Question:
Deaf people can be made to dance to music.Explain how ?
Answer:
If there is nothing wrong with the internal ear,deaf people can listen to music.This can be made possible by placing one end of a rod on a piano (or any other musical instrument) in such a way that it does not obstruct playing upon it.The other end of the rod can be gripped in the teeth.The music would reach the auditory nerve via rod and bones of the head.
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.
By how much does the speed of sound increase with rise of temperature ?
Q 3.
How is sound propagated through a material medium ? What is wave motion ?
Q 4.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 5.
How are compressions and rarefactions produced near a source of sound ?
Q 6.
What is audible range ?
Q 7.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 8.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 9.
Fill in the blanks :
v = ? × ?
Q 10.
What is Sound? Why it is important for us?
Q 11.
What is infrasonic? Give an example.
Q 12.
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 13.
What is a wave number?
Q 14.
What type of wave is represented by density- distance graph?
Q 15.
What is speed of sound in air?
Q 16.
What are the factors speed of sound wave depends upon?
Q 17.
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 18.
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 19.
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 20.
Guess which has a higher pitch : a guitar or a car horn ?
Q 21.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 22.
Explain how defects in a metal block can be detected using ultrasound.
Q 24.
Fill in the blanks :
Ripples waves on water surface are example of ____________.
Q 25.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 26.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is
440 m/s in a given medium.
Q 27.
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 28.
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 29.
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 30.
What are infrasonics ?
Q 31.
There are no echoes produced in small living rooms.Explain why echoes are produced only in large galleries and halls.
Q 32.
What do you mean by reverberation and reverberation time ? How is reverberation controlled ?
Q 33.
What is the range of frequencies of audio waves,infrasonics and ultrasonics ?
Q 34.
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.
Q 35.
Fill in the blanks :
The principle on which stethoscope works is _____ (reflection/ multiple reflection)
Q 36.
Fill in the blanks :
In a _____________ wave the particles of the medium oscillate in the direction in which the wave travels.
Q 37.
Fill in the blanks :
Existence of sound waves in an auditorium due to multiple reflections suffered by the walls and ceiling is called ____________.
Q 38.
What is a longitudinal wave?
Q 39.
How does the sound produced by a vibrating object in a medium reach your ear?
Q 40.
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 41.
If 20 waves are produced per second, what is the frequency in hertz?
Q 42.
Demonstrate an activity to show that sound requires a medium to travel.
Q 43.
Distinguish between loudness and intensity of sound.
Q 44.
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 45.
A person standing between two vertical cliffs and 680 m away from the nearest cliff,shouted.He heard the first echo after 4 s and the second echo 3 s later.Calculate (a) the speed of sound in air and (b) distance between the two cliffs.
Q 46.
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 47.
Explain how sound is produced by your school bell ?
Q 48.
Why are the ceilings of concert halls curved ?
Q 49.
Does sound follow the same laws of reflection as light does ? Explain.
Q 50.
How is ultrasound used for cleaning ?
