CHAPTER-14, SOUND

1. Which of the following is carried by the waves from one place too, another?

 
 
 
 

2. In a slinky (i.e., a long spring) which of the following type of waves can be generated?

 
 
 
 

3. In gases a sound wave is

 
 
 
 

4. A body produces sound only if it is

 
 
 
 

5. Sound waves cannot pass through

 
 
 
 

6. Sound waves having the following frequency audible by a human being are:

 
 
 
 

7. Hz is the unit of

 
 
 
 

8. The frequency of sound waves can be expressed in

 
 
 
 

9. The separation between two successive crests in a wave is

 
 
 
 

10. If the distance between a crest and its consecutive trough is L, then the wavelength of the wave is given by

 
 
 
 

11. If a wave completes 20 vibrations in 2.5 s, then its frequency is

 
 
 
 

12. During a thunderstorm, one observes lightning first and then hears the thunder, though both occur simultaneously. This is ,because

 
 
 
 

13. The relation between wavelength, frequency and wave velocity is

 
 
 
 

14. The reciprocal of frequency is

 
 
 
 

15. Waves formed over water surface are

 
 
 
 

16. A tuning fork is vibrating in air. The number of compressions going past a given point per second is the

 
 
 
 

17. The product of time-period and frequency is

 
 
 
 

18. When we pluck the wire of a sitar, the waves produced in its wire are

 
 
 
 

19. Sound waves are

 
 
 
 

20. A boat at anchor is rocked by waves whose crests are 100 m apart and whose velocity is 25 m/s. How often do the crests reach the boat?

 
 
 
 

21. What is the nature of the ocean waves in deep water?

 
 
 
 

22. Which is not the condition for hearing sound?

 
 
 
 

23. An instrument commonly used in laboratory to produce a sound of some particular frequency is

 
 
 
 

24. When a sound wave travels in air, the physical quantity which is transferred from one place to the other is

 
 
 
 

25. In case of longitudinal waves, the particles of medium vibrate

 
 
 
 

26. In case of transverse waves the particles of a medium vibrate

 
 
 
 

27. in the region of compression or rarefaction, in a longitudinal wave the physical quantity which does not change is

 
 
 
 

28. A slinky can produce in laboratory

 
 
 
 

29. The change in density/pressure of a medium from maximum value to minimum value and again to maximum value, due to the propagation of a longitudinal wave is called a complete

 
 
 
 

30. If the frequency of a wave is 25 Hz, the total number of compressions and rarefactions passing through a point in 1 second is

 
 
 
 

31. A stretched slinky is given a sharp push along its length. A wave travels from one end to another. The wave so produced is

 
 
 
 

32. The sound waves having a frequency more than 20,000 Hz are called

 
 
 
 

33. Calculate the wavelength of radio waves of frequency 109 Hz. The speed of radio waves is 3 x 108 m s-1.

 
 
 
 

34. A wave source produces 20 crests and 20 troughs in 0.2 sec. Find the frequency of the wave.

 
 
 
 

35. If the density of air at a point through which a sound wave is passing is maximum at an instant, the pressure at that point will be

 
 
 
 

36. An object moving at a speed greater than that of sound is said to be moving at

 
 
 
 

37. In which of the three media; air, water and steel, does sound travel the fastest?

 
 
 
 

38. An object is 11 km below sea level. A research vessel sends down a sonar signal to confirm this depth. After how long can it expect to get the echo? (Take the speed of sound in sea water as 1,520 m s-1.)

