Dispersion Relation for Waves on a String

Highlights of the activity

1. This integrated lab activity is designed to help upper-division undergraduate students observe different resonances and explore the dispersion relation for waves on a string.
2. Students used an experimental set-up to find the angular frequency of the wave.
3. The compare and contrast wrap-up discussion compiles each group's result to determine the dispersion relation for waves by plotting the angular frequency of the waves as a function of wave vector.

Reasons to spend class time on the activity

Students generally do not consider the dispersion relations in lower division course. We find that middle division students know that speed of a wave is the product of the wavelength and frequency, but they don't think of angular frequency as a function of wave number, nor are they aware of the different types of speed relevant in the study of waves: phase velocity, group velocity and material velocity. This activity is used to introduce these important ideas.

Reflections

• Reflections from the original implementation.

• Reflections from "official" adapters/adopters.

• Reflections from the general public.

Instructor's Guide

• Wiki version

Student Handouts

wvstringwaveshand.pdf

wvstringwaveshand.tex