1. What is the nature of sound waves?
a) Transverse
b) Longitudinal
c) Electromagnetic
d) None of the above
Answer: b) Longitudinal
Explanation: Sound waves propagate by compressions and rarefactions in the medium, which is characteristic of longitudinal waves.
2. The speed of sound is maximum in which medium?
a) Air
b) Water
c) Steel
d) Vacuum
Answer: c) Steel
Explanation: Sound travels fastest in solids because particles are closer, allowing quicker transmission of vibrations. It cannot travel in vacuum.
3. What is the unit of frequency?
a) Hertz
b) Decibel
c) Newton
d) Joule
Answer: a) Hertz
Explanation: Frequency is the number of oscillations per second, measured in Hertz (Hz).
4. Which of the following affects the speed of sound in air?
a) Temperature
b) Humidity
c) Pressure
d) Both a and b
Answer: d) Both a and b
Explanation: Speed of sound increases with temperature and humidity; pressure has negligible effect at constant temperature.
5. What is the audible range of frequency for a healthy human ear?
a) 20 Hz to 20 kHz
b) 10 Hz to 10 kHz
c) 50 Hz to 15 kHz
d) 5 Hz to 25 kHz
Answer: a) 20 Hz to 20 kHz
Explanation: Humans typically hear sounds between 20 Hz and 20,000 Hz.
6. The phenomenon of bending of sound waves around obstacles is called:
a) Reflection
b) Diffraction
c) Refraction
d) Interference
Answer: b) Diffraction
Explanation: Diffraction occurs when sound waves bend around corners or obstacles.
7. Echo is produced due to:
a) Diffraction
b) Reflection
c) Refraction
d) Resonance
Answer: b) Reflection
Explanation: Echo is the reflection of sound waves from a hard surface back to the listener.
8. If the frequency of a sound wave is doubled, its wavelength will:
a) Double
b) Halve
c) Remain same
d) Become zero
Answer: b) Halve
Explanation: Speed = frequency × wavelength. If speed is constant, increasing frequency halves the wavelength.
9. The loudness of sound depends on:
a) Frequency
b) Amplitude
c) Wavelength
d) Velocity
Answer: b) Amplitude
Explanation: Loudness is related to the amplitude of the sound wave; higher amplitude means louder sound.
10. The pitch of a sound depends on:
a) Amplitude
b) Frequency
c) Speed
d) Wavelength
Answer: b) Frequency
Explanation: Higher frequency sounds are perceived as higher pitch.
11. What type of wave is ultrasound?
a) Below 20 Hz
b) Between 20 Hz and 20 kHz
c) Above 20 kHz
d) None of the above
Answer: c) Above 20 kHz
Explanation: Ultrasound refers to sound waves with frequency higher than the audible range (>20,000 Hz).
12. In the Doppler effect, when the source approaches the observer, the frequency:
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero
Answer: a) Increases
Explanation: The observed frequency increases because the source moves closer, compressing wavefronts.
13. The time period of a sound wave with frequency 500 Hz is:
a) 0.002 s
b) 0.005 s
c) 2 s
d) 500 s
Answer: a) 0.002 s
Explanation: Time period 
seconds
14. Which of the following materials is best for sound insulation?
a) Steel
b) Wood
c) Air
d) Foam
Answer: d) Foam
Explanation: Foam absorbs sound energy effectively and reduces transmission.
15. What is the approximate speed of sound in air at room temperature?
a) 330 m/s
b) 1500 m/s
c) 3000 m/s
d) 0 m/s
Answer: a) 330 m/s
Explanation: At 20°C, the speed of sound in air is roughly 330 m/s.
16. Which physical quantity determines the energy carried by a sound wave?
a) Frequency
b) Wavelength
c) Amplitude
d) Speed
Answer: c) Amplitude
Explanation: Energy carried by a wave is proportional to the square of the amplitude.
