CYMATICS https youtu beQ 3 o Itp Va

CYMATICS https: //youtu. be/Q 3 o. Itp. Va 9 fs

WAVES REVIEW Frequency describes the number of cycles in one second. Period describes the number of seconds for one cycle. (Period and frequency are inverses of each other. )

WAVES REVIEW The speed of a wave depends only on the medium and can be calculated by multiplying the wavelength (distance between repeated points) by the frequency of the cycles. If the frequency of a wave increases, what must happen to the wavelength? What about the wave speed?

SOUND WAVES • As a source of sound vibrates, a series of compressions and rarefactions travels outward from the source. • Sound waves can travel in solids, liquids, and gases. • A young person can normally hear pitches with frequencies from about 20 to 20, 000 Hz. • Sound waves visualized: https: //youtu. be/px 3 o. VGXr 4 mo http: //plasticity. szynalski. com/tone-generator. htm http: //www. physicsclassroom. com/Physics-Interactives/Waves-and-Sound/Simple-Wave-Simulator-Interactive

Harmonic Frequencies on a String Fundamental Frequency First Harmonic (n=1) L = 1/2 λ Second Harmonic (n=2) L = 2/2 λ Third Harmonic (n=3) L = 3/2 λ

Harmonic Frequencies on a String

Harmonic Frequencies on a String The frequency of the nth harmonic.

Harmonic Frequencies on a String The frequency of the nth harmonic. Harmonic Number

Harmonic Frequencies on a String The frequency of the nth harmonic. Harmonic Number The speed of the wave on the string.

Harmonic Frequencies on a String The frequency of the nth harmonic. Harmonic Number The speed of the wave on the string. The speed only depends on the medium that the wave travels through.

Harmonic Frequencies on a String The frequency of the nth harmonic. Harmonic Number The speed of the wave on the string. The length of the string

SOUND FROM A PIPE STANDING WAVES IN OPEN AND CLOSED PIPES

OPEN PIPES Standing waves can also form in columns of air. Because the air particles can move freely at the open end of a pipe, each end of the pipe must be an antinode.

First Harmonic L = 1/2 λ Second Harmonic L = 2/2 λ Third Harmonic L = 3/2 λ

n = 1, 2, 3, … n=1 First Harmonic L = 1/2 λ n=2 Second Harmonic L = 2/2 λ n=3 Third Harmonic L = 3/2 λ

Harmonic Frequencies For An Open Pipe n = 1, 2, 3, … n=1 First Harmonic L = 1/2 λ n=2 Second Harmonic L = 2/2 λ n=3 Third Harmonic L = 3/2 λ

EXAMPLE (#12 ON STANDING WAVES PRACTICE) The range of human hearing is roughly 20 Hz to 20, 000 Hz. Based on these limits, what are the lengths of the longest and shortest pipes (open at both ends) you would expect to find on a pipe organ?

CLOSED PIPES For a pipe that is closed at one end, the air molecules at the closed end of the pipe cannot move, forming a node. A new set of waves is possible. http: //www. acs. psu. edu/drussell/Demos/Standing. Waves. html

http: //www. acs. psu. edu/drussell/Demos/Standing. Waves. html

Closed Pipe http: //www. acs. psu. edu/drussell/Demos/Standing. Waves. html

Harmonic Frequencies For A Closed Pipe http: //www. acs. psu. edu/drussell/Demos/Standing. Waves. html

EXAMPLE (#15 FROM STANDING WAVES PRACTICE) Aaron blows across the opening of a partially filled 0. 2 -m tall soft drink bottle and finds that the air vibrates with a fundamental frequency of 472 Hz. How high is the liquid in the bottle?

String (Fixed at Both Ends) n = 1, 2, 3, … Open Pipe n = 1, 2, 3, … Closed Pipe

When you play any instrument, any single note is actually a combination of harmonics, where the loudest note is the fundamental frequency. The additional harmonics combine with the fundamental frequency to produce a sound that is unique for that instrument. https: //youtu. be/VRAXK 4 QKJ 1 Q? t=19 s

MEASURING THE SPEED OF SOUND

STANDING WAVES IN A CLOSED PIPE (FROM CYMATICS) http: //youtu. be/s. Iop. Zn. MLe. Qo