What's a Wavelength?
Engineers apply their understanding of sound waves, wavelength, frequency and pitch in the design of theaters and auditoriums.Copyright (left) Peter Ginter, FermiLab http://www.fnal.gov/culture/NewArts/ramsey.shtml; (right) District of Columbia http://dgs.dc.gov/DC/DGS/Opportunities/RFP+to+Occupy+and+Operate+the+Lincoln+Theater
Students measure the wavelength of sounds and learn basic vocabulary associated with waves. As a class, they brainstorm the difference between two tuning forks and the sounds they produce. Then they come up with a way to measure that difference. Using a pipe in a graduated cylinder filled with water, students measure the wavelength of various tuning forks by finding the height the pipe must be held at to produce the loudest note. After calculating the wavelength and comparing it to the pitch of each tuning fork, students discover the relationship between wavelength and pitch.
Acoustical engineers use their understanding of the physics of sound to create products that maximize the sound output with good quality. Noise-canceling headphones are designed to cancel out wavelengths that come from outside the headphones. Engineers use the properties of sound when designing auditoriums and theaters to make sure that people located anywhere in the room can hear the sound well.
After this activity, students should be able to:
- Define wavelength, frequency, amplitude, pitch and node.
- Calculate wavelength and frequency using an equation.
- Relate a wavelength to pitch and frequency.