17. Beats are formed when:
a) Two sound waves of different frequencies interfere
b) Two sound waves of same frequency interfere
c) A sound wave is reflected
d) None of the above
Answer: a) Two sound waves of different frequencies interfere
Explanation: Beats arise due to interference of two waves of slightly different frequencies.
18. The unit of loudness is:
a) Hertz
b) Decibel
c) Watt
d) Newton
Answer: b) Decibel
Explanation: Loudness is measured in decibels (dB), a logarithmic unit.
19. What happens to the speed of sound when temperature increases?
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero
Answer: a) Increases
Explanation: Molecules move faster at higher temperature, increasing sound speed.
20. Resonance in sound occurs when:
a) Frequency of the sound matches natural frequency of the object
b) Amplitude is maximum
c) Speed of sound increases
d) Wavelength decreases
Answer: a) Frequency of the sound matches natural frequency of the object
Explanation: Resonance happens when an object vibrates with maximum amplitude at its natural frequency.
21. The wavelength of sound in air is maximum when its frequency is:
a) High
b) Low
c) Medium
d) None of the above
Answer: b) Low
Explanation: Wavelength 
. For a constant speed 
, lower frequency means longer wavelength.
22. Which part of the human ear helps in amplifying the sound?
a) Eardrum
b) Cochlea
c) Ossicles
d) Ear canal
Answer: c) Ossicles
Explanation: The ossicles (malleus, incus, stapes) amplify sound vibrations from the eardrum to the inner ear.
23. Which phenomenon explains why sound is louder near a wall?
a) Diffraction
b) Reflection
c) Interference
d) Resonance
Answer: b) Reflection
Explanation: Sound waves reflect off walls and superimpose, increasing loudness near the surface.
24. The time taken for one complete oscillation of a sound wave is called:
a) Frequency
b) Amplitude
c) Time period
d) Wavelength
Answer: c) Time period
Explanation: Time period is the duration of one complete cycle.
25. The velocity of sound depends primarily on:
a) Pressure and humidity
b) Temperature and medium
c) Frequency and amplitude
d) Wavelength and pressure
Answer: b) Temperature and medium
Explanation: Speed of sound varies mainly with the medium type and temperature.
26. When sound passes from warm air to cold air, it:
a) Bends towards the cold air
b) Bends away from the cold air
c) Remains straight
d) Reflects
Answer: a) Bends towards the cold air
Explanation: Sound bends towards the region of lower speed, which is cold air.
27. The minimum distance between two points which produce audible beats is:
a) One wavelength
b) Half wavelength
c) One-fourth wavelength
d) None of the above
Answer: b) Half wavelength
Explanation: Beats occur due to interference and the minimum path difference for audible beats is half wavelength.
28. What is the main cause of echo fading away?
a) Absorption
b) Reflection
c) Diffraction
d) Refraction
Answer: a) Absorption
Explanation: Echo fades because sound energy is absorbed by air and surfaces, reducing intensity.
29. The Doppler effect is not observed when:
a) Source is stationary and observer moves
b) Both source and observer move
c) Both are stationary
d) Source moves and observer is stationary
Answer: c) Both are stationary
Explanation: No relative motion means no change in observed frequency.
30. In an open organ pipe, the fundamental frequency is . Its first overtone will be:
a)
b) 
c)
d)
Answer: b)
Explanation: An open pipe supports all harmonics; the first overtone is the second harmonic (2f).
31. In a closed organ pipe, the first overtone frequency is:
a) Twice the fundamental
b) Three times the fundamental
c) Four times the fundamental
d) Equal to the fundamental
Answer: b) Three times the fundamental
Explanation: Closed pipe supports odd harmonics only, so the first overtone = 3 × fundamental.
32. Which of the following is a practical application of ultrasound?
a) Echocardiography
b) Radio transmission
c) Mobile communication
d) Radioactive dating
Answer: a) Echocardiography
Explanation: Ultrasound imaging helps visualize internal body organs.
