HW (for F on Monday, and A on Friday)

1.  Consider an organ pipe 0.7-m long and open on both ends.  Find the following:

a.  the wavelengths of the first 3 harmonics
b.  the frequencies of the first 3 harmonics (speed of sound is 340 m/s)
c.  the wave shapes associated with the first 3 harmonics - draw them
d.  What would happen if you cap this pipe on one end?
e.  What is the similarity between tubes open on both ends and strings fixed on both ends?

2.  Middle C is 261.6 Hz.  Find the following:

a.  the next two C's above this note (one and two octaves above)
b.  the C one octave below middle C
c.  C#, which is one semi-tone (or piano key or guitar fret) above C
d.  D, which is two semi-tones above C
e.  The wavelength of middle C, if the speed of sound is 340 m/s

(You will probably not be able to do c-e until the next class.)

3.  Practice with waves:

a.  Draw the graph of y = 2 sin(x)
b.  Draw the graph of y = 3 sin(2x)
c.  Draw the graph of y = 4cos(2x) + 2sin(3x)

Use this program (if helpful):

http://graphsketch.com/

4.  Practice with:  c = f l  (where l = lambda)

Find the frequency associated with a blue LED (450 nm).

5.  Recall the demonstrations with Chladni plates and the Ruben's (fire) tube.  Make sure you understand them.