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How does the sound produced by a vibrating object in a medium reach your ear?
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Explain how sound is produced by your school bell.
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Why are sound waves called mechanical waves?
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Suppose you and your friend are on the moon. Will you be able to hear any sound produced by your friend?
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Which wave property determines (a) loudness, (b) pitch?
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Guess which has a higher pitch : a guitar or a car horn?
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What are wavelength, frequency, time period and amplitude of a sound wave?
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How are the wavelength and frequency of a sound wave related to its speed?
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Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440 m in a given medium.
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A person is listening to a tone of 500 Hz sitting at a distance of 450 m from the source of the sound. What is the time interval between successive compressions from the source?
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Distinguish between loudness and intensity of sound.
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In which of the three media, air, water or iron, does sound travel the fastest at a particular temperature?
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An echo returned in 3 s. What is the distance of the reflecting surface from the source, given that the speed of sound is 342 ms-1 ?
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Why are the ceilings of concert halls curved?
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What is the audible range of the average human ear?
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What is the range of frequencies associated with
(a) Infrasound (b) Ultrasound ?
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A submarine emits a sonar pulse, which returns from an underwater cliff in 1.02 s. If the speed of sound in salt water is 1531 m s~1, how far away is the cliff?
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What is sound and how is it produced?
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Describe with the help of a diagram, how compressions and rarefactions are produced in air near a source of sound.
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Cite an experiment to show that sound needs a material medium for its propagation.
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Why is sound wave called a longitudinal wave?
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Which characteristic of the sound helps you to identify your friend by his voice while sitting with others in a dark room?
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Flash and thunder are produced simultaneously. But thunder is heard a few seconds after the flash is seen, why?
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A person has a hearing range from 20 Hz to 20 kHz. What are the typical wavelengths of sound waves in air corresponding to these two frequencies? Take the speed of sound in air as 344 ms-1.
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Two children are at opposite ends of an aluminium rod. One strikes the end of the rod with a stone. Find the ratio of times taken by the sound wave in air and in aluminium to reach the second child.
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The frequency of a source of sound is 100 Hz. How many times does it vibrate in a minute?
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Does sound follow the same laws of reflection as light does? Explain.
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When a sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound production remains the same. Do you hear echo sound on a hotter day?
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Give two practical applications of reflection of sound waves.
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A stone is dropped from the top of a tower 500 m high into a pond of water at the base of the tower. When is the splash heard at the top? Given, g = 10 m/s and speed of sound is 340 m/s .
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A sound wave travels at a speed of 339 m s-1. If its wavelength is 1.5 cm, what is the frequency of the wave? Will it be audible?
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What is reverberation? How can it be reduced?
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What is loudness of sound? What factors does it depend on?
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Explain how bats use ultrasound to catch a prey.
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How is ultrasound used for cleaning?
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Explain the working and application of a SONAR.
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A sonar device on a submarine sends out a signal and receives an echo 5 s later. Calculate the speed of sound in water if the distance of the object from the submarine is 3625 m.
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Explain how defects in a metal block can be detected using ultrasound.
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Explain how the human ear works.
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question_answer40)
Note is a sound
(a) of mixture of several frequencies
(b) of mixture of two frequencies only
(c) of a single frequency
(d) always unpleasant to listen
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question_answer41)
A key of a mechanical piano struck gently and then struck
again but much harder this time. In the second case
(a) sound will be louder but pitch will not be different
(b) sound will be louder and pitch will also be higher
(c) sound will be louder but pitch will be lower
(d) both loudness and pitch will remain unaffected
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question_answer42)
In
SONAR, we use
(a) ultrasonic waves (b) infrasonic waves (c)
radio waves (d) audible sound waves
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question_answer43)
Sound
travels in air, if
(a) particles of medium travel from one place to another
(b) there is no moisture in the atmosphere
(c) disturbance moves
(d) both particles as well as disturbance travel from one
place to another
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question_answer44)
When we change feeble sound to loud sound we increase its
(a) frequency (b) amplitude (c)
velocity (d) wavelength
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question_answer45)
In the given curve, half the wavelength is
(a) AB (b)
BD (c) DE (d)
AE
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question_answer46)
Earthquake produces which kind of sound before the main
shock wave begins
(a) ultrasound (b) infrasound (c)
audible sound (d) None of these
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question_answer47)
Infrasound can be heard by
(a) dog (b) bat (c)
rhinocerose (d) human beings
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question_answer48)
Before playing the orchestra in a musical concert, a
sitaris t tries to adjust the tension and pluck the string suitably. By doing
so, he is adjusting
(a) intensity of sound only (b)
amplitude of sound only
(c) frequency of the sitar string with the frequency of
other musical instruments
(d) loudness of sounds
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question_answer49)
The given graph shows the displacement versus time
relation for a disturbance travelling with velocity of 
. Calculate the wavelength
of the disturbance.
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question_answer50)
Which of the two graphs (i) and (ii) representing the
human voice is likely to be the male voice? Give reason for your answer.
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question_answer51)
A girl is sitting in the middle of a park of dimension 12m
x 12m. On the left side of it there is a building adjoining the park and on
right side of the park, there is a road adjoining the park. A sound is produced
on the road by a cracker. Is it possible for the girl to hear the echo of this sound?
Explain your answer.
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question_answer52)
Why do we hear the sound produced by the humming bees
while the sound of vibrations of pendulum is not heard?
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question_answer53)
If any explosion takes place at the bottom of a lake, what
type of shock waves in water will take place?
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question_answer54)
Sound produced by a thunderstorm is heard 10 s after the
lightning is seen. Calculate the approximate distance of the thunder cloud
(Given speed of sound 
).
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question_answer55)
For hearing the loudest ticking sound heard by the ear,
find the angle x in the given figure.
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question_answer56)
Why is the ceiling and wall behind the stage of good
conference halls or concert halls made curved?
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question_answer57)
Represent graphically by two separate diagrams in each
case.
(i) Two sound waves having the same amplitude but
different frequencies.
(ii) Two sound waves having the same frequency but
different amplitudes.
(iii) Two sound waves having different amplitudes and also
different wavelengths.
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question_answer58)
Establish the relationship between speed of sound, its
wavelength and frequency. If velocity of sound in air is 340 
. Calculate (i) wavelength
when frequency is 256 Hz.
(ii) frequency when wavelength is 0.85 m.
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question_answer59)
Draw a curve showing density or pressure variations with respect to distance
for a disturbance produced by sound. Mark the position of compression and
rarefaction on this curve. Also define wavelengths and time period using this
curve.
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