33. Noise can be reduced by:
a) Using sound-absorbing materials
b) Increasing sound frequency
c) Increasing amplitude
d) Using loudspeakers
Answer: a) Using sound-absorbing materials
Explanation: Materials like foam absorb sound waves and reduce noise pollution.
34. The energy of a sound wave is proportional to:
a) Frequency
b) Wavelength
c) Amplitude squared
d) Velocity
Answer: c) Amplitude squared
Explanation: Energy carried by sound is proportional to the square of amplitude.
35. The decibel scale is:
a) Linear
b) Exponential
c) Logarithmic
d) None of these
Answer: c) Logarithmic
Explanation: Decibel scale measures sound intensity logarithmically.
36. Which phenomenon causes a change in sound frequency due to motion?
a) Interference
b) Diffraction
c) Doppler effect
d) Resonance
Answer: c) Doppler effect
Explanation: Doppler effect describes frequency changes due to relative motion.
37. The sound waves in a room reflect multiple times causing:
a) Echo
b) Reverberation
c) Diffraction
d) Absorption
Answer: b) Reverberation
Explanation: Reverberation is the persistence of sound due to multiple reflections.
39. The pitch of a sound is high when:
a) Frequency is low
b) Amplitude is high
c) Frequency is high
d) Wavelength is long
Answer: c) Frequency is high
Explanation: Pitch depends on frequency; higher frequency means higher pitch.
40. The speed of sound in water is approximately:
a) 330 m/s
b) 1500 m/s
c) 5000 m/s
d) 100 m/s
Answer: b) 1500 m/s
Explanation: Sound travels faster in water than in air due to denser medium.
41. What happens to the wavelength of sound if the speed of sound doubles but frequency remains constant?
a) Doubles
b) Halves
c) Remains same
d) Becomes zero
Answer: a) Doubles
Explanation: . If doubles and stays constant, doubles.
42. The distance between two successive compressions in a sound wave is called:
a) Amplitude
b) Frequency
c) Wavelength
d) Time period
Answer: c) Wavelength
Explanation: The wavelength is the length of one complete wave cycle, including one compression and one rarefaction.
43. What is the effect of humidity on the speed of sound?
a) Speed decreases with humidity
b) Speed increases with humidity
c) Speed remains constant
d) None of the above
Answer: b) Speed increases with humidity
Explanation: Moist air is less dense than dry air, increasing sound speed.
44. What is the frequency range of infrasound?
a) Below 20 Hz
b) 20 Hz to 20 kHz
c) Above 20 kHz
d) None of the above
Answer: a) Below 20 Hz
Explanation: Infrasound refers to frequencies below human hearing range (<20 Hz).
45. The time taken for an echo to return from a surface 340 m away is:
a) 0.5 s
b) 1 s
c) 2 s
d) 4 s
Answer: b) 2 s
Explanation: Total distance travelled by sound = 2 × 340 = 680 m. Time = Distance/Speed = 680/340 = 2 s.
46. The frequency of a source is 100 Hz. What frequency will a stationary observer hear if the source moves towards him at speed 20 m/s? (Speed of sound = 340 m/s)
a) 106 Hz
b) 94 Hz
c) 100 Hz
d) 110 Hz
Answer: a) 106 Hz
Explanation: Doppler formula:
, here 
, 
, 
,
Hz.
47. The phenomenon of increase in amplitude when a sound wave matches the natural frequency of an object is called:
a) Reflection
b) Resonance
c) Diffraction
d) Interference
Answer: b) Resonance
Explanation: Resonance causes large amplitude oscillations when frequency matches natural frequency.
48. Which of the following instruments works on the principle of resonance?
a) Flute
b) Violin
c) Organ pipe
d) Both a and c
Answer: d) Both a and c
Explanation: Both flute and organ pipe produce sound by resonance.
49. The speed of sound in air at 0°C is approximately:
a) 273 m/s
b) 331 m/s
c) 343 m/s
d) 300 m/s
Answer: b) 331 m/s
Explanation: At 0°C, sound speed is about 331 m/s.
