1. Your bell ringer is on the whiteboard.

2. How do musical instruments work?

3. Wave review
Velocity is constant for any given medium, unless there are temperature variations.
Medium or temperature must be changed to change the velocity
Musical notes require a standing wave
v = fl

4. l = 2L l v=f*2L L How a Guitar String Vibrates
A node must be at either end.
l = 2L l
v=f*2L

5. Why multiple frequencies on one string?

6. How does a Guitar String Vibrate?
Fundamental frequency
1st Harmonic
2nd Harmonic
3rd Harmonic
4th Harmonic

7. fn = f1 n =# of ANTI-NODES Fundamental n=1 2nd Harmonic n=2
50 Hz
2nd Harmonic
n=2
100 Hz
3rd Harmonic
n=3
150 Hz
4th Harmonic
n=4
200 Hz

8. Tube Instrument Open at both ends

9. Tube Instrument - Open at both ends
Antinodes at either end!
l = 2L
v=f*2L

10. Tube Instrument Open at both ends
Antinodes at either end!
fn = f1
n: the # of NODES
v = 2fL

11. Tube Instrument - Closed at one end
Node
Antinode
l = 4L
v=f*4L

12. Tube Instrument – Open at one end
Node at closed end Anti-node at open end
fn = f1
v = 4fL