1 / 13

Announcements 2/22/11

Announcements 2/22/11. Prayer Dispersion lab due tonight Labs 4 & 5 due Saturday I will have office hours today. Ripple Tank image: wikipedia. Interference. Path length Constructive Destructive Demo: Moire pattern transparencies Video: Two outdoor speakers. Reading Quiz.

teresaherman
Télécharger la présentation

Announcements 2/22/11

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Announcements 2/22/11 • Prayer • Dispersion lab due tonight • Labs 4 & 5 due Saturday • I will have office hours today

  2. Ripple Tank image: wikipedia Interference • Path length • Constructive • Destructive • Demo: Moire pattern transparencies • Video: Two outdoor speakers

  3. Reading Quiz • In a standing wave, the points that have the maximum vibration are called: • nodes • antinodes

  4. Standing Waves • Demo: Rubber tubing Image from Wikipedia

  5. Standing Waves • Will occur whenever you have two waves (same frequency, wavelength) moving in opposite directions • Math: A cos(kx - wt) + A cos(kx + wt)  From trig.: cos(a–b) + cos(a+b) = 2cos(a)cos(b) • Can occur via refletions of a single wave! But timing (frequency) has to be just right for it to occur over & over again • Web demo, revisited http://www.colorado.edu/physics/phet/simulations/stringwave/stringWave.swf Image by Colton

  6. Demos • Video: http://stokes.byu.edu/standing_script_flash.html • Demo: “Ladies belt” • Videos: Bowling ball, goblet, [Tacoma Narrows bridge] • Demo: Trumpet “Resonance”

  7. Standing Wave Patterns • Back to Ladies belt demo • What kinds of patterns do you get? • “node” vs “antinode” • Harmonics

  8. Standing waves on a string: “Closed-Closed” • For stable patterns: L = _______ • What are the frequencies? • Relative to the fundamental frequency? L =_____ L=_____ L =_____ L

  9. Standing waves in air: “Open-Open” Open end Open end • Quick writing: draw what you think the second harmonic should look like • For stable patterns: L = _______ • What are the frequencies? • Relative to the fundamental frequency? • Demo: Trumpet, again L=_____ Example: organ pipe

  10. Standing waves in air: “Open-Closed” Open end Closed end • Quick writing: draw what you think the second, third, and fourth harmonics should look like • For stable patterns: L = _______ • What are the frequencies? • Relative to the fundamental frequency? • Why wasn’t trumpet in this category? L=_____

  11. Standing Waves in 2D • Again, from Wikipedia Advertisement for Physics 318!

  12. Standing Waves in 3D • From Colton and Wienkes, Rev. Sci. Instr., 2009 • Light waves, frequency = 10 GHz (microwaves) Do they exist? Class poll Advertisement for Physics 641! 

  13. Final Demo • Flame standing waves

More Related