Sound Top 100 MCQs With Answer and Explanation

1. Sound is produced due to —
A) Chemical reaction
B) Vibration of bodies
C) Heat energy
D) Light energy

2. The substance through which sound travels is called —
A) Conductor
B) Medium
C) Channel
D) Material

3. Sound cannot travel through —
A) Solids
B) Liquids
C) Gases
D) Vacuum

4. The S.I. unit of frequency is —
A) Hertz (Hz)
B) Newton (N)
C) Joule (J)
D) Watt (W)

5. The S.I. unit of sound intensity is —
A) Decibel (dB)
B) Hertz (Hz)
C) Joule (J)
D) Pascal (Pa)

6. Which of the following statements is true?
A) Sound travels faster in air than in solids.
B) Sound travels faster in solids than in gases.
C) Sound travels fastest in gases.
D) Sound cannot travel through solids.
Answer: B) Sound travels faster in solids than in gases.
Explanation: In solids, particles are close together, allowing faster vibration transfer.

7. The speed of sound in air at room temperature is approximately —
A) 150 m/s
B) 330 m/s
C) 500 m/s
D) 1000 m/s
Answer: B) 330 m/s
Explanation: Speed of sound in dry air at 25°C is about 343 m/s.

8. The loudness of sound depends on its —
A) Frequency
B) Amplitude
C) Speed
D) Pitch
Answer: B) Amplitude
Explanation: Greater amplitude → louder sound.

9. The pitch of a sound depends on —
A) Amplitude
B) Frequency
C) Wavelength
D) Velocity
Answer: B) Frequency
Explanation: Higher frequency → higher pitch.

10. The time taken for one complete vibration is called —
A) Frequency
B) Time period
C) Amplitude
D) Pitch
Answer: B) Time period
Explanation: T=1/fT = 1/fT=1/f, reciprocal of frequency.

11. The number of vibrations per second is called —
A) Wavelength
B) Amplitude
C) Frequency
D) Pitch
Answer: C) Frequency
Explanation: It indicates how many vibrations occur in one second.

12. Sound waves are —
A) Transverse waves
B) Longitudinal waves
C) Electromagnetic waves
D) Polarized waves
Answer: B) Longitudinal waves
Explanation: In sound, particles vibrate parallel to direction of wave propagation.

13. Sound travels fastest in —
A) Air
B) Water
C) Iron
D) Vacuum
Answer: C) Iron
Explanation: Sound travels fastest in solids.

14. The range of audible sound for humans is —
A) 0 – 100 Hz
B) 20 – 20,000 Hz
C) 2,000 – 2,000,000 Hz
D) Above 20,000 Hz
Answer: B) 20 – 20,000 Hz
Explanation: Sounds within this range are audible to the human ear.

15. Sound with frequency below 20 Hz is called —
A) Ultrasonic
B) Supersonic
C) Infrasonic
D) Subsonic
Answer: C) Infrasonic
Explanation: Sound below 20 Hz frequency is infrasonic.

16. Sound with frequency above 20,000 Hz is called —
A) Ultrasonic
B) Supersonic
C) Hypersonic
D) Subsonic
Answer: A) Ultrasonic
Explanation: Sound waves above audible range are called ultrasonic waves.

17. Which of the following animals can hear ultrasonic sounds?
A) Elephant
B) Bat
C) Cow
D) Cat
Answer: B) Bat
Explanation: Bats use ultrasonic waves for navigation (echolocation).

18. The speed of sound depends on —
A) Temperature of the medium
B) Nature of the medium
C) Both A and B
D) Amplitude
Answer: C) Both A and B
Explanation: Speed varies with temperature and density of the medium.

19. Echo is produced due to —
A) Refraction of sound
B) Reflection of sound
C) Diffraction of sound
D) Interference of sound
Answer: B) Reflection of sound
Explanation: Echo is a reflected sound heard after a time gap.

