Unit 11 – Sound (Short Questions)
Q.1 On what factor does frequency of tuning fork depends?
Q.2 What effect has the amplitude of a vibrating body upon loudness?
Q.3 Write two characteristics of sound.
Q.4 Define loudness. On what factor it can depend?
Q.5 Differentiate between the pitch and Quality of Sound.
Q.6 What is meant by zero bel?
Q.7 Define reflection of Sound.
Q.8 Why are sound waves called mechanical waves?
Q.9 What is meant by sound level?
Q.10 What is Echo? How much minimum distance for Echo?
Q.11 Describe properties of musical sound.
Q.12 Give two factors on which loudness of sound depends.
Q.13 What is meant by intensity of sound’! Write its unit.
Q.14 What is speed of sound through bass and iron at 25°C?
Q.15 What is the speed of sound in air at 25°C?
Q.16 What is meant by musical sound?
Q. 17 What is difference between Musical sound and Noise?
Q. 18 Write two advantages of acoustics protection.
Q. 19 State two uses of ultrasound in medical field.
Q.22 What is meant by pitch of sound? On which factors does it depend?
Q. 23 What is the difference between the Frequency and Pitch?
Q.24 Define resonance.
Q.25 Define “Bel”.
Q.26 Why the sound of women is shrill as compared to men?
Q. 27 What is the silent intensity of sound’! Write its range.
Q.28 Define Ultrasound and give its use.
Q.29 Why ultrasound is useful in medical field?
Q. 30 What is meant by soundless whistle?
Q. 31 Is there any difference between echo and reflection of sound? Explain.
Q. 32 In which sound moves faster, in solid or liquid? Why?
Q.33 What is Noise? Write its sources.
Q.35 Write the effects of noise pollution.
Q.36 Describe the factors on which a safe level of noise depends.
Q.37 How can noise pollution be reduced?
Q.38 Define acoustics.
Q.40 What is the difference between loudness and intensity of sound?
Q.1 On what factor does frequency of tuning fork depends?
Answer: Factors does frequency of tuning fork depends:
(i) Mass of prongs of wining fork.
(ii) Amplitude of prongs.
(iii) Stiffness of material of tuning fork.
Q.2 What effect has the amplitude of a vibrating body upon loudness?
Answer: The loudness is directly, proportional to the amplitude of the vibrating body. Larger is the amplitude of vibrating body greater will be the loudness.
Example: The sound produced by a sitar will be loud if we pluck its wires more violently. Similarly, when we beat a drum forcefully, the amplitude of its membrane increases and we hear a loud sound.
Q.3 Write two characteristics of sound.
Answer: There are two characteristics of sound, Quality and Pitch.
Quality: The characteristic of sound by which we can distinguish between two sounds of same loudness and pitch is called quality.
Pitch: Pitch is the characteristics of sound by which we can distinguish between a shrill and a grave sound.
Q.4 Define loudness. On what factor it can depend?
Answer:
Loudness: Loudness is the characteristic of sound by which loud and faint sounds can be distinguished.
Factors on which loudness depends upon:
a. Amplitude of vibrating body.
b. Area of vibrating body.
c. Distance from vibrating body.
Q.5 Differentiate between the pitch and Quality of Sound.
Answer:
Quality: The characteristic of sound by which we can distinguish between two sounds of same loudness and pitch is called quality.
Pitch: Pitch is the characteristic of sound by which we can distinguish between a shrill and a grave sound. It depends upon the frequency.
Q.6 What is meant by zero bel?
Answer: The barley audible and the faintest intensity of sound 10-12 Wm-2 is taken as reference intensity, called zero bel (a unit named after Alexander Graham Bell)
Q.7 Define reflection of Sound.
Answer:
Reflection of Sound: “When sound is incident on the surface of a medium bounces back into the first medium. This phenomenon is called echo reflection of sound reflection can occur from any distance.
Q.8 Why are sound waves called mechanical waves?
Answer: The sound waves are called mechanical waves because the direction of propagation of sound waves is along the direction of oscillating air molecules. This shows the longitudinal nature of sound waves.
Longitude waves arc type of mechanical wave, and in case of longitude waves the particle of the medium move back and forth the along the direction of the propagation of wave.
