Question:
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.
Answer:
(i) A buzzing fly informs us the presence of a nuisance.Had it not buzzed,we would have paid it no mind.
(ii) The lawn mower’s putt-putt tells us that our neighbour has finaly got around to cleaning up the jungle in his garden - disappearance of a nuisance.
(iii) The sound of a teakettle informs us that the time has come for a coffee break-presence of refreshment.
Thus,these sounds arouse various emotions -anger at the fly,satisfaction that your neighbour has ultimately got across the hint to clean the forest,and desire for coffee.
Sound
Q 1.
By how much does the speed of sound increase with rise of temperature ?
Q 2.
How is sound propagated through a material medium ? What is wave motion ?
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.
How are compressions and rarefactions produced near a source of sound ?
Q 5.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 6.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 7.
What is audible range ?
Q 8.
Fill in the blanks :
v = ? × ?
Q 9.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 10.
What is Sound? Why it is important for us?
Q 11.
What is infrasonic? Give an example.
Q 12.
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 13.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 14.
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 15.
What are the factors speed of sound wave depends upon?
Q 16.
What is a wave number?
Q 17.
What type of wave is represented by density- distance graph?
Q 18.
A bat emits ultrasonic sound of frequency 100 kHz in air.If this sound meets a water surface,what is the wavelength of (a) the reflected sound wave (b) the transmitted sound wave ?
Given speed of sound in air = 340 m/s and in water = 1486 m/s.
Q 20.
What is the range of frequencies of audio waves,infrasonics and ultrasonics ?
Q 21.
What is speed of sound in air?
Q 22.
A longitudinal wave is produced on a slinky.The frequency of the wave is 25 Hz and it travels at a speed of 20 cm/s. Find the separation between consecutive positions of maximum compressions.
Q 23.
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 24.
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 25.
Guess which has a higher pitch : a guitar or a car horn ?
Q 26.
Explain how defects in a metal block can be detected using ultrasound.
Q 27.
What are infrasonics ?
Q 28.
What is sound barrier ?
Q 29.
There are no echoes produced in small living rooms.Explain why echoes are produced only in large galleries and halls.
Q 30.
Fill in the blanks :
The principle on which stethoscope works is _____ (reflection/ multiple reflection)
Q 31.
Fill in the blanks :
Ripples waves on water surface are example of ____________.
Q 32.
Fill in the blanks :
In the case of ____________ wave, distance between two consecutive crests or troughs is known as wavelength.
Q 33.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 34.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is
440 m/s in a given medium.
Q 35.
Demonstrate an activity to show that sound requires a medium to travel.
Q 36.
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 37.
What is reverberation ? How can it be reduced ?
Q 38.
How is ultrasound used for cleaning ?
Q 39.
Draw a curve showing density or pressure variations with respect to distance for a disturbance produced by sound.Mark the position of compression and rarefaction on this curve.Also define wavelengths and time period using this curve.
Q 40.
What is a sonic boom ?
Q 41.
What propagates along with the waves ?
Q 42.
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 43.
What are transverse waves ?
Q 44.
What do you mean by reverberation and reverberation time ? How is reverberation controlled ?
Q 45.
What is SONAR ? How is it used to detect an underwater object and measure its distance
Q 46.
On what factors does the speed of sound in a material depend ?
Q 47.
Deaf people can be made to dance to music.Explain how ?
Q 48.
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 49.
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 50.
Fill in the blanks :
Waves which require a material medium for propagation are called _____________ waves. Example of such waves is _________. Light waves are ___________, because they can travel in vacuum.
