Question:
Fill in the blanks :
v = ? × ?
Sound
Q 1.
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 2.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 3.
How is sound propagated through a material medium ? What is wave motion ?
Q 4.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 5.
Hearing may be damaged by excessive noise.So our ears sometimes need protection from continuous loud sound. Hearing damage depends on the sound intensity level (decibel level)and the exposure time,and the exact combinations vary for different people.Normally,at 90 dB,it takes 8 hours or less for the damage to receptor nerves to occur.Further,it is found that if the sound level is increased by 5 dB,the safe exposure limit is cut to half.
(a) How long will it take for a sound of a very loud lawn mower (or a motorcycle) of 95dB to damage the hearing ?
(b) What is the nonstop exposure time for a 105 dB sound to damage the ear ?
(c) What should be done to protect the society from the danger of losing the divine gift of hearing power ?
Q 6.
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 7.
How are compressions and rarefactions produced near a source of sound ?
Q 8.
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 9.
How are the wavelength and frequency of a sound wave related to its speed?
Q 10.
What is audible range ?
Q 11.
By how much does the speed of sound increase with rise of temperature ?
Q 12.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is
440 m/s in a given medium.
Q 13.
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 14.
Why do we use upholstered seats in theatres and halls ?
Q 15.
Fill in the blanks :
Number of oscillations completed by the oscillator in one second is known as ___________.
Q 16.
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 17.
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 18.
Why are sound waves called mechanical waves ?
Q 19.
Deaf people can be made to dance to music.Explain how ?
Q 20.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 21.
Fill in the blanks :
v = ? × ?
Q 22.
Write differences between Transverse waves and Longitudinal waves.
Q 23.
Demonstrate an activity to show that sound requires a medium to travel.
Q 24.
Guess which sound has a higher pitch: guitar or car horn?
Q 25.
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 26.
What is the audible range of the average human ear ?
Q 27.
What are ultrasonics ?
Q 29.
Distinguish between music and noise.
Q 30.
Why sound waves are called mechanical waves?
Q 31.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 32.
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 33.
What is infrasonic? Give an example.
Q 34.
A periodic longitudinal Wave is sent on a slinky.The wave proceeds at a speed of 48 m/s and each particle oscillates at a frequency of 12 Hz.Calculate the minimum separation between the positions where the slinky is most compressed.
Q 35.
A man fires a gun towards a hill and hears its echo after 5 s.He then moves 340 m towards the hill and fires his gun again.This time he hears the echo after 3 s.Calculate the speed of sound.
Q 36.
Distinguish between loudness and intensity of sound.
Q 37.
Cite an experiment to show that sound needs a material medium for its propagation.
Q 38.
What is loudness of sound ? What factors does it depend on ?
Q 39.
What is a sonic boom ?
Q 40.
Discuss the role of medium in the propagation of sound.
Q 41.
How can you show that sound waves are longitudinal waves ?
Q 42.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 43.
Discuss the structure of human ear from auditory aspect only.
Q 44.
Fill in the blanks :
Waves transport _________ not matter.
Q 45.
Fill in the blanks :
Full form of SONAR is __________________________.
Q 46.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 47.
What is a mechanical wave?
Q 48.
What are wavefronts?
Q 49.
Can sound wave travel in vacuum?
Q 50.
Suppose you and your friend are on the Moon. Will you be able to hear any sound produced by your friend?
