Unit 11: Sound - Physics II - For Class X (Science Group) - MCQs, Fill in the blanks and Concept Map

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Unit 11: Sound
Physics II
For Class X (Science Group)

• MCQs From Text Book Exercise
• More MCQs
• Fill In The Blanks
• Abbreviations Or Symbols
• Units
• Concept Map

Multiple Choice Questions (MCQs)
From Text Book Exercise

Choose the correct answer from the following choices:
1. Sound is a form of:
(a) electrical energy
(b) mechanical energy ✔
(c) thermal energy
(d) chemical energy

2. Audible frequencies range that a normal human ear can detect is:
(a) 10 Hz and 10 kHz
(b) 20 Hz and 20 kHz ✔
(c) 25 Hz and 25 kHz
(d) 30 Hz and 30 kHz

3. The approximate value of the speed of sound in air at 0°C temperature is:
(a) 332 m/s ✔
(b) 34 m/s
(c) 17 m/s
(d) 680 m/s

4. Sound travels faster in solid as compared to gases because of:
(a) gas molecules are packed loosely
(b) sound does not travel faster through a solid than a gas
(c) solid molecules are packed tightly ✔
(d) gas molecules move faster.

5. The two factors that affect the speed of sound in the air are:
(a) humidity and volume of the air
(b) temperature and mass of the air
(c) volume and mass of the air
(d) temperature and humidity of the air ✔

6. The separation between two consecutive compressions of the sound wave is called:
(a) time period
(b) amplitude
(c) frequency
(d) wavelength ✔

7. The order of speed of the sound in different mediums from faster to slowest is:
(a) Gas → Liquid → Solid
(b) Liquid → Solid → Gas
(c) Solid → Liquid → Gas ✔
(d) Gas → Solid → Liquid

8. Ultrasound has several uses in medicine and industry. Which one has the use of ultrasound?
(a) Absorption
(b) Pre-natal scanning ✔
(c) Dispersion
(d) Measuring humidity of air

9. The cause of the echo is:
(a) absorption
(b) dispersion
(c) reflection ✔
(d) refraction

10. Which types of waves cannot travel through a vacuum?
(a) Sound waves ✔
(b) infra-red radiation
(c) Microwave
(d) X-rays

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More Multiple Choice Questions (MCQs)
From Chapter

11. Sound waves are:
(a) longitudnal waves ✔
(b) transverse waves
(c) electromagnetic waves
(d) All of these

12. To propagate, sound needs a material medium of:
(a) gases & liquids
(b) gases & solids
(c) liquids & solids
(d) gases. liquids & solids ✔

13. The speed of sound is the same in all mediums." This statement is:
{a) true
-(b) false ✔
(c) sometimes true
(D) depends on conditions

14. The speed of sound depends on the properties such as:
(a) the temperature of the medium
(b) pressure of the medium
(cj the density of the medium
(d) All of them ✔

15. The formula to find the speed of sound at temperature T in the air is:
(a) v = 331 √273K / T
(b) v = 331 √T / 273K ✔
(c) v = 273 √331K / T
(d) v = 273 √T / 331K

16. The speed of sound in air is directly proportional to the square root of the:
(a) absolute temperature ✔
(b) length of the sound column
(c) mass of the al; column
(d) All of these

17. Humidity increases, the density of the air _____ and sound travels _____.
(a) increases, faster
(b) increase. slower
(c) decreases, faster ✔
(d) decreases, slower

18. Loudness depends upon:
(a) wavelength
(b) wevefront
(c) frequency
(d) amplitude ✔

19. Pitch depends upon:
(a) wavelength
(b) wevefront
(c) frequency ✔
(d) amplitude

20. Quality of sound that distinguishes between a shrill and a flat sound is called:
(a) ultrasound
(b) pitch ✔
(c) loudness
(d) quality

21. The SI unit of sound of intensity is:
(a) W
(b) W/m
(c) W/m² ✔
(d) m

22. Over an eight-hour workday, the noise level recommended in most countries is usually:
(a) 85 - 90 dB ✔
(b) 95 -- 100 dB
(c) 105 - 110 dB
(d) 145 - 150 dB

23. At a temperature of 20°C, the speed of sound is:
(a) 300 m/s
(b) 310 m/s
(c) 320 m/s
(d) 340 m/s ✔

24. For hearing clear echoes, the minimum distance of the obstruction from the source of sound should be:
(a) 20 m
(b) 17 m ✔
(c) 14 m
(d) 7 m

25. To hear a clear echo, the time interval between the produced original sounds and the reflected one must be at least:
(a) 0.1 s ✔
(b) 0.5 s
(c) 0.7 s
(d) 1 s

26. The sound with frequencies above the upper limit of the human range of audibility is known as:
(a) infrasound
(b) Ultrasound ✔
(c) Both 'a' & 'b'
(d) None of them

27. Generally, we classify ultrasound as those having frequencies above:
(a) 200 Hz
(b) 2000 Hz
(c) 20,000 Hz ✔
(d) 200,000 Hz

28. Sound with frequencies below the lower limit of the human range of audibility is known as:
(a) Infrasound ✔
(b) Ultrasound
(c) Both 'a' & 'b'
(d) None of them

29. It is extensively used in marine applications:
(a) Echocardiography
(b) Ultrasonography
(c) Transducer
(d) SONAR ✔

30. If a wave completes 20 vibrations in 2.5s, then its frequency is:
(a) 200 Hz
(b) 50 Hz
(c) 20 Hz
(d) 8 Hz ✔

31. On increasing the temperature, the speed of sound in air:
(a) increases ✔
(b) decreases
(c) does not change
(d) becomes zero

