L26 波 Superposition Continued


Pre-Amble

  1. 好消息 News: Status on Milestones Part A (next try in final week)
  2. Review of Sound Waves and Wave Info

Viewgraphs (Knight) Continue (103-1 fr 24)

Standing Sound Waves: Boundary Conditions

Boundary Conditions

Close-Close Close-Open Open-Open
f = m v / 2L (m=1,2,3...)f = mv/4L (m=1,3,5...)f = m v / 2L (m=1,2,3...)

Open vs Closed pipes: Flutes vs Clarinets

Example: Find Ear Canal Resonant Frequency (Standing Wave)

Lear canal = [2 2.5] cm; vsound~330 m/s
for open-close tube → fm = m v / 4L (m=1,3,5...)
f1 ~ 330/0.1 ~ 3300Hz
f3 ~ 10kHz   f5 ~ 16kHz

  /   教學   /   物理   baixiaoming AT gmail.com