Chpt 17 Nature Production And Propagation Of Sound Waves

Question 1

1 Sound waves can be classified into two groups a) Elastic and magnetic waves b) Elastic and shock waves c) Transverse and longitudinal waves d)Electromagnetic and mechanical waves

Answer 1

Answer: b) Elastic and shock waves Explanation: The text states “Sound can be classified into two groups (1) Elastic waves which result when a material medium is strained beyond its elastic limit and (2) Shock waves which are”

Question 2

2 The movement encountered resulting in sound in air from sources include the ringing bell the movement of the mouth and the beating of a drum in some sources however there are no mechanical vibrations involved Such sources are found in a) aeroplanes b) pipes c) jet flow d) All of the above

Answer 2

Answer: c) Jet flow Explanation: The text explains that most sounds involve mechanical vibrations but there are some exceptions such as jet flow where no mechanical vibrations are involved

Question 3

3 Sound thus requires a medium to propagate energy In our discussions the particle transfer of motional energy capability of traveling through any medium is transferred from one molecule to another As the atoms or molecules of a medium are displaced from their normal positions internal _ constitute the restoring forces which accelerate these together and spread the in all directions around the source a) pressure gradient momentum b) elastic forces disturbance c) gravitational forces disturbance d) magnetic forces vibrations

Answer 3

Answer: b) Elastic forces disturbance Explanation: The excerpt discusses how the displacement of atoms or molecules in a medium creates internal elastic forces that act as restoring forces These forces then spread the disturbance in all directions

Question 4

4 The maximum pressure referred to ears as the threshold of pain is ___ Pascal a) 10 b) 20 c) 200 d) 30

Answer 4

Answer: b) 20 Explanation: “The minimum discernible change in pressure by the human ears is called the threshold of hearing and is 20 micropascal the maximum pressure referred to as the threshold of pain is 20 Pascal”

Question 5

5 The minimum change in power detectable by the human ear is ___ dB which is equivalent to a power change by 25% a) 1 b) 2 c) 3 d) 4

Answer 5

Answer: a) 1 Explanation: “The minimum power change from $P_1$ to $P_2$ then the number is 1db which is equivalent to a power change by 25%”

Question 6

6 Loudness is a tone is determined largely by its ___ This does not mean that intensity and loudness are the same a) amplitude b) frequency c) intensity d) wavelength

Answer 6

Answer: c) intensityExplanation: The passage states “Loudness of a tone is determined largely by its intensity” However it goes on to clarify that intensity and loudness are not the same thing

Question 7

6 Loudness is a tone is determined largely by its ___ This does not mean that intensity and loudness are the samea) amplitude b) frequency c) intensity d) wavelength

Answer 7

Answer: c) intensity Explanation: The text states “Loudness of a tone is determined largely by its intensity” but emphasizes that intensity and loudness are not the same

Question 8

7 The ear responds to a wide range of intensities spanning a factor of about ___ a) 10 b) 100 c) 10⁶ d) 10¹²

Answer 8

Answer: d) 10¹² Explanation: The text mentions that the ear responds to intensities spanning a factor of about 10¹²

Question 9

8 The phenomenon which involves the splitting of waves into two types as they propagate is known as a) rarefaction b) dispersion c) diffraction d) polarization

Answer 9

Answer: b) dispersion Explanation: The text refers to the splitting of waves into two types during propagation as dispersion

Question 10

9 A pure tone is characterized by a single frequency but real tones generated by musical instruments contain several frequencies The additional frequencies apart from the fundamental are known as ___ a) harmonics b) octaves c) overtones d) beats

Answer 10

Answer: a) harmonics Explanation: The text indicates that the frequencies other than the fundamental are called harmonics

Question 11

10 The human ear is capable of detecting frequencies between approximately ___ a) 10 Hz and 100 kHz b) 20 Hz and 20 kHz c) 50 Hz and 15 kHz d) 100 Hz and 10 kHz

Answer 11

Answer: b) 20 Hz and 20 kHz Explanation: The text specifies that the human ear can detect frequencies within the range of 20 Hz to 20 kHz

Question 12

11 The speed of sound in air increases with a) increasing temperature b) decreasing temperature c) increasing pressure d) decreasing humidity

Answer 12

Answer: a) increasing temperatureExplanation: The speed of sound is directly proportional to the square root of the temperature so it increases with higher temperatures.

Question 13

12 The Doppler Effect is observed when there is a relative motion between a) two observers b) source and medium c) source and observer d) medium and observer

Answer 13

Answer: c) source and observerExplanation: The Doppler Effect occurs when there is relative motion between the source of sound and the observer causing a perceived change in frequency.

Question 14

13 The sound intensity level is measured in a) hertz b) decibels c) pascals d) joules

Answer 14

Answer: b) decibelsExplanation: The sound intensity level is expressed in decibels (dB) a logarithmic unit of measurement.

