SOUND 8

Practice Paper

Subject : Physics
Class VIII .                                          Ch-  SOUND                                                             

                      

I. Fill in the blanks:                                                                                   

1. Sound is produced by __________
2. The vibration of a ________ produced sound in human beings.
3. The _______ sends vibration to the inner ear, from where signal go to the _____ and we are able to hear
4. The maximum distance to which a vibrating body moves on either side of its mean position to known as ______ of vibration.
5.  ________ is the time taken by a vibrating body to complete one oscillation.
6. The number of oscillations per second is called a _____ of oscillation.
7. The unit of frequency is ______.
8. Louder sound has a higher ________.
9. Higher is the _____higher is the frequency of vibration.
10. Noise pollution means ________sound.
11. Plantation on the roadside and elsewhere reduces the _______.
12. _______ is the reflection of sound which reaches the year after a gap of 1/10th of second or more.
13. The amplitude of sounds determined is loudness. Larger the amplitude louder is the sound and vice versa is also true
14. Sound is a form of energy which produces the _____ of hearing in our ears. 
15. Many other animals have vocal cords like human beings, _____ ,______ ,_____ and ____etc.
16. Birds have a ring of cartilage, called _______ in their windpipe. These rings are used by Birds to produce different type of sound. 
17. Insects like mosquitoes and cockroach produce sound by vibrating their ______ .
18. Frogs puff up their vocal sacs like a _______ to produce _______ sound. 
19. Speed of sound is ______ in solid ; followed by liquid and gas.
20. Speed of light is ______ than that of sound. 

II. Very Short Answer Type Questions :

1. What is sound?
2. How is sound produced?
3. Define loudness of sound.
4. Define noise pollution.
5. What is meant by eco?
6. What is the full form of SONAR?
7. Name the section of throat in which human voice is produced.
8. What is an ultrasound?
9. Name the two animals that use echolocation to guide themselves.
10. Define amplitude of vibration.
11. Which part of a human body is responsible for producing sound?
12. Define frequency.
13. Define the term pitch.
14. Define the term echo.
15. On what factor, does the loudness of sound depend?
16. Define 1 Hz.
17. What is the speed of sound in air ?
18. What is the speed of sound in water ?
19. Define the term 'quality of sound'?
20. Why humans cannot hear the sound of the whistle used for dog training?
21. How are frequency of a sound and pitch related?
22. How are amplitude of a sound and loudness related?

III. Short Answer Type Questions :

1. What is the use of reflection of sound?
2. What is the necessary condition for sound propagation?
3. In which medium among wood and water, will the sound travel faster?
4. What is the audible range of frequencies for human ear?
5. Write three difference between musical sound and noise.
6. Why does the walls, floor and ceilings are covered by sound absorbing materials in cinema hall and auditorium?
7. A pendulum produces 20 oscillations in 5 seconds. Calculate its time period?
8. Sound produced by a mosquito is quite different from the roar of a lion. Explain.
9. Write differences between musical sound and noise.
10. How is the human voice produced? Explain.
11. A pendulum oscillates 10 times in 5 seconds. Find the time period and the frequency of the oscillations.
12. Define amplitude and frequency of the wave.
13. What is the range of audible frequencies for a human?
14. Define pitch. State which has a low pitch voice: A woman or a man, a lion or a bird.
15. Explain the hazards of noise pollution.
16. Explain some measures to check noise pollution.
17. Write the name of three bone present in the inner ear. Explain the working also.
18. Define (i) Time period (ii) Oscillation (iii) Amplitude of oscillation .
19. Identify the part which vibrates to produce sound in the following instruments: (a) Dholak (b) Sitar (c) Flute.
20. What is the S.I unit of loudness, time period and frequency of a sound ?
21. Name two animals which can hear or produces ultrasonic sound  and why?
22. Why is the voice  of men, women and children different?
23. Sound needs a _______ for propagation. Sound cannot travel through _____, sound can propagate through all the three state of matter ______, ______, & ______. 
24. Audible frequency of a sound is ____ to _______ Hz. Inaudible frequency of a sound is _____to _____ Hz. Below 20 hertz is called ______ and that beyond ______ hertz is called ultrasonic.
25. The shrillness or flatness of sound is called the ______ of the sound . The ______ of sound determines is pitch. A _____ pitch sound has a _____frequency.

IV. Long Answer Type Questions:

1. Write the following voices having different frequencies in the increasing order of their frequencies : (i) voice of a child, (ii) voice of an adult male, (iii) voice of an adult woman.
2. Give reason: (i) During a thunderstorm, we see the lightning first and then hear the thunder. (ii) We do not hear the supersonic jets when they approach us, but hear a sudden boom after it has passed away.
3. Explain the working of all parts of the ear with a diagram.
4. Draw the diagram of larynx and explain its function.
5. How do we hear sound? Explain with the diagram.
6. What do you understand by the term noise pollution? Write some harmful effects of noise pollution.Suggest some ways of minimising noise pollution.
7. How would you describe the sound produced when (i)  the large number of vibrations are produced per second. (ii)  the amplitude is small. (iii)  the vibrations are produced at irregular intervals.
8. Explain how sound is produced by each of the following types of musical instruments. (i) Wind instruments. (ii) Stringed instruments.(iii) Percussion instruments.
9. Why do we hear the thunder a little after see the flash of lightning why do we not hear echo in our ordinary surroundings
10. The frequency of a given sound is 1.5 kilohertz. How many vibrations is it completing in one second?
    how birds and insects produce sound?
11. On a hot summer day, a little mosquito produces warning sound near your ear at a rate of about 3000 using beats per 5 seconds. What is the frequency in hertz, of the sound?
12. A pendulum oscillates 40 times in 4 seconds. Find out time period and frequency.
13. Explain briefly the mechanism of production of sound in human being.
14. What is the basic principle of working of Sonar? Explain its use.
15. What is the use of ultrasonic sound in medicine and industry?
16. Why do some people have hearing impairment? How do they communicate with others?
17. If we take oil instead of water, will we be able to hear the sound? Will the sound be more or less than water?

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