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.
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 2.
What is speed of sound in air?
Q 3.
Fill in the blanks :
The principle on which stethoscope works is _____ (reflection/ multiple reflection)
Q 4.
What type of wave is represented by density- distance graph?
Q 5.
Distinguish between loudness and intensity of sound.
Q 6.
What is Sound? Why it is important for us?
Q 8.
Fill in the blanks :
In the case of ____________ wave, distance between two consecutive crests or troughs is known as wavelength.
Q 9.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 10.
What are ultrasonics?
Q 11.
What is reverberation?
Q 12.
Fill in the blanks :
RADAR (Radio Detection And Ranging) works on _____________ principle which is used to determine the velocities and movement of aircrafts.
Q 13.
How is ultrasound used for cleaning ?
Q 14.
Radio Ceylon broadcasts at 25 m.What is the frequency of the station ?
Q 15.
Why are the ceilings of concert halls curved ?
Q 16.
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 17.
Deaf people can be made to dance to music.Explain how ?
Q 18.
Cite an experiment to show that sound needs a material medium for its propagation.
Q 19.
What is audible range ?
Q 20.
How can you make a building sound proof ?
Q 21.
What are transverse waves ?
Q 22.
What is SONAR ? How is it used to detect an underwater object and measure its distance
Q 23.
Fill in the blanks :
Number of oscillations completed by the oscillator in one second is known as ___________.
Q 24.
What is infrasonic? Give an example.
Q 25.
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 26.
A child hears an echo from a cliff 4 s after the sound of a pwerful cracker is produced.How far away is the cliff from the child ? (Take speed of sound in air as 340 m/s)
Q 27.
Write the name of the wave which propagates in terms of compressions and rarefactions.
Q 28.
What is sound barrier ?
Q 29.
Discuss the structure of human ear from auditory aspect only.
Q 30.
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 31.
Why sound waves are called mechanical waves?
Q 32.
How are the wavelength and frequency of a sound wave related to its speed?
Q 33.
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 34.
Distinguish between loudness and intensity of sound.
Q 35.
What is acoustical transite ?
Q 37.
What is sound ? Discuss the method of its production.
Q 38.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 39.
What do you mean by reverberation and reverberation time ? How is reverberation controlled ?
Q 40.
We see flash earlier than the thunder.Discuss.
Q 41.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 42.
Fill in the blanks :
Sound having frequency less than 20Hz is known as ___________.
Q 43.
Fill in the blanks :
Loudness of sound is measured in ___________.
Q 44.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 45.
Give examples of longitudinal waves.
Q 46.
What is a wave number?
Q 47.
Guess which sound has a higher pitch: guitar or car horn?
Q 48.
The sonic boom of an aircraft has a time period of 0 00005 s.Calculate the frequency of the sound produced.
Q 49.
Which wave property determines (a) loudness (b) pitch ?
Q 50.
The frequency of a source of sound is 100 Hz.How many times does it vibrate in a minute ?
