1st Year Physics Chapter 8 Waves Notes MCQs Bank

physics 11th notes Chapter 8

1. In open organ pipe

 
 
 
 

2. The velocity of sound in the air would become double then its velocity at 0°C at temperature?

 
 
 
 

3. Newton formula estimated the speed of sound?

 
 
 
 

4. For ultrasonic waves:

 
 
 
 

5. A stationary wave is set up in the air column of a closed pipe. At the closed end of the pipe.

 
 
 
 

6. The waves that require a material medium for their propagation are called

 
 
 
 

7. Waves transmit ________ from one place to another.

 
 
 
 

8. If the pressure of the gas is doubled, then the speed of sound:

 
 
 
 

9. When path difference is an integral multiple of wavelengths, the effect is called:

 
 
 
 

10. The speed of sound in hydrogen is _________ time than that in oxygen?

 
 
 
 

11. A wave in soft string reflects from a hard steel rod. Its phase difference relative in the incident wave will be?

 
 
 
 

12. For destructive interference of sound waves, the path difference between two interfering sounds should be?

 
 
 
 

13. It is possible to distinguish between transverse and longitudinal waves form the property of?

 
 
 
 

14. In a transverse wave the distance between a crest and a trough is equal to:

 
 
 
 

15. Doppler Effect applies to

 
 
 
 

16. At antinodes produced in sound waves:

 
 
 
 

17. Phase difference of 180° is equivalent to a path difference of:

 
 
 
 

18. The speed of sound is greater in solids than in gases due to high value of:

 
 
 
 

19. Radar system is an application of:

 
 
 
 

20. In a stationary wave, the particle velocity at the node is:

 
 
 
 

21. The periodic alternation of sound between the maximum and minimum loudness is called?

 
 
 
 

22. The particles in the wave separated through _______ multiple of λare out of phase to each other.

 
 
 
 

23. Waves are produced at the surface of the water by a pencil executing periodic motion if held vertically at a frequency of 50Hz are?

 
 
 
 

24. Which one is the correct relation for speed of sound?

 
 
 
 

25. If two waves of the amplitude of ‘x’ produce a resultant wave of amplitude ‘x’ then the phase difference between them will be?

 
 
 
 

26. The distance between two consecutive antinodes is:

 
 
 
 

27. When two identical traveling waves are superimposed, the velocity of the resultant wave:

 
 
 
 

28. The distance between a node and antinode is

 
 
 
 

29. Stars moving towards the earth show:

 
 
 
 

30. When the source of sound moves away from a stationary listener, then ___________occurs:

 
 
 
 

31. The number of beats produced per second is equal to?

 
 
 
 

32. The points of maximum displacement on a stationary wave is called

 
 
 
 

33. The wave speed of a wave in terms of its wavelength λ and period T is:

 
 
 
 

34. According to Laplace correction sound travel in air under the conditions of

 
 
 
 

35. Stationary waves are generated on a string of length “l”, its fundamental frequency is given by:

 
 
 
 

36. Increase in velocity of sound in air for 1°𝐶 rise in temperature is:

 
 
 
 

37. Sound waves do not travel in vacuum because

 
 
 
 

38. To monitor blood flow through major arteries, ultrasonic waves of which frequencies are employed?

 
 
 
 

39. The phase difference between particles being on either side of a node?

 
 
 
 

40. the speed at 2°𝐶 will be:

 
 
 
 

41. At the open end of an organ pipe:

 
 
 
 

42. Silence zone takes place due to:

 
 
 
 

43. According to Newton sound travel in the air under the conditions of which type of process?

 
 
 
 

44. The number of beats produced per second is equal to

 
 
 
 

45. Laplace expression for speed of sound in a gase is:

 
 
 
 

46. When a transverse wave is reflected on going from a denser to a rarer medium, then at the boundary the reflected wave undergoes a phase change of:

 
 
 
 

47. A distance between two consecutive nodes is:

 
 
 
 

48. Energy is not transferred by?

 
 
 
 

49. When two identical waves moves in the same direction, they give rise to:

 
 
 
 

50. Beats can be heard when the difference of frequency is not more than:

 
 
 
 

51. When a transverse wave is reflected on going from a denser medium to a rare medium, then:

 
 
 
 

52. Sound waves cannot travel through:

 
 
 
 

53. On loading the pong of a tuning fork with wax, its frequency?

 
 
 
 

54. Periodic alteration of sound between maximum and minimum loudness are called

 
 
 
 

55. In vibrating cord the points where the amplitude is zero, are called.

 
 
 
 

56. The wave that requires a material medium for their propagation are called?

 
 
 
 

57. The fixed ends of a vibrating string are

 
 
 
 

58. Beats are formed when two notes of frequencies 𝑓1 and 𝑓2 (𝑓1 > 𝑓2) are sounded together. The beat frequency will be:

 
 
 
 

59. The speed of stationary waves in a stretched string is independent of?

 
 
 
 

60. The velocity of sound in vacuum is:

 
 
 
 

61. When a wave is reflected on going from a rarer to a denser medium, then at the boundary the reflected wave will undergo a phase change of:

 
 
 
 

62. A simple pendulum has a bob of mass „m‟ and its frequency is „f‟. If we replaced the bob with a heavier one, say of „2m‟, then what will be its new frequency?