Question 15

14 Which phenomenon explains why sound waves bend around obstacles? a) interference b) diffraction c) reflection d) refraction

Answer 15

Answer: b) diffractionExplanation: Diffraction allows sound waves to bend around obstacles and spread into regions where there is no direct path.

Question 16

15 The fundamental frequency of a string depends on its a) length and mass only b) tension and length only c) tension length and mass per unit length d) tension only

Answer 16

Answer: c) tension length and mass per unit lengthExplanation: The frequency of a vibrating string is determined by the tension in the string its length and its linear mass density.

Question 17

16 In an open organ pipe the harmonic frequencies are in the ratio a) 1:2:3:4 b) 1:3:5:7 c) 2:4:6:8 d) 1:4:9:16

Answer 17

Answer: a) 1:2:3:4Explanation: An open organ pipe supports all harmonics and their frequencies are in integer multiples of the fundamental frequency.

Question 18

17 The frequency of beats is equal to a) the sum of two frequencies b) the difference of two frequencies c) twice the higher frequency d) twice the lower frequency

Answer 18

Answer: b) the difference of two frequenciesExplanation: The beat frequency is the absolute difference between the frequencies of two close frequencies .

Question 19

18 A sound wave in a medium is a) transverse b) longitudinal c) electromagnetic d) none of these

Answer 19

Answer: b) longitudinalExplanation: Sound waves in air or any medium are longitudinal as particles oscillate parallel to the direction of wave propagation.

Question 20

19 Ultrasonic waves have frequencies a) below 20 Hz b) between 20 Hz and 20 kHz c) above 20 kHz d) between 2 Hz and 200 Hz

Answer 20

Answer: c) above 20 kHzExplanation: Ultrasonic waves have frequencies greater than 20000 Hz beyond the range of human hearing.

Question 21

20 What determines the pitch of a sound? a) amplitude b) frequency c) speed d) wavelength

Answer 21

Answer: b) frequencyExplanation: Pitch is determined by the frequency of the sound wave. Higher frequencies produce higher pitches.

Question 22

21 The speed of sound is maximum in a) solids b) liquids c) gases d) vacuum

Answer 22

Answer: a) solidsExplanation: Sound travels fastest in solids due to their tightly packed particles allowing more efficient propagation of vibrations.

Question 23

22 When a tuning fork is struck against a hard surface it produces sound due to a) reflection b) refraction c) vibrations d) resonance

Answer 23

Answer: c) vibrationsExplanation: The sound produced by the tuning fork comes from its vibrating prongs which create sound waves in the surrounding air.

Question 24

23 The range of human hearing is a) 0–100 Hz b) 20 Hz–20 kHz c) 10 kHz–1 MHz d) 1 Hz–100 kHz

Answer 24

Answer: b) 20 Hz–20 kHzExplanation: Humans can typically hear sounds within the range of 20 Hz to 20000 Hz.

Question 25

24 Echo is caused by a) refraction of sound b) absorption of sound c) reflection of sound d) diffraction of sound

Answer 25

Answer: c) reflection of soundExplanation: Echoes occur when sound waves are reflected back from a surface and heard after a time delay.

Question 26

25 If the amplitude of a sound wave increases the sound will be a) louder b) softer c) higher in pitch d) lower in pitch

Answer 26

Answer: a) louderExplanation: Loudness is directly related to the amplitude of a sound wave; higher amplitude results in louder sounds.

Question 27

26 Which of these is a unit of frequency? a) decibel b) hertz c) joule d) watt

Answer 27

Answer: b) hertzExplanation: The unit of frequency is hertz (Hz) representing cycles per second.

Question 28

27 Sound cannot travel through a) solids b) liquids c) gases d) vacuum

Answer 28

Answer: d) vacuumExplanation: Sound requires a medium (solid liquidor gas) to propagate as it depends on particle vibrations.

Question 29

28 The phenomenon of persistence of sound in a big hall is called a) echo b) reverberation c) resonance d) diffraction

Answer 29

Answer: b) reverberationExplanation: Reverberation is the prolonged persistence of sound due to multiple reflections within a hall or enclosed space.

Question 30

29 A sound wave in air is an example of a) transverse wave b) longitudinal wave c) standing wave d) torsional wave

Answer 30

Answer: b) longitudinal waveExplanation: Sound waves in air are longitudinal as particle displacement is parallel to wave propagation.

Question 31

30 The quality or timbre of a sound depends on a) frequency b) amplitude c) waveform d) wavelength

Answer 31

Answer: c) waveformExplanation: The quality or timbre of a sound which distinguishes different sounds depends on the waveform of the sound wave.

Question 32

31 Which property of sound determines its pitch?a) amplitude b) frequency c) wavelength d) speed

Answer 32

Answer: b) frequencyExplanation: The pitch of a sound is determined by its frequency; higher frequency results in a higher pitch.

