Question 12 Marks
What is a musical sound? Give two examples of musical sounds.
Answer
View full question & answer→A pleasant sound is called music. Its like a treat to the ears.
Example:
$a.$ Beats.
$b.$ Tones.
Example:
$a.$ Beats.
$b.$ Tones.
Questions
questions in short. [2 marks ]
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Test yourself on this topic
26 questions · timed · auto-graded
Question 22 Marks
How does sound from a sound producing body travel through air to reach our ears?
Answer
View full question & answer→The air particles near the sound producing body vibrate and exchange energy, which is received by our ears and we are able to hear the sounds.
Question 32 Marks
What is meant by the $(a)$ 'pitch' of sound, and $(b)$ 'quality' of sound$?$
Answer
View full question & answer→The sensation of frequency is called “pitch” The high frequency indicates high pitch and vice-versa. 
Question 42 Marks
Out of a man and a woman:
$a.$ Who has shorter vocal cords$?$
$b.$ Who produces sound of higher pitch$?$
$a.$ Who has shorter vocal cords$?$
$b.$ Who produces sound of higher pitch$?$
Answer
View full question & answer→$a.$ Woman has short vocal chords. The male vocal chords are between $17\ mm$ and $25\ mm$ in length whereas of a woman are between $12.5\ mm$ and $17.5\ mm$ long.
$b.$ Woman produces sound of higher pitch.
$b.$ Woman produces sound of higher pitch.
Question 52 Marks
By how much will the loudness of a sound change when the amplitude of vibrations is:
$a.$ Doubled?
$b.$ Halved?
$a.$ Doubled?
$b.$ Halved?
Answer
View full question & answer→$a.$ Loudness is also doubled.
$b.$ Loudness is halved.
$b.$ Loudness is halved.
Question 62 Marks
Explain how, noise pollution (or excessive loud noise) is harmful to human beings.
Answer
View full question & answer→Noise pollution has adverse effects physical as well as mental behavior. The constant exposure to noise pollution can create many health related problems like hypertension, insomnia, mental disorder and may even lead to loss of hearing.
Question 72 Marks
Why a sound cannot be heard on the moon?
Answer
View full question & answer→Because moon does not have any atmosphere and sound its does not have any medium for sound to travel as sound does not travel in vacuum.
Question 82 Marks
Calculate the time period of a pendulum which is vibrating with a frequency of $10$ hertz.
Answer
View full question & answer→Time Period given by the inverse of the frequency. Time period = $ \frac{1}{\text{frequency}}$ = Time period =$\frac{1}{\text{10Hz}}=0.1 \text{sec}$
Question 92 Marks
What can be done along the roads to reduce noise pollution caused by traffic from reaching the residents of the area?
Answer
View full question & answer→The following measures which can be taken to reduce noise pollution caused by traffic from reaching the residents of the area:
$a.$ The residential area must be declared as no use of horns.
$b.$ The colonies must be established at a distance than the roads.
$a.$ The residential area must be declared as no use of horns.
$b.$ The colonies must be established at a distance than the roads.
Question 102 Marks
What differences will you hear in a sound if there is an increase in:
$a.$ Amplitude, and
$b.$ Frequency?
$a.$ Amplitude, and
$b.$ Frequency?
Answer
View full question & answer→$a.$ The sound will become loud on increasing the amplitude.
$b.$ The sound will become shrill on increasing the frequency.
$b.$ The sound will become shrill on increasing the frequency.
Question 112 Marks
What is a vibration (or an oscillation)? Define 'amplitude' of vibration of an object.
Answer
View full question & answer→The to - and – fro motion of an object in a medium is called vibration. Amplitude is the largest distance from the mean position of the object.
Question 122 Marks
State one observation from everyday life which shows that sound travels much more slower than light.
Answer
View full question & answer→In case of thunder, we see the lightening first and then the sound of thunder. This is because, the velocity of light in air is $3\times 108 m/s$ while the velocity of sound in air is $343\ m/s.$
Question 132 Marks
Out of solids, liquids and gases:
$a.$ In which medium sound travels slowest?
$b.$ In which medium sound travels fastest?
$a.$ In which medium sound travels slowest?
$b.$ In which medium sound travels fastest?
Answer
View full question & answer→$a.$ Sound travels slowest in gas medium.
$b.$ Sound travels fastest in solid medium.
$b.$ Sound travels fastest in solid medium.
Question 142 Marks
What is the frequency of the sound produced when the vocal cords are:
$a.$ Tight and thin?
$b.$ Loose and thick?