20. Minimum distance required for hearing a distinct echo is —
A) 10 m
B) 17 m
C) 34 m
D) 50 m
Answer: B) 17 m
Explanation: At 343 m/s, time gap of 0.1 s requires 17.15 m for sound to travel to and fro.

21. Echo is heard only after a certain interval of time because —
A) Sound needs time to travel to the reflecting surface and back
B) Sound is delayed by the ear
C) Sound travels slowly in air
D) Reflection takes time
Answer: A) Sound needs time to travel to the reflecting surface and back
Explanation: Echo is heard when reflected sound reaches after at least 0.1 second.

22. Which of the following cannot produce an echo?
A) Mountain
B) Wall
C) Pillow
D) Building
Answer: C) Pillow
Explanation: Soft surfaces absorb sound, not reflect it.

23. The persistence of sound after the source stops vibrating is called —
A) Echo
B) Reverberation
C) Resonance
D) Reflection
Answer: B) Reverberation
Explanation: Reverberation is multiple reflections of sound that prolong its duration.

24. The phenomenon of increase in amplitude when two waves of same frequency superpose is called —
A) Interference
B) Resonance
C) Diffraction
D) Reflection
Answer: B) Resonance
Explanation: Resonance occurs when the frequency of external vibration matches natural frequency.

25. The frequency of sound emitted by a vibrating object depends on —
A) Amplitude
B) Length and tension
C) Medium
D) Loudness
Answer: B) Length and tension
Explanation: In strings, frequency depends on length, tension, and mass per unit length.

26. The sound waves cannot travel through —
A) Air
B) Water
C) Steel
D) Vacuum
Answer: D) Vacuum
Explanation: Sound requires a medium; vacuum has none.

27. The sensation of sound stops soon after the source stops because of —
A) Persistence of hearing
B) Reflection
C) Absorption
D) Refraction
Answer: A) Persistence of hearing
Explanation: Human ear retains sound for about 0.1 seconds after it stops.

28. The device used to measure frequency of sound is —
A) Barometer
B) Hygrometer
C) Tuning fork
D) Tachometer
Answer: C) Tuning fork
Explanation: Tuning fork produces and measures standard frequencies.

29. In which medium does sound travel fastest?
A) Air
B) Water
C) Steel
D) Wood
Answer: C) Steel
Explanation: Solids have closely packed molecules, giving faster sound transmission.

30. The human ear can sense sound frequencies approximately between —
A) 1–10 Hz
B) 20–20,000 Hz
C) 2,000–200,000 Hz
D) 200–2,000,000 Hz
Answer: B) 20–20,000 Hz
Explanation: Audible range for humans.

31. Which of the following has the lowest speed of sound?
A) Air
B) Water
C) Steel
D) Iron
Answer: A) Air
Explanation: Sound travels slowest in gases due to large molecular separation.

32. Ultrasonic waves are used in —
A) Cooking food
B) Cleaning jewelry
C) Producing electricity
D) Communication through wires
Answer: B) Cleaning jewelry
Explanation: Ultrasonic waves remove dirt particles effectively by vibration.

33. SONAR is used to measure —
A) Distance of ship from the shore
B) Speed of aircraft
C) Depth of sea
D) Distance between two cities
Answer: C) Depth of sea
Explanation: SONAR (Sound Navigation and Ranging) uses reflected ultrasonic waves to measure depth.

34. The principle used in SONAR is —
A) Reflection of sound
B) Refraction of sound
C) Diffraction of sound
D) Polarization of sound
Answer: A) Reflection of sound
Explanation: SONAR works based on echo (reflected sound wave) principle.

35. The range of ultrasonic waves is —
A) Below 20 Hz
B) Between 20–20,000 Hz
C) Above 20,000 Hz
D) Below 10 Hz
Answer: C) Above 20,000 Hz
Explanation: Ultrasonic means above audible range.

36. Bats navigate in the dark by using —
A) Light
B) Infrasonic waves
C) Ultrasonic waves
D) Magnetic fields
Answer: C) Ultrasonic waves
Explanation: Bats use echolocation through ultrasonic sound.

