#### Acoustics Book Back Questions

10th Standard

Reg.No. :
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Science

Time : 00:45:00 Hrs
Total Marks : 30
4 x 1 = 4
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

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 s-1

(c)

165 ms-1

(d)

990 ms-1

3. 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

4. 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

5. 3 x 1 = 3
6. Rapid back and forth motion of a particle about its mean position is called _____

()

Longitudinal

7. If the energy in a longitudinal wave travels from south to north, the particles of the medium would be vibrating in _____

()

Amplitude

8. A whistle giving out a sound of frequency 450 Hz, approaches a stationary observer at a speed of 33 m s–1. The frequency heard by the observer is (speed of sound = 330 m s–1) ______.

()

500 Hz

9. 4 x 1 = 4
10. Infrasonic

11. (1)

22 kHz

12. Echo

13. (2)

Ultrasonography

14. Ultrasonic

15. (3)

Compressions

16. High pressure region

17. (4)

10 Hz

2 x 2 = 4
18. What will be the frequency sound having 0.20 m as its wavelength, when it travels with a speed of 331 m s–1?

19. Name three animals, which can hear ultrasonic vibrations.

20. 2 x 4 = 8
21. Why does sound travel faster on a rainy day than on a dry day?

22. A sound wave has a frequency of 200 Hz and a speed of 400 m s–1 in a medium. Find the wavelength of the sound wave.

23. 1 x 7 = 7
24. Suppose that a sound wave and a light wave have the same frequency, then which one has a longer wavelength?
a) Sound
b) Light
c) both a and b
d) data not sufficient.