50. When sound waves interfere constructively, the resulting sound is:
a) Loud
b) Soft
c) No sound
d) None of the above
Answer: a) Loud
Explanation: Constructive interference increases amplitude and loudness.
51. Which part of the ear converts sound vibrations into electrical signals?
a) Cochlea
b) Eardrum
c) Ossicles
d) Auditory nerve
Answer: a) Cochlea
Explanation: Cochlea contains hair cells that convert mechanical vibrations to nerve impulses.
52. The audible range for dogs is approximately:
a) 20 Hz to 20 kHz
b) 40 Hz to 60 kHz
c) 10 Hz to 30 kHz
d) 1 kHz to 10 kHz
Answer: b) 40 Hz to 60 kHz
Explanation: Dogs can hear higher frequencies beyond human audible range.
53. The minimum distance between two points where destructive interference occurs in sound waves is:
a)
b) 
c)
d) 
Answer: b)
Explanation: Destructive interference occurs at path difference of half wavelength.
54. The frequency of beats formed when two sound waves of 250 Hz and 254 Hz interfere is:
a) 4 Hz
b) 500 Hz
c) 2 Hz
d) 254 Hz
Answer: a) 4 Hz
Explanation: Beat frequency = 
Hz.
55. Which of the following has the slowest speed of sound?
a) Steel
b) Water
c) Air
d) Vacuum
Answer: c) Air
Explanation: Sound travels slowest in gases like air compared to liquids and solids.
56. A sound wave in air has a frequency of 1000 Hz and wavelength of 0.34 m. What is the speed of sound?
a) 340 m/s
b) 1000 m/s
c) 0.34 m/s
d) 3.4 m/s
Answer: a) 340 m/s
Explanation: Speed = frequency × wavelength = 1000 × 0.34 = 340 m/s.
57. What is the name of the region where air particles are spread apart in a sound wave?
a) Compression
b) Rarefaction
c) Crest
d) Trough
Answer: b) Rarefaction
Explanation: Rarefaction is the part of a longitudinal wave where particles are furthest apart.
58. The loudness of a sound is related to its:
a) Frequency
b) Amplitude
c) Wavelength
d) Speed
Answer: b) Amplitude
Explanation: Larger amplitude corresponds to louder sound.
59. The reflection of sound waves is called:
a) Echo
b) Reverberation
c) Diffraction
d) Refraction
Answer: a) Echo
Explanation: Echo is the reflection of sound heard after a delay.
60. The difference between echo and reverberation is:
a) Echo is single reflection; reverberation is multiple reflections
b) Echo is multiple reflections; reverberation is single reflection
c) Both are same
d) Echo has higher frequency
Answer: a) Echo is single reflection; reverberation is multiple reflections
Explanation: Reverberation is the persistence of sound due to multiple reflections.
61. What is the wavelength of a sound wave of frequency 680 Hz in air, where speed of sound is 340 m/s?
a) 0.5 m
b) 2 m
c) 5 m
d) 0.05 m
Answer: a) 0.5 m
Explanation: 
m.
62. In which medium does sound travel fastest?
a) Air
b) Water
c) Steel
d) Vacuum
Answer: c) Steel
Explanation: Sound travels fastest in solids like steel.
63. The pitch of a sound is determined by:
a) Amplitude
b) Frequency
c) Wavelength
d) Velocity
Answer: b) Frequency
Explanation: Higher frequency means higher pitch.
64. Which of the following devices is used to measure sound intensity?
a) Barometer
b) Ammeter
c) Decibel meter
d) Thermometer
Answer: c) Decibel meter
Explanation: Decibel meter measures sound intensity in decibels.
65. Which of the following describes the decrease in intensity of sound with distance?
a) Diffraction
b) Attenuation
c) Reflection
d) Resonance
Answer: b) Attenuation
Explanation: Attenuation is the gradual loss of intensity over distance.