37. The pitch of a sound increases if —
A) Frequency decreases
B) Frequency increases
C) Amplitude increases
D) Velocity decreases
Answer: B) Frequency increases
Explanation: Pitch is directly proportional to frequency.

38. The loudness of a sound depends on —
A) Frequency
B) Amplitude
C) Velocity
D) Medium
Answer: B) Amplitude
Explanation: Larger amplitude produces louder sound.

39. In a transverse wave, particles of medium vibrate —
A) Along the direction of propagation
B) Perpendicular to direction of propagation
C) In circular motion
D) Randomly
Answer: B) Perpendicular to direction of propagation
Explanation: Sound waves are longitudinal, but transverse waves vibrate perpendicular.

40. Sound cannot travel through vacuum because —
A) Sound is electromagnetic
B) Sound needs particles for transmission
C) Sound travels as light
D) Sound speed becomes infinite
Answer: B) Sound needs particles for transmission
Explanation: In vacuum, there are no particles to carry vibrations.

41. Sound waves in air are —
A) Longitudinal mechanical waves
B) Transverse electromagnetic waves
C) Transverse mechanical waves
D) Electromagnetic waves
Answer: A) Longitudinal mechanical waves
Explanation: Sound waves require a medium and particles vibrate parallel to the direction of wave motion.

42. The unit of wavelength is —
A) Second
B) Meter
C) Hertz
D) Newton
Answer: B) Meter
Explanation: Wavelength is distance between two consecutive crests or compressions → measured in meters.

43. The relation between speed, frequency, and wavelength of a sound wave is —
A) v=f/λv = f / \lambdav=f/λ
B) v=f+λv = f + \lambdav=f+λ
C) v=fλv = f \lambdav=fλ
D) v=f−λv = f – \lambdav=f−λ
Answer: C) v=fλv = f \lambdav=fλ
Explanation: Speed=Frequency×Wavelength\text{Speed} = \text{Frequency} × \text{Wavelength}Speed=Frequency×Wavelength.

44. The amplitude of vibration is the measure of —
A) Pitch
B) Loudness
C) Speed
D) Frequency
Answer: B) Loudness
Explanation: Loudness ∝ square of amplitude.

45. When the amplitude of vibration increases, sound becomes —
A) Softer
B) Louder
C) Sharper
D) Lower
Answer: B) Louder
Explanation: Greater amplitude → more energy → louder sound.

46. When frequency increases, pitch —
A) Decreases
B) Increases
C) Remains constant
D) Becomes zero
Answer: B) Increases
Explanation: Pitch depends directly on frequency.

47. Which sound has higher pitch?
A) Drum
B) Flute
C) Guitar
D) Bass horn
Answer: B) Flute
Explanation: Flute produces sound of higher frequency and pitch.

48. Which sound has lower pitch?
A) Whistle
B) Human voice
C) Drum
D) Bird chirping
Answer: C) Drum
Explanation: Drum produces low-frequency sound → lower pitch.

49. The speed of sound increases with —
A) Decrease in temperature
B) Increase in temperature
C) Increase in pressure only
D) Decrease in humidity
Answer: B) Increase in temperature
Explanation: Higher temperature → faster particle vibration → faster sound propagation.

50. Sound travels faster in —
A) Cold air
B) Hot air
C) Dry air
D) Vacuum
Answer: B) Hot air
Explanation: Speed increases with temperature and humidity.

51. Which of the following is not a characteristic of sound?
A) Loudness
B) Pitch
C) Quality
D) Speed
Answer: D) Speed
Explanation: Speed is a physical property; loudness, pitch, and quality are characteristics of sound.

52. The property that distinguishes two sounds of same pitch and loudness is —
A) Amplitude
B) Frequency
C) Quality or Timbre
D) Wavelength
Answer: C) Quality or Timbre
Explanation: Quality gives sound its unique tone (e.g., flute vs violin).

