Section A – Multiple Choice Questions (20 Qs)
Q1. Sound waves are:
a) Longitudinal
b) Transverse
c) Electromagnetic
d) Both (a) and (b)
Q2. The speed of sound in air at 25°C is approximately:
a) 200 m/s
b) 330 m/s
c) 1500 m/s
d) 3000 m/s
Q3. Which of the following media carries sound fastest?
a) Air
b) Water
c) Iron
d) Vacuum
Q4. Sound cannot travel through:
a) Solids
b) Liquids
c) Gases
d) Vacuum
Q5. Unit of frequency is:
a) Hertz
b) Newton
c) Decibel
d) Pascal
Q6. Time period of a sound wave is reciprocal of:
a) Wavelength
b) Velocity
c) Frequency
d) Amplitude
Q7. Pitch of sound depends on:
a) Frequency
b) Amplitude
c) Velocity
d) Medium
Q8. The loudness of sound is related to:
a) Frequency
b) Amplitude
c) Speed
d) Wavelength
Q9. Ultrasonic waves have frequencies:
a) Less than 20 Hz
b) More than 20,000 Hz
c) Between 20 Hz – 20,000 Hz
d) Equal to 1000 Hz
Q10. SONAR is based on:
a) Refraction
b) Reflection
c) Interference
d) Diffraction
Q11. The speed of sound depends on:
a) Pressure
b) Density and temperature
c) Volume
d) None
Q12. Which of these is an application of ultrasound?
a) Cleaning machines
b) Imaging in medical field
c) SONAR
d) All of these
Q13. The unit of sound level is:
a) Joule
b) Watt
c) Decibel
d) Hertz
Q14. If a tuning fork vibrates 256 times in one second, its frequency is:
a) 256 Hz
b) 128 Hz
c) 512 Hz
d) 100 Hz
Q15. The echo of a sound can be heard only if the distance between source and reflector is at least:
a) 17 m
b) 34 m
c) 50 m
d) 68 m
Q16. Sound is produced due to:
a) Vibration of particles
b) Reflection of waves
c) Heat
d) Light
Q17. The range of audible sound for humans is:
a) 2 Hz – 200 Hz
b) 20 Hz – 20,000 Hz
c) 200 Hz – 200,000 Hz
d) 2000 Hz – 200,000 Hz
Q18. Which property of sound is affected by amplitude?
a) Loudness
b) Pitch
c) Speed
d) Frequency
Q19. Sound waves in air are:
a) Transverse waves
b) Longitudinal waves
c) Electromagnetic waves
d) Polarized waves
Q20. Which of the following has the highest speed of sound?
a) Wood
b) Steel
c) Air
d) Water
Section B – True / False (10 Qs)
Q21. Sound can travel through vacuum. (T/F)
Q22. Frequency and pitch are directly related. (T/F)
Q23. The loudness of sound depends on amplitude. (T/F)
Q24. SONAR is based on reflection of sound. (T/F)
Q25. Human ear can detect ultrasonic sound. (T/F)
Q26. Speed of sound is higher in solids than gases. (T/F)
Q27. Echo is heard when sound reflects from nearby walls. (T/F)
Q28. Decibel is the unit of loudness. (T/F)
Q29. Sound travels faster in hot air than in cold air. (T/F)
Q30. Infrasonic sound has frequency less than 20 Hz. (T/F)
Section C – Fill in the Blanks (10 Qs)
Q31. The speed of sound in air at 25°C is about ______ m/s.
Q32. The unit of frequency is ______.
Q33. Loudness depends on the ______ of vibration.
Q34. Ultrasound has frequency greater than ______ Hz.
Q35. SONAR stands for ______.
Q36. The echo is heard only if the reflecting surface is at least ______ m away.
Q37. ______ is the time taken for one complete oscillation.
Q38. The range of audible sound for humans is ______ Hz to ______ Hz.
Q39. Sound travels faster in ______ than in air.
Q40. Pitch of sound depends on its ______.
Section D – Assertion Reason (10 Qs)
Q41. Assertion: Sound cannot travel in vacuum.
Reason: Sound needs a medium to propagate.
Q42. Assertion: Ultrasound is used to clean electronic parts.
Reason: Ultrasound can penetrate fine holes and cavities.
Q43. Assertion: Speed of sound is greater in solids.
Reason: Solids have high density and elasticity.
Q44. Assertion: Human ear cannot hear infrasonic sounds.
Reason: The range of human hearing is 20–20,000 Hz.
Q45. Assertion: Echo is not heard in a small room.
Reason: Minimum distance required for echo is 17 m.
Q46. Assertion: Loudness and pitch are same properties of sound.
Reason: Both depend on amplitude.
Q47. Assertion: The sound of thunder is heard after the flash of lightning.
Reason: Speed of sound is less than speed of light.
Q48. Assertion: Bats can fly in dark using ultrasound.
Reason: Bats emit and detect ultrasonic sound waves.
Q49. Assertion: Sound waves are mechanical waves.
Reason: They need a medium for propagation.
Q50. Assertion: Decibel is the unit of frequency.
Reason: Frequency is measured in Hertz.
Section E – Very Short Answer (1 mark, 10 Qs)
Q51. Define frequency.
Q52. What is the SI unit of sound level?
Q53. Define pitch.
Q54. Define loudness.
Q55. What is ultrasound?
Q56. Define infrasonic sound.
Q57. Write full form of SONAR.
Q58. What is the audible range of human ear?
Q59. Why can’t sound travel in vacuum?