66. Ultrasound waves have frequency:
a) 20 Hz to 20 kHz
b) Above 20 kHz
c) Below 20 Hz
d) None of the above
Answer: b) Above 20 kHz
Explanation: Ultrasound is beyond human hearing (>20,000 Hz).
67. Sonar technology uses:
a) Light waves
b) Sound waves
c) Radio waves
d) Infrared waves
Answer: b) Sound waves
Explanation: Sonar uses sound waves for underwater detection.
68. The phenomenon of change in direction of sound due to change in speed is called:
a) Reflection
b) Refraction
c) Diffraction
d) Interference
Answer: b) Refraction
Explanation: Refraction is bending of waves when passing through different media.
69. Which part of the ear acts as the ear drum?
a) Cochlea
b) Tympanic membrane
c) Auditory nerve
d) Eustachian tube
Answer: b) Tympanic membrane
Explanation: The tympanic membrane vibrates in response to sound waves.
70. The frequency of sound emitted by a tuning fork is 512 Hz. What is its time period?
a) 0.002 s
b) 0.005 s
c) 0.00195 s
d) 0.01 s
Answer: c) 0.00195 s
Explanation: 
s.
71. If frequency of sound is doubled, the pitch will:
a) Double
b) Halve
c) Remain same
d) Become zero
Answer: a) Double
Explanation: Pitch is directly proportional to frequency.
72. Echo can be heard clearly when the reflecting surface is at least:
a) 10 m
b) 15 m
c) 17 m
d) 34 m
Answer: c) 17 m
Explanation: Minimum distance for echo = 
m (assuming 0.1 s delay).
73. Which phenomenon allows us to hear someone speaking around a corner?
a) Reflection
b) Refraction
c) Diffraction
d) Interference
Answer: c) Diffraction
Explanation: Diffraction allows bending of sound waves around obstacles.
74. Loudness of sound depends on:
a) Frequency
b) Amplitude
c) Wavelength
d) Speed
Answer: b) Amplitude
Explanation: Higher amplitude means louder sound.
75. The threshold of hearing corresponds to sound intensity of:
a) 
b) 
c)
d) 
Answer: a)
Explanation: The minimum intensity humans can hear is approximately .
76. The ear converts sound energy into:
a) Electrical energy
b) Mechanical energy
c) Chemical energy
d) Light energy
Answer: a) Electrical energy
Explanation: Sound waves are converted into electrical impulses by the cochlea.
77. The unit of sound intensity is:
a) Watt
b) Decibel
c) Newton
d) Pascal
Answer: b) Decibel
Explanation: Intensity is measured in decibels (dB).
78. Which device uses the principle of Doppler effect?
a) Radar
b) Sonar
c) Ultrasonograph
d) All of these
Answer: d) All of these
Explanation: Radar, sonar, and ultrasonographs utilize Doppler effect principles.
79. The wavelength of sound in steel is 2 m and frequency is 500 Hz. Find speed of sound in steel.
a) 500 m/s
b) 1000 m/s
c) 1500 m/s
d) 250 m/s
Answer: b) 1000 m/s
Explanation: 
m/s.
80. Which of the following cannot propagate sound?
a) Solid
b) Liquid
c) Gas
d) Vacuum
Answer: d) Vacuum
Explanation: No medium, no sound propagation in vacuum.
81. The loudness of a sound increases when the amplitude:
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero
Answer: a) Increases
Explanation: Loudness depends on amplitude of sound wave.
82. In the Doppler effect, if source moves away from observer, the frequency:
a) Increases
b) Decreases
c) Remains constant
d) Doubles
Answer: b) Decreases
Explanation: Frequency decreases when source moves away.
83. The speed of sound in air increases by about 0.6 m/s for every:
a) 1°C rise in temperature
b) 1°C drop in temperature
c) 10°C rise in temperature
d) None of the above
Answer: a) 1°C rise in temperature
Explanation: Sound speed increases roughly 0.6 m/s per degree Celsius rise.