53. The speed of sound in air depends mainly on —
A) Frequency
B) Pressure
C) Temperature
D) Amplitude
Answer: C) Temperature
Explanation: Speed increases with temperature in gases.

54. The range of infrasonic sound is —
A) Below 20 Hz
B) Above 20,000 Hz
C) Between 20 and 20,000 Hz
D) 2,000–200,000 Hz
Answer: A) Below 20 Hz
Explanation: Sounds below human hearing range are infrasonic.

55. Which of the following animals can produce infrasonic sound?
A) Bat
B) Dog
C) Elephant
D) Cat
Answer: C) Elephant
Explanation: Elephants use infrasonic waves to communicate over long distances.

56. The phenomenon of reflection of sound is used in —
A) SONAR
B) LASER
C) RADAR
D) Infrared rays
Answer: A) SONAR
Explanation: SONAR uses reflected sound waves to determine underwater objects and depth.

57. The instrument used to record sound is —
A) Telescope
B) Microphone
C) Stethoscope
D) Barometer
Answer: B) Microphone
Explanation: A microphone converts sound into electrical signals for recording.

58. The device used by doctors to hear heartbeat is —
A) Telephone
B) Microphone
C) Stethoscope
D) Megaphone
Answer: C) Stethoscope
Explanation: It amplifies and transmits sound of heartbeat through reflection.

59. Sound waves cannot be polarized because —
A) They are transverse
B) They are electromagnetic
C) They are longitudinal
D) They have low frequency
Answer: C) They are longitudinal
Explanation: Polarization occurs only in transverse waves.

60. The speed of sound in air at 0°C is approximately —
A) 331 m/s
B) 340 m/s
C) 350 m/s
D) 300 m/s
Answer: A) 331 m/s
Explanation: The speed of sound at 0°C is 331 m/s and increases by about 0.6 m/s per °C rise in temperature.

61. Sound waves are examples of —
A) Electromagnetic waves
B) Transverse mechanical waves
C) Longitudinal mechanical waves
D) Stationary waves
Answer: C) Longitudinal mechanical waves
Explanation: Sound needs a medium, and particles vibrate parallel to wave direction.

62. The wave formed by the vibration of a stretched string is —
A) Longitudinal wave
B) Transverse wave
C) Stationary wave
D) Random wave
Answer: B) Transverse wave
Explanation: In a stretched string, particles vibrate perpendicular to the direction of wave propagation.

63. The speed of sound in a gas depends on —
A) Amplitude of wave
B) Density and elasticity of gas
C) Frequency of sound
D) Pressure of gas
Answer: B) Density and elasticity of gas
Explanation: v=E/ρv = \sqrt{E/ρ}v=E/ρ​, where E = elasticity, ρ = density.

64. The product of wavelength and frequency of a sound wave gives —
A) Amplitude
B) Velocity
C) Intensity
D) Power
Answer: B) Velocity
Explanation: v=f×λv = f × \lambdav=f×λ

65. The wavelength of a sound wave in air is 1.7 m and its frequency is 200 Hz. What is its speed?
A) 200 m/s
B) 300 m/s
C) 340 m/s
D) 400 m/s
Answer: C) 340 m/s
Explanation: v=f×λ=200×1.7=340 m/sv = f × \lambda = 200 × 1.7 = 340 \, m/sv=f×λ=200×1.7=340m/s

66. Which of the following is an example of reflection of sound?
A) Echo
B) Doppler effect
C) Reverberation
D) Both A and C
Answer: D) Both A and C
Explanation: Both echo and reverberation are caused by reflection of sound.

67. The repetition of sound due to reflection is called —
A) Echo
B) Vibration
C) Refraction
D) Interference
Answer: A) Echo
Explanation: Echo occurs when reflected sound is heard distinctly after 0.1 s.

68. Reverberation is undesirable in —
A) Halls
B) Open grounds
C) Forests
D) Empty fields
Answer: A) Halls
Explanation: Too much reverberation causes confusion and echo overlap in halls.

