Exam
Name__Sound waves_________________________________
MULTIPLE CHOICE.
Choose the one alternative that best completes the statement or answers the question.
1) Suppose the pressure of a gas is increased by a factor of 2 with the volume held constant. For a wave of the
same intensity and frequency, by what factor has the displacement changed?
A) 1.14
B) 0.877
C) 2.00
D) 0.71
2) A thermal gradient exists in an ideal gas (one where the ratio of pressure to density is proportional to
temperature, P/ρ
=
αT). At a temperature of 273 K the sound velocity is 1030 m/s. What is the velocity at
323 K?
A) 1219 m/s
B) 1121 m/s
C) 67.8 m/s
D) The constant γ is needed.
3) A small source of sound about 10.0 cm in diameter has an output power of 200.0 W. If the sound is projected
equally in all directions, what is the intensity in dB at a distance of 100.0 m from the source?
A)

28
B) 113
C) 143
D) 92
4) A sound wave in air has an intensity of 0.600 W/m
2
. For a wave with the same frequency and displacement,
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 Spring '11
 groisman
 Light, Wavelength, Standing wave, simple harmonic wave, Exam Name__Sound waves_________________________________

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