Developing and Researching PhET simulations for Teaching Quantum Mechanics

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Developing and Researching PhET simulations for Teaching Quantum Mechanics Sam McKagan, Kathy Perkins, Wendy Adams, Michael Dubson, Chris Malley, Sam Reid, Ron LeMaster, Carl Wieman University of Colorado at Boulder American Journal of Physics76, 406 (2008) http://phet.colorado.edu/quantum Research on Student Learning with QM sims PhET Project Overview • The Physics Education Technology (PhET) Project is an on-going effort to create a suite of interactive simulations and related education resources that aid in the teaching and learning of physics. • Elaborate Java- and Flash-based simulations • Support for educators and students with resources for both teaching and learning with these simulations • Developed using the results of education research and feedback from educators • Research to formally assess their influence on student learning and attitudes in a variety of settings • A large number of simulations exist and are being used in introductory physics courses around the country • Can be used in lecture demonstrations, recitation activities, or homework assignments • All PhET simulations are free and available at http://phet.colorado.edu Interactive Lecture and Homework – Photoelectric Effect[accepted to AJP; arXiv:physics:0706:2165] Interactive Lecture - Davisson-Germer: Electron Diffraction Why did Davisson & Germer see electrons deflected only at certain angles? After reading, before lecture w/ sim All students (N=59) Students who read (N=38) All students (N=74) Would the ammeter read zero current or a non-zero current if you were to: 7% After lecture w/ sim 8% 21% 1% 36% 31% 47% a. Double the intensity of the light? Why? b. Increase battery voltage? Why? c. Change material of target? Why? 32% 92% 29% electrons are waves, explain with interference: e.g.: ‘The electrons were only detected at certain angles because they were interfering constructively and destructively. It was important because it meant they were acting like waves.’ electrons are waves, no explanation: e.g.: ‘The reason for this result of seeing electrons only at certain angles is matter waves. The electrons are traveling with a certain wavelength, making it so they can only be deflected at certain angles.’ non-wave explanation: e.g.: ‘Shooting electrons at a neatly arranged lattice, the electrons that bounce off will have a higher probability of hitting another atom. Since all the atoms in the lattice are neatly arranged, they will create a series of pathways that the electrons will bounce down. Therefore, the angles they observed were the angles at which the electrons bounced down these “tubes”.’ blank / no explanation: e.g.: ‘You got me. I didn’t read.’ PhET simulations in Quantum Mechanics Applications Fundamental Principles Classic Experiments CONTEXT INTERACTION ANIMATION VISUALIZATION Find the tumor. Change the spacing and radius of atoms Visualize not just the interference pattern on the screen, but the process that creates this pattern. Watch electron waves tunnel through barriers Davisson Germer: Electron Diffraction Conductivity Simplified MRI Quantum Wave Interference Quantum Tunneling and Wave Packets Models of the Hydrogen Atom Fire the photon gun See electrons jump energy levels See the paths of alpha particles deflected by nucleus See electron waves diffract off atoms Semiconductors Neon Lights & Other Discharge Lamps Quantum Bound States See how photon behaves as a wave as it travels through space, and a particle when it hits the screen. Stern-Gerlach Experiment Rutherford Scattering See spins deflected through magnets Fourier: Making Waves Grab the semi-conductors and put them in the circuit Configure your atom’s energy levels Lasers Visualize phenomena that you can’t observe directly, such as atomic excitations, electrons, and photons Photoelectric Effect Nuclear Physics Invite to interact See time evolution of wave functions Blackbody Spectrum Double Wells and Covalent Bonding Directly manipulate fourier components and get instant feedback on how this changes the transform. Band Structure View light as photons or waves. Compare and contrast these representations to get a complete picture Laser explodes if it builds up too much power Compare the spectra of the sun and a light bulb See electrons ejected from plate with varying speeds. Watch them speed up or slow down when voltage is applied. Set up a chain reaction Student Responses to Quantum Sims Teaching with PhET simulations In-Class/Lecture Homework “Great sims, I can't imagine QM without them.” “The simulations were the best part of class, they practically answer physics questions all by themselves. I would recommend continuing to develop these and add more. Without these I think I would have been lost in the course.” “I definitely not only enjoyed the simulations, but I'd go as far to say that the simulations taught me the most about the course because I could really visualize the inner workings of the physics processes that we going on.” “I thought the simulations were great. It helped me to gain intuition about the topic. This is especially useful in quantum mechanics where • Use the sims as… • an effective means of communicating the instructors’ visual model to the students. • a means for interactive engagement within class using the Peer Instruction model with simulation-centered concept tests or interactive lecture demos. • a complementary learning-support tool for classroom demos. • a short pre-class activity to prepare students for class. • Use the sims as… • a method to promote active thinking with inquiry-based exercises designed around the simulations. • an alternative to or supplement for traditional introductory physics labs. Photoelectric Effect Sample Homework Problems Lasers: it is not normally possible to directly observe the described phenomena.” “The photon ray gun I first saw in lecture and that was very important to understanding the spread out nature of photons. I used the laser simulation on my own first and had to play with it to get it to lase, which was a good learning experience.” “This is what really clarified the difference between P and N-type and to figure out what orientation/arrangement is required for a LED to work.” “I related to this, for my mother has brain cancer. She has MRIs frequently as you could imagine. Now I know what is really going on every time she has one done.” Sample Concept Test Student Responses: Discharge Lamps Instructors observed that most students did not know the correct answer initially, but many were able to figure it out through discussion. Graphs that students drew, before seeing multiple choice options, closely matched given options. Acknowledgements Quantum Wave Interference The authors thank the Hewlett Foundation, NSF, and the Kavli Operating Institute for providing the support for the PhET Project. We also thank all the members of the PhET Team and the Physics Education Research at Colorado group (PER@C).