$a.$ Tight and thin?
$b.$ Loose and thick?
Answer
View full question & answer→$a.$ The frequency produced by tight and thin vocal chords is quite high. i.e. its high pitch sound.
$b.$ The frequency produced by loose and thick vocal chords is quite low i.e. its low pitch sound.
$b.$ The frequency produced by loose and thick vocal chords is quite low i.e. its low pitch sound.
Question 152 Marks
What is noise? Give two examples of sounds which are considered noise.
Answer
View full question & answer→The Unwanted sound that is unpleasant to ear is called noise.
Example:
$a.$ Loud music
$b.$ The noise of machines.
Example:
$a.$ Loud music
$b.$ The noise of machines.
Question 162 Marks
When we put our ear to a railway line, we can hear the sound of an approaching train even when the train is far off but its sound cannot be heard through the air. Why?
Answer
View full question & answer→Because the track is made of metals and sounds travel faster in solids than air. Thus, we can hear the sound of an approaching train even when the train is far off but its sound cannot be heard through the air.
Question 172 Marks
Name the characteristic of sound which depends on:
$a.$ Amplitude.
$b.$ Frequency.
$a.$ Amplitude.
$b.$ Frequency.
Answer
View full question & answer→$a.$ Loudness of the sound depends on amplitude.
$b.$ Pitch of the sound depends on frequency.
$b.$ Pitch of the sound depends on frequency.
Question 182 Marks
What is the difference between noise and music? Can music become noise sometimes?
Answer
View full question & answer→The Unwanted sound that is unpleasant to ear is called noise. A pleasant sound is called music. Music can become noise at many instances. Music is of many types and everybody may not like each type of music. When someone listens very loud music, it can be noise for someone else.
Question 192 Marks
Explain why, if we strike a steel tumbler with a metal spoon lightly, we hear a feeble sound but if we hit the tumbler hard, a loud sound is heard.
Answer
View full question & answer→ This is because the amplitude of vibrations is small when we beat the spoon lightly and so feeble sound is produced but when it is beaten with force then, amplitude of vibrations is large, so loud sound is produced.
Question 202 Marks
State the various measures which can be taken to control $($or reduce$)$ noise pollution in our surroundings.
Answer
View full question & answer→The following measures which can be taken to control $($or reduce$)$ noise pollution in our surroundings:
$a.$ Ban the use of loudspeakers after $9\ pm.$
$b.$ Ban the use of horns in the areas nearby hospital and school.
$a.$ Ban the use of loudspeakers after $9\ pm.$
$b.$ Ban the use of horns in the areas nearby hospital and school.
Question 212 Marks
State two methods of producing sound.
Answer
View full question & answer→Two methods of producing sound are:
$a.$ Beating the plate and spoon against each other.
$b.$ Playing guitar.
$a.$ Beating the plate and spoon against each other.
$b.$ Playing guitar.
Question 222 Marks
Why sound cannot travel through vacuum (or through outer space)?
Answer
View full question & answer→Because sound needs material medium to transfer energy from on particle to another particle. If there is vacuum, then no energy transfer takes place.
Question 232 Marks
What is ultrasound? State two uses of ultrasound.
Answer
View full question & answer→Ultrasounds mean the sounds having frequency greater than $20,000\ Hz.$
The uses of ultrasound are:
$a.$ They are used in sonography.
$b.$ They used in radars.
The uses of ultrasound are:
$a.$ They are used in sonography.
$b.$ They used in radars.
Question 242 Marks
How is pitch related to frequency?
Answer
View full question & answer→The pitch of a sound you hear depends on the frequency of the sound wave. A high frequency sound wave has a high pitch, and a low frequency sound wave has a low pitch.
Question 252 Marks
What is the frequency of a vibrating body whose time-period is $0.05$ second$?$
Answer
View full question & answer→Time Period given by the inverse of the frequency.Time period $=\frac{1}{\text{frequency}}$
Or frequency $=\frac{1}{\text{Time period}}$
$\Rightarrow\text{frequency}=\frac{1}{0.05\text{ Sec}}=20\text{Hz}$
Or frequency $=\frac{1}{\text{Time period}}$
$\Rightarrow\text{frequency}=\frac{1}{0.05\text{ Sec}}=20\text{Hz}$
Question 262 Marks
Why are the voices of men, women and children different?
Answer
View full question & answer→The length of vocal chords varies in all these three, which is the main reason for different voices. Men have the longest vocal chords, while female have little shorter vocal chords than men and children have the smallest vocal chords.