Question:
Explain how the human ear works.
Answer:
The functioning of the human ear is shown in Fig.
(i) The
outer ear collects sound waves which are conducted through the auditory canal.
(ii)These waves fall on the ear drum and set it into vibrations.
(iii) The
middle ear which is of the size of a small marble and houses osscicles (three bones : hammer,anvil and stirrup) amplifies these oscillations about 60 times.
(iv) The
inner ear which contains cochlea and is filled with a fluid converts these pressure variations into electrical signals.
(v)These electrical signals are conveyed to the brain via
auditory nerve for interpretation.
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 7.
Fill in the blanks :
In the case of ____________ wave, distance between two consecutive crests or troughs is known as wavelength.
Q 9.
What is reverberation?
Q 10.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 11.
What are ultrasonics?
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.
What are transverse waves ?
Q 15.
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 16.
What is SONAR ? How is it used to detect an underwater object and measure its distance
Q 17.
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 18.
What is infrasonic? Give an example.
Q 19.
Radio Ceylon broadcasts at 25 m.What is the frequency of the station ?
Q 20.
Distinguish between loudness and intensity of sound.
Q 21.
How can you make a building sound proof ?
Q 22.
What do you mean by reverberation and reverberation time ? How is reverberation controlled ?
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.
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 25.
Cite an experiment to show that sound needs a material medium for its propagation.
Q 26.
What is sound barrier ?
Q 27.
Why sound waves are called mechanical waves?
Q 28.
Why are the ceilings of concert halls curved ?
Q 29.
Write the name of the wave which propagates in terms of compressions and rarefactions.
Q 31.
Deaf people can be made to dance to music.Explain how ?
Q 32.
Fill in the blanks :
Loudness of sound is measured in ___________.
Q 33.
How are the wavelength and frequency of a sound wave related to its speed?
Q 34.
Calculate the wavelength of a sound wave having a frequency 300 Hz and speed 330 m/s.
Q 35.
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 36.
What is sound and how is it produced ?
Q 37.
Explain the working and application of a sonar.
Q 38.
What is audible range ?
Q 39.
What is persistence of hearing ?
Q 40.
What is sound ? Discuss the method of its production.
Q 41.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 42.
Discuss the structure of human ear from auditory aspect only.
Q 43.
Fill in the blanks :
Number of oscillations completed by the oscillator in one second is known as ___________.
Q 44.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 45.
Why transverse wave does not travel through air or gases?
Q 46.
What is a wave number?
Q 47.
Does sound follow the same laws of reflection as light does ? Explain.
Q 48.
What is loudness of sound ? What factors does it depend on ?
Q 49.
Explain how the human ear works.
