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.
How is sound propagated through a material medium ? What is wave motion ?
Q 2.
What is audible range ?
Q 3.
What is infrasonic? Give an example.
Q 4.
How are compressions and rarefactions produced near a source of sound ?
Q 5.
What are the factors speed of sound wave depends upon?
Q 6.
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 7.
What are ultrasonics?
Q 8.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 9.
By how much does the speed of sound increase with rise of temperature ?
Q 10.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 11.
What is speed of sound in air?
Q 12.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is
440 m/s in a given medium.
Q 13.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 14.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 15.
What is a wave number?
Q 16.
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 17.
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 18.
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 19.
Explain how sound is produced by your school bell ?
Q 20.
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 21.
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 22.
Why are sound waves called mechanical waves ?
Q 23.
What propagates along with the waves ?
Q 24.
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 25.
Why do we use upholstered seats in theatres and halls ?
Q 26.
Try to imagine what you would feel, what sort of person you would be,had you been born totally deaf.
Q 27.
Fill in the blanks :
A ________ (pulse/wave) is a form of disturbance which travels through a medium as a result of repetitive oscillations of the particles of the medium.
Q 28.
Fill in the blanks :
Full form of SONAR is __________________________.
Q 29.
Fill in the blanks :
v = ? × ?
Q 30.
What is a mechanical wave?
Q 31.
How does the sound produced by a vibrating object in a medium reach your ear?
Q 32.
Why transverse wave does not travel through air or gases?
Q 33.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 34.
If 20 waves are produced per second, what is the frequency in hertz?
Q 35.
Give an application use of ultrasonics.
Q 36.
What type of wave is represented by density- distance graph?
Q 37.
What is the audible range of the average human ear ?
Q 38.
Explain the working and application of a sonar.
Q 40.
Discuss the structure of human ear from auditory aspect only.
Q 41.
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 42.
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 43.
What is the difference between an echo and a reverberation ?
Q 44.
On what factors does the speed of sound in a material depend ?
Q 45.
Fill in the blanks :
Number of oscillations completed by the oscillator in one second is known as ___________.
Q 46.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 47.
Give examples of longitudinal waves.
Q 48.
Why sound waves are called mechanical waves?
Q 49.
What type of waves can travel in vacuum? Give example(s).
Q 50.
Three persons, A, B and C are made to hear a sound travelling through different mediums as given below:
| Persons | Medium |
| A | Iron Rod |
| B | Air |
| C | Water |
Who will hear the sound first? Why?
