Question:
What is persistence of hearing ?
Answer:
The sensation of sound persists in our brain for 0.1 s.This is called the persistence of hearing.
Sound
Q 1.
What are the factors speed of sound wave depends upon?
Q 2.
Fill in the blanks :
v = ? × ?
Q 3.
Why do we use upholstered seats in theatres and halls ?
Q 4.
What propagates along with the waves ?
Q 5.
Explain how sound is produced by your school bell ?
Q 6.
What is a wave number?
Q 7.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 8.
Explain how the human ear works.
Q 9.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 10.
Calculate the wavelength of a sound wave having a frequency 300 Hz and speed 330 m/s.
Q 11.
How is sound propagated through a material medium ? What is wave motion ?
Q 12.
Radio Ceylon broadcasts at 25 m.What is the frequency of the station ?
Q 13.
Try to imagine what you would feel, what sort of person you would be,had you been born totally deaf.
Q 14.
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 15.
What are ultrasonics?
Q 16.
What is reverberation ? How can it be reduced ?
Q 17.
Can sound wave travel in vacuum?
Q 18.
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 19.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440 m/s in a given medium.
Q 20.
Distinguish between loudness and intensity of sound.
Q 21.
Explain how defects in a metal block can be detected using ultrasound.
Q 22.
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 23.
Write the name of the wave which propagates in terms of compressions and rarefactions.
Q 24.
Can sound waves travel through vacuum ?
Q 25.
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 26.
Discuss the role of medium in the propagation of sound.
Q 27.
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 28.
Fill in the blanks :
In a _____________ wave the particles of the medium oscillate in the direction in which the wave travels.
Q 29.
Fill in the blanks :
Audible sound range is _________ to _____________.
Q 30.
Fill in the blanks :
Loudness of sound is measured in ___________.
Q 31.
What type of waves can travel in vacuum? Give example(s).
Q 32.
Describe with the help of a diagram,how compressions and rarefactions are produced in air near a source of sound.
Q 33.
Does sound follow the same laws of reflection as light does ? Explain.
Q 34.
Explain how bats use ultrasound to catch a prey.
Q 35.
Explain the working and application of a sonar.
Q 36.
What are infrasonics ?
Q 37.
Can you produce sound without utilizing energy ?
Q 38.
Distinguish between music and noise.
Q 39.
Describe an experiment to show that sound waves can be reflected.What are the laws of reflection of sound waves.
Q 40.
What travels faster : a rifle bullet or the sound of the shot fired from it ?
Q 41.
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.
Q 42.
Fill in the blanks :
Waves transport _________ not matter.
Q 43.
Fill in the blanks :
The distance between two consecutive compressions or two consecutive rarefactions is called the ______________.
Q 44.
What is a mechanical wave?
Q 45.
Why sound waves are called mechanical waves?
Q 46.
What is the audible range?
Q 47.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 48.
Give examples of organisms which can hear infrasonic?
Q 49.
Give an application use of ultrasonics.
Q 50.
What type of wave is represented by density- distance graph?
