ch 12 important quesction
Sound
Multiple Choice Questions
1.
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
2.
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
3.
In
SONAR, we use
(a)
ultrasonic
waves
(b)
infrasonic
waves
(c)
radio
waves
(d)
audible
sound waves
4.
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.
5.
When
we change feeble sound to loud sound we increase its
(a)
frequency
(b)
amplitude
(c)
velocity
(d)
wavelength
6.
In
the curve (Fig.12.1) half the wavelength is
7.
Earthquake
produces which kind of sound before the main shock wave begins
(a)
ultrasound
(b)
infrasound
(c)
audible
sound
(d)
none
of the above
8.
Infrasound
can be heard by
(a)
dog
(b)
bat
(c)
rhinoceros
(d)
human
beings
9.
Before
playing the orchestra in a musical concert, a sitarist 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 sound
Short Answer Type
Questions
10.
The
given graph (Fig.12.2) shows the displacement versus time relation for a
disturbance travelling with velocity of 1500 m s–1. Calculate the
wavelength of the disturbance
11.
Which
of the above two graphs (a) and (b) (Fig.12.3) representing the human voice is
likely to be the male voice? Give reason for your answer.
12.
A
girl is sitting in the middle of a park of dimension 12 m × 12 m. 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.
13.
Why
do we hear the sound produced by the humming bees while the sound of vibrations
of pendulum is not heard?
14.
If
any explosion takes place at the bottom of a lake, what type of shock waves in
water will take place?
15.
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 = 340 m s–1.)
16.
For
hearing the loudest ticking sound heard by the ear, find the angle x in the
Fig.12.4.
17.
Why
is the ceiling and wall behind the stage of good conference halls or concert
halls made curved?
Long Answer Type
Questions
18.
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.
19.
Establish
the relationship between speed of sound, its wavelength and frequency. If
velocity of sound in air is 340 m s–1, calculate
(i)
wavelength when
frequency is 256 Hz.
(ii)
frequency when
wavelength is 0.85 m.
20.
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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