## 08 December 2011

### NCERT 9th Physics Question Bank For - Sound

1.What are the uses of SONAR technique?

2. What does ‘SONAR’ stand for?

3.Which part of the ear turns pressure variations into electrical signals?

4.What is intensity of sound?

5. Why sound wave is called longitudinal wave?

6. What is a sound?

7. Why sound waves are called mechanical waves?

8. What is a crest and a trough in a wave?

9.Can sound wave travel through vacuum?

10. What is amplitude of a wave?

11. What is characterized by the amplitude of the wave?

12. What is characterized by the frequency of the sound wave?

13.What is reverberation?

14.What is the audible range of the average human ear?

15. In sound propagation, do

16. Does speed of sound in a

17. What should be the minimum distance between a sound source and reflector for a distinct echo?

18. What is a wave?

19. Explain why the ceilings of concert halls and conference halls made curved?

20. What is law of reflection in sound?

21. Priya clapped her hand near a cliff and heard the echo after 5 second. If the speed of sound be

330 m/sec, then find the distance of the cliff from priya?

22. What are ‘infrasonic’ and ‘ultrasonic’?

23. Calculate the time in which a tuning fork of frequency 234 Hz completes 26 vibrations.

24. We hear thunder sound a few seconds after the flash is seen even though they occur simultaneously. Why?

25. A sound wave has a frequency of 1500Hz and wavelength 25cm. How long will it take to travel 3

km?

26. Why and how is reverberation removed in an auditorium or a big hall?

27. State Laws of Reflection of Sound

28. Harry standing 440 m away from a wall fired a gun and heard its echo 2 s later. How is an echo

formed? Calculate the velocity of sound in air.

29. Explain how ultrasounds help to detect cracks and flaws in metal blocks.

30. Define time period of sound wave. What is its SI unit? How is it related with frequency?

31. Explain how compressions and rarefactions are produced in air near a source of sound.

32. How does sound reaches our ears?

33. What will happen to the loudness of a sound wave if its amplitude is doubled? Name a unit of

sound. Is loudness affected by change in frequency?

34. How do sound waves propagate?

35. Are the particles of the medium dragged along with the wave as sound wave propagates through

the medium? In which medium—solid, liquid or gas, does the sound wave travel fastest?

36. State any two characteristics of sound wave?why it is called mechanical wave? Find the distance

traveled by a sound wave of frequency 20 K Hz, wavelength 1.7 cm in 10 s.

37. .What are differences between music and noise?

38. How bat is able to fly in night?

39 .Discuss effect of temperature and humidity on speed of sound.

40.Why lightining appears before than thundering in rainy season?