# Topic: Chapter 5: Acoustics (Test 1)

Topic: Chapter 5: Acoustics
Q.1
When a sound wave travels through air, the air particles
A. vibrate along the direction of the wave motion
B. vibrate but not in any fixed direction
C. vibrate perpendicular to the direction of the wave motion
D. do not vibrate
Explaination / Solution:
No Explaination.

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Q.2
Velocity of sound in a gaseous medium is 330 m s–1. If the pressure is increased by 4 times without causing a change in the temperature, the velocity of sound in the gas is
A. 330 m s–1
B. 660 m s1
C. 156 m s–1
D. 990 m s–1
Explaination / Solution:
No Explaination.

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Q.3
The frequency, which is audible to the human ear is
A. 50 kHz
B. 20 kHz
C. 15000 kHz
D. 10000 kHz
Explaination / Solution:
No Explaination.

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Q.4
The velocity of sound in air at a particular temperature is 330 m s–1. What will be its value when temperature is doubled and the pressure is halved?
A. 330 m s–1
B. 165 m s–1
C. 330 × √2 m s–1
D. 320 / √ 2 m s–1
Explaination / Solution:
No Explaination.

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Q.5
If a sound wave travels with a frequency of 1.25 × 104 Hz at 344 m s–1, the wavelength will be
A. 27.52 m
B. 275.2 m
C. 0.02752 m
D. 2.752 m
Explaination / Solution:
No Explaination.

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Q.6
The sound waves are reflected from an obstacle into the same medium from which they were incident. Which of the following changes?
A. speed
B. frequency
C. wavelength
D. none of these
Explaination / Solution:
No Explaination.

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Q.7
Velocity of sound in the atmosphere of a planet is 500 m s–1. The minimum distance between the sources of sound and the obstacle to hear the echo, should be
A. 17 m
B. 20 m
C. 25 m
D. 50 m