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Using PhET simulations in a large lecture class – The Photoelectric Effect

Compiled by Sam McKagan, based on material by Sam McKagan, Carl Wieman, and Kathy Perkins
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This material is replicated on a number of sites as part of the SERC Pedagogic Service Project

Summary

Photoelectric Effect

This activity provides a complete curriculum for teaching the photoelectric effect using the PhET Photoelectric Effect simulation in a large-lecture modern physics course. It includes links to PowerPoint slides for two to three 50-minute lectures using Peer Instruction with clickers, and one homework assignment suitable for an online homework system. Research has demonstrated that students in classes using this curriculum have a better understanding of the photoelectric effect than students in classes using traditional instruction supplemented by a computerized tutor.

Learning Goals

Students should be able to...

Context for Use

This activity was originally designed to be used in a large-lecture modern physics course for engineering majors. It includes PowerPoint slides for two to three 50-minute lectures using Peer Instruction with clickers, and one homework assignment suitable for an online homework system. The homework was designed for the students to work together on it in small groups, and is probably most effective if they do so. Students in a modern physics course for engineering majors reported that they spent an average of 2 hours and 16 minutes on the homework and about half of them worked with other students on it.

The activity could be adapted for any course that covers the photoelectric effect, including an introductory undergraduate or high school physics course. In a course that does not use machine grading, some of the multiple choice questions on the homework could be changed to open-ended questions.

The activity is mostly conceptual, with some mathematical problems involving basic algebra. The content assumes a basic knowledge of electric fields, potentials, and circuits in order to interpret the experimental apparatus. It also assumes a basic knowledge of the wave nature of light. Slides 26-29 of the lecture assume a familiarity with potential energy functions. In a course that does not address this more advanced topic, these slides could be eliminated without losing the flow of the argument.

Description and Teaching Materials

This activity includes PowerPoint slides for two to three 50-minute lectures using Peer Instruction with clickers, and one homework assignment suitable for an online homework system. Both the lecture slides and the homework can be downloaded from the PhET activities database .

Teaching Notes and Tips

The photoelectric effect proves to be a much harder topic for students than it first appears. The two research papers listed in the References and Resources section (McKagan et al., 2009 and Steinberg et al., 1996) include detailed description of student difficulties and how to address them. Some common problems for students include:

The simulation can help students resolve all of these difficulties except the last one.

Assessment

A research paper by McKagan et al. describes the assessment of this activity by analyzing student responses to two exam questions. The first exam question, designed by Steinberg et al., was given to assess the learning goal of correctly predicting the results of experiments of the photoelectric effect. Students in classes using this curriculum performed well on all aspects of this question. The second exam question was given to assess the learning goal of describing how the results of the photoelectric effect experiment lead to the photon model of light. Most students were able to correctly describe both observations in the experiment and inferences about the photon model of light, but they could not necessarily reason about the connection between the two or distinguish between them. Both exam questions are described in detail in McKagan et al. and could be copied or adapted for assessment by other instructors.

References and Resources

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