Question:
Try to imagine what you would feel, what sort of person you would be,had you been born totally deaf.
Answer:
(i) You would not be able to enjoy music or speech,.
(ii) Only with great difficulty and long training would you learn to speak coherently.
(iii) It would be dangerous to move out in street because you could not hear an approaching car nor the warning of a bystander.
(iv) In short, half of life would not exist and the other half would be very complicated and dangerous.We should be thus grateful to God for giving us the faculty of hearing.
Sound
Q 1.
Why do we use upholstered seats in theatres and halls ?
Q 2.
What are the factors speed of sound wave depends upon?
Q 3.
Fill in the blanks :
v = ? × ?
Q 4.
What are ultrasonics?
Q 5.
What propagates along with the waves ?
Q 6.
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 7.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 8.
How is sound propagated through a material medium ? What is wave motion ?
Q 9.
What is a wave number?
Q 10.
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 11.
Explain how sound is produced by your school bell ?
Q 12.
Explain how the human ear works.
Q 13.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 14.
What are wavefronts?
Q 15.
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 16.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 17.
What is infrasonic? Give an example.
Q 18.
A person standing between two vertical cliffs and 680 m away from the nearest cliff,shouted.He heard the first echo after 4 s and the second echo 3 s later.Calculate (a) the speed of sound in air and (b) distance between the two cliffs.
Q 19.
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 20.
Sounds we hear inform us of the state of world around us,especially of that part of it which our other senses,such as touch and sight,cannot reach.Illustrate this with appropriate examples.
Q 21.
A boat anchor is rocked by waves whose consecutive crests are 100 m apart.If the wave speed of the moving crests is 20 m/s,calculate the frequency at which the boat rocks.
Q 22.
Calculate the wavelength of a sound wave having a frequency 300 Hz and speed 330 m/s.
Q 23.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 24.
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 25.
What is the audible range of the average human ear ?
Q 26.
What is audible range ?
Q 27.
What type of wave is represented by density- distance graph?
Q 28.
Guess which has a higher pitch : a guitar or a car horn ?
Q 29.
Explain the working and application of a sonar.
Q 30.
What travels faster : a rifle bullet or the sound of the shot fired from it ?
Q 31.
Try to imagine what you would feel, what sort of person you would be,had you been born totally deaf.
Q 32.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 33.
Fill in the blanks :
If a body repeats its motion, within fix interval of time, along a certain path, about a fixed point, it is said to have ____________.
Q 34.
Can sound wave travel in vacuum?
Q 35.
When you shout in front of a hill,your own shout is repeated.Explain.
Q 36.
What is persistence of hearing ?
Q 37.
Deaf people can be made to dance to music.Explain how ?
Q 38.
What type of waves can travel in vacuum? Give example(s).
Q 39.
Why transverse wave does not travel through air or gases?
Q 40.
If 20 waves are produced per second, what is the frequency in hertz?
Q 41.
Give an application use of ultrasonics.
Q 42.
Distinguish between loudness and intensity of sound.
Q 43.
The sonic boom of an aircraft has a time period of 0 00005 s.Calculate the frequency of the sound produced.
Q 44.
A sound wave has a frequency of 2
kHz and wavelengtl 35 cm.How long will it take to travel 1.5 km ?
Q 45.
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 46.
What are wavelength,frequency,time period and amplitude of a sound wave ?
Q 47.
What is reverberation ? How can it be reduced ?
Q 48.
Write the name of the wave which propagates in terms of compressions and rarefactions.
Q 49.
What is the minimum distance of the obstacle from the source of sound for hearing distinct echo ?
Q 50.
What is the difference between an echo and a reverberation ?
