Question:
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.
Answer:
mechanical waves, sound. electromagnetic waves
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 a wave number?
Q 12.
What is infrasonic? Give an example.
Q 13.
What is speed of sound in air?
Q 14.
What are the factors speed of sound wave depends upon?
Q 15.
What type of wave is represented by density- distance graph?
Q 16.
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 17.
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 18.
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 19.
Guess which has a higher pitch : a guitar or a car horn ?
Q 20.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 21.
Explain how defects in a metal block can be detected using ultrasound.
Q 23.
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 24.
Fill in the blanks :
Ripples waves on water surface are example of ____________.
Q 25.
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 26.
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 27.
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 28.
What are infrasonics ?
Q 29.
There are no echoes produced in small living rooms.Explain why echoes are produced only in large galleries and halls.
Q 30.
What do you mean by reverberation and reverberation time ? How is reverberation controlled ?
Q 31.
What is the range of frequencies of audio waves,infrasonics and ultrasonics ?
Q 32.
Fill in the blanks :
The principle on which stethoscope works is _____ (reflection/ multiple reflection)
Q 33.
Fill in the blanks :
Existence of sound waves in an auditorium due to multiple reflections suffered by the walls and ceiling is called ____________.
Q 34.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 35.
How does the sound produced by a vibrating object in a medium reach your ear?
Q 36.
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 37.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is
440 m/s in a given medium.
Q 38.
Demonstrate an activity to show that sound requires a medium to travel.
Q 39.
Distinguish between loudness and intensity of sound.
Q 40.
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 41.
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 42.
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 43.
Explain how sound is produced by your school bell ?
Q 44.
Why are the ceilings of concert halls curved ?
Q 45.
Does sound follow the same laws of reflection as light does ? Explain.
Q 46.
How is ultrasound used for cleaning ?
Q 47.
What is a sonic boom ?
Q 48.
What is sound barrier ?
Q 49.
What propagates along with the waves ?
Q 50.
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.
