Question:
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Answer:
longitudinal waves
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 is sound propagated through a material medium ? What is wave motion ?
Q 3.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 4.
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 5.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 6.
By how much does the speed of sound increase with rise of temperature ?
Q 7.
How are compressions and rarefactions produced near a source of sound ?
Q 8.
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 9.
Why are sound waves called mechanical waves ?
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.
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 12.
Fill in the blanks :
Number of oscillations completed by the oscillator in one second is known as ___________.
Q 13.
Fill in the blanks :
Ripples waves on water surface are example of ____________.
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.
What is audible range ?
Q 17.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 18.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is
440 m/s in a given medium.
Q 19.
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 20.
What is the audible range of the average human ear ?
Q 21.
Deaf people can be made to dance to music.Explain how ?
Q 22.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 23.
Fill in the blanks :
v = ? × ?
Q 24.
What is a mechanical wave?
Q 25.
Why sound waves are called mechanical waves?
Q 26.
What is a wave number?
Q 27.
Write differences between Transverse waves and Longitudinal waves.
Q 28.
What type of wave is represented by density- distance graph?
Q 29.
Guess which sound has a higher pitch: guitar or car horn?
Q 30.
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 31.
Explain the working and application of a sonar.
Q 32.
Why do we use upholstered seats in theatres and halls ?
Q 33.
Distinguish between music and noise.
Q 34.
Fill in the blanks :
If a body repeats its back and forth, to and fro or up and down motion along a certain path, about a fixed point, in a certain time interval then the motion of such objects is said to be _____________.
Q 35.
What is Sound? Why it is important for us?
Q 36.
Suppose you and your friend are on the Moon. Will you be able to hear any sound produced by your friend?
Q 37.
How does the sound produced by a vibrating object in a medium reach your ear?
Q 38.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 39.
Which wave characteristics determine the
(a) Loudness (b) pitch of sound?
Draw two different waveforms and mark these characteristics on it.
Q 40.
Distinguish between loudness and intensity of sound.
Q 42.
Fill in the blanks :
Waves transport _________ not matter.
Q 43.
Fill in the blanks :
In a _____________ wave the particles of the medium oscillate in the direction in which the wave travels.
Q 44.
Fill in the blanks :
Full form of SONAR is __________________________.
Q 45.
Fill in the blanks :
If the time interval between original sound and reflected sound is more than 1/10 second then original sound and reflected sound can be heard clearly. This reflected sound is known as _______.
Q 46.
Why transverse wave does not travel through air or gases?
Q 47.
If 20 waves are produced per second, what is the frequency in hertz?
Q 48.
What is reverberation?
Q 49.
What is infrasonic? Give an example.
Q 50.
What is acoustical transite ?
