Animated Ray Paths in MS Powerpoint
Jeffrey A. Nunn
Department of Geology and Geophysics, Louisiana State University
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A series of MS PowerPoint slides that illustrate ray paths for reflection and refraction. They can be used in lecture and/or laboratory assignments or posted on a web page for students to review on their own time. Animation allows students to see that different waves travel at different velocities. It also illustrates the relationship between distance and time for arrivals.
Undergraduate course in exploration and/or environmental geophysics Designed for a geophysics course
Skills and concepts that students must have mastered
Acoustic impedance, reflection, and refraction
How the activity is situated in the course
This is part of the first lecture on seismic principles.
Content/concepts goals for this activity
Interpret distance versus time plots for reflection and refraction using animated raypaths.
Higher order thinking skills goals for this activity
The animation allows students to synthesize the critical relationship between velocity/interface angle and ray path as well as the concept that integrating distance/velocity gives time which is the basis of all seismic analysis.
Other skills goals for this activity
Description of the activity/assignment
Students are shown a series of animations in powerpoint. Each powerpoint slide illustrates a basic concept in reflection and refraction (e.g., Snell's law, Crossover distance, Crossover time, dipping layers, multiple interfaces. As the slides are animated, students see the distance versus time relationships. These slides can be given to students so that they can review the concepts as many times as is necessary. Addresses student misconceptions
Determining whether students have met the goals
Students are given both exam questions and one laboratory exercise where they must sketch ray paths and the corresponding distance versus time plot.
More information about assessment tools and techniques.
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