#### Acoustics Model Question Paper

10th Standard

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Science

Time : 01:30:00 Hrs
Total Marks : 50
5 x 1 = 5
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. The frequency, which is audible to the human ear is

(a)

50 kHz

(b)

20 kHz

(c)

15000 kHz

(d)

10000 kHz

3. 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 x $\sqrt { 2 }$ m s-1

(d)

320/$\sqrt { 2 }$ ms-1

4. If a sound wave travels with a frequency of 1.25 x 104 Hz 344 ms-1, the wavelength will be

(a)

27.52 m

(b)

275.2 m

(c)

0.02752 m

(d)

2.752 m

5. 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

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

()

Longitudinal

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. A wave motion is a transfer of _______.

()

energy

10. In a region of compression there is ______ in volume.

()

decrease

11. SI unit of frequency is _________.

()

hertz

12. 5 x 1 = 5
13. Infrasonic

14. (1)

22 kHz

15. Ultrasonic

16. (2)

Distance

17. High pressure region

18. (3)

Compressions

19. Wavelength

20. (4)

frequency

21. Pitch

22. (5)

10 Hz

2 x 2 = 4
23. Assertion: Sound travels faster in solids than in gases.
Reason: Solid posses a greater density than that of gases.
Codes:
a. If both the assertion and the reason are true and the reason is the correct explanation of the assertion.
b. If both the assertion and the reason are true but the reason is not the correct explanation of the assertion.
c. If the assertion is true, but the reason is false.
d. If the assertion is false, but the reason is true.

24. Assertion: Distinguishing the loud sound from faint sound is called loudness.
Reason: The loudness of normal human voice is 100 dB.
Codes:
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Assertion is false but reason is true.

25. 6 x 2 = 12
26. What is a longitudinal wave?

27. What is the minimum distance needed for an echo?

28. Whatis the work of architectural acoustician?

29. Define wavelength.

30. What is particle velocity?

31. State the Doppler effect.

32. 3 x 4 = 12
33. Why does sound travel faster on a rainy day than on a dry day?

34. The thunder of cloud is heard 9.8 seconds later than the flash of lightning. If the speed of sound in air is 330 m s-1, what will be the height of the cloud?

35. Write the applications of echo.

36. 1 x 7 = 7
37. What are the factors that affect the speed of sound in gases?