 
 
 
 

39. Which of the following is an elastic wave?

 
 
 
 

40. A big explosion on the moon cannot be heard on the earth because

 
 
 
 

41. A person is listening to a tone of 500 Hz, sitting at a distance of 450 m from the source of sound. The time interval between successive compressions from the source is

 
 
 
 

42. An echo is returned in 3 s. If the speed of sound is 342 m s-1, then the distance between the source of sound and the reflecting body is

 
 
 
 

43. A submarine emits a sonar pulse, which returns from under water cliff in 1.02 s. If the speed of sound in water is 1531 m s-1, the submarine is at a distance of

 
 
 
 

44. A person can hear a sound of maximum frequency 20,000 Hz. If the speed of sound in air is 344 m s-1, the wavelength is

 
 
 
 

45. A boy stands 66.4 m in front of a high wall and then blows a whistle. If speed of sound is 332 m S-1, the echo is heard after

 
 
 
 

46. A boat at anchor is rocked by the waves, such that the distance between two consecutive crests is 100 m. If the wave velocity is 20 m s-1, the frequency of rocking boat is

 
 
 
 

47. Human ear cannot hear those mechanical waves whose frequency lies in the frequency range

 
 
 
 

48. Which one of the following properties of sound is affected by change in the air temperature?

 
 
 
 

49. A gun is fired in the air at a distance of 660 m from a person. He hears the sound of the gun after 2 s. What is the speed of sound?

 
 
 
 

50. A child hears an echo from a cliff 4 seconds after the sound from a powerful cracker is produced. How far away is the cliff from the child? Velocity of sound in air at 20°C is 344 m s-1.

 
 
 
 

51. A ship sends on a high frequency sound wave and receives an echo after 1 second. What is the depth of the sea? Speed of sound in water is 1500 m/s.

 
 
 
 

52. A boy sitting in a boat fires a gun. An observer P is at a distance of 50 m from the boat. Another observer Q is a diver, who is 50 m under water. Both hear the sound of gun, then

 
 
 
 

53. A sound wave has a frequency of 1000 Hz and a wave length of 34 cm. How long will it take to travel 1 km?

 
 
 
 

54. Two waves of sinusoidal waveforms have different wavelengths and different amplitude. They will be having

 
 
 
 

55. A source of sound of frequency 600 Hz is placed inside water. The speed of sound in water is 1500 m s-1 and in air is 300 m s-1. The frequency of sound recorded by an observer who is standing in air is

 
 
 
 

56. A light pointer fixed to one prong to a tuning fork touches a vertical plate. The fork is set vibrating and the plate is allowed to fall freely. If eight oscillations are counted when the plate falls through 10 cm, the frequency of the tuning fork is

 
 
 
 

57. The highest frequency produced by a man is 1700 Hz and that of a woman is 2780 Hz. The ratio of wavelengths of sound of man and woman are (speed of sound is 340 m s-1)

 
 
 
 

58. The wavelength and frequency of a sound wave in medium A is 20 cm and 1650 Hz. Keeping the medium same, if wavelength is changed to 16 cm, then new frequency is

 
 
 
 

59. A man stands between two cliffs and fires a gun. He hears two successive echoes after 3 s and 5 s. The distance between two cliffs is

 
 
 
 

60. Water waves are

 
 
 
 

61. An echo repeats two syllables. If the velocity of sound is 330 m s-1, then the distance of the reflecting surface is

 
 
 
 

62. A plane wave of sound travelling in air is incident upon a plane water surface. The angle of incidence is 30°. If the velocity of sound in water is 1400 m s-1, and the velocity of sound in air is 330 m s-1, there will be

 
 
 
 

63. If you go on increasing the stretching force on a wire in a guitar, its frequency

 
 
 
 

64. A pendulum vibrates with a time period of 1 second. The sound produced by it is

 
 
 
 

65. Flash and thunder are produced simultaneously. But thunder is heard a few seconds after the flash is seen. This is because

 
 
 
 

66. During night, distant sounds such as that of the traffic and the loudspeakers become louder than during day. This is due to

 
 
 
 

67. A longitudinal wave is produced on a toy slinky. The wave travels at a speed of 30 cm s-1 and the frequency of the wave is 20 Hz. What is the minimum separation between the consecutive compressions of the slinky?

 
 
 
 

68. Sound travels at a speed of 334 m s-1 in air. This means that

 
 
 
 

69. Non-mechanical wave can travel

 
 
 
 

Question 1 of 69