LECTURE 13
     questions after lecture

again, you should really be sure you can answer these

• QUESTIONS BEFORE LECTURE 13

now think about these

• I showed a vibrating string with a strobe light. How does the strobe light work (why did I use it)? When I varied the tension in the TV lecture, what two wave properties was that varying? Why?
• The big question: what did I demonstrate when I inhaled helium and sulfur hexafluoride? What wave properties was I changing and what stayed the same?
• How would a sound deadener based on interference work?