Answer:
The sound waves produced bounce back or gets reflected from the mountain or buildings and come to our ears, this reflected sound is known as Echo. To hear echo, the barrier reflecting the sound should be least at a distance of 17 meters.
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.
How is ultrasound used for cleaning ?
Q 13.
Fill in the blanks :
RADAR (Radio Detection And Ranging) works on _____________ principle which is used to determine the velocities and movement of aircrafts.
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.
What is audible range ?
Q 19.
What are transverse waves ?
Q 20.
What is SONAR ? How is it used to detect an underwater object and measure its distance
Q 21.
Fill in the blanks :
Number of oscillations completed by the oscillator in one second is known as ___________.
Q 22.
What is infrasonic? Give an example.
Q 23.
Cite an experiment to show that sound needs a material medium for its propagation.
Q 24.
What is sound barrier ?
Q 25.
How can you make a building sound proof ?
Q 26.
Discuss the structure of human ear from auditory aspect only.
Q 27.
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 28.
Why sound waves are called mechanical waves?
Q 29.
How are the wavelength and frequency of a sound wave related to its speed?
Q 30.
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 31.
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 32.
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 33.
Distinguish between loudness and intensity of sound.
Q 34.
Write the name of the wave which propagates in terms of compressions and rarefactions.
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.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 41.
Fill in the blanks :
Loudness of sound is measured in ___________.
Q 42.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 43.
Give examples of longitudinal waves.
Q 44.
What is a wave number?
Q 45.
Guess which sound has a higher pitch: guitar or car horn?
Q 46.
The sonic boom of an aircraft has a time period of 0 00005 s.Calculate the frequency of the sound produced.
Q 47.
The frequency of a source of sound is 100 Hz.How many times does it vibrate in a minute ?
Q 48.
Does sound follow the same laws of reflection as light does ? Explain.
Q 49.
What is loudness of sound ? What factors does it depend on ?
Q 50.
Explain how the human ear works.
