Question:
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 ?
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 are the wavelength and frequency of a sound wave related to its speed ?
Q 4.
How is sound propagated through a material medium ? What is wave motion ?
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.
What is audible range ?
Q 9.
By how much does the speed of sound increase with rise of temperature ?
Q 10.
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 11.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is
440 m/s in a given medium.
Q 12.
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 13.
Why do we use upholstered seats in theatres and halls ?
Q 14.
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 15.
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 16.
Why are sound waves called mechanical waves ?
Q 17.
Deaf people can be made to dance to music.Explain how ?
Q 18.
Fill in the blanks :
Number of oscillations completed by the oscillator in one second is known as ___________.
Q 19.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 20.
Fill in the blanks :
v = ? × ?
Q 21.
How are the wavelength and frequency of a sound wave related to its speed?
Q 22.
Write differences between Transverse waves and Longitudinal waves.
Q 23.
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 24.
What is the audible range of the average human ear ?
Q 26.
Distinguish between music and noise.
Q 27.
What are the characteristics of a sound ? Discuss each one of them briefly.
Q 28.
What is SONAR ? How is it used to detect an underwater object and measure its distance
Q 29.
What is Sound? Why it is important for us?
Q 30.
What is a longitudinal wave?
Q 31.
Give examples of longitudinal waves.
Q 32.
Why sound waves are called mechanical waves?
Q 33.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 34.
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 36.
What is infrasonic? Give an example.
Q 37.
Demonstrate an activity to show that sound requires a medium to travel.
Q 38.
Guess which sound has a higher pitch: guitar or car horn?
Q 39.
What is sound and how is it produced ?
Q 40.
Describe with the help of a diagram,how compressions and rarefactions are produced in air near a source of sound.
Q 41.
Give two practical applications of reflection of sound waves.
Q 42.
How is ultrasound used for cleaning ?
Q 43.
Explain how defects in a metal block can be detected using ultrasound.
Q 44.
Explain how the human ear works.
Q 45.
What are ultrasonics ?
Q 46.
What are infrasonics ?
Q 47.
What is acoustical transite ?
Q 49.
What is persistence of hearing ?
Q 50.
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.
