Class 9 Sound Important Questions

Important Questions Notes

Sound Important Questions

1. What do you mean by the intensity of sound ? What is the S.I. unit of intensity of sound?
2. Establish relationship between speed of sound, its wavelength and frequency.
3. Write the factors on which the speed of sound depends upon.
4. Waves of frequency 100 Hz are produced in a string as shown in figure. Give its : (a) amplitude, (b) wavelength, (c) velocity
5. The frequency of a source of sound is 100 Hz. How many times does it vibrate in a minute?
6. Flash and thunder are produced simultaneously. But thunder is heard a few seconds after the flash is seen, why ?
7. Distinguish between transverse and longitudinal waves.
8. What is reverberation? What are methods to reduce reverberation?
9. Define echo. Calculate the minimum distance between source and obstacle to hear an echo.
10. A stone js dropped into a well 44 m deep and the sound of splash is heard after 3.12 sec. Find the speed of sound in air.
11. What is pitch of a sound? Which wave property of sound determines the pitch of the sound? Draw the wave shapes for a low pitched and high pitched sound.
12. A particular transmitter of Aakashvani broadcasts at 420.5 m wavelength. Given the speed of radio waves 3 x 10⁸ ms^-1. Calculate the frequency at which the radio station broadcasts its programme.
13. Given that sound travels in air at 340 m/sec, find the wavelength of the waves in air produced by 20 kHz sound source. If the same source is put in a water tank, what would be the wavelength of the sound waves in water? Speed of sound in water is 1480 m/s.