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.
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.
How are compressions and rarefactions produced near a source of sound ?
Q 5.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 6.
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 7.
What is audible range ?
Q 8.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 9.
Fill in the blanks :
v = ? × ?
Q 10.
What are the factors speed of sound wave depends upon?
Q 11.
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 12.
What is SONAR ? How is it used to detect an underwater object and measure its distance
Q 13.
What is Sound? Why it is important for us?
Q 14.
What is infrasonic? Give an example.
Q 15.
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 16.
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 17.
Why are sound waves called mechanical waves ?
Q 18.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 19.
Fill in the blanks :
RADAR (Radio Detection And Ranging) works on _____________ principle which is used to determine the velocities and movement of aircrafts.
Q 20.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 21.
What is a wave number?
Q 22.
Write differences between Transverse waves and Longitudinal waves.
Q 23.
What type of wave is represented by density- distance graph?
Q 24.
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 25.
Which wave property determines (a) loudness (b) pitch ?
Q 26.
Explain how defects in a metal block can be detected using ultrasound.
Q 28.
What do you mean by reverberation and reverberation time ? How is reverberation controlled ?
Q 29.
What is the range of frequencies of audio waves,infrasonics and ultrasonics ?
Q 30.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 31.
What is speed of sound in air?
Q 32.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is
440 m/s in a given medium.
Q 33.
What is reverberation?
Q 34.
A person is listening to a tone of 500 Hz sitting at a distance of 450 m from the source of the sound. What is the time interval between successive compressions from the source?
Q 35.
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 36.
How does the sound produced by a vibrating object in a medium reach your ear ?
Q 37.
Guess which has a higher pitch : a guitar or a car horn ?
Q 38.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440 m/s in a given medium.
Q 39.
Why are the ceilings of concert halls curved ?
Q 40.
What are ultrasonics ?
Q 41.
What are infrasonics ?
Q 42.
What is sound barrier ?
Q 43.
There are no echoes produced in small living rooms.Explain why echoes are produced only in large galleries and halls.
Q 44.
What are multiple echoes ? Discuss any two of their important practical applications.
Q 45.
We see flash earlier than the thunder.Discuss.
Q 46.
On what factors does the speed of sound in a material depend ?
Q 47.
What travels faster : a rifle bullet or the sound of the shot fired from it ?
Q 48.
Fill in the blanks :
The principle on which stethoscope works is _____ (reflection/ multiple reflection)
Q 49.
Fill in the blanks :
Ripples waves on water surface are example of ____________.
Q 50.
Fill in the blanks :
In a _____________ wave the particles of the medium oscillate in the direction in which the wave travels.