Q60. Define time period of a wave.
Section F – Short Answer (2 marks, 10 Qs)
Q61. Differentiate between infrasonic, audible and ultrasonic sounds.
Q62. Why do astronauts communicate using radios in space?
Q63. Write two applications of ultrasound.
Q64. What are the factors on which loudness of sound depends?
Q65. Why do we hear more clearly on a warm day than a cold day?
Q66. Define echo and state the condition to hear it.
Q67. Give one use of SONAR.
Q68. Why does sound travel faster in solids than gases?
Q69. How is pitch different from loudness?
Q70. What is meant by the time period of sound?
Section G – Short Answer (3 marks, 10 Qs)
Q71. Derive the relation between frequency and time period.
Q72. Explain how bats use ultrasound to navigate.
Q73. Explain working of SONAR with diagram.
Q74. Why is multiple reflection of sound used in stethoscopes?
Q75. Give three differences between noise and music.
Q76. A person hears an echo after 3 seconds. Calculate distance of reflecting surface (v = 330 m/s).
Q77. Why are ceilings of concert halls curved?
Q78. Explain why thunder is heard later than lightning.
Q79. State three characteristics of sound waves.
Q80. What is reverberation? Write one method to reduce it.
Section H – Long Answer (4–5 marks, 10 Qs)
Q81. Derive expression for speed of wave in terms of wavelength and frequency.
Q82. Describe in detail the working and applications of SONAR.
Q83. What is ultrasound? Write four uses.
Q84. Explain structure of human ear with diagram.
Q85. A ship sends ultrasonic waves and receives echo after 1.5 s. Calculate depth of sea if speed of sound in water is 1500 m/s.
Q86. Derive relationship between wavelength, frequency and velocity of sound.
Q87. Why is multiple reflection of sound useful in musical instruments? Give examples.
Q88. What is reverberation? How can it be minimized in halls?
Q89. Describe the working of a sound wave in air with particle motion diagram.
Q90. Explain difference between longitudinal and transverse waves with suitable examples.
Section I – Numerical Questions (10 Qs)
Q91. Calculate frequency of sound wave of wavelength 0.5 m travelling with speed of 340 m/s.
Q92. Find time period of a tuning fork of frequency 512 Hz.
Q93. Calculate the speed of sound wave having frequency 256 Hz and wavelength 1.3 m.
Q94. A sound wave has frequency 330 Hz and wavelength 1 m. Find its speed.
Q95. A person hears echo after 2.5 s. Calculate distance of reflecting wall. (v = 330 m/s)
Q96. An ultrasonic wave of frequency 100 kHz travels in air at 340 m/s. Find its wavelength.
Q97. A sound wave has a wavelength of 2 cm and frequency 20 kHz. Find its speed.
Q98. An echo is heard after 4 s. Find distance of reflecting wall.
Q99. A sonar sends a sound wave and receives echo after 6 s. If velocity = 1500 m/s, find depth of sea.
Q100. A sound wave travels at 340 m/s and has wavelength 0.85 m. Calculate its frequency.
Section J – Case Study Questions (10 Qs)
Q101. (Noise Pollution)
Noise is an unwanted sound that causes discomfort. Sources include traffic, industries, loudspeakers, etc. Prolonged exposure may cause hearing loss and stress.
Q: (i) Define noise pollution.
(ii) Write two effects of noise pollution.
(iii) Suggest two methods to reduce it.
Q102. (Bats Navigation)
Bats produce ultrasonic sounds to detect obstacles. These sound waves reflect back after striking objects, helping bats to navigate in dark.
Q: (i) Which principle is used by bats?
(ii) What type of waves are used?
(iii) Give one human-made application of this principle.
Q103. (SONAR)
A ship uses SONAR to detect underwater objects. Sound waves are sent and reflected back from seabed.
Q: (i) Expand SONAR.
(ii) Write its working principle.
(iii) Give one application.
Q104. (Ultrasound in Medicine)
Doctors use ultrasound scanning to view internal organs and detect diseases.
Q: (i) Why is ultrasound used in medical field?
(ii) Write one advantage.
(iii) Write one limitation.
Q105. (Echo in Halls)
In big halls, echoes disturb speeches. This is avoided by soundproofing materials.
Q: (i) Define echo.
(ii) State condition for its formation.
(iii) Suggest two methods to reduce echoes.
Q106. (Human Ear)
The human ear helps us hear by collecting sound waves, amplifying them and sending signals to brain.
Q: (i) Name three parts of human ear.
(ii) Which part converts vibrations into electrical signals?
(iii) State the function of pinna.
Q107. (Earthquakes)
Earthquakes produce infrasonic and ultrasonic sounds. Animals often detect them earlier.
Q: (i) Define infrasonic sound.
(ii) Which frequency range is infrasonic?
(iii) Why can animals detect earthquake vibrations earlier?
Q108. (Thunder and Lightning)
We see lightning before hearing thunder.
Q: (i) Why does this happen?
(ii) Which travels faster – sound or light?
(iii) What is the approximate speed of sound in air?
Q109. (Ultrasound Cleaning)
Ultrasound waves are used to clean delicate objects like watches.
Q: (i) Why is ultrasound suitable for cleaning?
(ii) Give one other use of ultrasound.
(iii) Write frequency range of ultrasound.
Q110. (Multiple Reflection of Sound)
Multiple reflection is used in musical instruments and stethoscopes.
Q: (i) What is multiple reflection?
(ii) Write two instruments where it is used.
(iii) Why are soundboards used in auditoriums?