Question:
Discuss the role of medium in the propagation of sound.
Answer:
Refer to Art.6.5,Page 325.
Sound
Q 1.
How is sound propagated through a material medium ? What is wave motion ?
Q 2.
By how much does the speed of sound increase with rise of temperature ?
Q 3.
A hospital uses an ultrasonic scanner to locate tumors in a tissue. What is the wavelength of sound in a tissue is which the speed of sound is 1.7 km/s. The operating frequency of the scanner is 4.2 MHz. (1MHz = 10
6 Hz).
Q 4.
What is a wave number?
Q 5.
What is audible range ?
Q 6.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 7.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 8.
How are compressions and rarefactions produced near a source of sound ?
Q 9.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 10.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 11.
What is infrasonic? Give an example.
Q 12.
What is Sound? Why it is important for us?
Q 13.
What are the factors speed of sound wave depends upon?
Q 14.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 15.
Fill in the blanks :
v = ? × ?
Q 16.
What are ultrasonics?
Q 17.
What propagates along with the waves ?
Q 18.
What is speed of sound in air?
Q 19.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is
440 m/s in a given medium.
Q 20.
Why are sound waves called mechanical waves ?
Q 21.
Explain the working and application of a sonar.
Q 23.
Why sound waves are called mechanical waves?
Q 24.
Three persons, A, B and C are made to hear a sound travelling through different mediums as given below:
| Persons | Medium |
| A | Iron Rod |
| B | Air |
| C | Water |
Who will hear the sound first? Why?
Q 25.
If 20 waves are produced per second, what is the frequency in hertz?
Q 26.
An observer standing at the sea coast observes 54 waves reaching the coast per minute.If the wavelength of a wave is 10 m,find the wave velocity.
Q 27.
Fill in the blanks :
In a __________ wave the particles of the medium oscillate in a direction perpendicular to the direction in which the wave propagates.
Q 28.
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 29.
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 30.
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 31.
Explain how sound is produced by your school bell ?
Q 32.
Fill in the blanks :
Ripples waves on water surface are example of ____________.
Q 33.
Fill in the blanks :
Loudness of sound is measured in ___________.
Q 34.
What is a mechanical wave?
Q 35.
Why transverse wave does not travel through air or gases?
Q 36.
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?
Q 37.
A wave of wavelength 0-60 cm is produced in air and it travels at a speed of 300 m/s.Will it be audible ?
Q 38.
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 39.
Distinguish between loudness and intensity of sound.
Q 40.
What is loudness of sound ? What factors does it depend on ?
Q 41.
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.
Q 42.
What are ultrasonics ?
Q 43.
Can you produce sound without utilizing energy ?
Q 44.
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 45.
What is sound ? Discuss the method of its production.
Q 46.
How can you show that sound waves are longitudinal waves ?
Q 47.
What are transverse waves ?
Q 48.
Distinguish between music and noise.
Q 49.
What is SONAR ? How is it used to detect an underwater object and measure its distance
Q 50.
We see flash earlier than the thunder.Discuss.
