Question:
What type of waves can travel in vacuum? Give example(s).
Answer:
Electromagnetic waves can travel in vacuum. Sun light, X-rays are examples of electromagnetic waves.
Sound
Q 1.
How is sound propagated through a material medium ? What is wave motion ?
Q 2.
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 3.
By how much does the speed of sound increase with rise of temperature ?
Q 4.
What is a wave number?
Q 5.
How are the wavelength and frequency of a sound wave related to its speed ?
Q 6.
What is audible range ?
Q 7.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 8.
Fill in the blanks :
The product of wavelength of wave and its frequency gives _____________.
Q 9.
How are compressions and rarefactions produced near a source of sound ?
Q 10.
How does sound travel in gases and liquids as longitudinal or as transverse waves?
Q 11.
What is infrasonic? Give an example.
Q 12.
What are the factors speed of sound wave depends upon?
Q 13.
Obtain a relation between speed,frequency and wavelength of a wave.
Q 14.
What is Sound? Why it is important for us?
Q 15.
What is speed of sound in air?
Q 16.
Fill in the blanks :
v = ? × ?
Q 17.
Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is
440 m/s in a given medium.
Q 18.
What are ultrasonics?
Q 19.
Explain the working and application of a sonar.
Q 20.
What propagates along with the waves ?
Q 21.
If 20 waves are produced per second, what is the frequency in hertz?
Q 22.
Why are sound waves called mechanical waves ?
Q 24.
Fill in the blanks :
Ripples waves on water surface are example of ____________.
Q 25.
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?
Q 26.
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 27.
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 28.
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 29.
How can you show that sound waves are longitudinal waves ?
Q 30.
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 31.
Why sound waves are called mechanical waves?
Q 32.
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 33.
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 34.
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 35.
Explain how sound is produced by your school bell ?
Q 36.
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 37.
What are transverse waves ?
Q 38.
Distinguish between music and noise.
Q 39.
Fill in the blanks :
Number of oscillations completed by the oscillator in one second is known as ___________.
Q 40.
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.
Q 41.
Fill in the blanks :
Sound travels as successive ____________ and _____________ in the medium.
Q 42.
Fill in the blanks :
In a _____________ wave the particles of the medium oscillate in the direction in which the wave travels.
Q 43.
Fill in the blanks :
Loudness of sound is measured in ___________.
Q 44.
What is a mechanical wave?
Q 45.
How does the sound produced by a vibrating object in a medium reach your ear?
Q 46.
Why transverse wave does not travel through air or gases?
Q 47.
Guess which sound has a higher pitch: guitar or car horn?
Q 48.
A boat anchor is rocked by waves whose consecutive crests are 100 m apart.If the wave speed of the moving crests is 20 m/s,calculate the frequency at which the boat rocks.
Q 49.
The sonic boom of an aircraft has a time period of 0 00005 s.Calculate the frequency of the sound produced.
Q 50.
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 ?