 
 
 
 

63. Which of the following does not have any effect on the speed of sound in gases?

 
 
 
 

64. Two waves of equal frequency travelling in opposite direction produce:

 
 
 
 

65. Which organ produces a better quality of sound?

 
 
 
 

66. If the temperature increases the frequency of tuning fork?

 
 
 
 

67. In open organ pipe:

 
 
 
 

68. In vibrating cord, the points where the amplitude is maximum, are called?

 
 
 
 

69. Two wave trains of the same amplitude and frequency travelling in opposite directions along the same path in the same medium produce:

 
 
 
 

70. If the stretching force T of wire increases, then its frequency?

 
 
 
 

71. Which phenomenon can be applied to estimate the velocity of the star with respect to Earth?

 
 
 
 

72. Echo is the phenomenon of?

 
 
 
 

73. The velocity of sound in a vacuum is?

 
 
 
 

74. A set of frequencies, which is multiple of fundamental frequency is called:

 
 
 
 

75. The distance between any two consecutive crests or troughs is called

 
 
 
 

76. If a string vibrates in n loops, the wavelength of stationary waves will be:

 
 
 
 

77. Doppler effect applies to:

 
 
 
 

78. Which one is the correct relation for fundamental frequency of open and closed pipe?

 
 
 
 

79. The beats frequency (sensible) for a human car is?

 
 
 
 

80. Which property of wave motion distinguish a travelling wave from a stationary wave:

 
 
 
 

81. Laplace found that the alternate compression and refractions produced in sound waves follow?

 
 
 
 

82. Beats are result of?

 
 
 
 

83. The example of mechanical waves is:

 
 
 
 

84. Increase in the velocity of sound in the air of 1°C rise in temperature is?

 
 
 
 

85. Do dolphins navigate by using?

 
 
 
 

86. Which of the following is not the property of sound?

 
 
 
 

Short Questions

1. A transverse wave has a speed 200/sec. Find the wavelength λ of wave if frequency is kHz?
2. A transverse wave traveling in a denser medium is incident on a rarer medium. How the phase of the wave is affected?
3. A wave in produce along a stretched string but some of its particles permanently show zero displacement. What type of wave is it?
4. As a result of a distant explosion, an observer sense a ground tremor and then hear the explosion?
5. Cleary explain the difference between transverse and longitudinal waves?
6. Define longitudinal wave?
7. Define mechanical and electromagnetic waves give example of each.
8. Define transverse waves?
9. Describe the law of transverse vibrations of stretched strings?
10. Differentiate between constructive and destructive interference.
11. Differentiate between longitudinal and transverse waves.
12. Discribe three important cases of superposition?
13. Expain, how stationary waves are produced in air column organ pipes?
14. Explain how the speed of transverse wave in a string will change if its tension is made four times?
15. Explain the term “Beats”.
16. Explain the terms, crest trough, node and antinode?
17. Explain the terms: i) Crest ii) Trough
18. Explain why sound travels faster in warm air than in cold air?
19. How are beats useful in tuning musical instruments?
20. How should a sound source move with respect to the observer so that the frequency of its sound does not change?
21. How the velocity of a wave will change if “Tension” is made 16 times?
22. How wave length and frequency are related with the speed of propagation of a wave?
23. Is it possible for for two identical waves travelling in the same direction along a stering to give rise to a stationary wave?
24. Prove that the open pipe is richer in harmonics that of closed pipe?
25. State the principle of superposition.
26. Two waves of slightly different frequencies moving in the same direction along the same line produce beats. How beats are produced?
27. What are beats?
28. What are mechanical waves?
29. What are progressive waves?
30. What are stationary waves?
31. What are the condition of constructive and destructive interference?
32. What are the factors upon which speed of sound in air depends?
33. What are the type of organ pipes?
34. What are three kinds of waves?
35. What do you mean by interference?
36. What do you understand by harmonic series?
37. What features do longitudinal waves have in common with transverse waves?
38. What is Doppler’s effect?
39. What is effect of pressure and density on the velocity of sound?
40. What is effect of pressure on the speed of sound in gases?
41. what is effect of pressure on the speed of sound?
42. What is mean by the phase coherence? How does it affect the interference?
43. What is Netwon’s formula of spend of sound and describe the Laplace correction in Newton’s formula for air?
44. What is progressive wave? Give the name of two progressive waves.
45. What is radar?
46. What is reflection of waves? Describe the general rules for reflection of transverse wave from the boundary of two different media?
47. What is the effect of temperature on the speed of sound?
48. What is the frequency of the wave in the first mode of vibration of stretched string?
49. What is the principle of superposition?
50. Why are both odd harmonics produced in an open pipe?
51. Why are both only odd harmonic produced in a closed pipe?
52. Why does sound travel faster in solides than is gases?
53. Why Radar, cannot detect under water objects?
54. Why sound travels in hydrogen than that in oxygen?
55. Why stars moving towards Earth show a blue shift and those moving away show a red shift?
56. Why the pitch of sound increases when a observer moves towards a stationary source?
57. Write characteristics of stationary waves?
58. Write the formula for speed of sound at 0 ⁰C ?
59. Write three uses of Dopplerls effect?

