# Sound (SA)

Short Answer Type Questions-I (2 Marks)

1. Three persons, A, B and C are made to hear a
sound travelling through different mediums as
given below :
Persons Mediums
A Iron Rod
B Air
C Water Who will hear the sound first? Why? [2011 (T-II)] 2. (i) Define the time period of a wave.

(ii) Give the relation among speed of sound v,
wavelength l and its frequency v.
(iii) A sound wave travels at a speed of 339
ms–1. If its wavelength is 1.5 cm, what is
the frequency of the wave? [2011 (T-II)] 3. Draw a neat labelled structure of human ear,
depicting the auditory parts only. [2011 (T-II)] 4. A hospital uses an ultrasonic scanner to locate
tumours in a tissue. What is the wavelength of
sound in a tissue in which the speed of sound is

1.7 km/s. The operating frequency of the scanner
is 4.2 MHz (1MHz =106 Hz). [2011 (T-II)] 5. An echo is returned in 6 seconds. What is the
distance of reflecting surface from source? [given
that speed of sound is 342 m/s.] [2011 (T-II)] 6. 20 waves pass through a point in 2 seconds.
If the distance between one crest and adjacent
thorough is 1.5 m. Calculate : (a) the frequency (b) the wavelength [2011 (T-II)] 7. What is meant by reverberation of sound? Does
reverberation produce undesirable effects in big
hall or auditorium? If yes, how are the undesirable
effects avoided? [2011 (T-II)] 8. What is echo ranging? State any one application
of this technique. [2011 (T-II)] 9. A person is listening to a tone of 500 Hz sitting
at a distance of 450 m from the source of the
sound. Calculate the time interval between
successive compressions from the source? (Speed
of sound in air = 330 m/s) [2011 (T-II)] 10. Differentiate between low and high pitch sound
using neat and labelled diagram. [2011 (T-II)] 11. (a) Which wave property determines (1) loudness (2) pitch? (b) How are wavelength and frequency related
to speed of sound waves? [2011 (T-II)] 12. Define the following : (a) Transverse waves (b) Time period [2011 (T-II)] 13. Sound of explosions taking place on other
planets is not heard by a person on the earth.
Give reason. [2011 (T-II)] 14. A sonar device on a submarine sends out a signal
and receives an echo 5 seconds later. Calculate
the speed of the sound in water if the distance
of the object from the submarine is 3625 m. [2011 (T-II)] 15. Give two applications of ultrasound. [2011 (T-II)] 16. Represent graphically two sound waves having
same amplitude but different frequencies. [2011 (T-II)] 17. When the wire of a guitar is plucked, what types
of waves are produced in (i) air and (ii) wire?

18. A body is vibrating 6000 times in one minute. If
the velocity of sound in air is 360 m/s, find :
(a) frequency of vibration in hertz. (b) wavelength of the wave produced. [2011 (T-II)] 19. Waves of frequency 200 Hz are produced in a
string as shown in figure Find:
(a) amplitude of the wave (b) wavelength of the wave (c) velocity of the wave [2011 (T-II)]

20. Draw a graph showing a person with soft and
loud voice. [2011 (T-II)] 21. (a) Sound is produced when your school bell is
struck with a hammer. Why? (b) Which characteristic of sound helps to identify
your friend by his voice while sitting with
others in a dark room? [2011 (T-II)] 22. (a) Write factor on which pitch of a sound
depends?
(b) Draw a diagram to represent sound of (a) high pitch and (b) low pitch, of the same loudness.
[2011 (T-II)] 23. (a) Which wave property determines? (i) loudness (ii) pitch (b) Why are the ceilings of concert halls
curved? [2011 (T-II)] 24. Give one difference between transverse and
longitudinal wave. Give one example for
each. [2011 (T-II)] 25. What is an echo? Give minimum distance
required to hear an echo. Give one application
where principle of echo is utilised. [2011 (T-II)] 26. (a) What type of wave is represented by density
– distance graph? (b) What is meant by transverse wave? Give an
example. [2011 (T-II)]

OTHER IMPORTANT QUESTIONS

1. What is transferred by a wave motion, matter or energy? Support your answer by an example.

2. Derive a relation between wave velocity (v), wavelength (λ) and frequency (f).

3. Draw a diagram representing longitudinal wave.

4. What kind of wave is produced when sound energy propagates through air? Give two examples of longitudinal waves. 5. What do you understand by the terms (i) compression (ii) rarefaction, as applied to longitudinal waves.

6. A longitudinal wave is produced in a slinky, such that the frequency of the wave is 20 Hz and the speed of the wave is 30 cms–1. What is the minimum distance of separation between the consecutive compressions of the slinky?

7. Wavelength of ripples produced on the surface of water is 0.14 m. If the velocity of ripples is 42 ms–1, calculate the number of ripples produced in one second. 8. A boat at anchor is rocked by waves, such that distance between two consecutive crests is 100 m. If the wave velocity of the moving crests is 20 ms–1, calculate the frequency of rocking of the boat.

9. A plastic ruler is held near the rotating wheel of a bicycle, such that it produces sound every time the spoke of the wheel strikes it. If 20 clicks are produced in 0.4 s, calculate the frequency of sound produced.

10. A bat can hear sound at frequencies up to 120 kHz. Determine the wavelength of sound in air at this frequency. Take the speed of sound in air as 344 ms–1

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