Question 33

32 The speed of sound in air increases witha) decrease in temperature b) increase in humidity c) decrease in humidity d) increase in altitude

Answer 33

Answer: b) increase in humidityExplanation: Higher humidity increases the density of water vaporur which enhances the speed of sound in air.

Question 34

33 The time taken for one complete vibration of a sound wave is calleda) frequency b) amplitude c) wavelength d) time period

Answer 34

Answer: d) time periodExplanation: The time period is the duration of one complete cycle of vibration in a sound wave.

Question 35

34 Ultrasonic waves have frequenciesa) less than 20 Hz b) between 20 Hz and 20 kHz c) more than 20 kHz d) none of these

Answer 35

Answer: c) more than 20 kHzExplanation: Ultrasonic waves have frequencies greater than 20000 Hz beyond the range of human hearing.

Question 36

35 The phenomenon of sound propagation around obstacles is calleda) reflection b) diffraction c) refraction d) interference

Answer 36

Answer: b) diffractionExplanation: Diffraction occurs when sound waves bend around obstacles or spread after passing through small openings.

Question 37

36 Two waves of the same frequency and amplitude traveling in opposite directions producea) transverse waves b) longitudinal waves c) standing waves d) random waves

Answer 37

Answer: c) standing wavesExplanation: Standing waves result from the interference of two identical waves traveling in opposite directions.

Question 38

37 The loudness of a sound is measured ina) decibels b) hertz c) meters d) watts

Answer 38

Answer: a) decibelsExplanation: Decibels (dB) are used to measure the intensity or loudness of a sound.

Question 39

38 Sound travels fastest ina) helium b) hydrogen c) oxygen d) carbon dioxide

Answer 39

Answer: a) heliumExplanation: Sound travels fastest in helium due to its lower molecular mass compared to other gases.

Question 40

39 The reflection of sound waves in a largehard-surfaced area causesa) refraction b) reverberation c) dispersion d) diffraction

Answer 40

Answer: b)reverberationExplanation: Reverberation occurs when sound reflects off surfaces creating prolonged sound persistence.

Question 41

40 Which of these instruments uses the principle of sound reflection?a) radar b) sonar c)telescoped)microscope

Answer 41

Answer: b) sonarExplanation: SONAR (Sound Navigation and Ranging) uses sound reflection to detect objects underwater.

Question 42

41 The part of the ear that converts sound vibrations into electrical signals is thea) eardrum b) cochlea c) auditory nerve d) pinna

Answer 42

Answer: b) cochleaExplanation: The cochlea contains hair cells that translate sound vibrations into electrical signals sent to the brain.

Question 43

42 The speed of sound is maximum ina) solids b) liquids c) gases d) vacuum

Answer 43

Answer: a) solidsExplanation: Sound travels fastest in solids due to the closely packed molecules

Question 44

43 The minimum distance required for an echo to be heard isa) 10 m b) 17 m c) 25 m d) 50 m

Answer 44

Answer: b) 17 mExplanation: For an echo to be perceived the reflected sound must travel at least 34 m (to and fro) at the speed of sound in air.

Question 45

44 The hearing range of a healthy human ear isa) 0-10 Hz b) 10-100 Hz c) 20-20000 Hz d) 50-500 Hz

Answer 45

Answer: c) 20-20000 HzExplanation: Humans can hear sounds with frequencies between 20 Hz and 20000 Hz.

Question 46

45 Which phenomenon causes the twinkling of stars?a) refraction b) reflection c) dispersion d) scattering

Answer 46

Answer: a) refractionExplanation: Twinkling is caused by the refraction of starlight as it passes through Earth’s turbulent atmosphere.

Question 47

46 The primary component of a sound wave responsible for its loudness isa) amplitude b) frequency c) wavelength d) velocity

Answer 47

Answer: a) amplitudeExplanation: Loudness isdirectly proportional to the amplitude of the sound wave.

Question 48

47 Which type of wave is sound in air?a) transverse b) longitudinal c) electromagnetic d) torsional

Answer 48

Answer: b) longitudinalExplanation: Sound waves in air are longitudinal where particles vibrate parallel to the wave’s direction.

Question 49

48 The change in frequency of a sound wave due to motion between the source and observer is known asa) Doppler effect b) interference c) diffraction d) resonance

Answer 49

Answer: a) Doppler effectExplanation: The Doppler effect describes the frequency shift when the source or observer is moving relative to the other.

Question 50

49 A tuning fork produces sound due toa) electrical energy b) magnetic vibrations c) mechanical vibrations d) chemical reactions

Answer 50

Answer: c) mechanical vibrationsExplanation: A tuning fork vibrates mechanically to generate sound waves.

Question 51

50 Which of the following is used to measure the frequency of sound waves?a) ammeter b) barometer c) oscilloscoped) thermometer

Answer 51

Answer: c) oscilloscopeExplanation: An oscilloscope visually displays sound waves and allows measurement of their frequency.Would you like more questions?