69. Reverberation in big halls can be reduced by —
A) Using smooth walls
B) Using soft materials
C) Increasing ceiling height
D) Using hard materials
Answer: B) Using soft materials
Explanation: Curtains, carpets, and foam absorb sound and reduce reverberation.

70. Which among the following does not affect the speed of sound?
A) Temperature
B) Pressure
C) Medium
D) Frequency
Answer: D) Frequency
Explanation: Speed depends only on medium and temperature, not on frequency.

71. What is the speed of sound in water approximately?
A) 1500 m/s
B) 500 m/s
C) 330 m/s
D) 1000 m/s
Answer: A) 1500 m/s
Explanation: In water, sound travels faster than in air due to higher density.

72. The speed of sound is maximum in —
A) Air
B) Water
C) Wood
D) Steel
Answer: D) Steel
Explanation: Sound travels fastest in solids; among them, steel has high elasticity.

73. The pitch of a sound depends on —
A) Frequency
B) Amplitude
C) Loudness
D) Wavelength
Answer: A) Frequency
Explanation: Pitch increases with frequency.

74. The loudness of a sound is determined by —
A) Frequency
B) Amplitude
C) Velocity
D) Time period
Answer: B) Amplitude
Explanation: Loudness ∝ square of amplitude.

75. A sound of 60 dB is how many times louder than 30 dB?
A) 10 times
B) 100 times
C) 1000 times
D) 2 times
Answer: B) 100 times
Explanation: Loudness level increases tenfold for every 10 dB rise → 30 dB difference = 1000/10 ≈ 100× louder.

76. The speed of sound increases with —
A) Decrease in density
B) Increase in temperature
C) Increase in wavelength
D) Decrease in amplitude
Answer: B) Increase in temperature
Explanation: Higher temperature means faster molecular motion → faster sound transmission.

77. Which physical quantity remains constant when sound passes from one medium to another?
A) Speed
B) Frequency
C) Wavelength
D) Amplitude
Answer: B) Frequency
Explanation: Frequency is determined by the source; it does not change with medium.

78. The sound waves that cannot be heard by human ear are —
A) Audible
B) Ultrasonic and infrasonic
C) Musical
D) Mechanical
Answer: B) Ultrasonic and infrasonic
Explanation: Humans can hear only between 20–20,000 Hz; others are inaudible.

79. Sound waves transfer —
A) Matter only
B) Energy only
C) Both matter and energy
D) Neither
Answer: B) Energy only
Explanation: Sound waves carry energy, not matter, from one point to another.

80. When a sound wave travels through air, the air particles —
A) Move with the wave
B) Vibrate to and fro about their mean position
C) Move randomly
D) Move upward only
Answer: B) Vibrate to and fro about their mean position
Explanation: Sound is a longitudinal wave; particles oscillate back and forth around their equilibrium.

81. The loudness of a sound depends on —
A) Frequency
B) Amplitude of vibration
C) Wavelength
D) Velocity of sound
Answer: B) Amplitude of vibration
Explanation: Greater amplitude → louder sound → more energy in vibration.

82. The frequency of a note produced by a guitar string depends on —
A) Length, tension, and thickness of string
B) Volume of air
C) Shape of instrument
D) Temperature of air
Answer: A) Length, tension, and thickness of string
Explanation: These three factors determine the frequency and hence the pitch.

83. Sound energy is a form of —
A) Chemical energy
B) Mechanical energy
C) Electrical energy
D) Magnetic energy
Answer: B) Mechanical energy
Explanation: Sound is produced by mechanical vibrations of particles.

84. The frequency of a vibrating tuning fork increases if —
A) Its length increases
B) Its length decreases
C) Its material changes
D) Temperature decreases
Answer: B) Its length decreases
Explanation: Shorter fork → higher frequency → higher pitch.

