Sound Worksheet-11

Sound Worksheet-11

41. Draw labelled diagrams to represent (a) soft sound, and (b) loud sound, of the same frequency.

42. Explain the term 'pitch' of a sound. On what factor does the 'pitch' of a sound depend?

43. Draw labelled diagrams to represent sound of (a) low pitch, and (b) high pitch, of the same loudness.

44. What is meant by the quality (or timbre) of sound? On what factor does the quality (or timbre) of a sound depend?

45. Explain why, if we strike a table lightly, we hear a soft sound but if we hit the table hard, a loud sound is heard.

46. Give one use of ultrasound in industry and one in hospitals.

47. How is it that bats are able to fly at night without colliding with other objects?

48. Explain how, bats use ultrasound to catch the prey.

49. Explain how, flaws (or defects) in a metal block can be detected by using ultrasound.

50. Why are the ceilings of concert halls made curved? Draw a labelled diagram to illustrate your answer.

51. Draw a labelled diagram to show the multiple reflections of sound in a part of the stethoscope tube.

52. What is the range of frequencies associated with

(a) Infrasound, (b) audible sound and, (c) ultrasound?

53. (a) What is the difference between infrasonic waves and ultrasonic waves?

(b) Choose the infrasonic waves and ultrasonic waves from the following frequencies:

(i) 10,000 Hz, (ii) 30,000 Hz, (iii) 18 Hz, (iv) 50,000 Hz, (v) 10 Hz

54. What is the frequency range of hearing in humans?

55. Which of the following sound frequencies cannot be heard by a human ear?

(i) 10 Hz, (ii) 100 Hz, (iii) 10,000 Hz, (iv) 15 Hz, (v) 40,000 Hz

56. The echo of a sound is heard after 5 seconds. If the speed of sound in air be 342 m/s, calculate the distance of the reflecting surface.

57. The speed of sound in water is 1500 meters per second. How far away from an under-sea rock should a deep sea diver be so that he can hear his own echo?

58. State the laws of reflection of sound.

59. What is meant by 'reflection of sound'? What type of surfaces are the best for reflecting sound?

60. Name any two objects which are good reflectors of sound

61. What is an echo? How is echo formed?

62. What is the minimum distance in air required from a sound reflecting surface to hear an echo (at 20°C)?

63. A man standing 825. Metres away from a cliff (steep rock) fires a gun. After how long will he hear its echo? Speed of sound in air is 330 m/s.

64. What is ultrasound? What is the difference between ordinary sound and ultrasound?

Mention any three applications (or uses) of ultrasound.

65. What are infrasonic waves? Name two animals which produce infrasonic waves.

66. What are ultrasonic waves? Name two animals which can produce ultrasonic waves

67. The audible range of frequencies of an average human ear is from 20 Hz to 20 kHz. Calculate the corresponding wavelengths. (Speed of sound in air is 344m s^–1).

68. Define the following terms:

(a) Echolocation, (b) Echocardiography and, (c) Ultra sonography.

69. Name an animal which navigates and finds food by echolocation.

70. Which of the two produces ultrasonic waves: porpoise or whale?

Answer:

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53. (b) Infrasonic waves :18Hz, 10Hz; Ultrasonic waves : 30,000 Hz, 50,000Hz

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55. 10Hz ;15 Hz;  40,000Hz

56. 855 m

57. 75 m

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63. 5 seconds

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67. 17.2 m to 0.0172m

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69. Bat

70. porpoise