Long Questions

1. State and explain the principle of super position?
2. What are conditions for constructive interference and destructive interference?
3. Write any two applications of Doppler‟s effect?
4. What is apparent change in frequency when source is moving away from stationary observer?
5. Define mechanical waves and electromagnetic waves. Give examples of each.
6. What is the effect of variation of pressure on the speed of sound in gas?
7. Define transverse wave and Longitudinal wave.
8. Explain newton‟s formula of speed of sound in air and Laplace correction for speed of sound.
9. Prove that vt =v₀ + 0.16t
10. Write a note on Beats.
11. Define stationary waves. Show that frequencies of stationary waves in a stretched sting are quantized.
“12. Define stationary waves. Find the frequencies of stationary waves produced in organ pipe when it is
(a) Open at both ends (b) Closed at one ends Define and explain Doppler Effect in detail. “
“13. Define Doppler effect and explain
(a)   When observer moves towards source
(b)  When source move away from observer. “
14. The wavelength of the signals from a radio transmitter is 1500m and the frequency is 200kHz. What is the wavelength for a transmitter operating at 1000kHz and with what speed the radio waves travel.
15. Two speakers are arranged. The distance between them is 3m and they emit a constant tome of 344Hz. A microphone P is moved along a line parallel to and 4m from the line connecting the two speakers. It is found that tone of maximum loudness is heard and displayed on the CRO when microphone is on the center of the line and directly opposite each speaker. Calculate the speed of sound.
16. A stationary wave is established in a string, which is 120cm long and fixed at both ends. The string vibrates in four segments; at a frequency of 120Hz. determine its wavelength and the fundamental frequency.
17. The frequency of the note emitted by a stretched string is 300Hz. What will be the frequency of this note when: (a) Length of the wave is reduced by one third without changing tension, (b) The tension is increased by one-third without changing the length of the wire.
18. An organ pipe has a length of 50cm. Find the frequency of its fundamental note and the next harmonic when it is: (a) Open at both ends. (b) Closed at one end (speed of sound = 350ms⁻¹).
19. A church organ consists of pipes, each open at one end, of different lengths. The minimum length is 30mm and the longest is 4m. Calculate the frequency range of fundamental notes. (Speed of sound = 340ms⁻¹).
20. Two tuning forks exhibit beats at a beat frequency of 3Hz. The frequency of one fork is 256Hz. Its frequency is then lowered slightly by adding a bit of wax to one of its prong. The two forks then exhibit a beat frequency of 1Hz. Determine the frequency of second tuning fork.
21. Two cars P and Q are traveling along a motorway in the same direction. The leading car P travels at a steady speed of 12ms⁻¹, the other car Q, traveling at a steady speed of 20ms⁻¹, sound its horn to emit a steady note which P’s driver estimates has a frequency of 830 Hz. What frequency does Q’s own driver hear? (Speed of sound = 340 ms⁻¹)
22. A train sounds its horn before it sets off from the station and an observer waiting on the platform estimates its frequency at 1200 Hz. The trains then moves off and accelerates steadily. Fifty seconds after departure, the driver sounds the horn again and the platform observer estimates the frequency of 1140 Hz. Calculate the train speed 50 s after departure. How far from the station is the train after 50 s? (Speed of sound = 340 ms⁻¹).
23. The absorption spectrum of light galaxy is measured and the wavelength of one of the lines identified as the Calcium α line is found to be 478 nm. The same line has a wavelength of 397 nm when measured in a laboratory. (a) Is the galaxy moving towards or away from the earth? (b) Calculate the speed of the galaxy relative to Earth (Speed of light 3 x10⁸ms⁻¹).

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