Q.9 What is meant by sound level?
Answer:
Sound level: The difference (L-Lo) between the loudness L of an unknown sound and loudness L, of the faintest audible sound is called the
intensity level of sound of the unknown sound.
Q.10 What is Echo? How much minimum distance for Echo?
Answer:
Echo: When sound is incident on the surface of a medium it bounces back into the first medium. This phenomenon is called echo or reflection of
sound.
Minimum distance for Echo: The minimum distance to hear a clear echo is 17 m.
Minimum Time: Minimum time for echo is 0.1 s.
Speed of Sound: Speed of sound in air at normal temperature is 340 ms-1.
Q.11 Describe properties of musical sound.
Answer:
Musical sound: Such sounds which are pleasant to our ears arc called musical sounds.
Properties:
i. They have specific waveform.
ii. These sound has pleasant effect on our car.
Q.12 Give two factors on which loudness of sound depends.
Answer: Factors on which loudness depends upon are:
(i). Amplitude of vibrating body.
(ii). Area of vibrating body.
(iii). Distance from vibrating body.
(iv). Physical condition of car.
Q.13 What is meant by intensity of sound? Write its unit.
Answer:
Intensity of Sound: Sound energy passing per second through a unit area held perpendicular to the direction of propagation or sound waves is called intensity of sound.
Unit: Its unit is watt per square metre (Wm-2)
Q.14 What is speed of sound through bass and iron at 25°C?
Answer: Speed of sound through brass at 25°C is 4700ms-1 and speed of sound through iron at 25°C is 5950ms-1.
Q.15 What is the speed of sound in air at 25°C?
Answer: Speed of sound in air at 25°C is 346ms-1.
Q.16 What is meant by musical sound?
Answer:
Musical sound: Sounds which are pleasant to our ears are called musical sounds.
Example: Sound of flute, violin drum and harmonium etc.
Q. 17 What is difference between Musical sound and Noise?
Answer: Sounds which are pleasant to our ears are called musical sounds.
Example: Sound of flute, harmonium, violin. drum instruments.
Noise: Sounds which have jarring and unpleasant effects on our ears are called noise.
Example: Sound of machinery the slamming of a door, and sounds of traffic in big cities.
Q. 18 Write two advantages of acoustics protection.
Answer:
Following are the advantages of acoustics protection.
i) Soft porous materials. such as draperies and rays absorb large amount of sound energy and thus quiet echoes and softening noises. Thus by using such materials in noisy places we can reduce the level of noise pollution.
ii ) If the surface of class rooms or public halls are too absorbent. the sound level may be low for the audience.
Q. 19 State two uses of ultrasound in medical field.
Answer:
Two Uses of Ultra Sound
i ) Powerful ultrasound is being used to remove blood clots formed in arteries.
ii) Ultrasound is used to get the pictures of thyroid gland for diagnosis
Q.20 What is meant by SONAR?
Answer:
SONAR: Ultrasound is used to locate underwater depths or is used for locating objects lying deep on the ocean floor etc. The technique is called SONAR. SONAR Ranging is also used to see the shape and size of the objects.
Q.21 Define quality of sound.
Answer:
Quality of Sound: The characteristics of sound by which we can distinguish between two sounds of same loudness and pitch is called quality.
Example: While standing outside a room, we can distinguish between the notes of a piano and flute being played inside the room. This is due to difference in the quality of these notes.
Q.22 What is meant by pitch of sound? On which factors does it depend?
Answer:
Pitch or Sound: Pitch is the characteristics of sound by which we can distinguish between a shrill and a grave sound.
Factors Pitch of sound: It depends upon the frequency of wave. A higher frequency mean higher pitch.
Example: The frequency of the voice of ladies and children is higher than that of men. Therefore, the voice of ladies and children is shrill and high pitch.
Q. 23 What is the difference between the Frequency and Pitch?
Answer:
Frequency
- The number of vibrations or cycle of vibrating body In one second called frequency.
- The symbol of frequency is f.
3.The SI unit of frequency is Hz.
