Chapter 10 : Sound Waves: Characteristics and Applications | 50 MCQs | 5 Sets.
Set 1: Sound and Its Propagation (Questions 1–10)
1. Which activity can produce sound?
A. Keeping a bell motionless
B. Striking a bell
C. Freezing water
D. Switching off a lamp
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Answer: B. Striking a bell
2. The repeated to-and-fro motion of an object is called:
A. Reflection
B. Refraction
C. Vibration
D. Absorption
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Answer: C. Vibration
3. Human voice is produced mainly by vibrating:
A. Vocal cords
B. Teeth
C. Tongue bones
D. Eardrum
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Answer: A. Vocal cords
4. Sound requires which of the following to travel?
A. A material medium
B. Sunlight
C. A magnetic field only
D. A vacuum
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Answer: A. A material medium
5. Sound cannot travel through:
A. Water
B. Air
C. Steel
D. Vacuum
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Answer: D. Vacuum
6. Which statement about sound is correct?
A. Sound is a mechanical wave
B. Sound is always a light wave
C. Sound travels through empty space
D. Sound does not transfer energy
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Answer: A. Sound is a mechanical wave
7. In a sound wave travelling through air, air particles generally:
A. Travel from the source to the listener
B. Vibrate around their mean positions
C. Remain completely still
D. Change into energy
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Answer: B. Vibrate around their mean positions
8. Sound usually travels fastest through:
A. Gases
B. A vacuum
C. Solids
D. Empty space
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Answer: C. Solids
9. Sound waves in air are mainly:
A. Longitudinal waves
B. Electromagnetic waves
C. Transverse light waves
D. Waves that need no medium
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Answer: A. Longitudinal waves
10. In a longitudinal wave, particles vibrate:
A. Only in circles
B. Perpendicular to wave travel
C. Parallel to wave travel
D. Without any motion
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Answer: C. Parallel to wave travel
Set 2: Wave Properties (Questions 11–20)
11. A region of high pressure in a longitudinal sound wave is called:
A. Rarefaction
B. Compression
C. Wavelength
D. Amplitude
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Answer: B. Compression
12. A region where particles are farther apart in a sound wave is a:
A. Compression
B. Crest
C. Rarefaction
D. Trough
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Answer: C. Rarefaction
13. The distance between two successive compressions is one:
A. Time period
B. Frequency
C. Amplitude
D. Wavelength
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Answer: D. Wavelength
14. The SI unit of wavelength is:
A. Metre
B. Hertz
C. Second
D. Decibel
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Answer: A. Metre
15. Frequency tells us the number of complete oscillations occurring:
A. Per metre
B. Per second
C. Per kilogram
D. Per degree
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Answer: B. Per second
16. The SI unit of frequency is:
A. Joule
B. Metre
C. Hertz
D. Second per metre
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Answer: C. Hertz
17. The time required for one complete oscillation is called:
A. Time period
B. Wavelength
C. Loudness
D. Wave speed
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Answer: A. Time period
18. If a wave has a frequency of 4 Hz, its time period is:
A. 4 seconds
B. 2 seconds
C. 0.5 seconds
D. 0.25 seconds
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Answer: D. 0.25 seconds
19. Which formula gives the speed of a periodic wave?
A. Speed = frequency ÷ wavelength
B. Speed = wavelength × frequency
C. Speed = wavelength + frequency
D. Speed = time period × wavelength
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Answer: B. Speed = wavelength × frequency
20. A wave has a wavelength of 3 m and a frequency of 20 Hz. Its speed is:
A. 6 m/s
B. 23 m/s
C. 60 m/s
D. 120 m/s
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Answer: C. 60 m/s
Set 3: Frequency, Pitch and Loudness (Questions 21–30)
21. A sound with a higher frequency is generally perceived as having:
A. Higher pitch
B. Lower pitch
C. No pitch
D. No frequency
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Answer: A. Higher pitch
22. Which property is most directly associated with the loudness of a sound?
A. Time period only
B. Wavelength only
C. Amplitude
D. Wave direction only
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Answer: C. Amplitude
23. Sound level is commonly expressed in:
A. Metres
B. Decibels
C. Hertz
D. Seconds
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Answer: B. Decibels
24. Which sound would normally have the highest pitch?
A. A low-frequency drumbeat
B. A deep rumble
C. A slow, low note
D. A high-frequency whistle
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Answer: D. A high-frequency whistle
25. The approximate range of frequencies audible to a healthy young human ear is:
A. 20 Hz to 20,000 Hz
B. 0 Hz to 10 Hz
C. 200 Hz to 500 Hz only
D. 20,000 Hz to 50,000 Hz
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Answer: A. 20 Hz to 20,000 Hz