84. The wavelength of a 1000 Hz sound wave in air (speed = 340 m/s) is:
a) 0.34 m
b) 3.4 m
c) 34 m
d) 0.0034 m
Answer: a) 0.34 m
Explanation: 
m.
85. The difference in path length between two coherent sources producing constructive interference is:
a) 
b)
c)
d) 
Answer: b)
Explanation: Constructive interference occurs at path differences of multiples of .
86. Which phenomenon causes the twinkling of stars, similar to sound refraction?
a) Reflection
b) Diffraction
c) Refraction
d) Resonance
Answer: c) Refraction
Explanation: Atmospheric refraction causes twinkling of stars.
87. Sound intensity is highest at:
a) Nodes
b) Antinodes
c) Midpoints
d) None of these
Answer: b) Antinodes
Explanation: Antinodes are points of maximum amplitude.
88. Which of the following is not a property of sound?
a) Reflection
b) Refraction
c) Polarization
d) Diffraction
Answer: c) Polarization
Explanation: Sound waves (longitudinal) cannot be polarized.
89. Frequency of ultrasound used in medical imaging is about:
a) 20 Hz
b) 20 kHz
c) 2 MHz
d) 200 MHz
Answer: c) 2 MHz
Explanation: Ultrasound frequencies used for imaging are in MHz range.
90. The time period of a 256 Hz tuning fork is:
a) 3.9 ms
b) 4 ms
c) 0.39 ms
d) 0.004 s
Answer: a) 3.9 ms
Explanation: 
s = 3.9 ms.
91. Which one of the following devices uses ultrasound waves?
a) Microphone
b) Loudspeaker
c) Sonar
d) Radio
Answer: c) Sonar
Explanation: Sonar uses ultrasound for underwater detection.
92. The term used for the time interval between two successive compressions in a sound wave is:
a) Frequency
b) Wavelength
c) Time period
d) Amplitude
Answer: c) Time period
Explanation: Time period is the duration of one cycle of a wave.
93. The intensity of sound is maximum at:
a) Nodes
b) Antinodes
c) Midpoints between nodes and antinodes
d) None of these
Answer: b) Antinodes
Explanation: Antinodes are points of maximum displacement and energy.
94. What type of wave is sound?
a) Transverse wave
b) Longitudinal wave
c) Electromagnetic wave
d) None of these
Answer: b) Longitudinal wave
Explanation: Sound waves consist of compressions and rarefactions, a characteristic of longitudinal waves.
95. Which physical quantity is responsible for the loudness of sound?
a) Frequency
b) Amplitude
c) Velocity
d) Wavelength
Answer: b) Amplitude
Explanation: Larger amplitude corresponds to greater loudness.
96. When a sound wave moves from air to water, its frequency:
a) Increases
b) Decreases
c) Remains same
d) Becomes zero
Answer: c) Remains same
Explanation: Frequency is determined by the source and remains constant across media.
97. Which part of the ear amplifies sound?
a) Cochlea
b) Ossicles
c) Eustachian tube
d) Auditory nerve
Answer: b) Ossicles
Explanation: Ossicles amplify vibrations from eardrum to cochlea.
98. The speed of sound in air at 20°C is approximately:
a) 331 m/s
b) 343 m/s
c) 300 m/s
d) 350 m/s
Answer: b) 343 m/s
Explanation: Speed of sound at 20°C is about 343 m/s.
99. The number of vibrations per second is called:
a) Amplitude
b) Frequency
c) Wavelength
d) Time period
Answer: b) Frequency
Explanation: Frequency is the number of cycles per second (Hz).
100. The characteristic of sound that depends on frequency is called:
a) Loudness
b) Pitch
c) Intensity
d) Quality
Answer: b) Pitch
Explanation: Pitch depends on frequency; higher frequency means higher pitch.