Waves Lab

Topics: Sound, Wavelength, Wave Pages: 5 (1296 words) Published: August 26, 2013
PHY 101
Lab Report

Waves Lab

Purpose
The purpose of this laboratory experiment is to “investigate how the vibrating source affects selected characteristics of the sound produced” (Giancoli, 2006).

Materials
The following materials were used in the completion of this laboratory experiment: * Meter stick
* Two paper towel rolls / cardboard tubes
* Scissors
* Two rubber bands
* Wax paper
* Transparent tape
* Flashlight
* Balloon

Procedure

Part 1:
1. Hold one end of a meter stick down on a tabletop so that 20 cm of the stick extends past the edge of the table. 2. Pluck the end of the stick that is extending past the edge of the table to produce a vibration and sound. 3. Observe this vibration and sound created and record observations. 4. Repeat the step above with 40 cm extending off the edge of the table. 5. Repeat the step above with 60 cm extending off the edge of the table.

Part 2:
1. Cut a hole (approximately 1 cm in diameter) in the middle of one of the cardboard tubes. 2. Use a rubber band to secure a piece of wax paper over one end of the cardboard tube. 3. Make another kazoo following the same instructions as above, but cut the cardboard tube 10 cm shorter than the first tube. 4. Hum into each of your kazoos created above. Try to make the humming noise as consistent as possible in each tube. Observe and record how the length of the kazoo affects the pitch of the sound produced.

Part 3:
1. Cut the neck off the balloon. Replace the wax paper on the longer kazoo with the cut balloon, wrapping the rubber band around the end of the cardboard tube. The rubber band should hold the tightly stretched balloon over the end of the tube. Use tape to attach the small mirror to the balloon at the end of the tube. 2. Have another person shine a flashlight on the mirror while you hum into the kazoo. The flashlight should be positioned on so a spot of light is reflected on the wall (you may have to darken the room). 3. Observe how the light moves as you hum into the kazoo. Note your position and the position and angle of the kazoo and the flashlight. 4. Raise the pitch of your humming while keeping the loudness the same. 5. Observe how the spot of light differs from the step above. Keep the distance from the wall and the angle at which the light from the flashlight strikes the kazoo the same. 6. Repeat the above step while humming at a lower pitch. 7. Repeat the above steps, but this time, vary the loudness while keeping the pitch constant. (Giancoli, 2006)

Data
Part 1:

Length off table| Vibration| Sound|
20 cm| Fast, Small| Ringing sound, normal pitch|
40 cm| Slower, Larger| Lower pitch than original|
60 cm| Slow, Large| Even lower pitch|

Part 2:

Length of Kazoo| Pitch of Sound|
Original| Low|
10 cm Shorter| Higher|

Part 3:

Pitch| Loudness| Shadow|
Original| Original|  |
Higher| Original| Greater frequency|
Lower| Original| Smaller frequency|
Original| Higher| Greater amplitude|
Original| Lower| Smaller amplitude|

Calculations
No calculations are needed in the completion of this laboratory experiment.

Results
The longer the object suspended off of the table was, the lower the pitch was found to be. Similarly, the longer the kazoo was, the lower the pitch it created was. The higher the pitch of the kazoo with the balloon at the end was, the greater frequency the vibration created by the balloon was. The louder the sound in this kazoo was, the greater the amplitude the vibration created by the balloon was.

Conclusion & Analysis
This experiment analyzes sound waves, which are a type of longitudinal wave. Longitudinal waves “transfer energy in the same direction as the vibrating particles in the medium that is transferring the energy” (Giancoli, 2006). Therefore, in the case of sound waves,...

References: Giancoli, D.C. (2006). Physics (6th ed.). Upper Saddle River: Pearson Prentice Hall.
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