26. Sound frequencies below approximately 20 Hz are called:
A. Ultrasonic
B. Audible
C. Infrasonic
D. Supersonic
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Answer: C. Infrasonic
27. Sound frequencies above approximately 20,000 Hz are called:
A. Infrasonic
B. Ultrasonic
C. Subsonic
D. Ordinary audible sound
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Answer: B. Ultrasonic
28. Which animal is known for detecting very low-frequency sounds?
A. Elephant
B. Butterfly
C. Earthworm
D. Houseplant
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Answer: A. Elephant
29. Which animal uses ultrasonic sounds to help locate objects?
A. Cow
B. Sheep
C. Horse
D. Bat
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Answer: D. Bat
30. If the amplitude of a sound wave increases, its sound is generally perceived as:
A. Softer
B. Louder
C. Lower in frequency automatically
D. Unable to travel
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Answer: B. Louder
Set 4: Speed of Sound and Numerical Questions (Questions 31–40)
31. At ordinary temperatures, the approximate speed of sound in air is:
A. 3 m/s
B. 30 m/s
C. 340 m/s
D. 3,000 m/s
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Answer: C. 340 m/s
32. Sound generally travels faster in water than in:
A. Air
B. Steel
C. Many solids
D. Some metals
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Answer: A. Air
33. A sound wave has a frequency of 50 Hz and a wavelength of 4 m. Find its speed.
A. 12.5 m/s
B. 46 m/s
C. 100 m/s
D. 200 m/s
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Answer: D. 200 m/s
34. A wave travels at 300 m/s and has a frequency of 100 Hz. Its wavelength is:
A. 0.3 m
B. 3 m
C. 30 m
D. 300 m
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Answer: B. 3 m
35. A vibrating object completes 120 oscillations in 2 seconds. Its frequency is:
A. 30 Hz
B. 40 Hz
C. 60 Hz
D. 240 Hz
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Answer: C. 60 Hz
36. If a wave has a time period of 0.02 seconds, its frequency is:
A. 50 Hz
B. 20 Hz
C. 2 Hz
D. 0.5 Hz
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Answer: A. 50 Hz
37. The speed of sound in a medium depends mainly on the medium's:
A. Colour
B. Shape alone
C. Brightness
D. Physical properties and conditions
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Answer: D. Physical properties and conditions
38. If the frequency doubles while the wave speed remains unchanged, the wavelength becomes:
A. Twice as large
B. Half as large
C. Four times as large
D. Unchanged in every case
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Answer: B. Half as large
39. A sound takes 2 seconds to travel 680 metres. Its average speed is:
A. 170 m/s
B. 300 m/s
C. 340 m/s
D. 1,360 m/s
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Answer: C. 340 m/s
40. When sound moves from air into water, which property changes because the speed changes while the source frequency remains constant?
A. Wavelength
B. Source frequency
C. Oscillation rate of the source
D. The identity of the source
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Answer: A. Wavelength
Set 5: Reflection and Applications of Sound (Questions 41–50)
41. The bouncing back of sound from a surface is called:
A. Absorption
B. Reflection
C. Dispersion
D. Evaporation
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Answer: B. Reflection
42. A separately heard reflected sound is called:
A. Pitch
B. Frequency
C. Vibration
D. Echo
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Answer: D. Echo
43. For a distinct echo to be heard, the reflected sound should arrive after a gap of roughly at least:
A. 0.1 seconds
B. 0.001 seconds
C. 10 seconds
D. 100 seconds
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Answer: A. 0.1 seconds
44. If the speed of sound is 340 m/s, approximately how far away should a reflecting wall be for a distinct echo in ordinary conditions?
A. 3.4 m
B. 8.5 m
C. 17 m
D. 34 m
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Answer: C. 17 m
45. Which material is often useful for reducing unwanted sound reflections in a room?
A. Bare metal sheets
B. Soft acoustic panels
C. Polished marble alone
D. Smooth glass only
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Answer: B. Soft acoustic panels
46. SONAR uses sound waves to help determine the distance or position of objects, often underwater. Which waves are commonly used?
A. Radio waves
B. Visible light waves
C. X-rays
D. Ultrasonic waves
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Answer: D. Ultrasonic waves
47. The use of reflected ultrasonic sounds by bats to locate objects is known as:
A. Echolocation
B. Evaporation
C. Magnetisation
D. Photosynthesis
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Answer: A. Echolocation
48. Medical ultrasonography uses high-frequency sound waves to:
A. Produce radio signals only
B. Measure visible light
C. Form images of structures inside the body
D. Create a vacuum in the body
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Answer: C. Form images of structures inside the body
49. Which practice can help reduce noise pollution?
A. Unnecessary honking
B. Maintaining silencers and limiting loudspeaker volume
C. Playing loud music at night
D. Using louder vehicle horns
Show Answer
Answer: B. Maintaining silencers and limiting loudspeaker volume
50. Why can a person standing far away see a flash before hearing the associated thunder?
A. Thunder does not produce sound
B. Sound travels faster than light
C. Light requires air to travel
D. Light travels much faster than sound in air
Show Answer
Answer: D. Light travels much faster than sound in air