as much guidance as is given in the Explorations. Some Problems ask conceptual questions, while others require detailed calculations.  Typical uses for the Problems would be for homework assignments, in-class concept questions, and group problem-solving sessions.  Problems appear at the end of each chapter.

Physlet Conditions of Use

Instructors may not post the exercises from Physlet Quantum Physics 2E on the Web without express written permission from  Mario Belloni, Wolfgang Christian, and Anne J. Cox for the English language, and in all other languages from Mario Belloni, Wolfgang Christian, and Anne J. Cox.

Exercises using Open Source Physics (OSP) applets are copyright Mario Belloni and Wolfgang Christian in all languages and are clearly marked on the individual html pages. 

As stated on the Physlets Web site, Physlets (that is, the applets themselves) are free for noncommercial use.  Instructors are encouraged to author and post their own Physlet-based exercises.  In doing so, the text and script of Physlets-based exercises must be placed in the public domain for noncommercial use.  Please share your work!

More details can be found on the Conditions of Use page.

OSP Conditions of Use

Exercises using Open Source Physics (OSP) applets are copyright Mario Belloni, Wolfgang Christian, and Anne J. Cox in all languages and are clearly marked on the individual html pages.  Instructors may not post OSP-based exercises from Physlet Quantum Physics 2E on the Web without express written permission from Mario Belloni, Wolfgang Christian, and Anne J. Cox in all languages.

Web Resources

In addition to the interactive curricular material in this book and website, instructors may also wish to view the Physlet Quantum Physics Instructor's Guide.

Before You Start

Assigning Physlet Quantum Physics 2E material without properly preparing the class can lead to frustration as small technical problems are bound to occur without testing.  We use Physlets extensively in our quantum mechanics courses at Davidson College, but we always start the semester with a short tutorial whose sole purpose is to solve a Physlet problem in the way a physicist solves a problem; that is, to consider the problem conceptually, to decide what method is required and what data to collect, and finally to solve the problem.  As a follow-up, we then assign a simple Physlet-based exercise that must be completed in one of the College's public computer clusters.  This minimal preparation allows us to identify potential problems before Physlet-based material is assigned on a regular basis.

In response to these possible difficulties, we have written Chapter 1: Introduction to Physlets.  This chapter provides students and instructors with a guided tutorial through the basic functionality of Physlets.  After completing the exercises in Chapter 1, students and instructors alike should be in a position to complete the exercises in the rest of the book.  Before you begin, or assign material to students, you should also read the section on Browser Tests and System Requirements.


There are a great many people and institutions that have contributed to our efforts, and we take great pleasure in acknowledging their support and their interest.

Some of the exercises that appear in the book and website were originally created as part of an Associated Colleges of the South Teaching with Technology Fellowship with Larry Cain. We also thank Larry for providing many insightful comments and suggestions.  We thank our students at Davidson College for testing of Physlet-based material in the classroom and the laboratory.  Mur Muchane and the Davidson ITS staff have provided excellent technical support.  We would also like to thank the Davidson College Faculty Study and Research Committee and Dean Clark Ross for providing seed grants for the development of Physlet-based curricular material.  We also thank Nancy Maydole and Beverly Winecoff for guiding us through the grant application process. 

M.B. would like to thank Ed Deveney, Mike Donecheski, Andy Gavrin, Tim Gfroerer, Laura Gilbert, Tim Gfroerer, Kurt Haller, Ken Krane, Bruce Mason, Rick Robinett, and Gary White for many useful and stimulating discussions regarding the teaching of quantum mechanics with and without Physlets.

W.C. would like to thank the numerous students who have worked with him over the years developing programs for use in undergraduate physics education. Some of our best Physlets are the result of collaborative efforts with student coworkers. In particular, we would like to single out Adam Abele, Cabell Fisher and Jim Nolen.

A.J.C. would like to thank her colleagues at Eckerd College: Harry Ellis, Eduardo Fernandez, and Steve Weppner for their support and willingness to test Physlet-based materials in their classes. She also thanks her colleague (and father) Bill Junkin for invaluable discussions about teaching modern physics and quantum mechanics, suggestions on presenting concepts, and his review of much of this text.

The following authors have contributed curricular material (unless otherwise stated, the author of the Illustration, Exploration, or Problem narrative is also the script author): Morten Brydensholt, Andrew Duffy, Francisco Esquembre, Bill Junkin, Steve Mellema, and Chuck Niederriter.

The following authors have contributed Java applets: Dave Krider and Slavo Tuleja.

We would like to thank Ernest Berringer, Pui-Tak Leung, Bruce Mason, Joseph Rothberg, and Chandralekha Singh for reviewing the manuscript.

We express our thanks to Erik Fahlgren, Christian Botting, and their coworkers at Prentice Hall for supporting the development of  Physlet Quantum Physics and for all of their hard work getting this book to press on an accelerated schedule. 

We also wish to express our sincerest thanks to those who have encouraged us the most, our spouses and our children:

Nancy and Emmy
Barbara, Beth, Charlie, and Rudy
Mike, Jordan, and Maggie

Part of this work was supported by a Research Corporation Cottrell College Science Award (CC5470) and three Associated Colleges of the South Teaching with Technology Fellowships. Physlets and Open Source Physics applets are generously supported by the National Science Foundation under contracts DUE-9752365 and DUE-0126439.

1Previous simulation packages for quantum physics include Refs. [10, 11,12,13].

The OSP Network:
Open Source Physics - Tracker - EJS Modeling
Physlet Physics
Physlet Quantum Physics