Question:
Explain the working and application of a sonar.
Answer:
Refer Art.6.28,Page 355.
Sound
Q 1.
What are the factors speed of sound wave depends upon?
Q 2.
Fill in the blanks :
v = ? × ?
Q 3.
Explain how sound is produced by your school bell ?
Q 4.
What propagates along with the waves ?
Q 5.
Why do we use upholstered seats in theatres and halls ?
Q 6.
Explain how the human ear works.
Q 7.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 8.
Fill in the blanks :
Loudness of sound is measured in ___________.
Q 9.
Radio Ceylon broadcasts at 25 m.What is the frequency of the station ?
Q 10.
What is acoustical transite ?
Q 11.
What is the audible range?
Q 12.
What is a wave number?
Q 13.
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?
Q 14.
A bat emits ultrasonic sound of frequency 100 kHz in air.If this sound meets a water surface,what is the wavelength of (a) the reflected sound wave (b) the transmitted sound wave ?
Given speed of sound in air = 340 m/s and in water = 1486 m/s.
Q 15.
What is a sonic boom ?
Q 16.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 17.
Try to imagine what you would feel, what sort of person you would be,had you been born totally deaf.
Q 18.
Fill in the blanks :
Waves transport _________ not matter.
Q 19.
A ship sends out ultrasound that returns from the seabed and is detected after 3.42 s.If the speed of the ultrasound through sea water is 1531 m/s,what is the distance of the seabed from the ship ?
Q 20.
Distinguish between loudness and intensity of sound.
Q 21.
is sound wave called a longitudinal wave ?
Q 22.
What is reverberation ? How can it be reduced ?
Q 23.
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.
Q 24.
The sound of distant horses can be heard by applying the ear to the ground whereas it is inaudible if the ear is held a little distance above the ground.Explain.
Q 25.
Distinguish between music and noise.
Q 26.
Fill in the blanks :
Sound having frequency less than 20Hz is known as ___________.
Q 27.
Why sound waves are called mechanical waves?
Q 28.
Give examples of organisms which can hear infrasonic?
Q 29.
A sound wave has a frequency of 2
kHz and wavelengtl 35 cm.How long will it take to travel 1.5 km ?
Q 30.
A man standing at 51 m from a wall fires a gun.Calculate the time after which an echo is heard.The speed of sound is 340 m/s.
Q 31.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440 m/s in a given medium.
Q 32.
What is the audible range of the average human ear ?
Q 33.
Describe with the help of a diagram,how compressions and rarefactions are produced in air near a source of sound.
Q 34.
What is persistence of hearing ?
Q 35.
We see flash earlier than the thunder.Discuss.
Q 36.
Deaf people can be made to dance to music.Explain how ?
Q 37.
What travels faster : a rifle bullet or the sound of the shot fired from it ?
Q 38.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 39.
Can sound wave travel in vacuum?
Q 40.
What type of waves can travel in vacuum? Give example(s).
Q 41.
Calculate the wavelength of a sound wave having a frequency 300 Hz and speed 330 m/s.
Q 42.
The sonic boom of an aircraft has a time period of 0 00005 s.Calculate the frequency of the sound produced.
Q 43.
A child hears an echo from a cliff 4 s after the sound of a pwerful cracker is produced.How far away is the cliff from the child ? (Take speed of sound in air as 340 m/s)
Q 44.
An engine is approaching a hill at constant speed.When it is at a distance of 0.9 km,it blows a whisde,whose echo is heard by the driver after 5 s.If the speed of sound is 340 m/s,calculate the speed of the engine.
Q 45.
sonar emits pulses on the surface of water which are detected after reflection from its bottom at a depth 1531 m.If the time interval between the emission and detection of the pulse is 2 s,find the speed of : sound in water.
Q 46.
Why are sound waves called mechanical waves ?
Q 47.
What are wavelength,frequency,time period and amplitude of a sound wave ?
Q 48.
What is sound and how is it produced ?
Q 49.
Explain how defects in a metal block can be detected using ultrasound.
Q 50.
Which of the above two graphs : (a) and (b),[ Fig. representing the human voice is likely to be the male voice ? Give reson for your answer.
