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# Practice Waves Test

1. Define a wave , period , frequency .
2. In the jug band lab what was the manipulated variable? The water/air volume
3. Middle C has a frequency of 262 Hz. What is its period? period = 1 /freq = 0.0038 seconds
4. Define crest (top of wave), trough (bottom of wave)and wave velocity (is the distance a wave travels per second).
5. In the jug band lab what was the responding variable? the frequency of the tone produced
6. Define a transverse wave (the disturbance is perpendicular to the direction of wave travel) and longitudinal wave (the disturbance is parallel to the direction of wave travel).
7. In the jug band lab what were the controlled variables? using the same bottle, same person making tone, same equipment to measure freq.
8. A wave hits the shore every 5 seconds. What is the frequency of the waves? freq= 1/ period = 1/5 = 0.2 seconds
9. What is diffraction? the bending of waves around an obstacle or the edges of an opening
10. If the speed of sound is 343 m/s and a sound has a frequency of 262 Hz, what is its wave length? velocity = wavelength * freq. 343 ms-1 = wave length * 262 = 1.31 meters.
11. What is refraction? bending of a wave caused by differences in the wave speed in the medium (or the medium changes).
12. Place a pencil or pen in a glass of water. Use the fact that the speed of light changes with the medium it is in to explain what you see. Waves are bent (refracted) when the medium they travel in has a change in wave velocity.
13. In the elephant reading sound was bent upwards by temperature differences in the air close to the ground and the air a little ways above the ground. This bending of waves is called refraction.
14. Make a graph of speed of sound vs substances using the data below:
1. Air at 20 °C = 343 m/s
2. Helium = 965 m/s
3. Fresh water (25°C) = 1482 m/s
4. Sea water (25°C) = 1533 m/s
5. Wood = 3828 m/s
6. Steel = 5960 m/s

15. Sound waves are longitudinal waves.
16. Estimate the frequency of this wave captured by the TI-83 and CBL.

0.0137 seconds - 0.003 seconds = 0.0107 seconds (the time for two waves)

0.0107 seconds / 2 = 0.00535 seconds (period of one wave)

freq = 1/ period = 1/ 0.00535 s = 186.9 Hz

17. The diagram on the right is an example of diffraction.
18. Use the graph to estimate the speed of sound in the waters of the Great Salt Lake. The salinity of the Great Salt Lake is approx. 13%. Approx. 1672 m/s