32. On what factor does the quality of sound depend?
(a) Wavelength
(b) Waveform ✔
(c) Wave frequency
(d) Wave amplitude

33. Frequency of infrasonic waves is _____ than the frequency of ultrasound waves.
(a) less ✔
(b) more
(c) almost same
(d) none of the above

34. The unit of quantity on which the pitch of the sound depends is:
(a) hertz ✔
(b) metre
(c) metre/second
(d) second

35. Sound waves are produced by:
(a) Linear motion
(b) circular motion
(c) vibrating bodies ✔
(d) transitional motion

36. The loudness of sound varies directly with the vibrating body:
(a) intensity
(b) amplitude ✔
(c) pitch
(d) quality

37. The sensation of sound persists in our brain for about:
(a) 0.001s
(b) 0.2s
(c) 0.1s ✔
(d) lOs

38. Sounds of frequency higher than 20,000 Hz which are inaudible to the normal human ear are called:
(a) noise
(b) freqtiency
(c) ultrasonic ✔
(d) infrasonic

39. The loudness and amplitude of sound vary:
(a) directly ✔
(b) inversely
(c) Not related
(d) proportionally

40. The speed of sound varies with:
(a) humidity only
(b) temperature only
(c) pressure
(d) humidity and temperature ✔

41. Main sources of noise pollution are:
(a) transportation equipment only
(b) heavy machinery only
(c) musical instruments
(d) Transportation equipment and heavy machinery ✔

42. When the frequency of sound increases, the wavelength and period:
(a) becomes negative
(b) remains constant
(c) increases
(d) decreases ✔

43. As compared to air, the speed of sound in liquids and solids is:
(a) lower
(b) faster ✔
(c) equal
(d) zero

44. The reflection of sound is called:
(a) quality
(b) Loudness
(c) pitch
(d) echo ✔
45. Sound waves cannot pass through:
(a) air
(b) vacuum ✔
(c) solid
(d) liquid

46. The technique used to locate underwater depths or locating objects tying deep on the ocean floor is called:
(a) Echocardiography
(b) Ultrasonography
(c) Transducer
(d) SONAR ✔

47. A safe level of noise depends on:
(a) level of noise and exposure to noise
(b) area ✔
(c) pitch
(d) frequency

48. Bats can hear frequencies up to:
(a) 30,000 Hz
(b) 150,000 Hz ✔
(c) 180,000 Hz
(d) 15,000 Hz

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Fill In The Blanks

1. Sound is the form of energy related to the motion of vibrating molecules.
2. Sound is a longitudinal wave. 3. In longitudinal wave, the direction of vibration of molecules is parallel to the direction of wave motion.
4. Sound wave is comprised of successive compressions and rarefactions in the medium.
5. Compressions are regions where air pressure is slightly higher than surrounding air pressure.
6. Rarefactions are regions where air pressure is slightly lower than the surrounding air pressure.
7. Sound needs a material medium to pass through energy.
8. Sound cannot travel through a vacuum.
9. Sound waves travel at different speeds in different mediums depending on their properties.
10. The speed of sound is faster in solid materials and slower in liquids or gases.
11. Temperature affects the speed of sound in air.
12. Sound travels faster when the temperature of the medium rises.
13. Humidity slightly affects the speed of sound in air.
14. Sound travels faster when the humidity of the air rises.
15. Quality is the characteristic of sound by which we can distinguish between two sounds of the same loudness and pitch.
16. Sounds that are pleasant to our hearing sensations are called musical sounds.
17. Sounds that are unpleasant to our hearing sensations are called noises.
18. The high noise level has harmful effects on human health.
19. The range of audibility is the range of sound frequencies that a person can hear.
20. For tThe normal human ear, the lower limit of audible frequency is 20 Hz, and the upper limit is 20K Hz.
21. Ultrasound is the sound with frequencies above the upper limit of the human range of audibility.
22. The echo is the reflection of the sound after reflection from an obstacle.
23. In industry, ultrasounds can be used to detect cracks, cavities, and flaws in metal and concrete blocks.
24. Sound navigation and ranging (SONAR) is used to measure the depth of sea beds, locate and track submarines at sea, and locate explosive mines below the surface of the water.
25. Echocardiography uses ultrasound to produce the motional images of the heart and its valves.
26. Ultrasonography uses ultrasound to scan soft organs and tissues.

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Abbreviations OR Symbols

• ℃ stands for Degree Celsius
• dB stands for Decibel
• f stands for Frequency
• Hz stands for Hertz
• kHz stands for Kilohertz
• Km stands for Kilometres
• K stands for Kelvin
• m stands for Meter
• m/s stands for Meter per second
• 𝝆 stands for Density
• 𝛌 stands for Wavelength
• T OR t stands for Time
• s stands for Second
• SI stands for International System of units
• SONAR stands for Sound navigation and ranging
• v OR V stands for Speed
• W stands for Watt
• W/m² stands for Watt per square meter
• ∝ stands for Sign of proportionality

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Units

• Unit of Distance and Wavelength is Meter and Kilometer
• Unit of Frequency is Hertz
• Unit of Loudness Of sound is Decibel
• Unit of Sound Intensity OR Acoustic intensity is Watt per square meter
• Unit of Speed is Meter per second
• Unit of Temperature are Degree Celsius and Kelvin
• Unit of Time is Second

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Concept Map

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