Pitch :
i). Pitch is the characteristic of sound by which we can distinguish between a shrill and a grave sound.
ii). Pitch depends upon the frequency.
iii). A higher pitch means a higher frequency.
Q.24 Define resonance.
Answer:
Resonance: The increase in amplitude of oscillation of an electric or mechanical system exposed to a periodic force whose frequency is equal or very close to the natural frequency of the system.
Q.25 Define “Bel”.
Answer:
Bel: A unit for comparing two power levels, equal to the logarithm to the base ten of the ratio of the two powers is called bel.
Q.26 Why the sound of women is shrill as compared to men?
Answer: The pitch and frequency of sound of women is greater than sound of men, therefore sound of women is shrill as compared to men.
Q. 27 What is the silent intensity of sound’! Write its range.
Answer: Such sounds whose frequency is less than 20Hz and the human ear cannot respond to this sound is called silence intensities or infrasonic sound. It range is less than 20 Hz.
Q.28 Define Ultrasound and give its use.
Answer:
Ultrasound: Sounds of frequency higher than 20,000 Hz which are inaudible to normal car arc called ultrasound or ultrasonic sounds.
Uses: Ultra sounds are utilized in medical and technical field.
Q.29 Why ultrasound is useful in medical field?
Answer: Ultrasound is useful in medical field because in medical field, ultrasound waves are used to diagnose and treat different ailments. Ultrasonic waves are made to enter the human body through transmitters. These waves are reflected differently by different organs tissues or tumors etc. The reflected waves are then amplified to form an image of the internal organs
of the body on the screen.
Q. 30 What is meant by soundless whistle?
Answer:
Soundless whistle: Some people use silent whistle to call dogs whose frequency lies between 20,000 Hz to 25,000 Hz. It is silent for human but not for dogs. Because the audible frequency range for dogs in much higher.
Q. 31 Is there any difference between echo and reflection of sound? Explain.
Answer:
Reflection:
Reflection can occur from any distance.
Echo: While to hear an echo the minimum distance must he 17 m and minimum time interval must be 0.1 s.
Q. 32 In which sound moves faster, in solid or liquid? Why?
Answer: In solids speed of sound is faster than speed of sound in liquids. It is due to the fact that is solid. the particles of medium are very closely bond and by vibrations, sound energy is quickly transferred.
Q.33 What is Noise? Write its sources.
Answer:
Noise: Sound which has jarring and unpleasant effect on our ears is called noise.
Sources of Noise: Machines, vehicles and crowd of people are main sources of noise.
Q.34 What is noise pollution?
Answer:
Noise Pollution: Any form of sound which disturbs the normal functioning or any natural ecosystem or some human community is the cause or noise pollution. Noise pollution has become a major issue of concern in some big cities.
Q.35 Write the effects of noise pollution.
Answer: Noise has negative effects on human health such as:
(i) Hearing loss (ii) Sleep disturbance (iii) Aggression (iv) hypertension
(v) High stress levels, restless, depression and insomnia.
vi) Noise can also cause accidents by interfering with communication and work signals.
Q.36 Describe the factors on which a safe level of noise depends.
Answer: A safe level of noise depends on the following two factors:
i) The level (volume) of the noise.
ii) The period of exposure the noise.
Q.37 How can noise pollution be reduced?
Answer: Noise pollution can be reduced to acceptable level by replacing the noisy machinery with environment friendly machinery and equipment, putting sound reducing barriers, or using hearing protection devices.
Q.38 Define acoustics.
Answer:
Acoustics: The technique or method used to absorb undesirable sounds by soft and porous surface is called acoustic protection. Reflection of sound is more prominent if the surface is rigid and smooth, and less if the surface is soft and irregular.
Q.39 Define Reverberation.
Answer:
Reverberation: Sometimes, when sound reflects from the walls, ceiling and floor of a room, the reflecting surfaces are too reflective and the sound becomes garbled. Multiple reflections are called reverberations.
Q.40 What is the difference between loudness and intensity of sound?
Answer:
Loudness: Loudness is the characteristic of sound by which loud and faint sounds can be distinguished.
Intensity: Sound energy passing per second through a unit area held perpendicular to the direction of propagation of sound waves is called intensity of sound.