85. The sound produced by a drum is —
A) Low pitch and loud
B) High pitch and soft
C) High pitch and loud
D) Low pitch and soft
Answer: A) Low pitch and loud
Explanation: Drum vibrations are large and slow → low frequency (low pitch) but large amplitude (loud).

86. The sound produced by a whistle is —
A) High pitch
B) Low pitch
C) Loud
D) Harsh
Answer: A) High pitch
Explanation: Whistle produces sound with high frequency → high pitch.

87. The sound produced by a flute is —
A) High pitch
B) Low pitch
C) Loud
D) Unpleasant
Answer: A) High pitch
Explanation: Flute produces musical, high-frequency sound.

88. The quality of sound helps us to —
A) Identify loudness
B) Distinguish between two sounds of same pitch and loudness
C) Measure frequency
D) Measure amplitude
Answer: B) Distinguish between two sounds of same pitch and loudness
Explanation: Quality (timbre) makes each sound unique, e.g., violin vs flute.

89. The ear converts sound waves into —
A) Light energy
B) Electrical impulses
C) Heat
D) Magnetic energy
Answer: B) Electrical impulses
Explanation: The inner ear (cochlea) changes sound vibrations into electrical signals sent to the brain.

90. The working principle of a megaphone is —
A) Reflection of sound
B) Refraction of sound
C) Resonance
D) Multiple reflection
Answer: D) Multiple reflection
Explanation: A megaphone amplifies sound using successive reflections within its cone.

91. The speed of sound in air increases when —
A) Temperature decreases
B) Humidity increases
C) Pressure decreases
D) Air becomes dry
Answer: B) Humidity increases
Explanation: Moist air is less dense → sound travels faster.

92. Sound cannot travel through space because —
A) It moves too fast
B) There is no medium
C) It is absorbed
D) It is reflected back
Answer: B) There is no medium
Explanation: Sound requires particles to propagate; space is vacuum.

93. Infrasonic waves have frequency —
A) Below 20 Hz
B) Above 20,000 Hz
C) Between 20–20,000 Hz
D) Infinite
Answer: A) Below 20 Hz
Explanation: Infrasonic = frequencies lower than human hearing limit.

94. Ultrasonic waves have frequency —
A) Below 20 Hz
B) Between 20–20,000 Hz
C) Above 20,000 Hz
D) Above 2,000,000 Hz
Answer: C) Above 20,000 Hz
Explanation: Beyond audible range → ultrasonic waves.

95. The range of hearing of a young human being is —
A) 0–100 Hz
B) 20–20,000 Hz
C) 200–200,000 Hz
D) 2,000–2,000,000 Hz
Answer: B) 20–20,000 Hz
Explanation: Human ear can detect only sounds in this frequency range.

96. The speed of sound in iron is approximately —
A) 500 m/s
B) 1500 m/s
C) 3400 m/s
D) 5100 m/s
Answer: D) 5100 m/s
Explanation: Sound travels fastest in solids; for iron, about 5100 m/s.

97. The device used to detect sound under water is —
A) SONAR
B) RADAR
C) LASER
D) Infrared sensor
Answer: A) SONAR
Explanation: SONAR (Sound Navigation and Ranging) uses ultrasonic reflection to locate underwater objects.

98. When the source of sound moves towards the listener, the pitch —
A) Decreases
B) Increases
C) Remains same
D) Disappears
Answer: B) Increases
Explanation: Due to Doppler Effect, apparent frequency increases when source approaches.

99. The Doppler effect in sound is used in —
A) Determining speed of vehicles
B) Measuring temperature
C) Measuring density of gas
D) Detecting earthquake waves
Answer: A) Determining speed of vehicles
Explanation: Police radar guns use Doppler effect to measure speed via frequency change.

100. Which of the following waves can travel through vacuum?
A) Sound waves
B) Ultrasonic waves
C) Radio waves
D) Shock waves
Answer: C) Radio waves
Explanation: Radio waves are electromagnetic and can travel through vacuum, unlike sound waves.